Collins
Cambridge AS and A Level
Geography
Barnaby Lenon
lain Palöt
Robert Morris
Rebecca Kitchen
Andy Schindler
William Collins’s dream of knowledge for all began with the publication of his first book in 1819. A self­
educated mill worker, he not only enriched millions of lives, but also founded a flourishing publishing house.
Today, staying true to this spirit, Collins books are packed with inspiration, innovation and practical expertise.
They place you at the centre of a world of possibility and give you exactly what you need to explore it.
Collins. Freedom to teach.
Published by Collins
An imprint of HarperCollins Publishers
1 London Bridge Street
London
SEı 9GF
HarperCollins Publishers
1 st Floor
Watermarque Building
Ringsend Road
Dublin 4
Ireland
Browse the complete Collins catalogue at www.collins.co.uk
© HarperCollinsPublishers Limited 2016
Published 2016
ISBN 978-0-00-812422-9
10 9 8 7
All rights reserved. No part of this publication may be reproduced, stored in a retrieval system, or transmitted
in any form or by any means, electronic, mechanical, photocopying, recording or otherwise, without the prior
written permission of the Publisher or a licence permitting restricted copying in the United Kingdom issued by
the Copyright Licensing Agency Ltd, 90 Tottenham Court Road, London WiT 4LP
British Library Cataloguing in Publication Data.
A Catalogue record for this publication is available from the British Library.
Commissioned by: Anne Mahon
Project managed by: Vaila Donnachie
Picture research: the CollinsLearning team
Design: Kevin Robbins
Typesetting and artwork: Jouve Ltd
Cover design: Angela English
Printed and Bound in the UK using 100% Renewable Electricity at CPI Group (UK) Ltd
Special thanks to Alan Parkinson and the Geographical Association.
Cover image: Dead Sea sinkholes © Photostock-lsrael/Science Photo Library
Contents
Introduction
How to use this book
Locations of case studies used in the book
i: Hydrology and fluvial geomorphology
5
6
7
r
8-37
The drainage basin system
Discharge relationships within drainage bas ins
River channel processes and landforms
The human impact
10-15
15-20
20-29
29-37
2: Atmosphere;and weathei•
38-59
Diurnal energy budgets
The global energy budget
Weather processes and phenomena
The human impact
40-41
41-48
48-52
52-59
r
Plate tectonics
Weathering
Slope processes
The human impact
60-85
62-68
68-74
74-79
79-85
86-107
f
Natural increase: as a component of population change
Demographic tr ansition
Population-reso urce relationships
The managemeint of natural increase
88-96
96-98
98-106
106-107
Migration as a c:omponent of population change
Internal migrati on (within a country)
International miigration
The managemeint of international migration
108-129
110-119
119-124
124-129
114-115
130-155
Changes in rural settlement:s
Urban trends and issues of urbanisation
The changing structure of u rban settlements
The management of urban :settlements
f
Tropical climates
Landforms of tropical envirtanments
Humid tropical ecosystems and seasonally humid tropical ecosystems
Sustainable management oiFtrdpical environments
F
Coastal processes
Characteristics and formatican of coastal landforms
132-137
137-147
147-153
153-155
156-177
158-162
162-166
166-173
173-177
178-205
180-187
187-197
Contents
1
J
Coral reefs
Sustainable management of coasts
197-201
201-205
9: Hazardous environments
206-231
Hazards resulting from tectonic processes
Hazards resulting from mass movements
Hazards resulting from atmospheric disturbances
Sustainable management in hazardous environments
208-215
215-219
219-225
225-231
10: Hot arid and semi-arid environments
232-255
Hot arid and semi-arid climates
Landforms of hot arid and semi-arid environments
Soils and vegetation
Sustainable management of hot arid and semi-arid environments
235-242
242-250
250-254
254-255
11: Production, location and change
256-281
Agricultural systems and food production
The management of agricultural change
Manufacturing and related service industry
The management of change in manufacturing industry
258-268
268-271
271-278
278-281
12: Environmental management
282-307
Sustainable energy supplies
The management of energy supply
Environmental degradation
The management of a degraded environment
284-291
291-295
295-302
302-307
13: Global interdependence
308-337
Trade flows and trading patterns
International debt and international aid
The development of international tourism
The management of a tourist destination
310-318
318-324
324-334
334-337
14: Economic transition
338-367
National development
The globalisation of economic activity
Regional development within countries
The management of regional development
340-351
351-359
359-362
362-367
15: Geographical skills
368-384
Diagrams and graphs
Maps
Satellite images and aerial photographs
Data types
370-373
373-380
380-380
380-384
Glossary
Index
Acknowldegements
Key concepts
385-399
400—416
417-418
419
0
Introduction
Collins Cambridge International A and AS Level Geography Student Book, written by a team of
experienced geography teachers, is fully matched to the Cambridge A and AS Level Geography
syllabus (9696).
The book covers all the core syllabus topics, as well as the physical and human geography
options. The aim of the book is to help the student obtain the knowledge, understanding
and skills to succeed in their geographical studies.
Content is accessible and clearly organised, with a student-friendly layout. Content coverage
is suitable for the whole range of abilities. Illustrated throughout, it contains a wealth of maps,
photographs, graphs, diagrams and info-graphics to support the geographical content. Case
studies and locational examples are included to help provide context and real-life meaning.
As well as supporting studies at A Level and helping students to fulfil their potential
in the subject, it is to be hoped that they gain an awareness of some of the wider issues related
to specific topics. The understanding of current human and environmental problems,
the processes at work that create them and their possible solutions form the basis
of geographical study. In order to do this effectively, students need to be reading widely
and developing their own local case studies to supplement the examples given in the book.
Another important aspect of geographical study at this level is learning about the complexity
of many of the topics, namely the inter-relationships between human and physical processes,
the concepts of space and time and the impact they have on change within both the physical
and human landscape.
The development of a range of geographical skills also underpins A Level Geography and
the value of geography as a subject in today’s world. By undertaking fieldwork, students collect
both primary and secondary data to research an issue, then present and interpret the data
using a range of illustrative and statistical techniques. Finally, they analyse that data to reach
a conclusion about the issue under investigation before critically evaluating the methodology
they used. All these techniques are valuable transferable skills to take into higher education
and/or the workplace.
How to use this book
Sections of the book
This Student Book covers all the content in the Cambridge International AS and A Level
Geography syllabus. It follows the sequence of the syllabus and is divided into several sections.
Section i is colour codedEB0and matches the first three themes of the syllabus - hydrology
and fluvial geomorphology; atmosphere and weather; and rocks and weathering. This section
covers all topics included in Paper i - Core Physical Geography.
Section 2 is colour coded El and matches the next three themes of the syllabus - population;
migration; and settlement dynamics. This section covers all topics included in Paper 2 - Core
Human Geography.
Section 3 is colour coded green and matches the next four themes of the syllabus - tropical
environments; coastal environments; hazardous environments; and hot arid and semi-arid
environments. This section covers all topics included in Paper 3 - Advanced Physical Geography
Options.
Section 4 is colour coded brown and matches the last four themes of the syllabus - production,
location and change; environmental management; global interdependence; and economic
transition. This section covers all topics included in Paper 4 - Advanced Human Geography
Options.
Topics within each section follow the order of content within the syllabus.
Case studies
Case studies in every topic focus on particular locations around the world, providing real-life
examples and consolidating the themes being discussed. These different locations are shown
on the world map on the page opposite.
Now investigate
Each chapter also has suggestions of further topics for research, to expand your knowledge and
understanding.
Geographical skills
The last section, colour coded purple is an illustration and explanation of the many different
types of data that geographers collect, process and analyse. Many examples of how data can be
presented visually are illustrated in this section.
Glossary
The key terms are highlighted in the text like this, and are explained in the glossary. These are
words and phrases which have specific meanings in Geography- check out the meaning of
geographical vocabulary that you come across.
0
Locations of case studies used in the book
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
Inter-basin water transfer: The Aral Sea: Kazakhstan/Uzbekistan
Harnessing the River Harbourne: UK
Urban climate in Chicago: USA
Nevado del Ruiz volcano: Colombia
Aberfan mudflow: UK
Population growth: China
Inadequate food supply: Yemen
One-child policy: China
Seasonal migration to Goa: India
Push and pull factors: Turkey
Deadly migration routes: Mediterranean Sea
Urbanisation: Fiji
Rural economy, Hilmarton: UK
Mwandama: Rural issues: Malawi
Suburbanisation: Los Angeles and Tyson’s Corner: USA
Melbourne Docklands: Australia
Slum housing, Mtandire: Malawi
City transport infrastructure, Bogota: Colombia
Tropical rainforest ecosystem: Papua New Guinea
Savanna ecosystem, Queensland: Australia
32
35-37
55-58
77-78
82
89-90
105
106-107
111
112
114-115
121-122
135
136-137
140-141
144
153-154
155
173-175
175-177
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
Coastal erosion at Wamberal Beach: Australia
The Columbia River littoral cell: USA
Sand dredging at Diani Beach: Kenya
Tourism and coral reef management issues: East Timor
Managing the effects of earthquakes: Japan
Sustainable management of volcanic hazards: Montserrat
Sustainable management of areas of mass movement:Malaysia
Sustainable management of arid and semi-arid environments, Rajasthan: India
The Mojave desert: an arid area in a HIC: USA
Beef rearing, an extensive pastoral system: Australia
Market gardening, an intensive arable system: UK
The management of industrial change: Bangladesh
Electrical energy strategy: China
The Three Gorges Dam: China
Darfur: Sudan
FairTrade coffee: Vietnam
The Butler Model, Majorca: Spain
Ecotourism in the Galapagos Islands: Ecuador
A Transnational Corporation-Toyota
The management of development: Morocco
185
186-187
203
204-205
227
228-230
230-231
254
254-255
263-264
264-265
278-281
291-293
294-295
302-307
317
332
334-337
356
362-367
Drainage basins are areas of land where surface water converges
and joins another waterbody such as a sea or ocean. Over 47% of
the world’s land drains into the Atlantic Ocean, 13% into the
Pacific Ocean, 17% into the Arctic Ocean and 13% into the Indian
Ocean. Endorheic basins do not drain into an ocean. These are
closed basins where water converges on one point inside a basin
known as a sink.
Ob’-Irtysh basin
2 990 000 sq km
Karskoye
Finlay basin
Arctic Ocean
1
1 114 000 sq km
©
Indus basin
1 166 000 sq km
Zambezi basin
1 330 000 sq km
Ganges-Brahmaputra basin
1 621 000 sq km
Hydrology and fluvial geomorphol
Lena-Kirenga basin
2 490 000 sq km
Hydrology and fluvial geomorphology
Amongst the hillslopes and valleys of Earth, water has played a clear part in
shaping the landscape.
This chapter will look at the hydrological cycle and its interactions between
the atmosphere, lithosphere (geological world) and biosphere (living world).
The drainage basin system
The drainage basin system is a complex system that is governed largely by the
impact of hydrological conditions interacting with geology over time. It is an
area of land surrounding a principal waterway and its tributaries on a local scale.
The boundary of a drainage basin is known as the watershed and is simply
the highest contour of land surrounding a river or stream. Factors such as
climate, vegetation, soil structure and land use may influence the character and
geomorphological development of a drainage basin resulting in wide and varied
spatial differences.
Drainage basins can vary in size from the most extreme example; the Amazon
basin, which covers 40 per cent of South America - nearly 7 000 000 sq km and contains over 1100 tributaries, to the micro-scale that may contain just one
figure
figure
0
i.i A small tributary river of the upper Amazon Basin.
river or stream.
1.2 The major waterways of the Amazon Basin stretching across the northern part of South America.
Hydrology and fluvial geomorphology
figure
1.3 The forested banks of the Amazon River.
Drainage patterns
The pattern of streams and rivers within a catchment can vary greatly. Often
there are similar characteristics based on the underlying geology and structure
of the drainage basin. Here are four common types:
•
•
•
•
Dendritic
Dendritic - a tree-like pattern where water may converge (meet) from a
variety of directions before joining a main river channel.
Rectangular-where the streams and channels follow geological weaknesses
and gaps in blocky bedrock.
Radial-where water drains away from a central high point, hill or mountain
into separate channels.
Trellised - where streams follow slopes downhill and converge along areas
of eroded rock.
Rectangular
Endorheic drainage basins
Endorheic drainage basins are inland basins that do not drain to an ocean.
Instead their base level is an inland lake or sea. Around 18 per cent of all land
drains to endorheic lakes or seas or sinks. The largest of these consists of much
of the interior of Asia, which drains into the Caspian Sea, the Aral Sea and
numerous smaller lakes.
The drainage basin is known as an open system as water is not confined to a
specific location and can move from one state to the next at any given time. The
different stages are explored in Figure 1.5 in a simplified systems diagram.
Trellised
figure
1.4 Drainage basin morphology
Hydrology and fluvial geomorphology
***
**
storage in
figure
1.5 The hydrological cycle
Inputs
Drainage basins principally have one main input- precipitation (ppt), which
includes all forms of rainfall, snow, frost, hail and dew. Water is then stored
or transferred in the system for an indeterminate amount of time before its
eventual output in the form of evaporation (EVP), evapotranspiration (EVT)
and runoff.
Precipitation refers to the conversion and transfer of moisture from the
atmosphere to the land. Precipitation can be very variable and several factors
may impact the hydrology of an area: amount and extent of precipitation,
intensity, type, duration and geographical distribution.
Storage
Storage refers to the parts of the system that hold or retain water for periods of
time. They can be open stores on the surface of the land, within vegetation or
hidden deep within the rock structure. The amount of time that water is stored
for is dependent on the processes acting on it.
Interception refers to water that is caught and stored by vegetation. It is
affected largely by the size and coverage of plants, with large broadleaved
trees catching the most water (in summer). Intercepted water may still transfer
through the system using three main mechanisms:
•
•
•
interception loss - water retained by plants and later lost as evaporation
throughfall and leaf drip-water that is slowed by running off and dropping
from leaves, twigs and stems
stemflow-water that runs down branches and trunk to the ground.
Urban areas and areas that have been cleared for cultivation have much lower
rates of interception.
Hydrology and fluvial geomorphology
input
precipitation
I
output
interception
transfer
I
store
stemflow/
leaf drip
I
surface storage
surface runoff
(overland flow)
I
infiltration
I
soil moisture
storage
storage
th roughflow
-*■ channel storage -►
channel flow
I
variable level
percolation
I
water table
figure
groundwater
storage
groundwater/
base flow
river discharge
1.6 Systems diagram - inputs, transfers, stores and outputs
When vegetation absorbs moisture directly through its root system it
becomes stored within the organism/plant and is called vegetation storage.
The amount of water stored relates to the size and variety of plant and the local
conditions at any given time. A large leafy and ‘thirsty’ plant will require more
than a well-watered shrub.
Surface storage is the name given to any parts of the system where water
lies above the ground on the Earth’s surface. Within a drainage basin water
may naturally accumulate in lakes, ponds and puddles or through human
intervention whereby engineering creates structures to contain water such
as reservoirs and swimming pools. Surface stores have a high potential
evapotranspiration rate as there is a large amount of moisture available with
limited cover.
Channel storage refers to water that is contained within a river channel or
stream at any given time.
Groundwater storage refers to water that has become stored in the
pores and spaces of underlying rocks. Despite being hidden, this water is
fundamentally important to the hydrological system accounting for almost
97 per cent of all freshwater on Earth. Although a significant part of the
hydrological cycle, water contained here may be stored for 20 000 years.
Any large quantities of water are contained in aquifers. An aquifer is
an underground layer of water-bearing permeable rock or unconsolidated
materials (gravel, sand, or silt) that can be found at any depth. Those nearest
the surface are often used for water supply and irrigation. Areas that suffer
from a large extraction of groundwater through wells and pumps require good
recharge rates (where water stores naturally fill back up). Those areas with
little recharge consider groundwater to be a non-renewable resource. Many
groundwater reserves are being used at an unsustainable rate too.
Groundwater recharge occurs as a result of percolation, infiltration from
precipitation, leakage and seepage from the banks and beds of water bodies as
well as artificial recharge through from reservoirs and irrigation.
In 2013 large freshwater aquifers were discovered under continental shelves
off Australia, China, North America and South Africa. They contain an estimated
halfa million cubic kilometres of low salinity water that could be economically
processed into potable (drinkable) water.
Hydrology and fluvial geomorphology
Transfers
Overland flow is the movement of water over the land, downslope to a body
of water. It has two main mechanisms. Where precipitation exceeds the
infiltration capacity accumulated water will flow downslope due to the effects
of gravity. An alternative mechanism occurs when the soil saturation exceeds
its maximum capacity due to groundwater uplifting, base flow, and lateral
subsurface water discharges, resulting in the appearance of saturation excess
overland flow.
Channel flow is the movement of water within a defined channel such
as a stream or river. The speed and flow of the water will depend on a variety
of factors such as gradient and efficiency; these are considered in more
detail in river channel processes and landforms (pages 20-29). Base flow is
considered to be the lowest flow within a channel, often occurring due to a lack
of precipitation leaving only the influence of water trapped in rocks and soil.
It is maintained by groundwater seeping into the bed of a river. The channel
is topped up by precipitation events and the arrival of water through other
mechanisms such as throughflow, overland flow etc. It is relatively constant but
increases following wet conditions.
Throughflow refers to the movement of water through the soil substrata.
As the soil type of an area is closely linked to the underlying bedrock flow
rates through different soil profiles can be varied. Clay-rich soils are known for
their water retention whereas sandy loams are characteristically free draining.
The influence of land use also plays a part as it can influence soil density and
aeration (page 19).
Ground water flow is subsurface water (lies underthe surface of the ground)
that travels downwards from the soil and into the bedrock through cracks and
pores. This process is called percolation.
Differing rock types and structures will affect the flow of water into
underlying layers, with porous sedimentary/carboniferous rocks such as chalk
and limestone being the most effective carriers of water. The layers of rock that
become saturated form the phreatic zone (Figure 1.7 (a)) in which the uppermost
layer is known as the water table. Where there is a small area of underlying
impermeable substrata (aquiclude), water may be held higher up the basin
profile as a perched water table (Figure 1.7 (b)). Water that cannot pass through
the rock layers will emerge as a spring.
Outputs
Evaporation is the process by which water is converted to water vapour
in the atmosphere. This is most significant where there are large bodies
of water such as the oceans and seas and on a local scale - rivers
and lakes. Rates of evaporation are dependent on climatic variables
such as temperature, humidity and wind speed. Other factors include the
Hydrology and fluvial geomorphology
amount of water available, vegetation cover, and albedo (reflectivity of
the surface). Evaporation rates change throughout the day and with
seasonality.
Transpiration is the process of evaporation of water from plants
through pores (stomata) in their leaves. Broadleaved trees, such as
beech, can hold more water and so have greater potential for high
transpiration rates. Some species of plant, such as the saguaro cacti,
are specially adapted to retain moisture by reducing their rates of
transpiration.
Evapotranspiration is the combined effect of evaporation and transpiration
and represents the major output from the drainage basin system. In humid
areas 75 per cent of moisture may be lost in this way and up to 100 per cent in
arid areas.
River discharge is a measure of the volume of water moving in a river. It can
also be used to describe the output of river water from a drainage basin. At its
lowest point a river will discharge into an ocean. Although a river cannot change
catchments its drainage basin may be part of a larger complex system that links
a number of drainage basins.
In some cases water may escape from the system by other means not
highlighted by Figure 1.6. Some examples may include when geology at lower
levels may cause leakage allowing water to seep from one drainage basin to
the next; human water management initiatives may also modify the system by
creating reservoirs and dams affecting channel flow, by abstracting water for
irrigation, domestic and industrial use or through cross-basin transfers to aid
water shortages in adjacent areas.
Discharge relationships within drainage basins
River discharge
A river operates as a main conduit for water within a drainage basin. It is
essentially the equivalent route for water, as motorways are for cars, offering
the most efficient route for transportation. Precipitated water has a direct
influence on the level of water in the river. The quicker the response the greater
the influence on the existing flow. Additional water in the form of precipitation
will raise the water level above its base level. As water enters the river the river
level will rise. After a period with little or no water, river levels will fall. The
volume of water moving past a point in a river per given time (usually cubic
metres per second/litres per second) is called the discharge. Discharge can be
calculated as:
Q = AxV
Where: Q = discharge, A = cross-sectional area, V = velocity
The level of discharge is influenced by the rate of precipitation and the speed
at which water is transferred to the river.
Variations in discharge
A river’s flow is inherently influenced by the characteristics of the area and the
prevalent weather conditions acting on it. Different conditions in differing
locations may produce very different discharges over the course of a year. This
annual variation is known as its river regime.
Using data from Sauquet et al. (2008), we can see the huge range
in variation both over the year and from region to region throughout
France. Rivers of similar characteristics have been categorised into twelve
colour-coded types. From the data we can see there are some common
trends. For example there is a decrease in summer runoff, with the
exception of mountainous rivers to the south and east (see Figure 1.8 (a)
and 1.8 (b)).
Hydrology and fluvial geomorphology
River groups
figure
1.8 (a) Drainage patterns in France. The map shows the drainage basins colour coded to their respective graphs on the facing page.
Storm hydrographs
Hydrographs enable us to look at the relationship between rainfall and
discharge after each rainfall event as river levels top up and subsequently
drop over time. The response of a catchment to a rainfall event may be rapid
or gradual depending on many factors (outlined below). The shape of the
hydrograph may reflect the speed at which the water has travelled and the
obstacles and stores in its way.
Hydrographs are particularly important for identifying the potential risk of
flooding to an area.
There are several key features to any hydrograph. They represent the various
stages to the graph and help to identify the nature of the discharge. Most
hydrographs show time or duration on the x-axis followed by two scales on
the ji-axis- one for the rainfall/precipitation and one for discharge. Be sure to
identify which is which.
J
Hydrology and fluvial geomorphology
Group 9
Group 5
Group 1
0.25
0.20
Group 7
0.251---------------------------------
Group 8
0.251---------------------------------
0.20
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
1.8(b) Drainage patterns in France. The graphs show monthly variation in discharge for selected streams throughout France.
ra in fe ll (m m )
figure
figure
1.9 Hydrographs showing low peak discharge and storm discharge.
Hydrology and fluvial geomorphology
0
Base flow/groundwater flow-this is the ‘normal’ level of water in the
channel determined by the groundwater flow prior to a rainfall event.
Lag time-this is the period between the peak precipitation and the peak
discharge.
Peak flow/discharge - this is the maximum river discharge for any given
event measured in cubic metres per second m3s‘(cumecs).
Rising limb-this is the part of the graph that initially rises, indicating
the increasing level of water as determined by the combined rate of
surface runoff, throughflow and groundwater flow following a precipitation
event.
Storm flow-this is the additional discharge created as a result of a
precipitation event.
Falling limb/recession - this is the part of the graph that shows the
discharge decreasing and river levels falling back towards base level.
As the rain falls within the catchment it takes a variety of routes before
some of it enters the river (see Figure 1.5). As that water joins the river
the volume of water increases, thus increasing the discharge. Water that
rapidly flows into a river will have a more rapid rise in discharge. Water
that travels slowly to the river will have a more gradual effect on the level of
discharge.
Catchment hydrology
Catchment hydrology refers to the movement, distribution and quality of water
within a drainage basin. Whilst drainage basins vary in form there are common
principles that will shape the response of the area to any given event.
Infiltration rate
Infiltration is the flow of water (precipitation, irrigation) through the soil surface
into a porous medium under gravity action and pressure effects. The maximum
rate of infiltration for an event is the infiltration capacity.
Several factors control the rate of infiltration within the catchment/drainage
basin.
The morphology of the drainage basin
affects discharge in a number of ways.
The larger the drainage basin the greater
potential discharge but longer lag time
as precipitation is caught over a wider
area. Roughly circular shaped basins are
more likely to result in a ‘flashy’ rapid
response as precipitated water is more
likely to reach the river at the same
time having travelled an equal distance.
Steeper drainage basins will have a short
lag time as the influence of gravity will
increase the rate of flow to the river.
Hydrology and fluvial geomorphology
Types of precipitation
Flooding most frequently occurs after prolonged periods of rainfall when soil
stores are full and there is less drainage possible. The conditions preceding a
rainfall event can be referred to as antecedent conditions.
During cold conditions, water may be temporarily stored as snow or
ice. This means there is less water circulating through the system. It also
means that there may be a sudden release of water during times of thaw.
Annual flooding in Bangladesh is largely attributed to the combined
effects of monsoonal rain and seasonal snow-melt from the Himalayas to
the north.
There has been much speculation on the effects of climate change. Though
storms are not necessarily increasing in frequency, there does seem to be a
correlation with an increasing intensity. Intense storms are more likely to cause
floods as the ground is unable to absorb high quantities of water in a limited
amount of time.
Relief
The size and shape of the land affects the rate at which water can flow down
it. Slopes with an angle of less than 50 will have significantly greater rates of
infiltration. The greater the gradient, the greater the rate of surface runoff as
there is less opportunity for infiltration. Higher in the catchment, rivers may cut
steep incised valleys acting under the influence of gravity (as they seek to reach
the lowest point). As they travel downstream this influence is lessened and rivers
erode laterally creating flat, wide floodplains.
Parent material
The parent material refers to the underlying geology of an area and the origins
of the formed soil. The characteristics of the geology will determine the
permeability and ultimately how well the ground will drain.
Rock type
Rocks can be classified into three types based on their formation.
Sedimentary rocks are formed through the deposition of sediment and the
subsequent compression as additional layers are deposited above. They often are
porous (with air spaces), such as sandstone, or pervious (with cracks and bedding
planes), such as limestone. This means that water can pass through sedimentary
rocks. Rocks that allow water to pass through them are termed permeable.
Metamorphic rocks are sediments and rocks that have been transformed by
heat and pressure. The permeability of metamorphic rocks will depend on the
nature of the transformation.
Igneous rocks are formed by extreme heat and pressure in magmatic
environments and are more simply referred to as volcanic rocks. Examples
include basalt, usually formed in ocean environments, and granite, more
commonly found on land. Rocks such as these do not let water pass through
them and are called impermeable.
Soil type, structure and density
Soil is composed of rock fragments, organic matter, water, air, organic material
and organisms in varying proportions. The greater the clay content, the more
water retentive the soil is as clay particles bond together tightly restricting the
flow of water. A sandy soil is free draining as the larger sand particles provide
gaps and spaces for water to pass through. Most soils contain a mix but soils
become saturated easily when there are greater proportions of clay. Compare
the waves draining on a beach to boggy areas surrounding a river, for example.
Often floodplains contain a lot of small particles deposited by floods known as
alluvium. Beaches are almost exclusively sand.
Drainage density
The drainage density refers to the number of rivers and streams in an area. The
greater the number of rivers, the more easily the catchment will be able to drain.
This may produce a quick rise in the hydrograph and a greater probability of
flooding.
Antecedent conditions
These relate to the previous conditions that have affected an area such as
precipitation rates. An area that has experienced a high amount of precipitation
may have partially or fully saturated soil, increasing the rate of surface runoff.
Dry conditions would allow for greater water storage but too dry may mean the
ground has a baked impermeable crust, which makes infiltration difficult. In this
scenario water may run off the land creating a flashy response hydrograph.
Land use
The land use of an area may be hugely influential in determining catchment
response. ‘Land use’ simply refers to how the land is used or managed.
Urbanisation
Settlements are often heavily concreted spaces very different to those on open
moorland or arable farms. World urban populations are growing, resulting
in greater urbanisation and an increase in the risk of flooding. Water cannot
infiltrate through tarmac and concrete and, combined with gutters and drains
that channel and direct runoff, water can be carried at great speed to the nearest
waterways. Often runoff from roads and urban landscapes contains pollutants
and waste that are unnatural to a river environment and this causes damage to
the freshwater ecosystem.
figure i.io These diagrams show the relationship
between drainage density and discharge.
Hydrology and fluvial geomorphology
Vegetation
Vegetated areas have a greater capacity to intercept precipitation and absorb
soil moisture. The type, nature and extent of vegetation will determine its ability
to retain moisture. Estimates suggest that tropical rainforests intercept up to
80 per cent of rainfall (30 per cent of which may later evaporate) whereas arable
land may only intercept 10 per cent.
In the United Kingdom, large broadleaved deciduous trees have a larger
biomass and expansive canopy in the summer months leading to greater
interception rates than in winter where intake is greatly reduced due to the loss
of leaves in autumn months.
Deforestation is an activity widely associated with flooding. The removal of
vegetation whether for the clearance of land for development or harvesting of
a cash crop often has negative consequences and widespread implications on a
river regime. Flows can be considerably faster.
In addition, the stability of soil profiles can be compromised by logging
trails and disturbed ground with further areas vulnerable to erosion by the fast
flowing surface flows. The resultant runoff is often heavily silted, which makes
rivers thick and dirty with sediment. Areas heavily reliant on rivers for washing
and drinking are the first to suffer.
Tides and storm surges
The daily rise and fall of the tides affects the relative base level to which a river
flows. High spring tides may prevent water from discharging into the sea,
increasing the potential for flooding. Low pressure systems such as depressions
and tropical storms reduce the amount of air pressure acting on sea level
leading to a slight rise in water level at these times. This coupled with strong
winds create further pressure on low-lying coastal areas. Storm surges occur when
strong wind conditions affect a coastline, forcing waves landward and inland
through estuaries.
River channel processes and landforms
The long profile
The long profile is the name given to the gradient of a river from the start
of the river (source) to its mouth. Rivers always work under the influence of
gravity, cutting a path downhill through the landscape. The higher up a river’s
MIDDLE
COURSE
UPPER
COURSE
LOWER
COURSE
cross profiles
Vertical erosion
Channel is deeper and
characteristics
with hydraulic
wider
and processes
action, abrasion and
Vertical erosion
Deposition more important
attrition dominant
decreasing in
than erosion
processes
importance, more
lateral erosion and
Fine material deposited
Traction and
saltation at high
500 -
400 -
deposition
flow
Suspension is the
Load size is large
main transportation
and angular
type
V-shaped valleys
Channel is at its widest and
deepest, and may be tidal
Large amount of load but the
size is very small and very
rounded
Load becomes smaller
and less angular
300 -
o
200 100 -
ÖD
'Ö
Long profile is the
change in gradient with
distance. It starts off
steep but reduces with
distance from source,
and has a concave profile
sea or
ocean
0-1
-100
Source
figure
1
Hydrology and fluvial geomorphology
Increasing distance downstream
1.11 Long and cross profiles on a typical river.
Mouth
source is, the higher the gravitational potential. As a result the upper reaches of
a river are often steep with deeply incised valleys: the result of vertical erosion.
In the lower reaches however, as the gravitational pull is lessened, rivers tend
to expel their energy by eroding laterally across the landscape. A graded profile
shows an idealised view of a river’s change in altitude that is in equilibrium,
starting steeply and becoming ever more flattened. In reality changes in the
underlying geology and human influences (such as dams) may distort this
idealised view.
As water flows downhill under gravity it seeks the path of least resistance. In
the higher reaches the river has greater potential energy but channels are often
rough and poorly formed. Further downstream channels become wider, deeper
and more efficient as more water joins from tributaries and is able to shape a
smoother route.
The upper course
The upper course is a high-energy environment that experiences a high
level of erosion and turbulent flow. The source of the river can often be
found in boggy upland areas with no distinct channel or form. As water
accumulates it starts to carve out shallow paths in the soil and vegetation
before descending more rapidly under the influence of gravity. At altitude
the combined processes of weathering and fluvial erosion contribute to the
high level of bedload (sediments that lie on the riverbed) and large angular
material including frost shattered boulders and scree. Partly as a result of
the large material, traction (the largest stones, boulders and cobbles rolled
along the riverbed by strong turbulent flow) and saltation (a transportational
process where smaller bedload such as pebbles bounce along the riverbed) are
common.
figure
1.12 Characteristic turbulent flow of the upper
course, showing large rock debris.
figure
1.13 A sweeping curve of the middle course.
Rivers become more sinuous as they have more energy
to expel downstream.
The middle course
The middle course is a longer section of river characterised by a decreasing
gradient and greater lateral erosion. As a result the valley sides are less incised
than the upper reaches and the river starts to become more sinuous (winding).
The river itself here becomes more established with a greater number of
tributaries bringing additional water. There is a high proportion of suspended
load and bedload is smaller and less angular than upstream.
The lower course
The lower course is the low-lying portion of the river that joins with the sea. It
is characterised by wide flat sweeping floodplains and large meander bends. It
is the depositional zone of the river, featuring small rounded stones that have
been worked on by fluvial action and erosion. There is a high proportion of
suspended material in the low profile.
figure 1.14 The lower course where the river joins the sea
at the depositional zone.
Flow
A river’s function is to transport water to the lowest point of its catchment.
In doing so the water interacts with the landscape, channel and underlying
geology. The flow of the river is the manner in which the water travels. There are
three types of flow:
•
•
Laminar flow is characterised by a smooth horizontal motion often too
simplistic for complex natural river environments that have many changes,
steps and gradients. A laminar-style flow may be found in carefully managed
channellised sections on a relatively small scale where there are few
additional influences.
Turbulent flow is characterised by a series of erratic horizontal and
vertical spiral flows (known as eddies) that disturb the smooth appearance
of the water. Turbulent flow is the dominant method of flow in a river
figure
1.15 Turbulent glacial water in Norway.
Hydrology and fluvial geomorphology
environment. The amount of turbulence varies depending on the velocity
of the flow as well as the influence of friction and the energy available. The
greater the velocity, the greater the amount of spare energy after friction
and so the greater the turbulence.
•
Helicoidal flow is a corkscrew-like flow that is mainly found as water travels
around river bends. It is associated with meanders and the formation of
sediment bars and slip-off slopes.
The thalweg is the name given to the path of least resistance where water
flows the fastest. In a straight channel it can be found in the middle of the
channel under the surface of the water furthest from the influence of friction
from the riverbanks, riverbed and the air. On a bend, however, the fastest flow
will continue in a straight line before hitting the outside of the bend and being
reflected downstream.
Factors affecting river velocity
The velocity of a river is not determined by one single factor. There are
many factors that impact a river’s ability to transport water and sediment
downstream. Gradient, efficiency and bed roughness all determine how
well the water flows. The differing velocity will in turn affect the erosive and
depositional capacity of the river and its potential to shape the channel.
Drainpipes and waterslides are built the way they are for an efficient flow to
move water quickly. The closer the river is to a smooth semicircular form the
more efficient it will be. Man-made channels are often much more efficient
than natural ones.
The measure of efficiency can be determined by calculating the hydraulic
radius (HR).
HP _
cross-sectional area
wetted perimeter
(the width of the river across the contours
of the riverbed)
It is a ratio and has no units.
figure
Hydrology and fluvial geomorphology
1.16 Cross section showing velocity at a meander.
Erosion
The power of the water and the material that is carried will continually shape
and wear away the bed and banks of a river channel. There are four main
processes important in fluvial (water) environments:
•
•
•
•
Hydraulic action is the force of the water pushing into cracks and hitting
against the river’s banks. This repeated action weakens the riverbank as air
in the cracks is compressed and pressure builds up. Collapsing air bubbles
create small shock waves in a type of hydraulic action known as cavitation.
Unlike coastal environments where waves may be large and powerful,
hydraulic action is a slow and ineffective process of erosion.
Corrasion occurs when sediment in the river is thrown into or scraped along
(abrasion) the banks and bed of the river. This process is extremely common
and is the main form of erosion within a river. During times of high flow
or flood the river has a greater capacity to transport larger material, which
results in the greatest amount of damage. Potholes may form as stones
become trapped in depressions and hollows and are continually swirled
around by eddies in the turbulent flow.
Attrition is the process by which stones and sediment within the river
become increasingly rounded. As material is transported it collides with
other objects in the river. The collisions cause the stones to break into
smaller pieces and the edges and points of the stones to break off.
Corrosion or solution is a continuous chemical process that occurs
independently from river flow. Water that has slightly acidic properties,
for example as a result of decomposing organic material (humic acid) or
acid rain (carbonic acid), will chemically dissolve and weaken certain types
of rock. Limestone is composed of calcium carbonate and is particularly
vulnerable to corrosion.
Transport
In addition to the movement of water, rivers also become important conduits
forthe transport of sediment.
Rivers transport sediment in a number of ways. The mode by which sediment
is transported is related to the speed of flow and its size. Unsurprisingly, faster
flows can transport larger material. This is perhaps most noticeable in times
of flood when large boulders, trees and even cars may be carried by a river.
Material carried by a river is referred to as its load. Rivers can only carry so much
load depending on their energy. Capacity is the name given to the total load of
material actually transported. Competence is the name given for the maximum
size of material that a river is capable of transporting. The load is transported by
four main processes:
•
•
•
•
Traction is when the largest stones, boulders and cobbles are rolled along
the riverbed by strong turbulent flow. Often these sediments will lie
undisturbed on the riverbed until sufficient discharge is reached to displace
them.
Saltation is where smaller bedload such as pebbles, stones and gravel are
lifted and carried temporarily in the flow in a hopping or bouncing motion.
As turbulent flow is not constant the river will have varying amounts of
energy to lift and carry the load.
Suspended load is when very fine particles of sand and silt are carried
in suspension in fast flowing water. The faster and more turbulent the
water, the greater the amount and size of material that can be transported.
Suspended load is easier to see in the lower reaches of a river or after a
rainfall event where the water has a muddy brown appearance.
Dissolved load or solution is the process by which small dissolved
sediments and minerals are transported within the river. They form just
a small proportion of the total load but are significant as corrosion (or
solution) is constantly occurring.
Hydrology and fluvial geomorphology
Deposition
If the river no longer has energy to transport material it will be deposited.
As the competence (maximum particle size) and capacity (maximum load)
to carry material falls the largest boulders will be deposited first followed by
progressively smaller material. The amount of energy that a river has and the
likelihood it will deposit material is closely linked to flow conditions. Deposition
is more likely to occur:
•
•
•
•
following low periods of precipitation where river levels drop
where the river flow meets the sea
in areas of slow flow within a channel, such as on meander bends
when the load suddenly increases above the capacity, for example following
•
a landslide
when the water has carried the material outside of the channel, such as in
times of flood.
With the exception of material in solution, which will never be deposited,
river deposits tend to become smaller and more round closer to the sea.
However it must be noted that larger stones may be present along the entire
course of the river as the bed and banks are constantly being acted on by other
processes such as weathering and erosion.
Hjulstrom’s Curve
The relationship between particle size and velocity can be seen using
Hjulstrom’s Curve (Figure 1.17). The mean or critical erosion velocity curve
shows the approximate velocity needed to pick up and transport (in suspension)
particles of various sizes. The capacity of the river is responsible for most of the
subsequent erosion. The mean fall or settling velocity curve shows the velocities
at which particles of a given size become too heavy to be transported and so will
fall out of suspension and be deposited. There are three important features of
Hjulstrom’s curves:
•
The smallest and largest particles require high velocities to lift them. For
example, particles between 0.1 and 1 mm require velocities of around 100
mm/sec to be entrained, compared with values of over 500 mm/sec to lift
clay and gravel. Clay resists entrainment due to cohesion, gravel due to
•
•
weight.
Higher velocities are required for entrainment than fortransport.
When velocity falls below a certain level those particles are deposited.
figure
9 Hydrology and fluvial geomorphology
1.17 Hjulstrom’s Curve
Fluvial features: erosion
V-shaped valleys and interlocking spurs
The upper reaches of a catchment often experience large seasonal variations
and as a result the rate of erosion can vary greatly. Large angular boulders often
choke the upper channel, creating more friction and disrupting flow. During
times of peak discharge, such as periods of snow-melt, vertical erosion will be
high as there is a greater capacity for erosion. Though the generalised image
of a V is common, the extent and angle of incision will be dependent on local
factors such as rock type.
Interlocking spurs
As the river flows downstream it may be forced to wind through the landscape
creating protrusions of the riverbank in the valley known as spurs. As the river
continues to wind downstream in a zig-zag pattern the view along the course of
the river may be restricted as the spurs appear to knit together like clasped fingers.
figure
1.18 Interlocking spurs, Oxendale, England, UK
waterfall retreats
overhang
steep-sided gorge
develops as waterfall
retreats
ridges of hard rock
create an uneven slope;
this creates rapids
figure
1.19 Gorge formation
Rapids, waterfalls and pools
Rapids are areas of high velocity, turbulent flow. They are created by a sudden
change in gradient or a narrowing of the river. Contrastingly, pools are
areas of slow moving deep water that have low erosive capability and greater
deposition.
Waterfalls are large steps in the river as a result of differential erosion usually
attributed to bands of hard and soft rock. Water flowing over hard rock will
have relatively little impact erosively. Once it then meets a band of softer rock
there will be greater erosion. Over time the amount of erosion will be so great
that a noticeable step in the profile may be created. Continued erosion may
cause undercutting of the rock layers eventually resulting in rock collapse. The
fallen material is often large and angular and is forced to swirl around scouring
out a depression known as a plunge pool. As the process is repeated waterfalls
migrate upstream, leaving a deep steep-sided gorge, for example the falls at
Niagara are retreating at a rate of 1 m a year.
Fluvial features: erosion and deposition
Meanders
Meanders are created as the result of both erosion and depositional activities.
The snake-like path of a river (sinuosity) increases downstream.
_.
..
actual channel length
S in u os ity =-------- ;;:------ 5—
straight-line distance
Hydrology and fluvial geomorphology
figure
i.2o Ho-seshoe Falls, part of Niagara Falls on the USA/Canadian border.
figure
1.21 Retreat of Niagara Falls, 1678-2015
A low sinuosity river has a value of 1.0 (straight) whereas a high sinuosity
river may have a value above 4.0.
A meander is the term used for a bend in the river with a sinuosity greater
than 1.5. Though no agreed explanation for their formation occurs, it is generally
considered to relate to the energy balance of the river and not the result of an
obstruction within the channel or floodplain.
Meander form
Meanders have an asymmetric cross section (Figure 1.23). On the outside of
the bend, where flow is fastest, erosion deepens the channel. On the inside of
the bend, where flow is slower, deposition occurs. Helicoidal flow occurs where
surface water flows towards the outer banks while the bottom flow is towards
the inner bank. Variations in the flow create differences in the river cross
sections. The most characteristic features of meanders are river cliffs and slip-off
slopes or point bars.
River cliffs are formed on the outside of the bend where erosion is greatest.
The combined effect of hydraulic action and abrasion weaken the riverbank
causing it to collapse. Over time a steep bank will be formed with some of the
collapsed material remaining on the riverbed.
Conversely, on the inside of the meander bend where discharge is ata minimum
and friction is at its greatest, deposition is greatest. Sediment accumulates to create
a gentle sloping bar known as a slip-off slope or point bar. The particles are usually
graded in size with the largest material being found on the upstream side of the bar.
Riffles and pools are a sequence of alternating fast and slow flows as a result
of the differing energy states of the river. Riffles are shallow areas of fast flowing
oxygenated water. Pools are deeper areas with slow moving water.
Not all meanders have a regular form but they do have several key characteristics:
• The meander wavelength tends to be 10 times the channel width (X = 10 -14 W).
• Riffles and pools are spaced 5-7 times the channel width (riffle spacing
= 5 - 7 W or ~ Vz X).
figure
J
1.22 A sweeping meander
Hydrology and fluvial geomorphology
•
•
The radius of curvature of the bend is proportional to 2-3 times that of the
channel width (rc ~ 2 - 3 W).
Meander amplitude is 5-7 times the channel width (MA = 5- 7 W).
Meanders over time
Meanders constantly change and evolve. Whilst these changes may be relatively
gradual, the curvature of a meander grows with time. As continued erosion
occurs the river cliff will migrate back as deposition on the inside becomes
more stabilised, leading to movement of the river across the landscape.
Meander bends become more pronounced so that the path of the river no
longer becomes the most efficient route. The river may continue to erode the
outside of the bend before eroding a shortcut between meander bends, causing
a temporary straightening of the channel. Where this occurs a bend may
eventually become redundant. Isolated bends will become detached creating
a feature known as an oxbow lake or cutoff, which, due to its lack of fluvial
input, will dry up. Evidence of past meanders may be visible on the landscape as
meander scars. A tributary that runs parallel to a river within the same valley for
some distance before eventuallyjoining it is known as a yazoo tributary.
figure
1.23 Cross section of a meander showing its
asymmetric shape.
------ backswamp
figure
1.24 The middle course of a river highlighting the life cycle of a meander and oxbow lakes.
Rejuvination and sea level change
The lowest point of a river’s course is known as its base level. In most cases
this is the sea but on a localised scale it may be a pond, lake or reservoir.
The river is constantly trying to produce the most efficient route to its base
level whilst continually being influenced by the energy balance and outside
factors. Changes in base level affect the energy balance and a river’s ability to
erode.
Over our history there have been many changes to our sea levels. During the
last interglacial, 125 000 years ago, sea level was approximately 4 metres higher
(eustatic rise) than the present day due to thermal expansion and ice melt.
During the last ice age, 18 000 to 10 000 years ago, sea level was much lower
(eustatic fall) due to thermal contraction and as water was trapped as ice on
the land. Sea levels reduced by up to 120 metres on the west coast of England,
which encouraged deep vertical erosion. As a result many parts of Britain have
very deep estuaries known as rias that were scoured out when the sea level was
much lower, such as at Dartmouth in Devon.
figure 1.25 Dartmouth Ria. A ria is a drowned river valley
formed in glacial periods with characteristic deep channels.
Hydrology and fluvial geomorphology
figure 1.26 An entrenched meander on the San Juan
tributary of the Colorado River, USA.
Effect on fluvial features
In situations where a meandering river has been influenced by a change in base
level then entrenched meanders or incised meanders may form. The distinction
between the two forms relates to the speed of erosion. Incised meanders are
asymmetrical in shape as they are eroded more slowly. As the river channel
erodes vertically as well as laterally it will start to undercut on the outside of the
bend creating an overhang in the river cliff. The inside of the bend, due to the
continued deposition, will take the form of a gentle sloping bar.
Entrenched meanders are formed, geologically, more rapidly. As a result
the meanders tend to take a more symmetrical shape as they carve out a deep
winding gorge across the landscape such as the Grand Canyon. Entrenched and
incised meanders are more visual where they have cut through different layers
of bedrock. Gooseneck on the San Juan river, a major tributary of the Colorado
River, is a well known example of an entrenched meander heavily influenced by
the distorted uplift (or upwarp) of the Monument Plateau.
River terraces are areas of higher ground surrounding a river. They are the
former floodplains of the river that were carved out when it was higher up,
which are now above the current levels of flooding. Due to a change in base
level an increase in vertical erosion creates a newly cut river.
Fluvial features: deposition
Deposition of sediment occurs when there is a decrease in energy or an increase
in capacity that makes the river less competent to carry its load. Deposition can
occur at any stage along the river but it is most common in the lower reaches.
figure
1.27 The river terraces of the River Dovey,
Wales, UK.
Floodplains
Floodplains are large areas of flat land surrounding a river channel. They are the
areas most susceptible to flooding. Initially cut by a river, a floodplain is made
up of a large amount of alluvial deposits (silt) dropped during times of flood.
As a result they are often fertile and used extensively for agriculture. As the river
spills over the floodplain in times of flood, there is an increase in friction, a loss
of energy and resultant deposition of material. Repeated flooding causes the
deposits to build up in height forming a series of layers high above the bedrock.
The edge of the floodplain is marked by a slightly raised line known as a bluff.
Levees
When a river floods its banks the coarsest material is often deposited first
creating a ridge along the edge of the river channel. Over time more sediments
may be added to the ridge thus creating a natural preventative barrier to
flooding. In low lying areas such as in Holland and New Orleans artificial levees
have been built in response to the threat of flooding.
figure
1.28 Braiding on the White River, Washington, USA.
figure 1.29 The Nile Delta, Egypt, flowing into the
Mediterranean Sea.
0
Hydrology and fluvial geomorphology
Braiding
Braiding occurs when there is a high proportion of load in relation to the
discharge. This may be the result of seasonal changes and snow-melt, such as in
the Alps. At times of low flow the river may be forced to cut a series of paths that
converge and diverge as they weave through large expanses of deposited material.
Braiding begins with a mid-channel bar that grows downstream as the
discharge decreases following a flood. The coarse bedload is deposited first. This
forms the basis of bars and, as the flood is reduced, finer sediment is deposited.
The upstream end becomes stabilised and overtime can become vegetated. These
islandscan alter subsequent flows, diverting the river and increasing friction.
Deltas
Deltas are formed when large amounts of river load meet the sea and are
deposited. Deltas are usually composed of fine sediments that are dropped
during low energy conditions and are so called because they are triangular in
shape, which is similar to the shape of‘delta’, the fourth letter of the Greek
alphabet. As freshwater and saltwater mix, clay particles coagulate (stick
together) and settle to the seabed in a process known as flocculation.
The finest sediments are carried furthest and are the first to be deposited as
bottomset beds. Slightly coarser material is transported less far and deposited
as foreset beds, while the coarsest material is deposited as topset beds.
There are three main types of delta:
•
•
•
Arcuate delta - having a rounded convex outer margin, such as the Nile River.
Cuspate delta-where material is evenly spread on either side of the
channel, such as the Ebro Delta, Spain.
Bird’s foot delta - where the sediment is distributed around many branches
of the river (distributaries) in the shape of the claw of a bird’s foot, such as
the Mississippi Delta.
The human impact
The influence of humans on the hydrological cycle
Water resources are important to both society and ecosystems. As humans we
depend on reliable and clean supplies of freshwater water to sustain our health.
We also need water for agriculture, energy production, navigation, recreation and
manufacturing. Many of these uses put pressure on water resources and these
stresses are likely to be exacerbated by climate change and population growth.
In many areas, climate change as well as population expansion is likely to
increase water demand, while shrinking water supplies. Spatially, in some areas,
water shortages will be less of a problem than increases in runoff, flooding, or
sea level rise.
Human influences on the hydrological cycle may be both intentional and
unintentional. We have been naive in our approach to resource management
and continue to mismanage many of our resources such as water. There are
1.30 The bird’s foot shape of the Mississippi
Delta, USA.
figure
many components to the hydrological cycle and humans can have an impact at
each stage, affecting both water quantity and water quality.
Water quantity simply refers to the amount of water available. The flows of
the hydrological cycle vary both spatially with location - latitude, altitude and
continentality-and temporally, through seasonal changes.
It has long been documented that the climate has fluctuated and changed
since our atmosphere formed some 4 billion years ago, but there is more and
more evidence to suggest that human activities on the planet have increased
global temperatures by 0.8 °C over the last 30 years bringing about greater
disturbances. Whilst our understanding of weather and climate mechanisms
has never been better, the unpredictability of the weather means there is greater
potential for extreme events such as drought or flooding.
Water quality refers to the cleanliness and ultimately the usefulness of water
to our societies and environment. Humans are harnessing more water than ever
before and not all the practices we use to do this are efficient, clean or sustainable.
figure
1.31 Water polluted by copper mining at Geamana Lake, Romania.
Hydrology and fluvial geomorphology
Precipitation
In heavily industrialised areas and urban spaces precipitation rates are as much
as 10 per cent higher due to an increased number of pollutants and particulate
matter creating a greater extent and frequency of clouds.
For moisture to fall as rain, water vapour must attach to small particulate matter
in the atmosphere known as hygroscopic nuclei. As water vapour accumulates and
condenses to form clouds, droplets of water increase in size before falling under
the influence of gravity. According to Colorado’s National Centre for Atmospheric
Research (NCAR) there are over 150 legitimate weather modification programmes
taking place in 37 countries, though their complexity and cost vary greatly.
Cloud seeding is one strategy designed to encourage precipitation. Cloud
seeding injects more particulate matter into the atmosphere in order to create
rain. Silver iodine, carbon dioxide and ammonium nitrate are used and dispersed
either by aircraft or more commonly fired by cannon or rocket into the air.
The result of cloud seeding is largely inconclusive, in Australia it has been
suggested that precipitation has increased by 10-30 per cent on a small scale
and short-term basis. China is investing heavily in the technology with the
introduction of 40 000 field operatives.
Land use change
Urbanisation
An increase in urbanisation creates large impermeable surfaces, which reduce
the amount of interception and infiltration.
Urbanisation has a close relationship with flashy hydrographs. As water runs
over impenetrable surfaces and into drains it is carried rapidly resulting in a
quicker response in the river, raising levels and increasing flood risk. An increase
in urban surfaces increases runoff and the potential for flooding.
Deforestation and afforestation
The effect of vegetation removal on hydrology and streams, through land clearance,
is a common theme on populated landscapes. Now less than 1 per cent of Britain
is covered by natural woodland due to the expansive activities of humans. Whether
for land clearance, development or crop harvesting, the removal of vegetation can
have profound effects on the hydrological balance of an area. Where clearance is
large in relation to the vegetative coverage the effects will be heightened.
The rates of interception are determined by the type and extent of vegetative
cover. Much of the land’s surface has experienced some level of clearance and
modification, resulting in widespread deforestation. Deforestation reduces
evapotransipiration rates and increases surface runoff, resulting in a flashier
response and shorter lag time. Afforested areas will have a greater capacity to
absorb moisture and help bind the soil. Afforested areas are largely planted for
figure
Hydrology and fluvial geomorphology
1.32 Forest removal, Derbyshire, UK
commercial reasons though there are additional benefits in the form of habitat
creation and flood management
Infiltration is up to five times greater under forest compared to pasture.
Forested areas intercept precipitation before funnelling it ground-ward.
Bioturbation (the reworking of soil by animals, for example earthworms, or
plants) is often high in fertile forest with macro-invertebrates constantly aerating
the soil. Pore spaces are often larger and more plentiful than pastoral land
where the ground is heavily compacted where animals have trodden.
Storage
Dams and reservoirs
Although the impact is relatively small in relation to the rest of the hydrological
cycle, the effect of dams and reservoirs on evaporation and evapotranspiration is
significant. Large stores of open water such as reservoirs increase the potential for
evaporation. Where temperatures are high evaporation rates are also high. Lake
Nasser, for example, behind the Aswan Dam, loses up to a third of its water per year
due to evaporation. Water loss through evaporation can be reduced by creating
underground and covered storage using plastics or by using sand-filled dams, both
of which can be impractical for large applications. In warmer environments and
drought-prone areas many underground storage containers and water tanks are
used. In Africa they are known as jo-jo tanks and in China they are called shuijiao.
Water abstraction
Water abstraction is the removal of water either temporarily or permanently
from lakes, rivers, canals or from underground rock strata. The redirection
of this water from the natural flows within a drainage basin can be done for
commercial, industrial or domestic purposes. In many countries the use of
water resources are closely regulated. In the UK the Environment Agency
is responsible for assessing the impact of activities using their Catchment
Abstraction Management Strategy to ensure a sustainable approach to water
usage. Water abstraction laws in the UK are based on weather and climatic
predictions and trends.
There are many different reasons for water abstraction including irrigation,
groundwater withdrawal and inter-basin transfer/trans-basin diversion.
figure
1.33 Lake Nasser behind the Aswan High Dam,
Egypt.
Irrigation
Irrigation is used to increase the productivity of an area through water re­
direction, though the amount of water must be carefully managed to suit the crop.
The lea Valley is a desert area in the Andes and one of the driest places on
Earth. The asparagus beds developed there in the last decade require constant
irrigation, with the result that the local water table has plummeted since 2002
when extraction overtook replenishment. Two wells serving up to 18 500 people
in the valley have already dried up. Traditional small- and medium-scale farms
have also found their water supplies severely diminished.
Groundwater withdrawal per sector on the Peruvian coast
The rate of extraction for large-scale commercial agricultural purposes is rapidly
exceeding that of domestic and industrial use. As a result many local people are
suffering from a lack of accessible water in their neighbouring aquifers as many
large farms redirect the flow in order to ready their produce for export and profit.
Agriculture consumes 50 per cent of all water withdrawn. Little of this is for smallscale subsistence farming.
Conversely, the reduction in agricultural and industrial extraction in some
areas has led to an excess of water at groundwater level. There are several
associated problems with this:
•
•
•
•
•
figure
1.34 Freshly cut asparagus
an increase in spring and river flows
surface flooding and saturation of agricultural land
flooding of basements and underground tunnels
re-emergence of dry rivers and wells
chemical weathering of building foundations.
Hydrology and fluvial geomorphology
Case Study
The Aral Sea
West Siberian Plain
%
Ob'
Ş.
</>
\JraZ
Kazakh Steppe
Aral Sea
t»''
Elbrus Z
^urt
o a5642 & Plateau
^ucasus
<>
2
4^^
\ - v „J '^Urri Desert
■A? bounta'h*
Dasht-e Kavir
Lake
Balkhash
Alai Ra"9e
pamir
A
r
figure
1.35 Aral Sea catchment area
figure
1.36 The shrinking waters of the Aral Sea.
K2
8611
The Aral Sea is one example of how irrigation can have significant consequences
on an area. Formerly the fourth-largest lake in the world, spanning 68 000 sq
km, the Aral Sea has been steadily shrinking since its waters were first redirected
by Soviet irrigation projects in the 1960s. The loss of water from the Aral Sea to
a catchment some 500 km away has meant there has been a reduction in the
amount of evaporation and evapotranspiration in the basin, contributing to a
lack of cloud cover and resultant rain. The frequency and intensity of rainfall is
thought to have declined over the past 30 years.
The drying up of the Aral Sea is often considered to be one of the greatest
management disasters in history. Between 1954 and i960 the government of
the former Soviet Union ordered the construction of a 500 km-long canal that
would take a third of the water from the Amudar’ya River to an immense area
ofirrigated land in order to grow cotton in the region. Some 5 per cent of the
nearby reservoirs and wetlands have become deserts and more than 50 lakes
from deltas, with a surface area of 60 000 hectares, have dried up. Although
irrigation made the desert bloom, it devastated the Aral Sea.
The blowing dust from the exposed lakebed, contaminated with agricultural
chemicals, became a public health hazard. The salty dust blew off the lakebed and
settled onto fields, degrading the soil. Croplands had to be flushed with larger
and larger volumes of river water. The loss of the moderating influence of such
a large body of water made winters colder and summers hotter and drier. As the
lake dried up, fisheries and the communities that depended on them collapsed.
The increasingly salty water became polluted with fertilisers and pesticides.
In 2005 the World Bank and the government of Kazakhstan constructed a
13 km dam at a cost of US$85 million. By 2008 fish stocks had returned to their
i960 levels. In 2008 the North Aral was subject to a US$250 million project to
rejuvenate the area, though progress is slow.
figure
1.37 Boats in what is now desert around the Aral
Sea, Uzbekistan.
Hydrology and fluvial geomorphology
Groundwater
Human activity has seriously reduced the sustainable potential of groundwater
in some parts of the world.
If the use of groundwater exceeds the recharge of groundwater, the water
table will drop. Many groundwater stores are in a stable state of equilibrium
where recharge and discharge are equal.
One of the main problems of groundwater abstraction is in coastal areas,
namely saltwater intrusion. This is the movement of saltwater into an aquifer
that previously held freshwater. For decades many coastal communities around
the United States have experienced saltwater intrusion.
Overextraction can lead to subsidence. As water is moved from the rock,
sediment particles fill pore spaces previously filled with water. The result is
a compression of the land and a reduction in height of the land. This can be
particularly problematic when occurring under structures and buildings. Railway
lines and pipes can be ruptured.
Industrial usage
Mining
Mining can deplete surface and groundwater supplies. Groundwater withdrawals
may damage or destroy streamside habitat many miles from the actual mine site.
In Nevada, the driest state in the United States of America, the Humboldt River is
being drained to benefit gold mining operations along the Carlin Trend. Mines in
the northeastern Nevada Desert pumped out more than 580 billion gallons of water
between 1986 and 2001-enough to feed New York City’s taps for more than a year.
Mining can affect water quality in a number of ways, for example heavy metal
contamination, such as arsenic being leached out of the ground, sulphide-rich
rocks reacting with water to create sulphuric acid, chemical agents designed to
separate minerals that leak into nearby water bodies, erosion and sedimentation
from ground disturbance that can clog waterways and smother vegetation and
organisms as well as silting up fresh drinking water.
Energy generation
Hydropower uses the force of water to turn turbines. This has little impact on
the quantity and quality of water as it is largely returned with little change in
state. Less sustainable energy uses involve the use of water for fossil fuel and
nuclear energy production. In each, water is converted to steam that powers
the turbine in order to generate electricity. This water is then returned to
surrounding bodies of water, rivers and lakes with a lower oxygen content at
differing temperatures, threatening fish populations and freshwater habitats.
Several types of data can be collected to
help hydrologists predict when and where
floods might occur:
•
Monitoring the amount of rainfall
occurring on a real-time basis.
•
Monitoring the rate of change in
river stage on a real-time basis, which
can help to indicate the severity and
immediacy of the threat.
•
Knowledge about the type of storm
producing the moisture, such as
duration, intensity and aerial extent,
which can be valuable for determining
the possible severity of the flooding.
•
Knowledge about the characteristics of
a river’s drainage basin, such as soil­
moisture conditions, soil saturation,
topography, vegetation cover,
impermeable land area and snow
cover, which can help to predict how
extensive and damaging a flood might
become.
In the UK the Met Office collects and
interprets rainfall data and works with
the Environment Agency to issue flood
watches and warnings as appropriate.
Recurrence intervals refer to the probability
of a flood occurring based on past flow
states compiled over at least a 10 year
period. Often people use them to infer
magnitude where a i in 100 year flood
will exceed that of a i in 40 year flood.
Hydrologists determine the recurrence in­
terval based on previous flow states and the
probability that the discharge will exceed
that able to be contained by the channel. A
1 in 100 recurrence interval refers to a 1 per
cent probability that the river will reach a
certain discharge for that river. Several 100
year floods could still occur within 1 given
year as the data is based on averages. A100
year storm over a catchment may not nec­
essarily equate to a 100 year flood as many
factors will influence the rate of drainage.
■ Hydrology and fluvial geomorphology
Causes of flooding
Flooding can be classed as an inundation of water covering the land’s surface.
Most commonly flooding is the result of excessive precipitation caused by
low pressure depressions that bring storm clouds with great vertical extent.
Flooding occurs when water exceeds the capacity of a river channel although it
can be the result of a rising water table or coastal inundation.
In situations where floodwater travels at great speed there is increased
likelihood of damage. In the case of the Boscastle flood (2004), the extreme
nature of the flood uprooted trees and carried cars into a narrow channel,
further exacerbating the flood.
Prediction: forecast and warning
Floods are considered the most serious type of natural disasters in the world
due to their frequency and intensity affecting widespread populations. On
average flooding contributes to 10 000 deaths per year globally with projections
showing an increase due to climatic instability and population growth.
Much of modern flood prediction utilises technology and relies on computer
models and simulation software that use algorithms (mathematical formulas)
based on the characteristics of an area. The use of precipitation data as well as
relief, land use and saturation rates may all be used to help forecast flow rates
from a few hours to a few days. Due to recent technological advances such as
greater computing capability, reduced errors and better physical modelling,
more effective use of data, flood forecasting and warning has never been better.
However, despite this, due to the unpredictable nature of our weather there is
still a high percentage of risk in many areas.
Satellites, radar and climate modelling have all helped to track global weather
systems and statistical models are used with flood histories to try to predict the
results of expected storms.
In the UK the Environment Agency has thousands of monitoring stations across
many major river networks. Most of the measurements used to make predictions
are taken electronically by sensors in the river, stored on site and then automatically
sent back to databases used by forecasting systems. River and seawater level
measurements are now also sent from telemetry systems and published online.
Despite this, due to the flashy nature of many of our river systems, many properties
in England and Wales have less than six hours of flood warning time. In the case of
Boscastle in 2004, the town had less than three hours’warning.
Scale and impact
Large drainage basins often provide greater opportunity for warning as the water
has further to travel, delaying its impact. In the case of the Brahmaputra and Ganges
rivers that run into Bangladesh, bringing meltwater down from the Himalayas,
settlements may have up to 72 hours to prepare for a flood event. However the
extent of the flood has the potential to be more severe. In the 2007 Bangladesh
flood 1000 people lost their lives and 9 million more were made homeless.
Prevention and amelioration
Extreme weather events only become hazardous when there is a population
that may be affected. As the global population grows more and more people
are marginalised and forced to live in hazardous areas simply due to a lack of
space. This, combined with the greater frequency and intensity of some weather
events, increases a population’s vulnerability and their capacity to cope.
Often in Middle Income Countries (MICs) economic losses exceed social
losses as more and more buildings are built on floodplains. Floodplains are
desirable places to build because of their building potential as easily accessible
flat land. However this is not without risk.
Flood protection can take a number of forms, such as loss-sharing
adjustments and event modifications.
Loss-sharing refers to mechanisms designed to help cope with a flood.
They include insurance payments and disaster aid, the latter of which may take
the form of money, equipment and technical assistance. In MICs insurance is
an important loss-sharing strategy though not all houses will be eligible for
insurance and many homeowners underestimate the impact of flood damage.
Event modifications refer to actions that limit the ability of the flood to do
damage and impact on people’s lives.
River management
Rivers can be managed in a variety of ways but are most commonly managed to
minimise flood risk. There are several approaches to river management that can
be categorised into hard engineering and soft engineering.
Hard engineering requires the use of rock or concrete structures that have
been purposely constructed to protect an area. Often these are less in keeping with
the natural aesthetics of an area but are much more responsive to flood risk and
erosion though not without consequence. Types of hard engineering include dams,
channelisation, levees, storm drains and culverts, and barrages. Channel modification
is the term used to describe a change in stream flow as a result of human
activities. In many cases channel modification is the result of hard engineering and
channelisation but in some instances channel modification may include a softer
approach and the inclusion of natural features such as riffles and pools.
Soft engineering tends to follow a more sensitive approach to maintaining
and controlling river flow. Approaches seek to utilise the natural environment
where possible and use natural and local materials to modify the river whilst still
maintaining its character.
Washlands are areas of land that are
periodically allowed to flood in order to
reduce pressure on settlements further
down river. The land is often agricultural
where loss of earnings may be in some
part subsidised.
Riffles and pools can be ‘manufactured’
Case Study
River Harbourne: Harnessing
Examples of soft engineering approach­
es include afforestation, washlands and
riffle and pool sequences. Afforestation
refers to the planting of water tolerant
trees to stabilise soil and slopes whilst
increasing the potential for intercep­
tion and absorption. Though not as
aggressive as many hard engineering
techniques they often are utilised as part
of an integrated management strategy
which has the added benefit of habitat
construction.
the
Harbourne
As far back as 1938 the rural Devon village of Harbertonford has recorded
regular flooding. In the past 60 years the village has been flooded 21 times.
The River Harbourne flood defence scheme was constructed in 2002 to
combat regular flooding of properties and access roads to the village. Though
not a large scale construction, it is perhaps one of the best examples of
sustainable river management in Southwest England.
Flow in the River Harbourne varies from less than 1 cumec at low flows, to
28 cumecs for a 10-year flood flow, through to 300 cumecs for a PMF event
(Probable Maximum Flood). The flashy nature of the catchment means there is
little warning for the residents of the village to prepare for the flooding and the
misery it may cause. One elderly resident of the village had resorted to living
solely on the upper floor of her house
much like a weir to encourage the river
to respond differently. Fast flowing areas
can be created to move water quickly
from an area and pool sequences can be
used to reduce the erosive capacity.
1.39 The Palmer Dam is an earth mound dam designed to control the flow of water entering
Harbertonford, South Devon.
figure
Hydrology and fluvial geomorphology
Why does the river flood?
The River Harbourne is a small river tributary of the River Dart, in Devon. There
are a number of reasons for flooding.
Physical factors
• There has been an increased frequency in the number of intense rainfall events.
• The river starts 350 m above sea level on the impermeable granite bedrock
of Dartmoor.
• Dartmoor receives 2020 mm of rainfall annually, twice as much rain as lower
surrounding coastal areas.
• From the moor the river cuts through steep narrow valleys on to slate
bedrock descending 300 m in 12 km.
• For the size of catchment the river has a high drainage density.
• The village of Harbertonford lies at the confluence of three rivers - the River
Harbourne, the Harberton Stream and the Yeolands Stream.
Human factors
• Many properties are built on the low-lying floodplain in the central area of
•
•
the village.
The A381 road has been widened over the years to cope with traffic pressures,
thereby increasing the amount of runoff flowing directly to the river.
Traditionally some water was extracted along mill leats to power the local
mills, which have since closed.
How is the river managed?
Harbertonford is designated as a Conservation Area and several listed
structures, including the village bridge, are contained within it. Atlantic salmon,
bullhead, sea trout and brown trout occur in the river and protected species are
also present within the catchment, including otter and common dormouse.
With this in mind it was important that any flood management works must be
sensitive to the environment.
The river is managed using a variety of hard and soft engineering techniques.
The aim of the scheme was to provide a range of flood defence measures
whilst enhancing the local environment. As a result it was decided that the
scheme should use natural local materials where possible in keeping with the
surroundings with minimum need for maintenance.
The scheme has two main features - an upstream flood storage reservoir,
and flood defence works through the village. This option has reduced the risk of
flooding from one in three years to a minimum of once in 40 years.
Upstream
• Wetland area and flood storage area: 1 km upstream from the village of
Harbertonford a wildlife area was created containing flood-resistant trees and
shrubs. The area directly upstream from the dam will become a 41 000 sq m
water storage area in times of flood. Local schoolchildren will monitor the
afforested area as part of an ongoing partnership.
• The Palmer Dam: Built to control the flow of the river, this earthen mound
was constructed using locally excavated materials. The dam gates can be
controlled to restrict river flow in times of flood. A culvert was created to
allow the free movement offish up and downstream of the dam, whatever
the flood conditions.
figure
1.40 Students measuring the channel at
Harbertonford village green.
Hydrology and fluvial geomorphology
Through the village
• Bed-lowering: In order to keep the aesthetic quality of the central village
green, the riverbed was lowered to increase the river’s carrying capacity
without the need for flood walls.
• Channelisation: Throughout the lower sections of the village, along Bow
Road, a 200 m wall has been created to protect the residential area from
overtopping. The river is now twice as wide. The wall on the bend of the river
is reinforced to reduce erosion.
•
•
•
Storm drains: Storm drains have been added to reduce the impact of flood
water entering the main channel from Harberton Stream.
Riffles and pools: Due to the extensive work a system of riffles and pools
were created to maintain the river’s natural flow whilst providing habitats for
macro-invertebrates.
New culvert: A new culvert to allow water to flow under the main road was
installed to relieve pressure on the existing drainage network.
figure
1.41 Plan of the Harbertonford flood defence scheme.
Flood hazard mapping
Food hazard mapping is used to identify areas that are susceptible to flooding
when the discharge of a stream exceeds the bankfull stage. Using historical data
on river stages and the discharge of previous floods, along with topographic
data, maps can be constructed to show areas expected to be covered with
floodwater for various discharges or stages. They can also be used to highlight
properties and infrastructure at risk, which allows planners and insurance
companies to produce cost benefit analysis.
NOW INVESTIGATE
1
Suggest reasons why a hydrograph for one location will experience
changes overtime.
2
Suggest reasons why two hydrographs in adjacent catchments may
show different characteristics for the same rainfall event.
Hydrology and fluvial geomorphology
ning
Rainfall
900 million tonnes
22 531 km per hour
the amount of rainfall the
the speed of a lightning bolt
Grand Banks,
Newfoundland, Canada
is the foggiest place in
the world with 206
300 000 volts
foggy days per year
the average amount of electricity
lightning discharges to the ground
158
Antarctica gets only
16.5 cm of rain
the number of lightning
or snow per year - the driest continent
strikes a year in Kifuka,
on earth is not a hot desert
Democratic Republic of the Congo
Blizzards
ice
4000
the weight of the heaviest hailstone,
the number of fatalities caused by the
Gopalganj, Bangladesh 1986
deadliest recorded blizzard which struck
31102 mm
the greatest annual snowfall, Mount Rainier,
Washington, USA, Feb 1971 - Feb 1972
38 cm wide by
20 cm thick
the size of the world's largest snowflake,
Fort Keogh, Montana, USA in 1887
2200 fatalities
On 12 March there were
Over
4 simultaneous tropical
were due to a deadly heatwave
storms in the South Pacific:
in India in May-temperatures
Olivyn, Western Australia;
rose to 45-47
°C
Nathan, Queensland, Australia;
Bavi, Western Pacific and
0 - no severe thunderstorms
In May the Antarctic sea ice
in the USA between 1 January
extent was
and 25 March’, the first time
above the 1981-2010 average
since records began in 1970
12.1 per cent
Tornadoes
Storms
2
In 1931 a tornado in Mississippi lifted an
Atm osphere and weather
the duration of the longest lasting tropical
83 tonne train
cyclone, Hurricane/Typhoon John in 1994,
3 out of 4
tornadoes occur
in the USA
Typhoon Haiyan, also known as Typhoon
Yolanda in the Philippines, was one of the
strongest tropical cyclones ever recorded,
with gusts of 275 km per hour
^Sunshine________________
re
The ten warmest years ever recorded have all
occurred since 1998
Yuma, Arizona, USA has around 4015 hours
56.7 °C
on earth
of sunshine per year (11 hours per day)
making it one of the sunniest places
the highest shade temperature
recorded, Death Valley, California,
USA in July 1913
47.3 °C
the hottest March temperature ever
recorded in Africa, at Vioolsdrif,
South Africa in 2013
14 802
the number of heat related deaths
during a heatwave in France in 2003
°C
°C
By comparison the
Sichuan Basin in southwest
China has as little as 1000
hours
of sunshine per year or
2.7 hours per day
The World’s average
The May Arctic sea ice
May temperature was
extent was
the warmest since
below the 1981-2010 average
5.5 per cent
records began
May was the all-time
The Atacama Desert, one
wettest
of the driest places on earth,
month
on record in central USA
had
24 mm of rain in a
thunderstorm in March
39
Atmosphere and weather
Diurnal energy budgets
100
units
scattered at edge
of atmosphere
absorbed by
water vapour, ],£
dust,CC>2
reflected
by clouds
a
absorbed
by clouds
r-i heats
land or sea
LAND or SEA
figure
reflected
by surface
2.1 Typical incoming (short-wave) solar radiation
(loo units)
IQ passes into space
The net radiation balance at the Earth’s surface is therefore:
(incoming solar radiation + atmospheric counter-radiation)(reflected solar radiation + outgoing terrestrial radiation)
atmospheric
counter-radiation
absorbed by
atmosphere
and reraaiated
back to surface
terrestrial
radiation
qq
LAND or SEA
figure
100
units
2.2 Typical outgoing (long-wave) radiation (100
units)
long-wave radiation to space
clouds block
(much greater if skies are clear)
radiation escaping
sensible heat
transfer by winds
latent heat from
condensation as
fog or dew forms
Sensible heat conducts to the surface
and at first warms the air above it.
Once the ground has lost all its heat, it
becomes cold and cools the air above it
figure
J
Daytime energy budgets
The word ‘diurnal’ means the 24-hour period of day and night
During the day heat comes from the Sun (in the form of short-wave solar
energy). Some of the solar radiation from the Sun (sometimes called insolation)
is scattered at the edge of the atmosphere, some is reflected back from clouds,
some is reflected off the Earth’s surface, some is absorbed by water vapour, dust
or carbon dioxide (CO J, and some is absorbed by the ground, which then heats
up (Figure 2.1).
The proportion of solar radiation reflected from areas of the Earth’s surface is
called the albedo. The albedo of a snow-covered mountain is 60 %, for a desert
it is 30 %, 13 % for an equatorial forest, 8 % for an ocean. Surfaces with a low
albedo, like the sea, are better able to absorb more heat.
The energy coming from the Sun is short-wave radiation. It heats the ground
and is then reradiated as infrared long-wave radiation known as terrestrial
radiation. Some of this terrestrial radiation passes into space but most is
absorbed by water vapour, CO2 and other gases in the atmosphere, which then
heats up. It is then returned as counter-radiation to the ground - atmospheric
counter-radiation (Figure 2.2). This is a vital source of heat - without it the
surface temperature of the Earth would fall by 25 °C.
2.3 The night-time energy budget.
Atmosphere and weather
Most of this net radiation balance is used to evaporate water turning it into
water vapour. When heat is used to evaporate water it becomes latent heatthat is, ‘hidden heat’ because when the water vapour condenses back into water
droplets it emits heat- the latent heat. Because energy is needed to overcome
the molecular forces of attraction between water particles, the change from
liquid water to water vapour- evaporation - requires an input of energy, causing
a drop in temperature in its surroundings. If the water vapour condenses back
to a liquid the latent energy absorbed during evaporation is released.
Sensible heat is the heat we feel. When air or water moves from one place to
another, taking its temperature with it, this is called sensible heat transfer.
Night-time energy budgets
At night with a cloudless sky the ground reradiates heat back into space and
eventually becomes cold. The air just above the ground is cooled by the cold
ground and if the humidity is high this causes water vapour in the air to
condense (turn to liquid), which is a cause of dew - water droplets on grass - or
fog.
If the sky is cloudy, however, there is less loss of long-wave radiation to
space. The clouds will return some of the radiation back to the ground and
temperatures will not fall as much.
The difference in temperature between day and night is called the diurnal
range. The diurnal range is greater in places with no clouds (such as deserts)
because there are no cloud barriers to solar radiation arriving in the day and no
cloud barriers to stop heat from the ground reradiating back into space at night.
Deserts are hot in the day and cold at night as a result.
The diurnal range is also influenced by the sea. The sea is cooler than the
land in summer so coasts affected by strong onshore breezes will be cooler than
places further inland.
The global energy budget
More heat is received in places nearer to the equator than places nearer to the
North or South Poles. In fact there is a net gain of radiation equatorward of
40° from the equator, a net loss poleward of 40°. These two zones would get
progressively warmer and colder respectively if there was not some transfer of
heat from the warming to the cooling zones; this heat transfer is carried out by
wind and ocean currents.
One important way in which heat is transferred is the thermohaline
circulation (Figure 2.4). Thermo means temperature and haline means salt,
and these currents reflect variations in temperature and salt content. The
thermohaline circulation is sometimes called the ocean conveyor belt. Warmer,
less saline water flows at the surface, cooler, saltier water flows in the deep
oceans. For example, the Gulfstream flows polewards on the surface from the
equator up towards Europe, cooling as it does so. Eventually the water sinks in
the North Atlantic because it is cold and more saline, both of which increase the
density, and it then moves back south as deep water.
The surface current becomes more saline over time because wind on the sea
surface causes evaporation but this removes only water molecules, resulting in
an increase in the salinity of the seawater left behind.
figure
2.4 Thermohaline circulation
Seasonal variations in pressure and wind belts
Figure 2.5 (a) is a simplified model of the distribution of pressure belts around
the globe. In reality these pressure belts are interrupted by the effect of the
irregular distribution of land and sea on pressure, but the general model still
applies as can be seen from Figure 2.5 (b) and Figure 2.5 (c) with cloud over the
equator (low pressure) and clear skies in the sub-tropics (high pressure).
Atmosphere and weather
air
POLAR
CELL .
figure
sinks
figure 2.5 (c) Global pressure belts and winds:
view of Africa and Europe from space.
2.5 (a)Theoretical model of global pressure belts
and winds.
The overhead sun moves north in the northern hemisphere summer and
south in the northern hemisphere winter and this causes the pressure belts to
move a little north and south, following the Sun (Figure 2.6).
Winds blow from high to low pressure but are deflected by the Coriolis
Force (spinning of the Earth) so, instead of going directly from high to low they
approach at an angle.
Around the equator where heating is greatest, air rises because warm air is
less dense; this gives the Equatorial low pressure belt. Low pressure is simply
air that is rising. This area is also called the Intertropical Convergence Zone
(ITCZ) because winds from north and south converge here.
Around 30° north and south of the equator the air which rose at the equator
starts to descend. Descending air creates high pressure so this is called the
sub-tropical high pressure belt. At ground level the air returns to the equator as
trade winds, completing a cycle called the Hadley Cell (Figure 2.5 (a)).
Warm air from the sub-tropical high pressure belt also moves poleward in
the Ferrel Cell until it meets cold air from the Arctic at the Polar Front. At this
point the air rises, creating low pressure - the temperate low pressure belt
(temperate means mild temperatures).
Air rising at the Polar Front moves poleward at high levels and descends at
the poles (forming the polar high pressure system) and then returns at ground
- 50"
40“
level as polar easterly winds, completing a cycle called the Polar Cell.
The pressure/wind belts shift north then south with the overhead sun
(Figure 2.6). Places in the centre of a pressure belt, such as the Sahara Desert,
are in the same pressure belt all year round; in the case of the Sahara this is
the sub-tropical high pressure belt. It rains very little when pressure is high.
The Mediterranean, however, is covered by the sub-tropical high pressure belt
in summer (when it is hot and dry) but in winter that belt shifts south and the
Mediterranean comes under the temperate low pressure belt and this creates
- 30'
their wet season.
Latitude
polar high
north
- 90'
80'
70'temperate low
sub-tropical high
60'
20" -
- 10'
Seasonal pressure cells
The model shown in Figure 2.5 is disrupted by the irregular distribution of land
- 0" -
equatorial low
10"
-20"
-30"
sub-tropical high
40"
50°
temperate low
polar high
JANUARY
figure
sub-tropical high
-60"
temperate low
70“
80"
90"
south
polar high
JULY
2.6 Global pressure belts move north and south
with the seasons.
Atmosphere and weather
and sea. High pressure tends to form over cold continental interiors in winter
(cold air sinks) and low pressure forms over heated continents in summer
(because hot air rises) (Figure 2.7).
The Indian monsoon is a product of this phenomenon. In winter high
pressure dominates over India and as a result winds blow out and it is dry. In
the summer low pressure builds and winds blow in; having come from Australia
across the Indian Ocean they are warm and humid and bring heavy rain - the
monsoon.
The effect of seasonal pressure cells is less in the southern hemisphere
because the continents taper and less land is far from the sea.
January pressure and winds
H/ru
H
An area of high
air pressure
" An area of low
air pressure
~
►
figure
Wind direction
2.7 (a) Pressure cells in January.
July pressure and winds
HIGH
n,'an
An areaofhigh
air pressure
IOW
An area of low
air pressure
----------- ►
figure
Wind direction
2.7 (b) Pressure cells in June.
Atmosphere and weather
Atmosphere and weather
Global temperature
There are six main influences on global temperature - latitude, the sea, ocean
currents, altitude, cloud and winds.
Latitude
Latitude is the distance a place is from the equator. The Sun is overhead or
nearly overhead at the equator all year round but at the poles the Sun is at a
greater angle to the ground (Figure 2.10). This means that when the Sun’s rays
pass through the atmosphere the angle of incidence is greater at the poles and
they therefore have a greater thickness of atmosphere to pass through - so
more heat is lost in warming the atmosphere. This greater angle of incidence
means that any given unit of energy is spread over a greater area at the poles
and more is reflected. The key factor is the angle of incidence: it is wrong to say
that ‘the equator is closer to the Sun than the poles’.
figure
2.10 The influence of latitude on temperature.
Latitude also affects the length of summer and winter. The Earth is tilted at
an angle of 66|° to the Sun and it moves round the Sun once every 3651 days.
In January the South Pole is tilted towards the Sun and it is summer in the
southern part of the globe (the southern hemisphere). In January the North
Pole is tilted away from the Sun so it gets less heat - it is winter. By July these
positions have reversed: the South Pole is tilted away from the Sun, giving it
winter, the North Pole is tilted towards the Sun, giving summer (Figures 2.8, 2.9
and 2.11).
JANUARY
figure
2.11 The tilt of the Earth creates the seasons.
The equator remains the same distance from the Sun all year round so areas
on the equator have no summer or winter.
Figure 2.11 also shows how the movement of the Sun round the Earth affects
the length of day and night. In January the North Pole is pointed away from the
Sun and the Sun’s rays only reach the northern hemisphere for a smaller part of
the day. But in January the South Pole is tilted towards the Sun so it gets long
days and short nights. By July the reverse is true - north of the equator days are
longer, south of the equator nights are longer.
All year round the lengths of the days do not vary at the equator: there are 12
hours of daylight and 12 hours of darkness every day of the year.
Atmosphere and weather E
The sea
Water has a greater specific heat capacity than land (specific heat is the amount
of heat required to raise the temperature of one unit of a substance by i °C). The
specific heat capacity of water in Joules/kg °C is 4181 but for soil it can be as low
as 2000. So it requires more heat to warm up water than ground. This is one
reason why water is cooler than the land in summer, so places close to the sea
or a large lake are cooler than places further inland.
Furthermore, the sea conducts heat down to greater depths whereas on land
heat is concentrated on the surface. Water also reflects more solar radiation than
land and it can evaporate, which cools it.
Once the sea or lake has been warmed by the summer sun, however, it retains
its heat better than the land. So the sea is warmer than the land in winter.
So the effect of the sea is to make nearby land areas cooler in summer
and warmer in winter. Such places have a maritime climate - a lower annual
temperature range. Places inland have hotter summers and colder winters and
this is called a continental climate.
If the sea had no influence then the hottest month of the year would be
the month when the Sun is most directly overhead -June/July in the northern
hemisphere-and the coldest months would be those when the Sun is at
the lowest angle and days are shortest- December/January in the northern
hemisphere. But because the sea takes a long time to cool down and then warm
up there is a seasonal lag - in the northern hemisphere the warmest month is
often August and the coldest month is often February.
figure
1.12 Maritime and continental climates in summer and winter.
Ocean currents
The spinning of the Earth creates a force (the Coriolis Force) that makes
oceans flow in currents, which are clockwise in the northern hemisphere and
anticlockwise in the southern hemisphere (Figure 2.13). If a current is flowing
from the poles towards the equator it carries cold polar water into warmer areasthese are cold currents. If a current flows from the hot equator towards the
poles it carries warm water into colder areas - these are warm currents. For
example, the North Atlantic Drift makes south-west England 12 °C warmer in
January than it would otherwise be.
Altitude
If you walk up a mountain it becomes colder at a rate of about 6.5 °C for every
kilometre. This is because the thin air of higher altitudes cannot hold heat.
Cloud
The hottest parts of the world are not on the equator but a little to the north
and south of it (Figure 2.9). This is because equatorial regions have much cloud,
which reflects the heat of the Sun. Further from the equator, in the sub-tropics,
the sky is clearer and temperatures higher.
Atmosphere and weather
Ocean currents
------- ►
Cold
—i►
Warm
' ►
Seasonal (changes speed or direction due to seasonal winds)
figure
2.13 Ocean currents
Warm
figure
2.14 Air masses over North America, January and July
Atmosphere and weather
Winds
Winds transfer warm or cold air from one place to another. So places in
the northern hemisphere, for example, are cold when winds blow from the
north - or from the east in winter (when the interiors of continents, with
their continental climate, are so cold). When winds blow from the south,
temperatures rise.
Winds that blow regularly and have uniform characteristics are called air
masses. Figure 2.14 shows which air masses affect North America. Warm winds
are called Tropical, cold winds are called Polar (T and P). Wet air masses from the
sea are called maritime (m), dry air masses from the land are called continental (c).
The hottest winds areTc (Tropical continental) because they blow from the
hot land.
Weather processes and phenomena
Atmospheric moisture
Humidity means the amount of moisture in the air. Warmer air can hold more
water than cold air.
When air is holding the maximum amount of water possible at a given
temperature it is saturated. Air holding less moisture than this is unsaturated.
If you try to add water vapour to saturated air or if you lower the temperature,
water vapour will condense out as water droplets.
Absolute humidity is the water content of air expressed in grams per cubic
metre. Air will be more humid if it has passed over water but dry if it has
dropped all its moisture as precipitation and moves inland.
Relative humidity is the amount of water vapour in the air expressed as a
percentage of the amount that would be present if the air was saturated. If the
temperature of a body of air rises, it can hold more water vapour and the relative
humidity therefore falls. If the temperature falls, it can hold less water vapour
and the relative humidity rises. At 100 per cent relative humidity the air is
saturated and the temperature at that point is called the dew point. The height
at which a body of air reaches the dew point is called the condensation level.
If you heat water it evaporates, changing from a liquid (water) to a gas (water
vapour). If you cool air to below its dew point temperature some water vapour
will condense out as water droplets. This is what happens in a cloud that is
rising (and getting cooler).
Condensation is when water droplets form after air is cooled to its dew point.
There are several ways this can happen:
•
radiation from the ground during a clear night-the cold ground cools the
•
•
•
•
layer of air above it
a warm wind blowing over cold ground
warm air meeting cold air
movement of air from warmer to colder latitudes
by ascent up a mountain.
Frontal
Sublimation is the transition of a substance directly from a solid to gas
without passing through the intermediate liquid phase, for example snow
evaporating without first melting.
sudden heavy rain
hot sun
warm
air
rises
air heated by ground
Precipitation
Precipitation includes rain, snow and hail. Precipitation happens when a body of
moist air is forced to rise. It rises, cools to below the dew point and water vapour
(a gas) condenses into water droplets (a liquid) creating a cloud. There are
three ways air can be forced to rise and this leads to three types of precipitation
(Figure 2.15):
1
2
Orographic-forced up by a mountain.
Frontal - warm air meets cold air and the lighter warm air is forced up over
the cold. The line where warm and cold air meet is always called a front.
3
Convectional - hot ground heats the air above it. The heated air becomes
ground heats up
Convectional
figure
2.15 Causes of precipitation
Atmosphere and weather
less dense as a result and rises.
Different parts of the world are affected by these three types of rainfall in
different ways. Orographic rain obviously occurs where there are mountains.
When winds have passed over mountains they descend, making rain unlikely;
this is called a rain shadow. This is why one side of the mountains is often wet,
and the other side is dry.
Frontal rain is commonest in the mid-latitudes where warm air coming up
from the tropics meets cold air from the poles. The weather systems that result
are called mid-latitude depressions.
Convectional rain is most common in equatorial and tropical regions which
are hot and where air is rising (the equatorial low pressure belt). Sub-tropical
deserts avoid much convectional rain because the prevailing high pressure
(descending air) prevents air rising far enough to reach the dew point.
Figures 2.16 and 2.17 show the distribution of precipitation in two halves
of the year. You can see that equatorial and mid-latitude areas are wet all year
round because they are low pressure all year round. In low pressure air rises,
cools and water vapour condenses to give rain. The sub-tropics, such as the
Sahara Desert, are dry all year round because air is descending in the sub­
tropical high pressure belt. North Africa is dry in the summer (high pressure)
and wet in the winter (low pressure). India is wet in the summer (low pressure)
and dry in the winter (high pressure).
Figure 2.18 shows the total precipitation for the year. You can see that
equatorial areas are the wettest (low pressure all year; heavy convectional rain
due to heat). The driest areas are:
•
•
•
in the sub-tropical high pressure belt, such as the Sahara Desert
In high latitudes in the northern hemisphere (polar high pressure and also
because cold air cannot hold much moisture)
in the rain shadow of mountains, such as the Andes in South America, the
Rockies in North America and the Himalayas in central Asia.
400- 599 mm
200- 399 mm
under 200 mm
figure
2.16 World distribution of precipitation during northern summer (May to October).
Atmosphere and weather
200 - 399 mm
under 200 mm
figure
2.17 World distribution of precipitation during northern winter (November to April).
figure
2.18 World distribution of total annual precipitation.
Ta Atmosphere and weather
stratus
(2 km or lower)
figure
2.19 Cloud types
Clouds
Clouds are of course caused in the same three ways as precipitation - by air
rising.
Not all clouds produce rainfall because clouds are caused by rising air- so
the raindrops have to be heavy enough to overcome the force of this rising air.
Furthermore, the droplets in clouds are too small to fall - their average size
is 0.1 mm while a raindrop is 0.5- 2.0 mm - so for a raindrop to form one or
more things have to happen:
1
2
3
There must be sufficient turbulence in the cloud to allow cloud droplets to
hit each other and coalesce (merge) to form raindrops.
Raindrops need a small particle of salt, soot, or dust to form around these are called condensation nuclei. If these are not present, droplets of
sufficient size will not form.
Snowflakes are formed and melt before they reach the ground.
figure
2.20 Cumulus clouds over Swifts Creek, Australia.
Snow
Snow is formed when water vapour condenses at a temperature below freezing­
point, passing directly from gas to solid state and forming small spicules of
ice. These unite into crystals that are either flat hexagonal plates or prisms. If
condensation continues these crystals unite into snowflakes and if the lower
atmosphere is cold enough they will reach the ground without melting. For
snow to form and fall there must be plentiful moisture in the atmosphere, a
sufficiently low temperature and fairly calm conditions inside a cloud.
Hail
Hail is common in mid-continental interiors in summer. It falls from lofty
cumulonimbus clouds, frequently at the passage of a cold front and after
exceptional local heating. Ascending air currents carry drops of water up until
they freeze into ice pellets. Drops of super-cooled water (water which has
figure 2.21 Cirrus clouds over the La Silla
Observatory, Chile.
Atmosphere and weather
managed to remain liquid even when the air around is below freezing) collide
with these ice pellets and freeze round them as a layer of clear ice. The pellets
may be carried still higher so water vapour freezes directly onto them.
Hailstones may rise and fall several times in a cloud before becoming so
heavy they fall to earth. This is why, if a large hailstone is cut in half, it may have
layers of clear ice (frozen water) and opaque ice (frozen water vapour).
Dew
Dew is water droplets on the surface of bodies such as grass that have been
cooled by the cold ground so the water vapour condenses as water droplets.
This normally happens when night-time radiation of heat from the ground
makes the ground cold - it then cools the layer of air immediately above it. The
necessary conditions for dew are air with a high humidity, clear skies to allow
radiation from the ground back into space, and calm conditions so that the layer
of air just above the ground remains in place long enough for it to be cooled.
High pressure creates these conditions.
Dew is a vital source of water for plants and crops in semi-arid countries
such as the Canary Islands and Israel.
night
calm air
high pressure
clear sky
heat radiates
out to space
cold ground cools air above it
------------------------------------------- --------------- —
Radiation fog
TadiationTog
«round cools
Fog
Fog is humid air that has fallen below the dew point and condensation has
formed a dense cloud of water droplets. To create fog you need calm conditions
(otherwise the fog is simply blown away), humid air and cooling. There are four
types of fog (Figure 2.22): radiation, advection, frontal and hill fog.
Radiation fog forms when the ground has cooled due to radiation from the
ground, usually at night in an anticyclone (high pressure)- clear skies with little
wind. This is common in river valleys because the air is humid and cold air,
being denser than the surrounding air, sinks down into the valley.
Advection fog forms when warm air passes over a cold surface - such as
warm air from the sea passing onto the land in winter or warm air from the
land passing over a colder sea in summer. For example, the Grand Banks
off Newfoundland in eastern Canada has fog 70-100 days a year caused by
warm air from the Gulf Stream meeting cold air from the Labrador Current
a mid-latitude depression
(Figure 2.13).
Frontal fog occurs when warm air meets cold air at a front. A front is a line
between warm and cold air.
Hill fog occurs when air is forced to rise up a slope and cools.
For fog to form you need condensation nuclei such as salt, dust or soot. Fog
is common in urban areas where coal is burnt including many cities in China
and such fog is often called smog.
The human impact
The greenhouse effect and global warming
The glass of a greenhouse admits short-wave solar radiation but blocks the
outgoing long-wave radiation, causing the inside of the greenhouse to heat up.
Carbon dioxide and other greenhouse gases in the atmosphere do the same
thing - they block some of the radiation trying to escape from the Earth into
space, they absorb that heat and reradiate it back into the atmosphere. In this
way they can cause the temperature of the Earth’s atmosphere to rise-this is
Hill fog
figure
2.22 Fog types
Atmosphere and weather
the enhanced greenhouse effect.
Carbon dioxide emissions have risen because of burning coal, oil and gas
since the beginning of the Industrial Revolution. The current level of CO2 in
the atmosphere is measured at the scientific recording station at Mauna Loa in
Hawaii. For periods in the distant past carbon dioxide levels are measured in air
bubbles trapped in the Antarctic or Greenland ice sheets. These measurements
together show that CO2 levels before industrial emissions began were 260-280
parts per million (ppm) and are now 401 ppm, possibly the highest level for
20 million years (Figure 2.23). So carbon dioxide levels have risen by 45 per cent
so far.
410
figure 2.23 Commissions show seasonal oscillations with each year’s maximum occurring during late
spring and then declining during the growing season as plants remove some of the atmospheric CO .
In addition to burning coal, oil and gas, carbon dioxide is produced by
burning wood and peat. Deforestation is another cause of global warming
because trees absorb carbon dioxide and the decomposition or burning of cut
trees releases CO2.
Other greenhouse gases are methane, ozone, chlorofluorocarbons (CFCs)
and nitrous oxide. Methane levels have risen 0.5-2 per cent a year due to
increasing numbers of cattle and paddy fields. CFCs are a man-made gas
used in aerosols, solvents and refrigerators. Nitrous oxides in the atmosphere
have increased by 8 per cent since the Industrial Revolution and come from
farming-from nitrogen fertilisers used on farms and the waste products of
farm animals.
The increase in greenhouse gases is thought to be a cause of global
warming. The Earth’s average surface temperature has risen about 0.7 °C
since 1900. More than 90 per cent of the additional heat has gone into ocean
warming with the remainder warming the atmosphere, so this is thought to
lead to the melting of snow and ice, glacier retreat, a decline in Arctic sea ice
and subsequent sea level rises. It might also result in the earlier timing of the
spring flowering of plants, reduced precipitation in sub-tropical latitudes and
increased precipitation at subpolar latitudes and on the equator. Many scientists
also believe that global warming is a cause of more extreme weather such as
heat waves and tropical cyclones.
It terms of the impact on plants and animals, it is expected that global
warming will lead to the poleward shift of plant and animal ranges and damage
to species most sensitive to temperature change such as Arctic tundra, mangroves
and coral reefs.
Sea water is naturally alkaline; increases in CO2 may lead to a decrease in
alkalinity because the carbon dioxide dissolves in sea water. This relative acidity
could further damage coral reefs and fish stocks.
Climate change is monitored by the Intergovernmental Panel on Climate
Change (IPCC), set up under the auspices of the United Nations. The IPCC
predicts that global mean sea levels could rise by 0.18-0.59 metres over the
course of the current century. Coastal flooding would be expected as a result
of this rise and the flooding would be worst in areas close to sea level, such as
the delta of the River Ganges in Bangadesh and low-lying islands such as the
Maldives.
The United Nations Framework Convention on Climate Change
(UNFCCC) is an international treaty first negotiated in 1992 that has been
signed by over 190 countries. In 1997 the Kyoto Protocol gave all High
The 2015 UN Paris Conference was
significant because all 196 countries
agreed to try to limit global warming
to a figure under 2 °C and to transfer
resources from richer to poorer countries
to help them achieve this. In a bid to spur
governments to lift their ambition, the
agreement includes a series of reviews of
emissions targets that countries will need
to undertake. These reviews will start in
2020, and then happen every five years. The
agreement says greenhouse gas emissions
should reach a peak as soon as possible and
then slide rapidly, so the total amount of
atmospheric pollution is brought to zero
by the latter half of the century.
Atmosphere and weather
Income Countries (HICs) targets for cutting emissions from the 1990 level by
2008-12; the European Union agreed to cut emissions by 8 per cent. These
targets were succeeded by the Doha Amendment in 2012, which established
further targets. In the UK, for example, the government’s new goal (set in
2013) was to produce 30 per cent of electricity in the UK through renewable
methods (wind, solar, tidal) by 2020 and to cut greenhouse gas emissions by
50 per cent by 2025 from 1990 levels.
Issues with climate change policies
Most scientists agree that the increase in carbon dioxide and other greenhouse
gases is causing global warming. A minority are less sure-the temperature of
the Earth is not steadily rising but going in fits and starts and the temperature
of the planet has been higher than it is today in the distant past. Since the end
of the Little Ice Age 200 years ago there have been two warming periods1860-80 and 1910-40-just as great as that of the past 30 years. In other words,
greenhouse gases are only one of several influences on temperature: other
important influences are the amount of heat emitted by the Sun (which varies),
the distance of the Earth from the Sun (which also varies), variations in the tilt
of the Earth’s axis, changes in the amount of volcanic dust in the atmosphere
and the movement of the continents by continental drift.
Global warming over the past 35 years has been slower than many scientists
originally predicted - only two-tenths of a degree per decade and slowing
almost to a halt in recent years.
As for the other predicted effects of global warming, there has been no
clear increase in the frequency or severity of storms or droughts and no
acceleration of sea-level rise. Arctic sea ice has decreased but Antarctic sea-ice
has increased.
Scientists who research climate change have a strong vested interest in
proving that it is a big problem - they need the problem to exist if they are to
get research grants. There is always the danger of bias in their research.
Another big unknown is the extent to which global warming and the
associated changes can be seen as a slow and gradual process happening over
many years, or whether there is a tipping point at which suddenly problems will
escalate. For example, it has been postulated that the melting of the Arctic ice
could trigger changes in ocean currents in the North Atlantic. The thawing of
the permafrost in northern Russia and Canada could release carbon dioxide and
methane, which would accelerate global warming.
Some people may benefit from global warming while others will suffer.
Farms in Canada and northern Europe, for example, may benefit from
warmer conditions. Farming zones will shift poleward 250 km for each 1 °C
of warming. MICs and Low Income Countries (LICs) are likely to suffer more:
figure 2.24 Projected annual mean temperature change.
These maps show projected change in annual mean surface
air temperature given moderate growth in CO2 emissions,
for three time periods, compared with the average
temperature for 1980-99.
Atmosphere and weather
if temperature rose 3 °C, for example, there might be a drop in crop yields
across Africa of 35 per cent.
There is much uncertainty about what level of warming will be manageable.
The level recommended by the IPCC is 2 °C but there is debate about whether
this is too much.
Another difficult area is knowing what should be done about global
warming. LICs object to MICs and HICs suggesting that they should burn less
coal, oil or gas - after all, developed countries are prosperous partly because
of the economic progress they have made on the back of burning fossil fuels.
China is building one coal-fired power station every week because to not do
so would be hugely harmful to their economy and the poor in that country.
The disadvantages of global warming, to which humans can adapt, are
outweighed by the massive benefits of fossil fuels.
Some countries feel that there is little point in their cutting back on use of
fossil fuels while India and China continue to build large numbers of fossil-fuel
based power stations. Unless all countries work together, the efforts of those
cutting back will have little impact.
11
Mean temperature
llllllll Annual mean temperature
°C
figure 2.25 Mean temperatures in New Zealand show tremendous annual variation, and are far more
significant than the modest long-term trend shown by the blue line.
figure
2.26 Sea levels in Vanuatu in the South Pacific peaked in 2009 then fell back.
Fossil fuels are still the cheapest and most reliable form of energy for
the majority of countries. In the UK the government has encouraged the
construction of wind farms as a more sustainable form of energy and one that
does not produce greenhouse gases. But wind farms are expensive, they are
regarded by many people as ugly, and they are only efficient when the wind is
blowing. It is hard to store electricity so conventional power stations burning
coal, oil or gas are a more reliable source of energy than wind farms.
At a global level renewable energy sources such as wind and solar have
contributed almost nothing to cutting carbon emissions. Wind power
generates i per cent of the world’s energy, solar power generates even less
than that.
Case Study
Urban
climate:
Chicago
The flat terrain of the Midwest and Lake Michigan make Chicago’s weather
unpredictable and frequently extreme. Summer is very warm and often humid.
The highest temperatures occur throughout July and August and can reach
35-38 °C. The coldest days are usually in January when the temperature can drop
below-18 °C. Chicago receives an average annual rainfall of 80.5 cm per year.
Temperature
Chicago, with a population of 2.7 million people, is warmer than the
surrounding rural areas - it is an urban heat island. The temperature difference
Atmosphere and weather
Figure 2.27 Chicago
can be as great as 3 °C on a sunny day and 6 °C at night in winter. These
temperature differences have a number of causes:
Building materials have a lower specific heat capacity than grass and trees.
Specific heat capacity is the amount of heat required to raise one unit of
the material 1 °C. The specific heat capacity of concrete is 800 Joules/kg °C
1
2
3
whereas for soil it can be 2000 Joules/kg °C. So concrete heats up more
quickly in the day, warming the air around it.
Rural areas have more wet surfaces (in towns, rivers are often covered and
water runs off into drains). Evaporation from these wet surfaces produces
cooling because heat is absorbed by the process of evaporation.
Buildings are heated, and vehicles and air conditioning systems generate heat.
Types of area
figure
Atmosphere and weather
2.28 Temperature profile across Chicago in June.
4
5
Buildings act as a barrier to winds. As winds could in theory convey
cooler temperatures from Lake Michigan, this has the effect of keeping
the city warmer.
Buildings with dark surfaces such as roof tiles have a lower albedothey reflect less solar radiation, absorb more and become hotter. Dark­
coloured tarmac, often used as a road surface, has a low albedo.
The denser the built-up area, the hotter it tends to be, so the central
business district is the warmest part of the city.
Temperature contrasts are greatest when wind speeds are low because
wind will carry in cool air from outside the city. Wind speeds are always
lowest when air pressure is high.
The urban heat island effect tends to be greater in winter because more
heat is being generated to keep buildings warm. The effect is also greater
at night because buildings store heat generated during the day and slowly
emit it at night. A field in a rural area is pointing towards the sky and will
reradiate long-wave radiation back into space if the sky is clear. A canyon
of buildings does not point towards the sky and this lack of a ‘sky view’
impedes reradiation.
The City of Chicago government aims to mitigate the urban heat
island effect by giving grants to residents and firms who plant rooftop
gardens and trees in their gardens. They have also resurfaced pathways
in the city with surfaces that have a higher albedo and thus reflect more
solar energy. Figure 2.29 shows the resulting decline in the albedo in
recent years.
figure
2.29 Chicago albedo change, 1995-2009.
Atmosphere and weather
figure
2.30 Chicago tries to cool the urban heat island.
Humidity
Chicago is less humid than the surrounding rural areas because:
1
2
The city is warmer, and higher temperatures lower the relative humidity.
Precipitation is quickly removed from the surface into drains. Surfaces in
3
towns are impermeable and water runs off quickly into drains. In rural areas
water is held in the soil and this raises the humidity of the air above.
Vegetation in rural areas emits water vapour by the process of transpiration.
Precipitation
Because Chicago is warmer, the hot air is more likely to rise and if it has a high
humidity it will cause convectional rainfall (page 48)- short intense bursts of
rain and thunderstorms.
Urban areas produce particles of dust (notably soot) and these act as
condensation nuclei, which encourage rain production (page 49).
Because of the warmer temperatures there is less snow in the city than
surrounding areas.
Winds
Winds are lower in Chicago than the countryside because the buildings act as
barriers (wind breaks). On the other hand, long streets with tall buildings can
act as wind tunnels-winds are funnelled down the street - and Chicago is
notoriously gusty as winds are channelled round buildings (eddying).
Atmosphere and weather
NOW INVESTIGATE
1
Investigate the climate of the country in which you live. What are the precise influences on month-by-month
temperature and rainfall averages?
2
Look up the temperature and precipitation levels in different parts of the country where you live. What are the
reasons for these variations?
3
Look at the map of weather records shown in Figure 2.31. Research these places and explain why each experienced
the record they did.
4
Make a list of all the possible consequences of climate change.
5
Research the various responses in different countries to the challenge of climate change.
Atmosphere and weather
Intermediate
Porphyritic-aphanitic
Raindrop
impressions
Ultramafic
Felsic
Mafic
Abrasion
Obsidian
Fine grained
Basalt
Rhyolite
Glassy
Composition
types
Vesicular
Scoria
Root wedging
Erosional
agents
Andesite
Tuff
Composition
Sediments
Peridotite
Coarse grained
Texture
Diorite
Classification
Pegmatitic
Sedimentary
structures
Weathering
agents
Examples of volcanic
igneous rocks
Volcanic
Plutonic
Flute
casts
Ice wedging
Pyroclastic
Porphyriticphaneritic
Exfoliation
Granite
Gabbro
Weathering
and erosion
Examples of plutonic
igneous rocks
Subduction zones
The Rock Cycle
Divergent boundaries
Boundary
types
Igneous
rock
Magma pockets
Igneous
Rocks
Formation
Lava domes
Igneous rock
identification
methods
Volcano
types
Cinder cones
Igneous Rocks
Formed from molten
rock called magma.
Made up of interlocking
crystals and usually
very hard to break.
Volcanoes
Visual
Composite
Modal analysis
Petrographic
Melting
Shield
Geochemical
Hazards
Lava flows
Directed blasts
. ,
,
.
Avalanches and
landslides
Earthquakes
Pyroclastic flows
Tsunamis
Tephra
Volcanic gases
Lahars
Pyroclastic surges
The Rock Cyc e is a continuous process which can
take millions of years. The physical characteristics
of a rock will depend on its origin, the environmental
conditions in which it is found and the processes of
weathering and erosion it is exposed to on the
surface of the earth.
Magma
Melting
Metamorphic Rocks
Igneous or sedimentary
rocks changed (metamorphosed)
as a result of intense heat and/or
pressure within the Earth’s crust.
Ripple
marks
Fossil plant
roots
Mud
cracks
Well rounded
Sand
Animal
tracks
Reaction with
hydrochloric acid
Poorly sorted
Graded
bedding
Size of
particles
Relative
smoothness
Well sorted
Hardness
Range of
clast sizes
Clast size
Compacting and
cementation etc.
Calcite
Clast rounding
Dolomite
Physical
properties
Sedimentary
identification
Gypsum
Minerals
Sedimentary
breccia
Sedimentary
rock
Dolostone
Sedimentary
Rocks
Sandstone
Examples of
sedimentary rocks
Sedimentary Rocks
Formed from sediment
grains deposited by water,
wind or ice. Formed in
layers, called “beds’1 or
“strata”, and often
contain fossils.
U
Mudstone
Limestone
Formation and
lithification
Evaporite
Metamorphic
rock
Conglomerate
Pressure and
heat
Cementation
— Types of
metamorphism
Heat
Low
Impact
Fluids
present
Pressure
Intermediate
Contact
High
Formation
Meteorites
and comets
High
Significant
Low
Fault zones
Subduction zones
Shear
Bake zones
None
Some
Intermediate
Rocks and weathering
Cross
bedding
It is estimated that the Earth was formed about 4.6 billion years ago (4600
million years ago) by mass planetary movements in space. It is believed that
the explosive energy resulting from the birth of our Sun was the momentum
needed for space debris to combine for over 20 million years before forming
the planets we now recognise in our solar system. A complex process of meteor
showers, gravitational movements and volcanism would then slowly help to
sculpt a home for life.
Most of what we recognise on Earth today is the result of the last 600 million
years with human life only identified as existing within the last 195 000 years.
The Earth and its features have been in constant evolution being continually
grown, shaped and eroded through many physical processes that are still
operating today.
The continued movement of the Earth and corresponding shifts in climate
and global position have resulted in varying characteristics. The characteristic
formed at a particular time or period has been given a name based on modern
interpretation and discovery. Through each time period the Earth’s creatures
have lived and died.
Plate tectonics
The notion of plate tectonics was first instigated in 1912 by German
meteorologist Alfred Wegener whose work included the theory of continental
drift. Though many people had professed to notice the similar shapes and
jigsaw-like fit of some continents and land masses, Wegener sought to find
evidence from a variety of sources to prove his theory that the continents were
slowly drifting across the surface of the Earth. Many were sceptical, seeing no
clear mechanism for such large scale movements.
From the evidence outlined below, Wegener deduced that at one time
the Earth was one land mass - a super continent known as Pangaea.
Pangaea later split into Gondwanaland and Laurasia before breaking
into additional landmasses over time. Now it is widely accepted that the
continents are indeed moving in different directions under the influence of
large thermic currents under the surface of the Earth. Wegener’s pioneering
discoveries have led to greater depth of study and more comprehensive
evidence.
Evidence for plate tectonics
• Geology: Many rocks of a similar age, structure and composition have been
found on land masses now thousands of miles apart. For example, the Blue
schist of North Wales were formed with those of the east coast of the USA.
• Fossils: Fossils have been found of key species in Africa, India and Antarctica.
Fossils of the fern Glossopteris have been found in all southern continents as
well as Lystrosaurus- a large mammal-like dinosaur that was not known to
swim or fly.
figure
3.1 Pattern of continental drift from Pangaea to the
present day.
Rocks and weathering
figure
3.2 Lystrosaurus, fossil evidence for plate tectonics
•
Climatic evidence: Evidence of ice sheets and glaciers has been found in
the tropics. Even during the Earth’s coldest periods it was impossible for
ice to be formed there unless these areas were once closer to the poles.
Coal has been found in Antarctica. Coal forms in tropical conditions.
•
•
This means that Antarctica must have been closer to the equator at some
stage.
Sea floor spreading: In 1962 Harry Hess studied the age of rocks across the
Atlantic. He determined that as new rock is created from plate movements
widening the Mid-Atlantic Ridge older rocks are pushed to the edges.
Estimates suggest that the Atlantic is widening by an average of 2 cm
each year.
Paleomagnetism: During underwater volcanic eruptions, basaltic lava
is intruded into the crust and cools. Everytime new rock or minerals
are created, the magnetic orientation of the time is imprinted in them.
Experiments have shown a periodic reversal of the magnetic field showing
a pattern of alternating north-south aligned sediments.
The structure of the Earth
The Earth is often classed as spherical though its equatorial diameter is slightly
wider than its polar diameter. It is composed of a series of layers ranging in
density and thickness to its centre. Each layer has specific characteristics that are
fundamental to the mechanisms of plate tectonics and continental drift. Many
comparisons are made to the structure of an egg, which clearly defines three
parts - the shell, white and yolk corresponding to the crust, mantle and core
respectively. Whilst this is useful as a visual aid, the true nature of the complex
interactions can only be explained with a more detailed understanding.
north pole
figure
3.4 Structure of Earth
The lithosphere
The lithosphere is the outermost layer composed of the crust (the Earth’s outer
layer) and the rigid upper part of the mantle. It is the lithosphere that was
‘cracked’ into tectonic plates during the Earth’s formation. There are seven major
plates, eight minor plates and a number of smaller fragments known as micro
plates. These plates are rigid and sit on the semi-molten mantle below known
as the asthenosphere. The largest plates are the Antarctica, Eurasian and North
American plates.
Rocks and weathering
&
Active volcano
figure
3.5 Plate boundaries and direction of movement
Recent volcanic eruption
between 1965 and 2015
Major earthquake zone
0
Major earthquake
between 1965 and 2015
Plates can be divided into two main categories based upon their formation
and the composition of the rocks or crust they are made up of.
Continental plates are on average 125 km thick, reaching their greatest
thickness at large mountain ranges. The continental crust (known as sial) is
composed of older lighter granitic rock that is rich in minerals such as silica and
may range from 5-70 km thick.
Oceanic plates are thinner than continental plates, only reaching a thickness of
50-100 km thick, of which the upper 5-10 km may be crust. They are composed
of younger and denser rock of balsaltic origin. The boundary between the crust
and the mantle is known as the Mohorovicic Discontinuity or Moho for short.
Plate movement and boundaries
The Earth’s core still retains much of its radioactive heat from its early
formation. As the radioactive isotopes break down, the immense heat generated
creates convection currents within the mantle. The hot molten, viscous rock
is then forced to rise and older rock descends creating a cycle that allows the
overlying plates to drift along. However this process is impossible to verify, even
with modern technology, and as a result several additional theories have been
sought to explain continued plate movements.
The slab-pull mechanism is also referred to as dragging theory. In this
scenario the oldest edge of a plate furthest from the molten magma becomes
cooler and more solid. This solid denser material descends at a subduction
zone. Hotspots are vertical plumes of magma that can be found both at plate
boundaries and within the middle of a plate. Hotspots occurring within a plate,
such as Hawaii which is centrally located in the Pacific Plate, are referred to as
intraplate hotspots and are characterised bu volcanic activity. As the tectonic
plates move, upsurging magma will continue to be extruded creating a trail of
volcanic islands.
The mechanism for plate movement is still a subject of debate.
The edge of a plate is called its boundary or margin. Plates interact with each
other as they move. This movement is largely restricted to three main directional
motions - convergent (together), divergent (apart) and transform (side-by-side) —
but there are four associated margin types, which are summarised in Table 3.1.
Rocks and weathering
table
3.1 Types of plate boundary
Image
Name
Explanation
Divergent
Atlantic
Ocean
North Amerle,n
,
,
Mid-Atlantic
Eurasian
plate
Constructive
plate
boundary
Transform
Conservative margin
Conservative
plate
boundary
Destructive
plate
boundary
oceanic crust
continental crust
lithosphere
thosphere
asthenosphere
A constructive plate boundary
occurs when tectonic plates
move apart creating an
upwelling of magma from
beneath. As the plates rarely
move rapidly and with little
contact with each other,
seismic activity is less. Volcanic
activity may be present.
The North American and
Eurasian plates are moving
away from each other along the
line of the Mid-Atlantic Ridge.
Iceland lies on this divergent
boundary and has formed due
to this and a hotspot.
A conservative or transform
boundary is characterised
by two plates moving side
by side. Often plates will
move at different rates or in
different directions, which
puts increased stress between
the two ‘slabs’. As friction
increases so too will the
potential for earthquakes.
A classic example is the San
Andreas fault in California. The
Pacific plate is moving more
rapidly northwest than the
North American plate by an
average of 30 mm a year. The
fault is 1300 km long, extends to
at least 25 km in depth, and has
a northwest-southeast trend.
A destructive plate boundary
results from a convergence of
oceanic and continental plates.
As they are forced into each
other the denser oceanic plate
subducts under the thicker
less dense continental plate.
The subducting plate becomes
increasingly magmatic due to
intense heat and pressure as it
is destroyed. Volcanic activity
may result along with seismic
The Andes have been created by
the eastward movement of the
Nazca plate towards the South
American plate by 79 mm each
year. The descending Nazca plate
is forced down beneath the South
American plate causing it to
fracture and deform. This results
in shallow focus earthquakes
and a deep ocean trench.
Explosive andesitic magma
creates volcanoes such as the
stratovolcano Lascar in Chile.
Convergent
activity.
Collisional
plate
boundary
continental crust
continental crust
lithosphere
"
asthenosphere
J
lithosphere
— ancient oceanic
crust
continental-continental convergence
Ocean plate­
ocean plate
boundary
oceanic crust
continental crust
lithosphere
asthenosphere
oceanic-oceanic convergence
lithosphere
Example
A collisional plate boundary
occurs when plates of equal
thickness and densities
collide. Though this may be
at a relatively slow rate, the
extreme pressure is great
enough to develop huge
mountain chains. Continental
crust is thickest here and as
a result magmatic intrusions
are rare.
The Himalayan mountain range
and Tibetan plateau formed as
a result of collision between the
Indian plate and the Eurasian
plate. The Himalayas are still
rising by more than 1 cm per
year as India continues to
move northwards into Asia,
which explains the occurrence
of shallow focus earthquakes
in the region. According to
seismological data, the ground
beneath Kathmandu may have
moved about 3 m southward as
a result of the 2015 earthquake.
Subduction zones may also
be formed at an oceanicoceanic convergence zone.
In this situation the melted
subducting plate may result
in submarine volcanoes that
may eventually breach the
surface to form islands. As
these islands occur along a
boundary several chains may
be formed and are referred
to as Island Arcs. Oceanicoceanic subduction results in
seismic and volcanic activity.
The islands of Japan and the
Philippines sit at the junction
of several plates, the Eurasian
plate, the Philippine plate and
the Pacific plate. The Ryukyu
Islands are an island arc
created by the Philippine plate
subducting below the Eurasian
plate.
Rocks and weathering
(b) Period of reverse magnetism
(c) Period of normal magnetism
figure
3.6 (a), (b) and (c) Divergent plate boundaries, sea floor spreading.
Sea floor spreading
Divergent plate boundaries occur more commonly in the oceans and are
responsible for creating large oceanic ridges and, in combination with other
factors, islands such as Iceland.
It was not until the early 1960s that the concept of sea floor spreading was
considered one of the mechanisms of continental drift. In the Atlantic this
constant ‘conveyor belt’ motion is creating enough new ocean floor to widen the
Atlantic ocean by 2 cm a year, meaning continental North America and Europe
are slowly moving further apart.
Since the 1960s, sea floor spreading has been investigated extensively. When
lava cools on the sea floor magnetic grains in the rock align themselves in
accordance with the Earth’s magnetic field at the time of cooling. This effect of
paleomagnetism can be seen in Figure 3.6.
Subduction zones
Subduction zones occur at collisional plate margins where there is a
difference in plate density. In oceanic-continental plate collisions they are
generally formed where denser oceanic plates descend under a continental
plate into the hot molten layers of the upper mantle. Subduction usually takes
place at angles of 30-70°, experiencing an increase in gradient with depth.
The dip of the subducting plate is inversely proportional to the speed at which
the plates converge. There are several features associated with subduction
zones:
•
•
Oceanic trenches or deep-sea trenches are long narrow depressions in
the surface of the seafloor along a plate boundary formed as a result of the
descending oceanic plate. Oceanic trenches form the deepest parts of the
ocean and range between 6000 and 11 000 metres deep where the Mariana
trench lies to the east of the Pacific Ocean.
A Benioff zone (sometimes referred to as a Wadati-Benioff zone) is a planar
zone of seismicity corresponding to a subducting plate. A planar zone is a
zone along a line or plane within the rock structure. Wadati-Benioff zone
earthquakes develop along the boundary between the two plates as friction
dictates (Figure 3.7).
3
Rocks and weathering
•
Fold mountains and folded sediments are formed by the compression of
marine sediments trapped between the converging lithospheric plates at a
convergent boundary. These marine sediments are distorted under extreme
pressure and thrust upward creating a chain of mountains and volcanoes.
The Himalayas are a fine example of fold mountains created by sediments
in the Tethys Sea that are now influenced by orographic uplift and continue
to shape the greatest mountain range and highest mountain on Earth,
Mount Everest.
• deep earthquakes
(mainly thrust faulting)
figure
3.7 Benioff zone
figure
3.9 Mount Everest and nearby Himalayan peaks including Nuptse and Lhotse.
figure
3.8 Formation of fold mountains
Rocks and weathering
F
Orogenesis
Mountain building is the term given to areas of the Earth's surface that
experience up-thrusting as a result of convergent plate boundaries. All of the
major mountain chains are the result of this process of mountain building or
orogenesis and are formed by a combination of inter-plate deformities. The
Himalayas is perhaps the best example of orogenesis, created by the AustralianIndian plate forcing into the Eurasian plate some 70 million years ago. Though
the effects of this are still ongoing, the rate of uplift is lessened and countered by
the effects of weathering and erosion on the mountaintops. The Andes is another
example of mountain building, this time created by the force of the collision and
resultant subduction of the Nazca plate under the South American plate.
Weathering
Weathering is the natural process of decomposition and disintegration of rock
in situ (original position). Unlike fluvial erosion (river erosion), weathering is
brought about by changes in atmospheric conditions such as temperature,
moisture and wind acting on a stationary object. The intensity of the weather
conditions will be reflected in the rate of weathering, decomposition and
disintegration. The rate of weathering will also be heavily influenced by the type
and structure of the rock. Weathering is greatest where:
•
•
•
there are extreme weather conditions
there are poorly resistant rock types
the rock has been exposed for a long time.
There are two main types of weathering: mechanical (physical) weathering
and chemical weathering.
Mechanical weathering
Mechanical or physical weathering is the disintegration of rock into smaller
particles through mechanical processes without a change in the chemical
composition of the rock. Mechanical weathering is more likely to be as a result
of forces acting on the rock. This type of weathering is more common in high
altitude areas, arctic areas and deserts where vegetation is sparse. The weathered
material usually forms sand.
There are four main types of mechanical weathering: freeze-thaw, salt
crystallisation, thermal expansion and pressure release.
Freeze-thaw (frost shattering)
This process occurs when ice crystals are formed from water in cracks and
joints at o °C. As water, on freezing, occupies 9 per cent more volume, it exerts
pressure within the joints. Eventually, after continued freeze-thaw, pieces of rock
figure 3.10 Frost shattered rock litter on the slopes
surrounding Great Staple Tor, Devon, UK.
may be shattered from the main body.
Freeze-thaw is most effective in periglacial and alpine regions where
moisture is plentiful and there are frequent fluctuations above and below
freezing point. As a result it is often possible to see evidence in the form of scree
and blockfields. Scree or talus are the names given to a collection of shattered
material that lies at the foot of a steep slope. Blockfields (felsenmeer) are large
angular blocks that have become detached from the main rock body and are
usually found on gentler slopes. On Dartmoor much of the granite tors have
been subjected to frost shattering, creating large expanses of‘rock litter’ on the
slopes below them known as clitter fields.
figure
3.11 Honeycomb weathering in a Cambrian
sandstone,-Timma Valley, Negev Desert, Israel.
0
Rocks and weathering
Salt crystallisation (salt weathering)
Salt crystallisation results from the expansion of salt particles that have entered
pore spaces within the rock. It is particularly common in coastal environments
where sea cliffs are exposed to sea spray but can be found wherever there is
water with a high proportion of salt, usually as a result of high evaporation
rates. As temperature rises the salt crystals expand and grow exerting pressure
on the rock. A type of salt weathering that creates cavities in a rock surface is
known as pitting or honeycomb weathering due to its aerated appearance.
Thermal expansion (insolation weathering)
Thermal expansion is found in areas with a large diurnal (daily) temperature
range such as hot deserts. One such example is Snake River Plain in the USA,
which experiences an average daily high of 38 °C and a night-time low of 5 °C.
Rocks heat up and expand by day but contract at night weakening the outer
layers of rock and creating peeling or exfoliation. Despite the dry conditions
of deserts it is widely believed that moisture or mineral particles are essential
ingredients for rock disintegration.
Temperature may affect rocks in a number of ways. Block disintegration
occurs in heavily jointed rock, where splits are formed along weaknesses
which then break in to large easily defined pieces. Granular disintegration is
the breakdown of rock into small pieces, where joints and weaknesses are less
defined. In addition to these, layers of rock may peel off the exterior surfaces
exposing new surfaces underneath, this is known as exfoliation.
Pressure release
Pressure release is the process where overlying rocks are removed by erosion.
Many rocks have been formed under extreme amounts of pressure over millions
of years. One example is the granite batholith of Dartmoor, which was formed
by an igneous intrusion into overlying sedimentary layers.
The weight of overlying layers squashes lower layers during formation
and forces the rock to contract under pressure. The eventual erosion of these
upper layers allows the unroofed lower layers to relax and crack. A common
comparison is the feeling you get when you take off a large rucksack and your
back and spine is able to relax after carrying a heavy weight. Pressure release can
be identified by large horizontal cracks and joints that resemble bedding planes
but are not bedding planes. These are known as pseudo bedding planes. As the
cracks and joints are further worked on by other processes they become wider
and deeper.
Rocks that may be exposed to a horizontal shift in pressure through such
things as a landslide or coastal rockfall may experience vertical pressure release
cracks, though they are often smaller and further apart due to relatively less
pressure.
3.12 Granite batholiths in Dartmoor
National Park, UK.
figure
Chemical weathering
Chemical weathering is the decomposition of rock resulting from a chemical
change. Often this is the result of the interaction between rocks and moisture,
which leads to dissolved particles and the formation of clays. Chemical
weathering is more likely to take place in warm moist vegetated areas.
There are several processes of chemical weathering that may operate in
isolation or in combination.
•
Oxidation: occurs when rocks become exposed to air. Often this can be seen
as earth is moved, holes are dug or mass movement exposes underlying
rock and soil. Iron-rich soils and rocks may appear grey or blue in colour
until exposed to the air. The previously ferrous soil and rock will then oxidise
and change to a ferric state, turning a rusty orange colour. This same
process occurs in iron-rich metals that become exposed to air. Cars, for
example, will rust once the outer paint layers have been stripped away and
the metal becomes exposed to weathering.
4FeO + O; = 2Fe2O3
ferrous oxide + oxygen = ferric oxide
•
Hydrolysis: is particularly significant in the decomposition of rocks to form
clays. Hydrolysis is the process by which chemical bonds are broken and
the components partner up to form different elements. Hydrolysis literally
means reaction with water. Hydrolysis is a reaction involving the breaking
of a bond in a molecule using water. The reaction mainly occurs between a
hydrogen ion in water molecules and often changes the pH of a solution.
Rocks and weathering
On granite landscapes hydrogen in water reacts with minerals in the rock
and are washed through attaching to silicic acid and potassium hydroxyl in
•
figure
3.13 Malham’s limestone pavement, Yorkshire,
•
UK, where carbonation has been accentuated by biological
weathering.
a process known as chelation. Here positive ions attach to negative ions to
form a bond. The end product is a fine grey clay called kaolin (also known as
china clay), which is considered a mineral of national strategic importance in
many countries for its widespread use in glossy paints, magazine print and
even as a bulking agent in pharmaceuticals.
Acidification: is the process by which liquids become acidic and is a
common way in which rocksand minerals are dissolved. The greaterthe
concentrations of acids, the greater the effect of weathering.
Carbonation: is the process where carbon dioxide, often from rainwater,
produces carbonic acid (H;CO3). This is a weak acid solution that reacts with
calcium carbonate rocks, such as chalk and limestone. As a result of this
interaction rock will dissolve away rock, creating such features as limestone
pavements.
Carbonation: CaCtJ heat > CaO + CO2
•
Acid rain and solution: is caused by greater concentrations of carbon
dioxide, sulfur dioxide and nitrogen oxide as a result of human activities.
These gases then form acids as they combine with water vapour and fall as
rain. As with carbonation, acid rain attacks limestone and chalk more readily
but also other soft rocks such as sandstone.
•
Hydration: is related to the absorption of water by rocks. Certain rocks
are particularly capable of absorbing water into pores and cracks in their
structure. The rocks then swell, sometimes repeatedly in alternating dry and
wet conditions and can even change state. One such example is gypsum,
which is produced as a result of anhydrite absorbing and locking away
moisture. This process is reversible but only if the gypsum is heated to
around 200 °C. This process is actually known as a physio-chemical process
as a result of the water exerting a pressure on the rock.
Biological weathering
Biological weathering is the combined processes of mechanical (physical) and
chemical weathering. Tree roots and plants have the ability to grow in cracks
and joints in rock. As they grow they force the cracks and joints to widen
figure 3.14 The effects of chemical and biological
weathering often do not occur in isolation. Generally there
is a combination of processes present in the decomposition
through physical pressure until they eventually become detached. It is also
claimed that burrowing animals and macro invertebrates may play a small role
of rocks.
in this process.
2] intense weathering
□ moderate weathering
figure
Rocks and weathering
| slight weathering
I
I unweathered rock
3.15 The relationship between temperature and precipitation and its effect on depth of weathering
(from Strakhov, 1967).
0
|
The decomposition and decay of organic material is also responsible for the
chemical breakdown of rocks. The greater the amount of moisture, acidity and
temperature acting on a rock can all increase the rate of chemical weathering.
This is often referred to as organic action.
Controls of weathering
Climate
Climate is a major control in the type and rate of weathering taking place in
an area. Whilst it may be expected that the greater the extremes in climate
the greater the weathering, the pattern is not always so clear to see. There is a
complex relationship between temperature and precipitation and its effect on
the depth of weathering, which can be seen in Strakhov’s diagram (Figure 3.15).
Attempts to map weathering across the United States showed that there were
too many variations to produce a conclusive pattern over large spatial scales.
However on a local scale it can be observed that as temperature and precipitation
increase so too does the depth and extent of weathering on a rock face.
In 1950 Louis C. Peltier, an American physicist and climatologist, attempted
to predict the global variation of weathering for any given place based on mean
annual temperature and mean annual rainfall. He noticed some important
characteristics:
Mechanical weathering - frost shattering is an important process that
operates around o °C but will not operate:
•
•
•
•
•
during extreme cold or prolonged periods of freezing temperatures
during prolonged periods of warm temperatures
when there is little moisture available to freeze and expand in cracks and
joints
when there is too much moisture to freeze
when thick vegetative cover protects against insolation.
Figures 3.16 (a), (b) and (c) highlight the relationship between types of
weathering and atmospheric conditions.
Rainfall (mm)
figure 3.16 (a) Mechanical weathering: X =
too warm and heavy rainfall, Y = too warm and
insufficient moisture.
figure 3.16 (b) Chemical weathering:
Z = insufficient temperature and moisture to
allow the chemical breakdown of rocks.
figure 3.16 (c) Weathering in relation to mean
annual temperature and rainfall.
Chemical weathering:
• It is thought that the rate of chemical weathering doubles with every 10 °C
temperature rise.
• In tropical environments surface flows are considered an influential
mechanism for removing the heavily decomposed rock material that has led
to a lowering of the landscape.
Rocks and weathering
0
Geology
The type and structure of rock also determines the rate of decomposition and
figure
disintegration.
Rocks can be categorised into sedimentary, metamorphic and igneous
based on their formation. Compressed sedimentary rocks tend to have a
weaker structure than those formed with intense heat and pressure. Due to the
extremes experienced igneous rocks tend to be the most structurally resilient.
However it is important to note that different rock types are susceptible to
different weathering agents.
Limestone, for example, is a sedimentary calcium carbonate rock formed
from the decomposition of marine life. Limestone is particularly susceptible
to acid carbonation. Granite on the other hand, an extremely resistant igneous
rock formed from the cooling of molten magma, is prone to hydrolysis due to
the presence of feldspar. Therefore, whilst degree of resistance is an important
control of the weathering process, chemical composition and mineral content are
also crucial in determining the rate of decomposition.
Quartz also has an influence on weathering. Rocks composed of quartz may
be more resistant to weathering than rocks made up of less-resistant minerals.
Quartz is rarely affected by dissolution (dissolving a solid to form a solution),
hydrolysis, and oxidation, therefore rocks composed almost exclusively of the
mineral quartz will break down more slowly than other common rock types.
Sand on a beach is made up almost completely of quartz grains because
chemical weathering alters less resistant feldspar minerals and the resulting
3.17 The relationship between rock types.
clays are deposited elsewhere by streams or shoreline currents.
Weathering rate
SLOW
--------------------------------------►
FAST
BEDROCK TYPE
Mineral solubility in water
Low (e.g. quartz)
Moderate (e.g. feldspar)
High (e.g.) calcite
Massive
(e.g. basalt)
Some zones of weakness
(e.g. schist)
Very fractured or
thinly bedded
(e.g. slates and shales)
Rock structure
,
CLIMATE
Extreme variation, moderate
temperature variation (and/or
exposure to extreme temperatures,
hot OR cold)
Stable temperature and/or
no exposure to extremes
in temperature
Temperature
High
Moderate
Low
Rainfall
SOIL AND ORGANIC CONTENT
Thickness of soil layer
None-bare rock
Thin to moderate
Thick
Low
Moderate
High
Organic content
LENGTH OF EXPOSURE
Short
Moderate
Long
Moderate
Gentle slopes
TOPOGRAPHY
Steep slopes
figure
3.18 Factors controlling rates of weathering
Rocks and weathering
Arctic Circle
Equator
Mountain
I
Ice cap
Tundra climate —Polar
Sub-arctic
Continental climate (1)
Continental climate (2)
—Temperate
Temperate
Wet subtropical^
figure
table
| Mediterranean
Semi-arid
. . ,
i*. HAnd
Desert climate J
Rainy tropical climate (3)"1_
.
Rainy tropical climate (4)J
roPlca
(1) - with warmest month below 22 °C
(2) - with warmest month above 22 °C
(3) - with no winter, coolest month above 18 °C
(4) - constantly wet throughout the year
3.19 Climate regions
3.2 Climate regions and conditions
Climate region
Conditions
Polar
Characterised by heavy mechanical weathering as a result of freeze-thaw and frost shattering. During
permanently frozen periods weathering will be minimal. There is a lack of biological activity.
Temperate
Temperature and precipitation levels fluctuate throughout the year. Mechanical and chemical weathering
both prominent. Breakdown of rock moderate. In deciduous forests biological weathering high and
coniferous low with acidic soils and chemical breakdown.
Arid
Evaporation exceeds precipitation as rainfall levels are low and temperature is high. High mechanical
weathering and low chemical weathering due to a lack of moisture. High diurnal temperature range
leading to thermal expansion (disintegration), salt weathering.
Tropical
High temperature and rainfall throughout the year with some seasonal variation in moisture. A high
proportion of chemical weathering especially limestone areas. Usually intense deep weathering with iron,
hydroxides and alumina oxides. Biological weathering also predominant due to the extensive vegetative cover.
Mediterranean
Dry conditions predominate, which limit the amount of chemical breakdown though there is some
seasonal variation. Hot summer temperatures lead to greater amounts of mechanical weathering, such as
thermal expansion and salt weathering.
Mountains
High altitude provides cold conditions characteristic of both polar and temperate regions. High rainfall
associated with unstable air and orographic uplift provides high moisture content required for much
weathering. During winter months freeze-thaw and frost shattering will be common on exposed slopes.
At lower altitudes coniferous trees may cover the slopes, offering some limited chemical weathering especially hydrolysis of granite massifs.
Rocks and weathering
Slope processes
Slope processes are exogenetic processes operating on an inclined surface
of the Earth. These surfaces may vary in inclination and be found within any
environment including sub-aerial (exposed) and sub-marine (underwater).
Generally however the term refers to hill slopes where gravitational influence
exceeds the force of resistance.
Slope development occurs over time and results largely from the interaction
of the climate and rock type as well as the vegetation, soil and human activity
occurring there. The nature of the slope influences the hydrology of a drainage
basin, its form and features.
Sheetwash or sheet erosion is the process
by which soil is washed downstream
following rainfall activity. Usually it
involves two mechanisms. Firstly, soil
particles are loosened or detached from
the top soil layer by the impact of rain
splash. Secondly, sheet erosion or wash
carries material away within the surface
wash or surface flow (also known as
overland flow). Continued sheet wash can
eventually cause the scouring of channels
within the slope system leading to a
series of micro-channels known as rills,
which may later form in to larger gullies.
Rocks and weathering
Rock geology, structure and lithology
Whilst geology refers generically to the study of the Earth, the rock structure refers
to the rock form and lithology to its physical characteristics. The shape of a slope
may be heavily influenced by individual properties of a rock or indeed combination
of rocks within an area. Degree of resistance, angle of orientation and dip, type
and extent of faults and folds all play their part in the resultant forms.
One example is the African Rift Valley. Here divergence of the tectonic plates
has allowed the land to fall relative to the surrounding area. Faults may create
steep slopes as land is displaced, which creates rift valleys. More gentle activity
may cause the land’s surface to buckle but not break, creating fold mountains
and gentle slopes. Heavily jointed rock is vulnerable to weathering and erosion as
water and chemicals can weaken deep within the rock structure.
Soil and aspect
The soil profile is largely determined by the parent material underlying the
slopes but is in part formed by the breakdown of organic material on the
surface. Its structure and texture will largely determine how much water it
will hold and the ability of vegetation to grow. Clay soils have the ability to
bind or coagulate and form large impermeable layers that may be prone to
waterlogging. Large angular rock fragments that are partially decomposed
parent rock are referred to as regolith. Regolith is often unconsolidated (loose
stones, randomly distributed within a soil profile), with irregular orientation and
dip, and can affect the stability of the slope. Heavily periglacial head deposits
often contain frost-shattered material that was added to the creeping soil during
the last glacial phase 15 000 years ago. Frozen slopes that faced the sun were
more prone to seasonal melting allowing soil and debris to flow downslope
by solifluction (‘solum’ meaning soil and ‘Auction’ meaning Aow). North
facing slopes by contrast receive less sunlight, which creates an asymmetric
form. South facing slopes tend to be Aatter and longer, which means greater
movement and slip, whereas north facing slopes are shorter and steeper. In this
regard aspect is also a key component in shape morphology.
Vegetation
Whilst there is much variation in the shape and extent of vegetation the nature
of plant forms allows roots to bind soil and stabilise the land.
According to Osman (2006), studies in Malaysia have shown that there is
a signiAcant relationship between root length density, soil water content and
slope stability. Slopes with high root density (due to dense vegetation on the
surface) are less likely to undergo slope failure. This is because a high root
length density results in low soil water content, which in turn results in an
increase in shear strength and a decrease in soil permeability. It is suggested
that root length density and soil water level could be used as indicators of slope
stability and possibly could be used to predict future slope failure.
Climate and weather
The impacts of climate on weathering have to a certain extent been explored
in Weathering (pages 68-73). As a general rule warm moist areas are more
susceptible to weathering, which allows a greater range of weathering to occur.
In terms of form though, environments that have a greater level of moisture
and Auvial action (inAuence of rivers and streams) will experience more rounded
slopes and debris. The chemical breakdown of material is more likely to form
clays, which in turn produce low slope angles. Arid areas conversely tend to form
more angular jagged cliffs and slopes with sharp angular debris with larger more
grainy materials.
Where heavy rain is present the land may become heavily saturated and the
resultant increase in weight can lead to slumping and mass movement.
figure
3.21 Mass movement features
Rocks and weathering
Mass movement and landforms
Mass movement is the movement of downhill weathered rock material (regolith,
soil, rocks and loose stones) underthe influence of gravity. It differs from
mass transport, which is the movement caused by water, wind and ice. In mass
movement this weathered material falls, rolls, slides or flows downhill and can
create both subtle and dramatic changes to a slope profile.
Three basic mechanisms of mass movement can be identified: slide, flow
and heave.
•
•
•
figure
Slide is the movement of a cohesive unit with minimal internal dislocation
and deformation.
Flow, in contrast, distorts and shapes to the land over which it travels
like a viscous liquid. The rate of flow, just like a river, is influenced by its
gravitational potential.
Heave refers to the slow expansion and movement of debris to the surface
perpendicular to the slope. Heave raises the slope profile, often in a series of
ridges or mounds.
3.22 Carson and Kirkby mass movement classification model
In attempting to classify mass movements Carson and Kirkby (1972)
identified the importance of moisture in assisting the process. The result is
a classification based on three factors: the speed of flow, angle of slope and
moisture content.
Slow movements
Soil creep is a slow moving phenomenon that usually occurs on vegetated
slopes in temperate regions at a rate of less than 1 cm/yr. There are two main
causes of soil creep: alternating wet and dry periods cause the soil to expand
then contract. During wet periods the soil absorbs more water, becomes heavier
and moves downhill under the influence of gravity. In periods with little or no
rainfall the soil dries out and contracts.
An alternative cause is from freeze-thaw. During freezing ice crystals expand
forcing regolith closer to the surface of the slope. When the ground later thaws
the displaced material falls back but underthe influence of gravity will end up
further down the slope.
Soil creep occurs on slopes greater than 50 and can be identified by a series
of horizontal ridges running across slopes with a similar shape to that of shallow
Rocks and weathering
steps. Further evidence may be seen from the displacement of fences and
vegetation, which may be stretched or torn.
Solifluction is related to the seasonal melting of frozen layers in periglacial
environments. It is often considered to be soil flow though the exact translation
relates to the influence of the sun (sol) rather than the soil itself. Soliflucted
material can travel between 5 cm and ı m per year where vegetation cover is
limited. In summer months the topsoil will become saturated from the melting
of ice, not only increasing the weight within the soil but also lubricating its
descent under the influence of gravity.
Flow movements
Earthflows are caused by heavily saturated slopes averaging between 50 and 15°
at a rate of 1-15 km per year. Mudflows however are often more dramatic and
rapid and exceed 1 km per hour. Mudflows require a higher saturation level
than earthflows, which can be the result of extreme rainfall or, as in the case of
Nevado del Ruiz (see Case Study), rapid glacial melting.
Case Study
Nevado del Ruiz
figure
3.23 Nevado del Ruiz location map
On 13 November 1985 a small eruption produced an enormous lahar that buried
and destroyed the town of Armero in Tolima, Colombia, causing an estimated
25 000 deaths.
A lahar is a large mud and debris flow as a result of volcanic activity. The
combination of seismic activity, glacial instability and extreme temperatures all
played their part in the deadliest mudflow in history. Below is the BBC news
report.
13 November 1985
About 20 000 people are feared dead after a volcanic eruption in northern
Colombia.
Four towns in the Andes region are reported to have been buried when ash
spewed out of the volcano Nevado del Ruiz, causing a mudslide.
Rocks and weathering
The worst-affected town was Armero, the province of Tolima’s second largest
city, about 50 miles from the Colombian capital, Bogota.
Armero, which lay in a valley below the 4937 m high volcano, was virtually
destroyed - buried by the mud and rubble that swept down onto it
The fatal eruption happened during the night when most of the town’s
27 000 residents were in bed.
Nevado del Ruiz, known locally as the ‘Sleeping Lion’, had not erupted for
nearly 150 years.
Increased activity
Even though it is located only 500 km from the equator, the volcano’s summit is
figure
3.24 Nevado del Ruiz, Colombia
covered with snow.
The volcano had given some warning of increased activity - in recent months
there had been some rumblings from the crater- but the authorities had told
Armero residents it was safe to remain in the city.
The initial blast began on Wednesday afternoon when ash came showering
down.
An evacuation was ordered but abandoned when the volcano went quiet at
about 1900 local time.
However, just after 2100 local time a more serious eruption began causing
the summit’s icecap to melt and carry mud and debris down the mountain at
speeds of up to 50 km an hour.
Rapid movements
Slides
The fundamental difference between slides and flows is that flows suffer internal
deformation whilst slides move together and are not affected by internal
derangement.
Rocks that are orientated with the angle of slope are particularly susceptible
to movement. There are two main types of slide:
•
J
Rocks and weathering
Planar landslides are caused when weathered rock becomes detached from
the parent rock usually along a plane or joint. As a result the break is often
clean and straight. Gravity pulls the material as one down the angle of slope
until it reaches the bottom or a point of friction where resistance is greater
than gravity. The exposed upper cliff is known as a scarp.
•
Rotational slides are sometimes referred to as slumping and are formed
on a curved failure surface, causing the upper surface to tilt back. This is
often caused as saturated weaker rocks such as clays slide over stronger or
impermeable rock. Such features are common in areas of seasonal melt and
coastal cliffs.
Sudden movements
Rockfalls are sudden debris movements caused by extreme chemical and/or
mechanical weathering, earth movements or coastal wave action. They occur on
exposed slopes exceeding 40° with rocks that can become fragmented as a
result of their structure.
A debris avalanche is a sudden catastrophic collapse (landslide) from an
unstable steep-sided mountain, most frequently on volcanoes. They can either
be hot-forming as the result of an expanding magma chamber within the
cone, or cold - as a result of seismic instability. The Mount St Helens eruption
of 1980 experienced a highly unstable bulge on its northern flank 2.9 km3 in
volume that ultimately gave way to a devastating debris avalanche.
figure
3.26 Rockfall warning sign
The human impact
The physical processes leading to slope development are varied and complex.
Slopes and slope processes are further complicated by the modification of the
landscape by humans. The human impact is identified as the intentional or
unintentional, beneficial or harmful, direct or indirect effects human activities
have on the environment and living things. There are many examples of how
human activities have altered weathering and rocks, slope stability and have
influenced mass movement.
figure
3.27 Landslide during the rainy season in Thailand.
Rocks and weathering
figure
3.29 Scarred earth where tropical rainforest has been cleared by human activity.
Land overuse and clearance
Deforestation
Deforestation is the clearing of the Earth’s surface, often resulting in land
degradation and disturbed ecosystems. Forest clearance is largely done for
financial gain though some small-scale sustainable approaches are readily
practiced by many societies. Not all deforestation is intentional and clearance
may be the result of overgrazing following wildfires or climatic pressures
or more simply through mismanagement. Largely however farmers and
agri-businesses intentionally clear forest to plant crops and graze livestock.
Loss of vegetation has wide implications for the stability and structure of
underlying soil and rock, although much profitable agricultural land occurs on
low gradient accessible slopes.
Other includes fires, mining, urbanisation, road construction, dams.
Logging generally results in degradation rather than deforestation,
but is often followed by clearing for agriculture.
figure
3.30 Causes of deforestation in the Brazilian Amazon rainforest, 2000-2005
figure
3.30 Aggregated forest loss in the Brazilian Amazon, 1988-2013
Urbanisation and slope stability
Overcrowded areas such as Rio dejanerio have simply run out of space. The
safest building land has already been used forcing the newest settlers to find
space on already crowded hillsides. As the climate is hot and wet year-round
there are optimum conditions for chemical weathering of the bedrock and high
saturation risk due to the soft impermeable terrain. Many recent migrants have
built temporary shelters in slum or favela areas on steep impractical hillsides.
The excessive numbers of these temporary settlements puts increased pressure
on the slopes making them even more vulnerable.
Mining and extraction
Mining and extraction are concerned with the removal of minerals and deposits
from under the Earth’s surface. More often than not it is done at great expense
and effort with detrimental effects on the landscape for a monetary gain. Mining
can be broadly split into surface mining and underground mining.
Quarrying is a form of extraction where rock material is removed through
cutting and blasting of exposed rock faces. Quarrying is often used in the
construction industry.
Environmentalists and conservationists have held mining and extraction
operations responsible for some of the most devastating and far-reaching
effects on the environment. The process of mining fossil fuel and minerals
defaces the land with great scars and pits, destroys ecosystems and has
many undesirable side effects such as water pollution and the disturbance of
hydrologic systems.
The movement and relocation of rock debris, soil and unwanted matter is
necessary for many excavation activities. Processes involved in extracting
valuable minerals are often heavily concerned with what to do with the waste
material or overburden. Granite landscapes are particularly desirable for their
source of kaolin (china clay), which is a mineral of National Strategic Importance.
The granite is made up of quartz, mica and feldspar, but it is only the
weathered kaolin contained within the feldspar that is extracted. Using extreme
pressure rock fragments are hosed to extract the fine particulate clays before
being transported in suspension to large settling pools. Over 80 per cent of
the rock material that is extracted from the ground is discarded.
The resultant waste material has then to be landscaped and often forms a
series of shapely terraced mounds or ridges of huge vertical extent. Much care
is taken to landscape the unconsolidated rock material in order to effectively
minimise the risk of slope instability and landslides. Overtime the slopes may
again become vegetated.
figure 3.32 A China clay pit showing the characteristic
aqua blue settling pools and heavily uniform landscaped
hills resulting from the waste material.
Rocks and weathering
Case Study
The mudflow atAberfan
Where dumping occurs in populated places there is greater potential for hazard.
In the case of the Welsh mining village of Aberfan, near Merthyr Tydfil, the
mismanagement of coal waste led to a devastating mudflow. The disaster at
Aberfan is an example of slope overloading.
The South Wales coalfield was one of the largest coal deposits across Britain,
with large thick deposits that could be accessed through deep mines. In order
to access the desired seams much rock waste was removed but with little space
to put it in the narrow Welsh valleys, it was deposited on high ground away
from the surrounding settlements. On 21 October 1966, following high levels
of precipitation, saturated soil, rock and shale started to flow downhill. Over
100 000 m3of debris engulfed part of the town in minutes, including a local
junior school. The disaster occurred at 9:00 am, just minutes after the children
had moved inside. Of the 147 deaths 116 were children and five were teachers.
Just a few hours later and the school would have broken up for half term. Great
rescue efforts were made but only a few lives were saved. The official enquiry
blamed the National Coal Board for extreme negligence. Since then legislation
has been passed regarding the removal and storage of waste material and
potentially dangerous heaps have been lowered and landscaped.
figure
3.33 British coalfields in the nineteenth century.
water spring
buried by tip 7
railway
canal
footpath
building
spoil heap tip 7
spoil heaps
muc and waste slide
--------- 1100 m
figure
3.34The Aberfan mudflow
Rocks and weathering
gardens
Excavation
Excavation refers to the cutting and removal or displacement of rocks and
soil. Excavation must be done before any modern construction may begin,
whether it is a building such as property and housing or infrastructure such as
roads or to lay communications. Often the larger the structure the bigger the
excavation must be. The 828-metre-high Burj Khalifa in Dubai was constructed
at a cost of US$1.5 billion and covers 309 000 sq m. In preparation the site
was extensively excavated and 196 sheet piles were added, each at 50 m depth.
To stabilise the disturbed land and to strengthen any weaknesses within the
rock 45 000 sq m’of concrete weighing no 000 tonnes was laid. During the
construction process engineers had to be aware of the implications of thermal
expansion of the building materials, the shift of the ground layers, and the
shear stresses resulting from building tilt. Digital clinometers and thermal
sensors were used to monitor the building throughout construction and an
integrated measurement system was used to monitor ground displacement and
disturbance.
figure 3.35 Landslide damage in Kas, Antalya.Turkey, 2014. Heavy rainfall caused the road to collapse,
sending earth and rock onto the town below.
Water on the land
Water leakage has often been linked to landslides. Whereas rainfall is a natural
incidence, leaking from pipes or sewage is not. The water gets absorbed
in the land and makes it heavier. When soil gets heavier gravity has more
influence and the excess moisture can act as a lubricant, reducing friction
and increasing the potential for sliding. In addition to leakage widespread
urbanisation is increasing the amount of the Earth’s impermeable surfaces.
Rather than allowing the slow infiltration of water, excessive runoff in
combination with extreme weather events has increased the potential for land
disturbance.
Acid rain or acid precipitation is caused by a chemical reaction that begins
when compounds such as sulfur dioxide and nitrogen oxides are released into
the air. These substances can rise very high into the atmosphere where they
mix and react with water, oxygen and other chemicals to form more acidic
pollutants, known as acid rain. Heavy industry over the last 150 years is largely
the cause of such concentrations of acids in the atmosphere. At Bleaklow in the
Rocks and weathering
Peak District, UK, atmospheric pollution from the surrounding collieries has
made the peat moorland more acidic than lemon juice. The implications for this
are widespread.
Acid conditions of such proportions create uninhabitable environments
for plant and animal life. As a result of these biodiversity deserts there is
also a lack of vegetation to bind the peat together. Not only is the exposed
peat a huge releaser of carbon dioxide, it is also easily eroded. Peat lands
are highly absorbent and as a result are very effective at flood prevention in
upland areas, storing water and releasing it gradually. Eroded peat also poses
problems for our water supply as water companies have to spend more on
cleaning the water.
figure
3.36 Eroded peat bogs in the Peak National Park, UK.
Solutions
With greater understanding of our rocks, soils and slopes and the mechanisms
that affect their stability, humans have sought ways to reduce their impact on
the landscape. Extensive research has been carried outas well as important
technological advances that allow us to not only improve our existing practices
but also push boundaries in new areas.
Slope stability analysis is designed to assess human-made (e.g.
embankments, road cuts, open-pit mining, excavations, landfills etc.) or natural
slopes using mathematical models to measure the angles of slopes and
weight of soil, rock and debris and whether the forces of gravity and friction
are in balance. Stable slopes are ones in which these forces are balanced or
heavily weighted towards a rigid, stable structure. The main objective of slope
stability analysis is to find areas that are potentially at risk of movement and
therefore potential hazard. Since 2003, slope stability radar has been developed
to remotely scan a rock slope to monitor the spatial deformation of the face.
Small movements of a rough wall can be detected with sub-millimetre accuracy
by using interferometry techniques.
Landslide hazard analysis and mapping can provide useful information for
catastrophic loss reduction and can assist in the development of guidelines for
sustainable land use planning. Since many factors are considered for landslide
hazard mapping, a Geographic Information System (GIS) is an appropriate
tool because it has functions of collection, storage, manipulation, display and
analysis of large amounts of spatially referenced data that are increasingly used
in hazard prediction and mitigation.
Structural engineering refers to the design and implementation of
stabilising strategies and equipment. There are soft engineering and hard
engineering approaches that can be used with varying effect. Soft engineering
strategies utilise more natural approaches in keeping with the surrounding
Rocks and weathering
local environment. Such strategies may involve the use of plant vegetation to
bind the soil and intercept rainfall. In addition improved drainage channels
may prevent slopes becoming saturated and divert moisture away from lines
of weakness such as rock joints and bedding planes. Landscaping is another
approach that may seek to reduce the gradient of a slope or rock face in order to
limit the likelihood of slippage, deformation or rockfall.
Hard engineering approaches rely on the construction of physical structures
that may support or hold earth and rock in place. Along many alpine roads wire
nets and gabion baskets are used to protect from rockfall. In addition sheet
piling may be used to stake the slope, holding hard structures together. Other
examples include retaining walls that are designed to restrain soil to unnatural
slopes. Retaining walls are used to bind soils between two different elevations,
often in areas of terrain possessing undesirable slopes or in areas where the
landscape needs to be shaped severely and engineered for more specific
purposes, such as hillside farming or roadway overpasses.
NOW INVESTIGATE
1
Investigate how tectonic forces have helped shape islands such as
Iceland or Hawaii.
2
Investigate the formation of granite landscapes and the processes
that help shape them today.
3
Investigate world examples of mining and mineral extraction and
how they have impacted the landscape.
Rocks and weathering
.
ue\°Vrt'e<'
a ^e35UrefT'e"t
of a country’s achievements in three areas: longevity,
bv life expectancy at birth; knowlegde is measured
n(ievity « rneaSUre hined gross primary, secondary and tertiary school
....... .. ......
In 2014 the UN Development Programme
introduced a system of fixed cut-off points
(0.55. 0.7 and 0.8) between HDI categories.
These points will be used for at least five years.
Gr°uPs
Population
87
ion
Natural increase as a component of population change
World population growth
Figure 4.1 shows the way that the world’s population has grown - very slowly
from the time humans evolved as a species, reaching the first billion (1000
million) in 1804. After 1850 the growth started to accelerate, reaching 2 billion by
1927, 3 billion by i960, 4 billion by 1974, 5 billion by 1987, 6 billion by 1999 and
7 billion in 2011. The acceleration of population growth after 1850 was because
of the fall in the death rate.
Since the late 1960s the rate of population growth has started to decline
because of a fall in the birth rate across all continents. Because so many people
had been born in the previous 30 years even if couples only had two children
per family the population still grew- many more being born than dying. This is
why the world population is expected to rise to 8 billion by 2029 and probably
9 billion by 2150. Some but not all estimates believe the world’s population
will peak at 10 billion after which it will fall. Within the lifetime of most people
reading this book, the population of the world will decline. The growth rate is
currently 1.2 per cent a year; this will fall to less than 1 per cent by 2020 and less
than 0.5 per cent by 2050. Table 4.1 shows the variability of growth rates across
different continents. Africa has easily the highest growth rate but Asia has easily
the largest population.
table
Population
4.1 Populations and growth rates, 2015
Total population
Growth rate per year
World
7.5 billion
1.2%
Africa
1.2 billion
2.5 %
North America
360 million
0.4 %
Latin America
650 million
1.2%
Asia
4.5 billion
1.1%
Europe
745 million
0%
Oceania
42 million
1.1%
It is important to understand that a high proportion of the world’s
population is concentrated in just a few countries. What happens in these
countries will determine the future of global population change (Table 4.2).
Some terminology
• Natural increase is the balance between births and deaths in any year and
is expressed as a percentage of the total population size at the beginning
of that year.
• Birth rate is the number of live births in a year per 1000 people alive at
the beginning of that year.
• Death rate is the number of deaths in a year per 1000 people alive at the
beginning of that year.
• Fertility rate represents the number of children that would be born alive
to a woman if she were to live to the end of her childbearing years.
• Infant mortality rate is the number of children who die before the age of
one per 1000 children born alive.
• Life expectancy indicates the number of years a newborn infant would life
if prevailing patterns of mortality at the time of its birth were to stay the
same throughout its life.
table
4.2 The most populous countries in the world, 2015
Country
Population (millions)
China
1360
India
1300
USA
325
Indonesia
260
Brazil
210
Pakistan
193
Nigeria
190
Bangladesh
165
Russia
142
Mexico
130
Japan
126
Philippines
106
Ethiopia
103
Vietnam
97
Egypt
88
Case Study
China
China has the largest population in the world (1.36 billion in 2015), which is
around 20 per cent of the world total. Table 4.3 shows that China’s population
has been very high compared to other countries for the past 2000 years.
table
4.3 Population growth in China
Date
Population
AD 2
58 000 000
800
70 000 000
1000
87 000 000
1200
105 000 000
1500
110 000 000
1800
260 000 000
1900
400 000 000
1964
695 000 000
1990
1134 000 000
2000
1 266 000 000
2010
1 340 000 000
United Nations projections
figure
2030
1 393 000 000 (peak)
2050
1 296 000 000
2100
941 000 000
4.2 Population growth in China
In 1950 the death rate was 18 per 1000 and the life expectancy only 35 years.
After that date the death rate fell steadily except during a famine between
1958 and 1961 caused by the Chinese government’s failed reorganisation of
agriculture. The death rate fell to 6.4 per 1000 in 2002 and has since risen to 7.2
as the population has aged. Life expectancy is now 74.
The birth rate in 1950 was 37 per 1000. During the 1970s the birth rate
fell from 33 per 1000 to 18 per 1000 because of reduced infant mortality, the
increased employment of women, urbanisation and birth control campaigns.
Today the figure is 12 per 1000.
The natural increase rate in 1950 was 1.9 per cent. With the decline in the
Population
death rate it rose to a peak of 2.8 per cent in 1964 and then, with the fall in the
birth rate, to 0.5 per cent today. The population will decline after 2030 because
the death rate will exceed the birth rate (Figure 4.2).
Year
figure
4.3 Birth and death rates in China
Death rate and mortality across the world
The death rate may be influenced by:
1 The age structure: When a high proportion of the population is old, the death
rate is higher because old people are more likely to die than younger people.
2
Health and nutrition: The death rate has fallen in all countries in recent
years because of a combination of improved agriculture, the availability of
food aid and the growth of medical services. In some countries the death
rate has risen locally because of famine, war, AIDS or Ebola disease but in
most parts of the world mortality is declining as conditions improve. In
Bangladesh, for example, child mortality (deaths of children under five per
1000 live births - a good index of health) fell from 144 in 1990 to 41 in 2012.
Within countries poorer people will have lower life expectancy. The average
life expectancy in the USA for black men is 72.2 compared to 76.6 for white
3
4
5
men, who are richer on average.
Urbanisation: In the nineteenth century in Britain death rates were higher
in cities because of the greater prevalence of infectious diseases; rural areas
had cleaner air and better access to food. Today death rates are lower in
cities than in rural areas in most LICs because of the greater availability of
medical services in urban areas.
Level of economic development: As countries develop, a higher proportion
of the population go to live in cities, where the death rate is lower.
As a country develops it goes through an epidemiological transition - a shift
from death caused by infectious disease such as cholera and tuberculosis or
insect-carrying disease such as malaria to degenerative diseases associated
with a higher standard of living: cancer, heart attacks and strokes.
Gender: Women generally live longer. In the USA, for example, life
expectancy for white females is 81.3 while for white males it is 76.6. Women
also have lower rates of infant mortality, except in a very few LICs where
6
there is relative neglect of female children.
Wars: In the Second World War (1939-45) 24 million people were killed in
the Soviet Union, which was 14 per cent of the 1939 population. A high
proportion of these were men, so the impact on the demography of the
country was significant.
Population
figure
4.4 Death rates across the world
Birth rate and fertility across the world
There are many influences on the birth rate and fertility.
Economic
A country’s level of economic development is very important In countries
where most people are still farmers and children can help farm the land birth
rates are higher. In places with a lower life expectancy due to hunger or disease
parents may have more 'insurance children’ to ensure that a few survive. In LICs
children are needed to support parents in their old age. Compulsory education
of children tends to lower birth rates as does raising the status of women - the
more educated women are and the higher their status, the lower the birth rate.
As more women take paid jobs, fertility rates tend to fall.
Related to economic development is urbanisation. Fertility rates tend to be
lower in cities because children are harder to support than in rural areas and
family planning is more freely available. Rural areas in MICs/LICs have higher
birth rates partly because contraception is expensive, supplies harder to come by
and the population may have less knowledge of family planning.
Social
If a country experiences large-scale immigration from a country that typically
has a high fertility rate, then these people may bring their expectations about
large families with them. For example, migrants to Britain in the period 2000-15
had larger families than was usual for the UK.
The age structure of the population is an important influence on birth rate.
If there are many people in the child-bearing age bracket (15-45) then the birth
rate will be higher. That is the reason why the birth rate tends to be higher in
places with recent immigration of large numbers of working-age people.
The same is true of sex ratios. In places with an imbalanced sex ratio such as
China, where more boys are born than girls, the birth rate will be depressed.
Religious belief has historically had a big impact on birth rates. Some
religions, such as Catholicism, oppose the use of contraception and historically
this has resulted in Catholic countries having higher birth rates.
In times of war the birth rate is low but this is compensated for by a ‘baby
boom’ immediately after the war- families who delayed having children during
a war have these children when the war ends.
Population
Educational attainment level normally has a bearing on the birth rate. From
U.S. Census Bureau data we know that, among women who were finishing
their childbearing years (ages 40-44) in 2010, those with less than a high school
qualification had the most children (2.56), and those with advanced degrees had
the fewest (1.67) (Figure 4.5).
figure
4.5 Number of children born to women in the USA, grouped by educational achievement
of the mother.
Political
Government policies can influence the birth rate. Pro-natalist polices encourage
couples to have children. For example, in 1987 pro-natalist policies were
introduced in Singapore because the birth rate had fallen to only 1.4 children per
couple. The government’s policy was defined by the phrase ‘Have three or more
children if you can afford it’- which was essentially a way of saying they wanted
educated couples with good jobs to have children, not uneducated citizens who
would require more welfare aid if they had larger families. The government’s
Social Development Network (SDN) encourages educated Singaporean couples
to marry and procreate.
Mothers with a third or fourth child get generous financial benefits. If
a mother had three O level passes in one sitting, she would qualify for an
enhanced child benefit. Families with more than two children get priority access
to schools and housing. There are subsidies for each child in a government-run
or government-approved childcare centre. The hospital costs of a third child
are reduced. Abortions of convenience are discouraged. Women undergoing
sterilisation with fewer than three children receive compulsory counselling. A tax
rebate is given to mothers who had their second child before the age of 28.
The Singaporean policy has had limited effect so far. The majority of women
in Singapore are very well educated, have good jobs and prefer to devote their
early lives to their careers and leisure. The fertility rate remains low at 1.25.
Anti-natalist polices (to limit births) are described in the Case Study (on
China) on pages 106-7.
The means by which the birth rate changes are use of contraception, age of
marriage and proportion of people marrying. Countries where people do not
get married or form partnerships before they are 28 or so have lower fertility
rates than countries where the average age of marriage is ten years younger
because the latter group have more years available to them within which to have
children. Historically, in times of hardship the proportion of women who never
marry and have children rises.
Population
Birth rate is the number of births per thousand of the population in one year.
figure
4.6 Birth rates across the world
The natural increase rate is the difference between the crude birth rate and the
crude death rate.
Arctic Circle
Tropic of Cancer
Natural increase rates
-1--0.1
0-0.9
1-1.9
>ic ofCapricorn
2-2.9
3-3.9
no data
Statistics are for 2013.
World average 1.1
figure
4.7 Natural increase rates across the world.
Population
0
Dependency ratio
The dependency ratio is the ratio between the number of dependents and
those who are economically active. ‘Dependents’ are defined as being of two
types: those aged under 15 and those over 64 (too young and too old to have a
job). So the dependency ratio expressed as a percentage is calculated from the
following formula:
Number of children (0-14) and elderly (over 64) x
Number of people aged 15-64
Obviously the dependency ratio is inaccurate because it does not take into
account those who are unemployed, those who choose not to work, those
who work after the age of 64 (which more do as pensionable age has risen)
and the fact that in many countries children aged 16-21 do not have paid jobs.
But it is useful as an indicator of the burden of support that is likely to fall on
economically active people.
So if the dependency ratio is the proportion of dependents per 100 working­
age population, 40 is low, 60 is high. The average for the whole world is 51.
Countries with high birth rates have high dependency ratios because there
are so many children: Uganda’s dependency ratio is 102.
Countries with long life expectancy have high dependency ratios because old
people live longer: Japan’s dependency ratio is 62.
Countries which had a high birth rate 65 or more years ago have high
dependency ratios because all those babies are now aged 65 or above. This is
true of much of Europe because of the baby boom after the Second World War.
The birth rate in China was high 40-55 years ago; since the 1970s the country
has had a very low birth rate so in 10 or so years’ time, when the large number
of people aged 40-55 start to retire, the dependency ratio will worsen - there will
be many old people as a proportion of those of working age.
Countries with a large number of migrant workers have a low dependency
ratio. In the United Arab Emirates the dependency ratio is just 19.
See Table 4.4 for the current pattern of young and old people per continent.
table
44 Young and old people per continent, 2015
% aged under 15
Africa
% aged over 64
41
4
North America
19
14
South America
26
8
Asia
25
7
Europe
6
17
Oceania
24
11
Issues with a young population
Having a very young population means that a higher proportion of a country’s
income has to be spent on pre- and post-natal care and on schools. Women
are less likely to have paid employment because they are looking after
children.
Issues with an old population
Having a large number of old people (see the age/sex structure diagram for
Japan on page 95, for example) means that a higher proportion of a country’s
income has to be spent on healthcare, welfare services and pensions in HICs.
There is an increased demand for small homes suitable for the elderly. Buildings
need to be adapted for wheelchair access and disabled facilities. Pressure grows
population (in thousands)
figure
4.8 Age/sex structure diagram of Zimbabwe, 2015
Population
to raise the age at which people can retire.
Because old people are more likely to vote than younger people, and because
there are many of them, old people become important politically: political
parties adjust their policies to appeal to the retired.
Age/sex structure diagrams
Age/sex structure diagrams are bar graphs of population age with the
population divided into males and females. The number of people in any age
male
100+
95-99
90-94
85-89
80-84
75-79
70-74
6S-69
60-64
55-59
50-54
45-49
40-44
35-39
30-34
25-29
20-24
15-19
10-14
5-9
0-4
group will always be affected by the combined effect of death rates, birth rates,
immigration and emigration.
Zimbabwe
An age/sex structure diagram typical of a LIC: high birth rate (many children),
high death rate (few old people). (Figure 4.8)
Brunei
There are fewer people in each five-year group over the age of 50 than those
younger than 50. This is despite the fact that the birth rate was higher when the
older people were born (40-80 years ago). There are two possible explanations
for the smaller number of older people: one is that they have died - the death
rate was higher in the past- and the other is that there has been migration into
the country of younger people in the past 40 years. We know that a third of the
workforce in Brunei is foreign-born so it is likely to be a combination of these
two factors.
female
age group
20
15
10
5
0
population
0
10
5
15
20
(in thousands)
figure
4.9 Age/sex structure diagram of Brunei, 2015
figure
4.10 Age/sex structure diagram of China, 2015
China
The 2015 age/sex structure diagram of China shows various features:
1
2
3
4
5
Fewer people aged 50-59. This was due to a fall in birth rates during a period
called the Great Leap Forward (1958-61) when the communist government
began forced industrialisation and private farms became state collectives.
Farm yields fell leading to famine; an estimated 30 million people died.
During that time infant mortality rates rose and birth rates fell.
Rise in number of people aged 40-49. The Great Leap Forward was
abandoned and the birth rate rose to its normal level.
Fewer people aged 30-39. This was due to the one-child per family policy
introduced in 1979.
Rise in number of people aged 20-29. This was because the many people
born in 2 (above) now had children.
Fall in number of people aged 0-19. This is due to the one-child per family
policy. The numbers of people aged 0-4 show a slight rise, reflecting a
relaxation of the one-child policy since 2000.
United States
The age/sex structure diagram of the United States shows:
1
Little variation in the birth rate/immigration rate between 1956 and 2015
(people aged 0-59).
2 After the age of 59 people start to die off.
3 In the case of the smaller aged 65-69 bar, there was a low birth rate during
the Second World War.
4 There are more elderly women than men.
population (in millions)
male
female
age group
100+
95-99
c 90-94
85-89
80-84 _____ 1
75-79
70-74
65-69
60-64
55-59
50-54
45-49
40-44
35-39
30-34
25-29
20-24
15-19
10-14
5-9
0-4
12
8
4
00
4
8
12
population (in millions)
figure
4.11 Age/sex structure diagram of USA, 2015
male
age group
female
Japan
The age/sex structure diagram forjapan shows:
1
A large number of people aged 65-69 - these are people born between
1948 and 1952. This represents a baby boom after the Second World War
caused by the fact than many couples delayed having children during the
war itself.
2
3
Some 20-30 years later these same baby boomers (born 1948-52) had babies,
producing more people now aged 40-49 years old.
A low birth rate in recent years together with a large number of old people.
population
figure
(in millions)
4.12 Age/sex structure diagram ofJapan, 2015
Population
Demographic transition
Demography is the study of human population. The five-stage demographic
transition model (Figure 4.13) is based on the experience of England after
1700.
figure
4.13 Demographic transition model
Stage 1: Before 1750
Death rates were high because of disease (the Black Death wiped out a third
of the population of Europe in the fourteenth century), famine caused by bad
weather and poor harvests, and wars.
The birth rate was high because there was high infant mortality - so
families needed several children in order to ensure that enough survived,
because at a time when most people were farmers children were a useful form
of labour, and because there was no support for elderly parents other than
their children.
The birth rate tended to rise and the death rate fell when there were good
harvests. When harvests were bad or there was an outbreak of war or disease the
birth rate fell because people married later (so women had fewer child-bearing
years available to them) and a higher proportion of people did not marry. So
there was some fluctuation.
Overall, however, both the death rate and birth rate were high so they
cancelled each other out and natural increase rates were low.
Stage 2:1750-1880
The death rate fell for three reasons:
• Hygiene improved and this reduced death from disease. Cotton was
imported from America, Egypt and India and cotton clothes, which are
easier to keep clean, replaced wool. Soap began to be used. There was a
growing awareness of the link between hygiene and health, such as John
Snow’s research, which showed the link between a polluted well in Soho
•
(part of London) and the distribution of cholera victims.
In the late nineteenth century governments tried to improve the urban
environment. Municipal corporations were created and they built sewers to
take waste away from cities and treat it.
Population
•
More food was available because of the Agricultural Revolution (improved
farming methods) and the import of grain from North America (made
possible by the invention of the steel plough to cultivate the prairies and the
steel ship to transport grain).
The birth rate was little changed because at this stage the factors keeping the
birth rate high were still in place. The increased supply of food even caused the
birth rate to rise in some areas.
Because the death rate fell and the birth rate remained high, the natural
increase rate rose.
Stage 3:1880-1930
Now the birth rate began to fall. The death rate had fallen so there was less
need to have ‘insurance children.’ Because of the Industrial Revolution more
people moved from the countryside to towns for work; in towns children were
less useful. Laws were passed to limit the age at which children could work and
education became compulsory. There was a growing realisation that having
many children could depress the family’s standard of living.
Because the birth rate fell, the natural increase rate fell.
Stage 4:1930-1980
The death rate fell further because of the development of modern medicine and
rising standards of living.
The birth rate fell further because of the rapid expansion of education
for women and the development of contraception. The birth rate fluctuated
- down during periods of economic austerity such as the 1930s and during
wars (1914-18 and 1939-45), up during periods of economic boom (the 1960s),
up after the wars because parents had delayed having children during the war.
Baby booms repeat themselves after 20-30 years because if many children are
born in the 1960s, for example, then 20-30 years later those same people have
children.
Because the birth rate fell, the natural increase rate fell.
Stage 5:1980-present
Old people are now living longer and the birth rate remains low. So the
proportion of the population who are older has risen. This fact pushed the death
rate up simply because old people are more likely to die.
The birth rate was pushed up by the arrival of immigrant families, especially
in the period 2000-2010. Immigrants from Eastern Europe tended to be aged
20-30, which is in the child-bearing age bracket. Many immigrants went to work
in London so the birth rate in London was especially high.
Natural increase remained low.
How useful is the demographic transition model?
1
It is a simplification. In England in the nineteenth century urban areas had
a lower birth rate but their death rate remained high because of disease.
Different social classes had different experiences, with the death rate
remaining higher for poorer groups.
2 France had no stage 2 at all. The birth rate fell earlier than in England
because under the 1804 Napoleonic Code when parents died their land had
to be divided amongst all their children; if you had many children, their
individual plots of land would be too small to be useful. Italy, in contrast,
had a long stage 2: most people in Italy were Catholic, a religion which
banned abortion and the use of contraception. In the 1930s the fascist
3
government encouraged families to have many children.
Although most LICs have passed through stages 2 and 3 of the demographic
transition, comparisons with England could be misleading:
Population
&
•
•
•
•
•
•
The death rate in LICs has fallen for different reasons. In England
modern medicine played little part in the early fall of the death rate.
In LICs successful campaigns against the killer diseases of cholera,
polio, typhoid, malaria, yellow fever, tuberculosis and smallpox have
been important. In Sri Lanka, for example, the death rate fell 34 per
cent between 1946 and 1947 because spraying coastal areas with DDT
eliminated malaria-carrying mosquitoes.
In LICs the death-delaying innovations (improved agriculture,
food imports, hygiene and medicine) all arrived in a short period of
time.
The birth rate was and is higher in many MICs/LICs than it ever was
in England. The birth rate in England in 1720 was 33 per 1000 but in
some African countries today it is over 40 per 1000. The reason for
this higher birth rate is that people are marrying younger and a higher
proportion are marrying than was the case in England at an equivalent
stage. This is why the highest level of natural increase ever reached in
England was below 2 per cent; the natural increase rate for Africa is
currently 2.5 per cent and in Uganda it is 3.4 per cent.
When England went through stage 2 the population size was small
(20 million); in many MICs/LICs the populations are very large (China1360 million, India-1300 million, Indonesia - 260 million).
LICs are at the beginning of their economic development; when
England went through stage 2 it was one of the most prosperous
countries in the world.
The ‘excess population’ of England migrated in the nineteenth century
to North America, Australia, New Zealand and South Africa; today few
countries have this pressure-release valve of mass emigration.
Population, development and age structure
As a country develops and passes through the demographic transition so the
age structure will change (Figure 4.14).
Stage 2: Early expanding
Stage 1: High stationary
Zimbabwe, 2015
Democratic Republic of the Congo, 2015
male
age group
9876543210
male
age group
100+
100+
95-99
95-99
90-94
90-94
85-89
85-89
80-84
80-84
75-79
75-79
70-74
70-74
65-69
65-69
60-64
60-64
55-59
55-59
50-54
50-54
45-49
45-49
40-44
40-44
35-39
35-39
30-34
30-34
25-29
25-29
20-24
20-24
15-19
15-19
10-14
10-14
5-9
5-9
0-4
0-4
0123456789
percentage of total population
figure
female
9876543210
0123456789
percentage of total population
4.14 Age/sex structure diagrams showing how the shape of the age/sex structure diagram of a country changes as it develops.
Population
female
Stage 4: Low stationary
Stage 3: Late expanding
Argentina, 2015
male
age group
UK, 2015
female
age group
female
100+
95-99
90-94
85-89
80-84
75-79
70-74
65-69
60-64
55-59
50-54
45-49
40-44
35-39
30-34
25-29
20-24
15-19
10-14
5-9
0-4
percentage of total population
Stage 5: Declining
Japan, 2015
age group
female
100+
95-99
90-94
85-89
80-84
75-79
70-74
65-69
60-64
55-59
50-54
45-49
40-44
35-39
30-34
25-29
20-24
15-19
10-14
5-9
0-4
percentage of total population
Population-resource relationships
Population-resource relationships: theories
In this section we first consider three theories relating to population-resource
relationships:
•
•
•
Rev. Thomas Malthus’s theory
Ester Boserup’s theory
the concepts of overpopulation, underpopulation and optimum population.
Rev. Thomas Malthus
In 1798 Rev. Thomas Malthus published an influential book, An Essay on the
Principle of Population. He claimed that populations would always tend to rise
to a level where they exceeded the resources (especially food) able to support
them, at which point population levels would crash. Population, he said, tends
to double -1, 2,4, 8,16 - while food supplies at the same time only grow
arithmetically-1,2, 3,4, 5.
When the population became too great the death rate would rise due to war,
disease and famine - all caused by food shortages. In addition, when food was
expensive the birth rate would fall because people would marry later and avoid
having so many children.
figure
4.15 Rev. Thomas Malthus
Population
In the 1960s and 1970s, when the world’s population was growing fastest,
a number of books were published which echoed the Malthusian theory that
population rose to exceed resources. In 1968 the American biologist Paul R.
Ehrlich published The Population Bomb, which begins with the statement “In the
1970s hundreds of millions of people will starve to death in spite of any crash
programs embarked on now.”
In 1972 a research association called The Club of Rome published a report
called Limits to Growth that used computer modelling to show that the rapidly
growing population was about to exceed the resources available to support it.
These people are sometimes called neo-Malthusian because they all echo
Malthus’s early theory- they assume that there are ecological limits to growth,
whether food, water, soil, fertiliser or fossil fuels.
Biologists also talk about the carrying capacity of an area - the population
it can support without environmental degradation. Carrying capacity is an
ecological term that applies to animals - when the population of a species of,
for example, red deer exceeds the capacity of the environment there will be
inadequate fodder, soil erosion will take place, and the population of deer will
collapse.
These concepts are of some but limited value. Malthus wrote his book right
at the beginning of the Agricultural Revolution and the Industrial Revolution
in England - the application of technology to farming and manufacturing in
England, technologies which would spread around the world in the nineteenth
and twentieth centuries. This was bad luck for him because both these events
allowed food and industrial production to move ahead much faster than
population growth. Malthus was proved wrong.
Food shortages affecting humans (as opposed to wild animals) are not
normally due to population growth. Over the past 40 years food production
has grown faster than population in most parts of the world, largely due to
technological innovation. Between 1950 and 2000 the human population
increased two-and-a-half times but food production more than tripled.
Food shortages affecting humans are more often due to inequality and
poverty - there is enough food to feed the world but the poorest people cannot
afford it. Sometimes food shortages are due to wars, which prevent food getting
to places it is needed and which generate refugees who lack the resources
needed to grow or buy food.
The International Institute for Applied Systems Analysis (IIASA) in Austria
has looked in detail at areas of as-yet uncultivated land in the world that could
be brought into production: land with good soil which would be watered by
rain and would not need deforestation. They have concluded that 1.3 billion
hectares of unused land could be profitably farmed - equivalent to 80 per cent
of all the crop fields today. Some of this ‘spare’ land is in North America and
Russia but most of it is in South America and Africa. So the world has plenty
of farmland.
The huge gap in crop yields between Eastern Asia and Africa suggests
that the best way of increasing the world’s food supply is to apply western
technology to areas which have not yet had access to it (Africa). Large parts of
sub-Saharan Africa have good soils, good rainfall, but crop yields that are less
than a quarter of what they could be. The problems are neither ecological nor
demographic-the problems are poverty, poor infrastructure, weak markets,
lack of skills, harmful government regulations and poor trade terms.
Malthus believed that population growth always led, overtime, to hunger.
There is a completely contrary school of thought which states that when
population grows and food shortages loom this stimulates innovation and food
supplies grow. This is shown in Ester Boserup’s model (Figure 4.18).
figure
4.17 Crop yields per hectare compared to attainable
yields
100 Population
Ester Boserup
Ester Boserup (1910-99) was a Danish economist who studied agricultural
development. She found, for example, that traditional farming methods
involved ‘slash-and-burn’- cutting down the forest, burning it and planting
crops. If yields began to decline after a couple of years the farmers would move
on and clear another area of forest. But once the population began to rise
there was inadequate land to feed the population using the slash-and-burn
method so farmers were forced to experiment with fertilisers, hoes and other
technologies - which led to significant yield improvements.
figure
4.18 Ester Boserup’s model
All the evidence suggests that as a country develops economically the birth
rate falls until natural increase is at a low level. In 1965 the world population was
growing at 2.0 % a year; this has fallen to 1.2 % in 2015, will fall to less than 1 %
by 2020 and less than 0.5 % by 2050 (Figure 4.19).
Overpopulation, underpopulation and optimum population
Overpopulation means a situation where the population of an area exceeds the
carrying capacity of that area. The term can apply to a country or to the whole
planet. Symptoms of overpopulation are:
•
•
•
•
•
as the population grows the average standard of living or quality of life
declines
food shortages
water shortages
environmental deterioration such as soil erosion, air pollution,
deforestation, declining fish stocks, species extinction or, in the context of
the whole planet, global warming
congestion.
Population
EE
Underpopulation means a situation where the population is at too low a level
to make full use of the resources it possesses. An increase in the population
would lead to a bigger workforce and more production per person.
Optimum population is a theoretical state where any increase or decrease in
population might lead to a lower standard of living or lower quality of life.
The concepts of overpopulation, underpopulation and optimum population
are also controversial. Malthus’s theory implied that populations would always
rise until they exceeded the carrying capacity of the area, leading to war, disease
and famine. His theory persuaded people in nineteenth-century Britain that
giving help to the poor could be counterproductive - they would simply have
more children and the situation would become even worse.
But as we know, Malthus was wrong. Since i960 populations have risen fast
with limited numbers of wars and rapidly declining numbers of deaths from
disease or famine. Technology has greatly increased food supply. Improved
transport and communications have enabled food aid to reach areas of
shortage.
Residents of a city may feel that it is overpopulated (too much traffic, high
house prices, air pollution) but at the same time incomes and production levels
are high.
Many environmental problems caused by humans have been overcome. Air
pollution caused by burning coal, a huge problem in Britain before i960, was
largely eliminated by government legislation (the Clean Air Acts), which forced
people to use smoke-free coal and alternative cleaner sources of energy.
Today most informed people believe that hunger is caused not by population
levels but by poverty and inequality-there is enough food in the world, but it is
unequally distributed.
Population-food supply relationships: reality
The Food and Agriculture Organization of the United Nations (FAO) estimated
that about 805 million people were chronically undernourished in 2012-14,
down more than 100 million compared to the previous decade. Sub-Saharan
Africa has the highest prevalence of undernourishment, with only modest
progress in recent years; around one in four people in the region remains
undernourished.
Famines (many dying because of hunger) are much less frequent than they
used to be. In the first part of the twentieth century millions died in famines in
China and India. The last famine on this scale was in China between 1959 and
1961 and was caused by the communist government reorganising agriculture,
rather than a natural event. Large famines in the past 20 years have been:
•
•
•
1998 Sudan, caused by war and drought
1998-2000 Ethiopia, caused by drought and war with Eritrea
1998-2004 Democratic Republic of the Congo, caused by war
•
•
2011-12 Somalia, due to drought
2012 Sahel region of Africa, due to drought.
But none of these was as severe as famines in the past, partly because of food
aid from the international community.
figure
4.20 Norman Borlaug
102 Population
Technology to the rescue
The American Norman Borlaug, working out of a research centre in Mexico,
developed high-yielding varieties (HYVs) of wheat suited to hot climates and these
were introduced to India in the late 1960s, helping to double their wheat production
in only six years. This, and other measures, was called the ‘Green Revolution’.
At the same time another American, Henry Beachell, developed a highyielding variety of rice at the International Rice Research Centre in the
Philippines and this was adopted throughout Asia.
Within 20 years wheat and rice production in Asia had doubled.
HYVs are not without their critics. The HYVs need additional water and
fertiliser to grow well. They are not ‘miracle’ seeds but plants better able to grow
if they are given extra inputs. So HYVs were more easily adopted by wealthier
farmers. As a result richer farmers benefitted most and were able to buy the land
of poorer farmers.
HYVs need fertiliser and this is made from fossil fuels. Fossil fuels are
expensive, finite in quantity and are of course implicated in climatic change.
The introduction of HYVs meant that a wider variety of types of wheat and
rice were replaced by one species. This carries the risk of disease that attacks the
new strain, thereby causing disaster.
HYVs, genetically-modified crops, animal breeding to produce larger or more
productive animals, fertilisers, pesticides, irrigation, new forms of machinerythese technological innovations have all hugely increased agricultural production.
A dairy cow in 1900 produced 2000 litres of milk a year; now, with enough feed,
she can produce up to 10 000 litres.
This technology is unevenly distributed. The gap in production between the
HICs and the MICs/LICs has widened. Lagging behind has been sub-Saharan
Africa where many farmers still use hand tools, make little use of industrial
fertilisers and where yields per hectare are little higher than they were a hundred
years ago. So the world as a whole produces enough food for everyone, but it is
unevenly distributed and the poorest areas suffer food shortages.
Population: food relationships - five types of country
1 Big traditional food producers
According to the Food and Agriculture Organization (FAO) of the United
Nations, only 41 countries are net exporters of food. The HICs that export food
include the USA, Canada, Australia, New Zealand and France. Most of these
countries have a good climate and rich soil. The USA, for example, has a long
growing season and much good soil. Farmers use hybrid seeds, nitrogen
fertilisers and pesticides. The road, rail and air infrastructure is excellent,
markets are efficient, the government is well organised.
So the biggest food exporter in the world is the USA where less than 3 per
cent of workers are engaged in agriculture. Much of this food is exported to
MICs/LICs where up to 75 per cent of the workforce are farmers.
2 Emerging food exporters
These are countries that have started to export food relatively recently - Brazil,
Argentina, Uruguay, Paraguay, Bolivia, Russia, Ukraine, Kazakhstan, Thailand,
Vietnam and Myanmar. Some, like Russia and Ukraine, have a great deal of
arable land per person, some have rich soils such as the deep loess soil of
Argentina. The fertile river deltas of Thailand, Vietnam and Myanmar have good
rainfall and year-round warmth allowing three rice harvests a year. Brazilian
food production grew after the discovery in the 1960s that the infertile soils of
the central plains could be improved by adding lime and phosphorus. A version
of the soybean, which grew in temperate parts of China, was developed for
tropical Brazil and production of this has increased greatly.
3 Countries that are just self-sufficient
This includes some countries with huge populations such as China, India,
Pakistan, Bangladesh and Indonesia. These are countries where food production
has kept up with population growth but they need most of this production to
feed their own people. They have benefitted from the use of high-yielding seed
varieties and other western technologies.
4 High income food importers
These are countries with limited land or limited water or dense populations.
They are not able to grow enough food but they are high enough in income to
import food. These include oil-rich Middle East states such as Saudi Arabia, as
well as Japan, South Korea and the UK.
figure
4.21 Major commodity exporters and importers,
2011.
Population 103
5 Low income food importers
Low income countries that do not produce sufficient food include parts of
Central America, Asian countries like the Philippines, as well as North Africa and
the Middle East. But the largest group of countries in this category are in subSaharan Africa; this region has average yields of 1.2 tonnes of grain per hectare
compared to 8 tonnes in North America and Europe. Coastal cities survive by
importing food from abroad while inland farmers grow food forthemselves with
limited connection to urban markets. These farmers have too low an income to
buy the technology that would allow yields to improve. The populations of these
countries have grown fast- Egypt, for example, from 28 million in i960 to 88
million in 2015. Governments are often corrupt or weak, wars and civil unrest are
common.
Possible limits to food production
There is some concern that, despite the marvellous progress in terms of food
production of the past 50 years, we cannot expect the same rate of progress
in the future. Crop yields are no longer rising as fast as they did in the period
from 1960-90. High-yielding plant varieties may have now reached the limit of
increased yield. Bacteria, fungi and weeds have evolved to become resistant to
chemicals.
In some parts of the world land is in short supply: most suitable agricultural
land is already in use and much good land is being lost to construction, to
house a growing population. Since 1945 Japan has lost a third of its arable area
to urban development. Over-cultivation and over-grazing are causing some
farmland to become degraded, especially in drier areas.
Water supplies are finite. Around 40 per cent of the world’s food is produced
on land which is irrigated. Much of this comes from aquifers under the
ground. Some of the water stored in such aquifers fell as rain in a previous
wetter climate and will not be replenished. Some others are replenished but
not as fast as the water is pumped out. For example, the aquifer under the
North China Plain, which produces half of China’s wheat, is falling by 3-6
metres a year.
Climate change may be worsening the situation: one of the hottest years
recorded in the USA was 2012. In the Great Plains there was little rain for two
months of the summer. The US Department of Agriculture declared natural
disasters in over half the states in the country. The hot, dry weather destroyed a
sixth of the maize crop and an eighth of the soybeans. Weather events like this
may be becoming more frequent. The insurance group Munich Re suggests that
the number of extreme weather events has tripled since 1980- possibly due to
climate change.
Finally, more and more farms are producing non-food crops, especially
biofuels. Maize contains starch that can be broken down into sugars and
distilled into ethanol. The ethanol can then be blended with petrol to produce
a fuel that works in vehicles. In 2007 the US Congress passed the Energy
Independence and Security Act, which required the use of 164 billion litres of
renewable fuel by 2022 with up to 68 billion litres coming from maize, all of it
subsidised by the US government. The aim was to reduce US dependence on oil
imports. As a result, by 201140 per cent of US maize was used to make petrol.
This has limited maize exports to the rest of the world.
104 Population
Case Study
A COUNTRY WITH INADEQUATE FOOD: YEMEN
Yemen in southern Arabia is one of the poorest countries in the world. Progress
in economic and social development over recent years has been slow, mainly
as a result of political instability and weak governance. The security situation is
fragile and unpredictable, with conflict in the north, secessionists in the south
and an increasing presence of militant groups, including Al-Qaeda. In 2015,
26 per cent of the population was undernourished.
The population of Yemen is 25 million and the fertility rate of 4.4 children per
woman is amongst the highest in the world. Food supply cannot match this.
There is limited availability of land suitable for cultivation because much of
the country is mountainous. Water is scarce because of low rainfall and limited
piped water. Despite this nearly two-thirds of the country’s people depend on
agriculture, and more than 90 per cent of water is used for irrigation. Farming
methods are primitive and there is little use of modern technology.
Much of the available land is not used for growing food but for the narcotic
leaf qat, which commands a high price on local markets; 40-50 per cent of water
for agriculture is used to irrigate qat.
For these reasons Yemen is highly dependent on food imports. About 90
percent of wheat and 100 percent of rice, the country’s two main staples, are
imported. Such high exposure to the international food market makes the
country vulnerable to international food price rises.
Most export revenue comes from oil; in 2015, more than 90 per cent of
foreign exchange earnings were from exports of oil and gas. Oil exports have
been reduced by attacks on the pipelines that carry crude oil to the ports,
resulting in lower foreign exchange earnings and limiting the funds available for
importing essential commodities, including food.
Low agricultural productivity contributes significantly to poverty, as nearly
two-thirds of the country’s people depend on agriculture for their livelihoods.
Currently, about 5 million people in Yemen depend on food aid.
To support the restoration of stability, the government’s National Food
Security Strategy (NFSS) aims to make 90 per cent of the population foodsecure by 2020. To meet these goals, the NFSS action plan includes measures
to decrease qat production and consumption, reduce Yemen’s vulnerability to
global food price shocks and promote the sustainable use of water. Efforts to
fight poverty in rural areas, increase farm incomes and create more jobs are
centred on measures to increase access to inputs - such as improved seed
varieties of grains and oilseeds-and to upgrade agricultural marketing.
figure
Yemen.
4.23 Qat being sold in the local market in Lahij,
The management of natural increase
Case Study
China:
the one-child policy
The Chinese one-child per family policy ran from 1979 to 2015. The aim was to
reduce the rate of population growth because the government could see that at
prevailing rates of growth the country would face shortages of food and other
resources in the future. The population had risen from 550 million in 1950 to nearly
1000 million in 1979-a much greater size than any other country in the world. The
population was rising fast because of the falling death rate- life expectancy had
risen from 36 in 1950 to 67 in 1979. Chinese planners estimated that the optimum
population for China was 700 million and the plan was to reduce the population
to that level by 2080. During the 1960s the government had encouraged couples
to have children so by 1979 there were huge numbers of people coming into child­
bearing age; even if each couple had only one child there were so many of them
that the population was set to grow rapidly for some years to come.
The rules were that no woman could marry under the age of 20, that in order
to have a baby a permit was required and permits would only be granted to
women of the right age who had not already had a child. If a woman became
pregnant without a licence she would be ‘encouraged’to have an abortion.
Women were given free contraception and pre-natal classes. Individual areas
were set targets for enforcing these rules. If a woman managed to have a
child with a licence, that child would receive free nursery care and education.
Women with one child would be sterilised. If a woman went on to have a second
child without a licence the couple would face a severe fine, but there were no
penalties for having twins.
The policy was largely applied to urban areas. In rural areas couples were
allowed two children but with a two-year gap.
j.ta
Population
The policy worked only because China had long been a country where the
government had a big influence over the daily lives of people and most were
accepting of the government’s rulings. Decisions by the government could be
enforced by provincial governments and by nominated leaders in state-owned
factories and farms. Even at street level women known as the ‘granny police’
were chosen to check that local couples were following the new rules.
Results of the policy
• The birth rate fell dramatically. Between 1979 and 2011 200-400 million
births that would have happened were prevented. It is now thought that the
population will peak at around 1.4 billion in 2030 and then fall.
• Because many couples preferred a boy to a girl many girl babies were
aborted or killed at birth or given away for adoption. As a result there are
now 117 boys for every 100 girls.
• Most children have no brothers, sisters, cousins or aunts/uncles.
• There are fewer children to support parents and grandparents in their old
age. This leaves the older generations relying on retirement savings or
charity.
• The only-children are often spoilt, over-indulged and have been dubbed
‘little emperors.’
• The policy violates human rights by forcing women to have abortions or be
sterilised. People have a right to have as many children as they wish.
In 2013 the rules were relaxed and more couples were permitted to have two
children. However, relatively few chose to do so. Since 1979 China has become
much more educated and children are expensive. The government is anxious
that so few young people will have to support so many old people, and in 2015
the two-child policy became universal.
NOW INVESTIGATE
1
Look up the current age/sex structure diagram of the country in
which you live and explain it in terms of birth rates, death rates and
migration.
2
Find an example of a country that has pro-natalist policies - policies
designed to increase the birth rate. Why were such polices needed?
What steps did the government take? Have they worked?
3
In the country where you live, what are the issues relating to the
age structure of the population and the way it is expected to change
over the next 50 years?
Population 107
The graphics on this page represent the migrant
population situation in the world and for selected
countries. Migrant population is defined as an
estimate of the number of people living in a country
or area other than that in which they were born.
Spain
-296 036
North America
53.1M
World
International Migrant
Population 2013
231.5M
Latin America and
the Caribbean
8.5M
5
Migration
Qatar
-17 422
Europe
72.4M
Asia
70.8M
Africa
18.6M
Oceania
7.9M
109
Migration as a component of population change
What is migration?
Migration is a subject that academic geographers have devoted more time to
than the other aspects of population geography, so what is migration? It is
defined by the United Nations as “the permanent or semi-permanent change
of residence of an individual or group of people”, where permanent means
for more than one year. It is however a much more complex picture than that
statement suggests and it is a topic that provokes discussion throughout the
world.
The three criteria of distance, time and origin are often used in an attempt
to classify migration patterns. To explain these movements further it is usual to
subdivide them into internal migration where people move within international
boundaries, such as from province to province, and international migration
where migrants cross from one sovereign country to another. International
migration has specific terms for the people making these moves referring to
immigration and immigrants for people moving into a country and emigration
and emigrants for people moving out. The terms in-migration and out­
migration refer to the corresponding internal migratory movements. If the total
number of people entering an area exceeds the number leaving it is said to
have a positive net migration balance and if the reverse is the case then the net
migration will have a negative balance.
figure
5.1 Issues relating to migration
Types of migration
Migrations start from an origin or source nation and end at a destination or
host nation depending on whether the migration is internal or international.
A migrant stream might develop if sufficient numbers of migrants share a
common origin and destination; a good example of this would be the 1950s and
1960s migration from the West Indian islands to the UK.
Where migrants make the reverse journey, for whatever reason, a counterstream might develop, such as UK migrants going to Australia and then
becoming dissatisfied with their new home and returning to the UK. These
counter-streams tend to have fewer people moving along them. Most
migrations take the form of step migrations, with migrants making several
short moves but each time moving to a slighter larger or more important
settlement.
110 Migration
Village to
market town
Market town to
regional city
Regional city to
national conurbation
The West Indian migrations also exhibited chain migration where migrants
from specific islands migrated to specific areas of London following earlier
arrivals who had established themselves in these districts.
Circular migration, sometimes called repeat migration, is the temporary and
usually repetitive movement of a migrant worker between home and host areas,
typically for the purpose of employment It represents an established pattern of
mobility, whether cross-country or rural-urban.
Case Study
Seasonal migration to Goa, India
Raj is a DVD salesman. He is married with a nine-month-old daughter and
comes from the ancient city of Hampi in Karnataka, India. For the last 13 years
he has spent eight months a year selling to tourists on the beaches of Goa. The
rest of the year, during the monsoon season, he is a farm labourer back home.
It is a precarious way to earn a living but it is his job - he has no other skills
other than his winning ways and ready smile. His income is dependent upon
the number of tourists in Goa and a bad tourist year means a difficult year
for him and his family. Nevertheless he supports his immediate family and
his extended family back home to whom he sends money (remittances) every
month. Of course the DVDs are copies but at the equivalent of US$1.50 each,
with all the most recent titles available long before they are in the shops at
home, tourists are happy to buy.
figure
figure 5.2 The SS Empire Windrush carried immigrants
from the West Indies to England for the first time in 1948.
5.3 Beach DVD seller
Migration
So why do people migrate?
Pull factors: Perceived by migrant
Push factors: Reality
Greater job opportunities
Poor qua ity of life
Higher standard of living
Disasters
City life - ‘bright lights’
Marriage
Area able to support population
Harsh environment
Family members already there
Economic hardship
Persecution
Permitting factors:
Population pressure
Infrastructural improvements, new roads/
rail connections, internal air traffic etc.
Lack of work
Major development project, needing labour
figure
5.4 Push and pull factors
Case Study
Push
and pull factors in
Turkey
Whilst considering all the possible factors for migration it is important to look
at a real world example to see if the negative pushes and the positive pulls
apply to reality. In Turkey according to a recent census nearly 28 per cent of the
population was born in a different province to the one they now reside in. This
figure goes up to 62 per cent for the area around Istanbul, a major province that
has attracted migrants for years. Over half of the migrants are in the 15-29 age
group and have a better than average level of education.
Push factors include:
• low rural incomes
• lack of job opportunities
• inadequate infrastructure in rural areas
• poor facilities in the villages
• a lack of services in villages and remote rural areas.
These factors all encourage out-migration but there are also the issues of:
• improving education levels, especially for girls
• improving transportation and communications
• skill and information levels of would-be migrants
• presence of earlier migrants in destination areas.
It is important to note that information, a willingness to take risks, and the
existence of social networks are important push factors. Some of these push
factors could also be described as pull factors.
Whilst rural-urban migration was important in the mid twentieth century,
towards the end of the century two changes occurred; urban-urban migration
and, to a lesser extent, urban-rural migration.
The pull factors encouraging these would-be migrants included:
• job seeking, 20 per cent for men and 10 per cent for women
• education beyond secondary level
• issues related to a member of the household, for women this was very
important with over 50 per cent of female migrants moving for marriage or
Migration
•
following a husband/partner
the level of socio-economic development of a province
•
•
•
being located in a coastal area
development in terms of industry and tourism
having developed provinces as neighbours.
Voluntary or forced migration?
Most migration is the result of free choice made by a migrant as an individual
or as part of a group. However, more than 20 million people are currently being
forced to migrate or feel that they need to leave their homes and/or country.
Examples of these migrations are shown in the following table.
table
5.1 Types of migration
Voluntary
Example
Forced
Example
Between High Income
Countries (HICs)
Workers from across Europe moving
to the UK following EU expansion
Between HICs
Eastern to Western Europe after the fall of
the Iron Curtain
Skilled labour
Engineers moving throughout
the world
Between Low Income
Countries (LICs)
Botswana, Eswatini (Swaziland) and
Lesotho to South Africa for work
Between LICs
Rwanda to DR Congo, also in Sudan and
Ethiopia after conflict
Labour migrants
Mexicans to the USA
Labour
migrants
Horn of Africa to Mozambique, sub-Saharan
Africa to Europe (Italy and Spain)
Refugees
Montserrat to Antigua following
the volcanic eruption
Refugees
Balkan ethnic cleansing, Kosovans to
Albania
Asylum seekers
Vietnamese to Australia
Asylum
seekers
Kurds from Iraq to Europe, Syrians from
the civil war to Greece and then on into
other European countries.
Some theoretical considerations
Various researchers and academics have attempted to classify migration types
and to try and explain the factors at work and the likely outcomes. These can be
divided into four main categories: typologies, general principles, gravitational
models and push-pull models. These categories have been followed in recent
years by a number of other approaches.
An attempt to identify types of migration was made by William Peterson in
the late 1950s. He identified five types of migration: primitive, impelled, forced,
free and mass. Each type was further subdivided into conservative migration
and innovative migration. The former was when migration was undertaken to
preserve a certain standard of living and the latter was an attempt to improve
the individual’s standard of living.
1
2
3
Primitive migrations are best described as the movements of nomadic
pastoralists and that of shifting cultivators. Availability of rainfall and the
fertility of soils being the main determinants of migration patterns, such as
in parts of the Sahel.
Impelled migration takes place under threat or perceived threat, either
physical or human. The evacuation of a region prior to a volcanic eruption,
such as the area around Mt Pinatubo in the Philippines or the wholesale
movement of the population of Montserrat. Since the Boxing Day tsunami
(2004) countries likely to be affected by similar events have procedures in
place to move people to places of safety should such a threat present itself.
From the human point of view the movement of people with the partition
of India in 1946 remains one of the largest ‘migrations’ under duress in
modern times although the movements of people in the Middle East as a
result of the upheavals in that region are beginning to rival it.
Forced migrations are similar to impelled migrations but without the lack
of choice. Indeed following the partition of India minority groups of Hindus
remained in the new largely Muslim state of Pakistan and groups of Muslims
remained in the now Hindu India. Forced migrations are all too common,
slaves from West Africa to the Caribbean and southern states of the USA, Asian
Indians form Idi Amin’s Uganda in the 1970s, movement of ethnic groups
during the Balkan conflicts of the 1980s and 1990s, and the conflicts between
Burundi and Rwanda (1993-2005), which resulted in the displacement of
many thousands of people. Physical events can also cause forced migrations.
Natural disasters, such as volcanic eruption, flood and drought, as well as
environmental tragedies, such as the Chernobyl disaster (1986), can also be
factors in forced migrations.
Migration
4
The distinction between free and mass migrations is only one of the
numbers involved. In terms of size the largest movement of people was that
of Europeans to North America from the mid seventeenth century onwards.
Case Study
The Mediterranean’s deadly migrant routes
Figures reported in September 2015from the International Organization for Migration
(IOM) showed that more than 3000 migrants were believed to have died crossing the
Mediterranean Sea, compared with 96 for the same period in 2014. As many as 800
migrants were feared drowned after one incident when their boat capsized in Libyan
waters south of the Italian island of Lampedusa. The IOM estimated that as many as
30 000 migrants could die in 2015 were this rate to continue.
figure
5.5 Migrant deaths, January-November 2014.
These figures refer only to deaths that have been reported;
unknown numbers are not recorded, and as such this map
represents only a base minimum.
Migration
The Mediterranean crossing is by far the most dangerous. According to
the IOM, taking all international migrant crossings up to mid-April 2015 into
account nearly 8 out of 10 deaths had taken place in the Mediterranean. Within
the Mediterranean, the Central migration route from North Africa to Italy and
Malta is the deadliest. In 2014 a total of 3279 migrants were killed on the journey
across the sea to Europe. The majority perished on the Central Mediterranean
route. Some 912 out of 954 of the deaths by mid-April 2015 had been on routes
towards Italy, however the IOM estimate some 21191 migrants have reached the
Italian coasts alive during the same period.
The vast majority of the migrants who die on this Central Mediterranean
crossing began their journey in sub-Saharan Africa.
In 2015 the second highest number of migrants died in the Horn of Africa
where less than 1 in 10 deaths occurred.
In 2014 the African nations with the most migrants reaching Italy
were Eritrea, Mali and Nigeria.
Mediterranean deaths by region of origin
figure
table
5.7 Migrant deaths, January-April 2015
5.2 Migrant arrivals in Italy, 2014
Migrant arrivals to Italy by sea, 2014
Country of origin
Men
Women
Minors
Total
25 155
6203
10 965
42323
24 061
6076
4192
34 329
Mali
9382
27
529
9938
Nigeria
6989
1454
557
9000
7409
28
1270
8707
Syria
Eritrea
The Gambia
General principle theories of geographical mobility
General principle theories were largely developed to explain geographical
mobility. The Laws of Migration, proposed by Ernst Georg Ravenstein in
1889, were intended to explain the movement of people without regard to
any particular temporal situation or location. Ravenstein’s work was based on
movements within Great Britain and he was writing at a time of intense internal
and international migration. He gave migration a number of characteristics,
namely:
the greatest body of migrants travel short distances
this produces currents directed towards great commercial centres
Migration
•
each current has a compensating counter-current in the opposite
•
•
•
•
direction
both currents display similar characteristics
long distance movements are directed towards great commercial centres
people in urban areas migrate less than people in rural areas
males migrate more over long distances and females migrate more over
short distances.
Additions to these laws:
• Most migrants are between 20-34 years of age.
• People mainly move for economic reasons.
• Urban housing development is inadequate for the influx of migrants so
ghettos/shanties are formed.
The Gravitational model developed by Stouffer is an attempt to explain why
migrants might settle for a location other than their intended destination.
Sometimes referred to as an ‘intervening opportunity’ model, the Gravitational
model states that: "The number of persons going a given distance is directly
proportional to the number of opportunities at that distance and inversely
proportional to the number of intervening opportunities.”
Having studied 116 interstate migration flows within the United States,
Stouffer argued that the volume of migration had less to do with distance and
population totals than with the opportunities available in each location. More
recent work by Wadycki analysing over 2000 migration flows has confirmed
Stouffer’s original assertions.
intervening
opportunities
r allow migrants to
- become satisficers obtaining what they
are content to accept
Current \
locations/
source region
with negative
\
feel
/
/
better
housing
figure
more job
opportunities
'Desired \
location/host
region with
positive
perception/
better
environment
5.8 Stouffer’s intervening opportunity model
The Stouffer model was later revised by Zipf with his Inverse Distance Law,
which states that: "The volume of migration is inversely proportional to the
distance travelled by the migrants and directly proportional to the populations
of the source and the destination.”
The push-pull model was refined by Lee in his Principles of Migration.
He was attempting to bring together and simplify all aspects of migration
‘theory’ that existed at that time. His revision of Stouffer was to introduce
intervening obstacles that needed to be overcome before migration could
take place. He further suggested that both source and destination possessed a
range of attributes and that each possible migrant would view these attributes
differently depending on their age, gender, class and marital status. What
might be seen in a positive light by one person may well be a negative factor
in the eyes of someone else. These factors would operate differently at the
source than at the destination as the latter would always have a degree of
uncertainty about it. This would be particularly true in the case of international
migration.
3
Migration
figure
5.9 Lee’s push-pull theory
The idea of push and pull factors has been further explored by Mabogunje
in attempting to explain rural-urban migration patterns in Africa. In
Mabogunje’s framework the model takes into consideration both economic
and social factors but also the environment of change operating within the
continent at present. The model sees not just cause and effect but a system
where there is interdependence and self-regulation and modification. There
is a continuous action and reaction, so urban economic expansion will
stimulate migration from villages close to urban areas; whilst a decline in the
economy will reduce those flows of migrant labour and may lead to a reversal
of the flow.
Equally important are any adjustments that may occur in the source region.
Fewer agricultural workers as a result of the out-migration may lead to an
increase in per person income for those remaining in the rural economy. These
families remaining may benefit from monies sent back to the village in the form
of remittances. Although it is possible that the new urban arrivals will use any
increases in income to spend on their new homes.
A further consideration is developed by Byerlee who uses a cost-benefit
model by which he considers migration as the outcome of a cost-benefit
calculation. He suggests that the decision to migrate will be taken when the
benefits of such a move are exceeded by the costs. This was an approach
pursued by Todaro. Migrants usually are quite well informed as to what
to expect when they arrive at their destination as there is a steady flow of
information back to the source region from earlier migrants. Although they may
not find employment immediately they are prepared to take a risk and stay in
the city rather than return to the country. In this way if they are successful in
finding work the financial rewards are far higher than in their home area. Stark
extended this idea by suggesting that families make the decision to migrate in
order to improve their economic status. One member of the family migrates,
sends remittances home, and then if the migration is successful economically
other members of the family follow.
table
5.3 Recent approaches to migration studies
Migration
Effects
determinants
Economic
Method of analysis
Family
Individual
Positive
Todaro
Institutions
Stark
Push-pull
Negative
Sociological
Marxist
Structuration theory
Gender analysis
Marxist theory sees labour migration as an inevitable process as economies
move towards a capitalist model and workers become divorced from the land.
Migration is essential for capitalist production, which is located in urban areas
Migration
thus initiating the scale of rural-urban migrations seen in China over the last
20 years.
Structuration theory includes individual motives and those structural
and cultural factors and rules within which migrants have to operate.
Gender analysis has become a significantly more important approach in
recent years, examining the different approaches to migration by men and
by women.
Income per person (USS)
figure
5.10 Income and migration
So what might stop you? Obstacles and barriers to migration
When considering internal migrations the only real issues are distance and cost
and this will vary from country to country. Clearly internal migration in the USA
is a more significant issue than in the UK. International migration however
is a more difficult scenario. The major constraints are the immigration laws
operated by individual countries, the lengths to which some governments will
go to enforce these laws, and the risks that people will take to avoid these laws
in orderto get into a country.
In the period prior to World War I the international movement of people was
almost totally unrestricted, indeed the USA would take anyone just as long as
they were not a convict, lunatic or prostitute although these restrictions were
extended to include Chinese, a group that was also discriminated against by the
British government immediately after the Second World War.
After the Second World War (particularly in Europe) there was such a
shortage of workers that although there were controls they were hardly applied.
This was a time of West Indian immigration to the UK and of considerable
immigration of‘Gastarbeiters’ (guestworkers) to West Germany, especially from
Turkey.
Since 1800 Australia has built its population through immigration. Between
1788 and the 1940s government policy was to exclude anyone not of European
descent. However in recent years the Migration Program has shifted in favour
of a skill based selection regardless of where people came from, the aim being
to attract those professions and trades which would benefit the country as a
whole. In 2002-3 71 per cent of the 93 000 migrants qualified in the skilled
migration category with a further 20 000 skilled workers to boost the labour
force, and targets announced for another 97 500. Despite the increased ethnic
and cultural diversity this has brought, many in Australia argue that immigrants
should speak English and behave like the rest of the population in order to
figure
5.11 Armed guard on the Mexican side of the
US-Mexico border.
118 Migration
integrate as quickly as possible.
Surface Management
MB &LW
■i IMitvy
Humane Borders
Fro nt eras Compasivas
m6söN!
243W 33 St.
Tucson, AZ 86713
52 0-398-50 S3
hap://www humaneboniers org
figure
5.12 Deaths on the Arizona border, 1999-2015
Internal migration (within a country)
The movements within this topic are of four main types:
• rural-rural
• rural-urban
• urban-urban
• urban-rural.
In LICs the main movement is rural-urban, although there are examples
of agricultural expansion in previously unexploited areas such as in parts of
the Amazon Basin. The Brazilian government has been encouraging farmers
from other regions within the country to move. The most common form of
movement is rural-urban, often from peripheral regions into core areas. In LICs
there are marked economic differences between these types of regions when
compared to the differences in HICs. Urban-urban movements usually take the
form of step migration with migrants moving to small market towns before
moving again and finally ending in a major urban centre, often the capital.
Urban-rural migration, a counter-stream movement, is dominated by urban
dwellers returning to their rural home region often as a result of a failure to
adapt to urban life and find work. Following the global recession many Chinese
workers who had retained their rural registration, or Hukou, returned to their
villages in the hope of finding work on the family farm.
In HICs there is a much stronger stream of counterurbanisation with city
dwellers moving out to rural regions because infrastructure and communication
networks allow them to live in the countryside but work in the city.
The causes of internal migration
Whilst the underlying specific causes may vary from LIC to HIC, the influence
of the core-periphery concept remains the same. In many ex-colonial countries
the development of an economy based on the exploitation of primary resources
will have led to the movement of people to the coast and the inevitable port
development and the processing of those raw materials. Post-colonial development
will have seen varied levels of inward investment and limited industrialisation.
figure
5.13 Hukou registration book
figure
5.14 Beijing railway station, China
As seen in earlier sections, migration occurs as a response to two sets of
factors - one in the origin and one at the destination. It is often these perceived
factors at the destination that set migration in motion. More often than not it is
economic factors that precipitate such a move and not just population growth.
Increasing populations often outstrip the ability of local resources to cope and
migration acts as a release valve.
figure
5.15 Urban growth rate in Africa
120 Migration
Case Study
Fiji
Walsh in his study of the urbanisation of Fiji examined the reasons why
islanders migrated to the capital, Suva, and other towns around the coast.
PAPUA?
NEW GUINEA
*1
SOLOMON
1
»ISLANDS
Honiara B a
Port
Moresby
C
oral
TUVALU
Ç.
■ Vaiaku
'American
Futuna Islands
JSamoa
L (^ance)^^p-iai^ (USA)
Sea
jCairns
Coral Sea
Islands Territory
(Australia)
Tokelau
(New Zealand)
Port Vila
New
Caledonia
(France)
'
•
Fl^
-J
O; ■
-Suva
TONGA
Noumea'
Rockhampton
(New Zealand)
Nukualofa
AUSTRALIA
^/coast"°™ ^land
oasr
■a
Kermadec
Islands
(New Zealand)
Lord Howe Island
o Newcastle (Australia)
°Sydney
■ r„ J :
^Melbourne
1 Q s m a n
Geelong
0 L.
Tasmania
0 Hobart
figure
(Australia)
O c fz
ç ,,
A ea
-Auckland
North $
Island ' '
NEW
ZEALAND /
,
oChristchurch
South
r Chatham Islands
Island
(New Zealand)
Dunedin
5.16 Fiji location map
Some 52 per cent of the population of the islands is now urban based and
Walsh suggests the following reasons for this move from a largely rural sugar
growing economy to one that includes garment making, processing of sugar,
coconuts and ginger and a growing tourist industry.
•
•
•
•
•
Indians, originally brought in as plantation workers, are not allowed to
own land so drift to the towns.
After independence many locals went in search of administrative jobs.
Incomes in rural areas are only 25 per cent of those in Suva.
Urban incomes have been growing six times faster than in rural areas.
Many people move to escape the traditional social structure based on
communalism in order to accumulate individual wealth.
However there are consequences of such movements and in Fiji:
•
Severe rural depopulation has threatened the livelihoods of those who
remain.
• Rural families become dependent on remittances from urban family
members.
• Disruption of family life - often children are left behind in the care of
elderly relatives.
• Severe housing shortages in the towns to which the migrants have moved,
with large numbers of people ending up as squatters.
• Pressure on services such as health and education.
• Large numbers of migrants who despite their level of education lack
the necessary skills to do the jobs that become available and so work
in the informal economy.
Migration
Urban-urban migration
Urban-urban migration takes two forms: the step migration already referred
to but also movement within the same urban area, which is a largely HIC
occurrence. Migrants will often initially stay with friends or relatives when they
first arrive in the city but as they become more established they are able to move
away from squatter camps and migrant areas.
Intra-urban migration
Improved income levels mean that property can be acquired in ‘better’ areas and
housing improvements can take place. Changes in family status often mean a
move to a larger property or the building of additional rooms. In cities in HICs
the movement of people out towards the suburbs used to be a characteristic
life stage movement. The reason for this movement is to improve lifestyle, or
to move to a more desirable school catchment area. However the movement
of people in cities has become confused as areas in the centre have become
available for residential use with the decline of old industries and people have
moved back into the centre.
Counterurbanisation
Counterurbanisation is almost entirely a phenomenon of the developed world,
although the twenty-first century has seen it begin in Chile, Argentina and
Brazil. This process involves the shift of populations from older industrial core
areas into peripheral areas as well as a move from larger centres to smaller
towns. Initially in western countries this was a response in major industrial cities
to inner city deprivation and overcrowding with people moving from towns
and cities to new towns, estates or commuter towns and villages. In the UK
new towns, such as Harlow and Crawley just beyond London’s Green Belt, and
estates were built mainly as a result of government schemes launched after the
Migration
figure
5.18 A squatter settlement in Kenya, potentially the first home for some migrants.
Second World War to re-house people from deprived inner cities. The intention
was that the largely working class population of these inner areas would be re­
housed in areas that were fully planned and that provided modern housing and
facilities and new industrial estates. Housing developments in commuter towns
and villages in rural areas some distance from urban centres are mainly aimed
at middle class or socially mobile people because they can easily access nearby
towns and cities by car, bus or maybe train. The cause of this movement was
that after the Second World War people wanted a better quality of life, with less
pollution and without the crime of urban environments.
During the war years and immediately afterwards employers started to
move to rural areas following damage to buildings from bombing, and this
added to the cause of counterurbanisation by attracting people with new jobs.
Between 1981 and 1996 rural areas gained more than 1 million jobs. In more
recent years internet use and the British government’s proposals to roll-out
high speed broadband into rural areas has allowed people to move away
from the towns and cities where they previously worked to more pleasant
environments.
There has been increasing demand for second homes or homes to be
bought by retired people, particularly in attractive rural areas such as National
Parks and Areas of Outstanding Natural Beauty, due to generally higher levels
of affluence. This comes at a time when rural economies need to generate
a higher level of income. Many agricultural businesses are struggling and
one way for them to make money is to sell unwanted land or buildings for
residential use.
One of the effects of counterurbanisation has been the impact on local
services. With large numbers of commuters moving into nearby towns and
cities to work many of the services they require, such as shops, schools, post
offices and other professional services, are accessed in these urban areas. This
has had the effect of forcing village and small town providers to close because
they are not getting enough business. Counterurbanisation also affects the
figure
5.19 The reliability of rural
broadband is the subject of much debate.
figure
5.20 Rural business park, Chichester, West Sussex, UK
Migration 123
CHICHESTER BUSINESS PARK
Meteor Court
8
NEW AIR-CONDITIONED OFFICES
3,100 - 30,850 SQFT TO BE BUILT
K
layout of rural settlements; modern housing is built on the outside of the area
and industrial estates are built on large main roads leading into settlements,
often on land that was previously farmed.
Local young adults may be forced to leave the area to find jobs. House
prices rise dramatically as a result of the rise in demand from people wanting
to live in, and commute from, rural areas. Older properties are sometimes
cleared to make way for executive housing developments, which in turn
contributes to the rise in house prices at the lower end of the market for first
time buyers.
Some farmland is given over to the provision of golf courses to provide for
the new inhabitants of rural areas.
figure
5.21 New development
figure
5.22 Derelict property
5.23 New housing
International migration
International migration is a major global issue creating great debate and
confusion over the terms used to describe the migration. Very few countries
are willing to accept large numbers of migrants no matter how desperate the
need of the migrant, no matter what benefits they may bring to the receiving
country. In an earlier section the term ‘voluntary migration’was dealt with
and the factors that might determine such a decision. So what has led to the
situation where, by 2013, nearly 214 million people live outside the country of
their birth?
There has been a massive rise in migration linked to work and to education.
It is estimated by the British government that there could be as many as 660 000
foreign students in the UK by the 2020s. The number of foreign-born people of
working age in the UK more than doubled from 2.9 million in 1993 to slightly
more than 6 million in 2013. A significant change has been the increase of female
migrants who now make up nearly 50 per cent of all migrants worldwide and in
2013 female migration to the UK exceeded male migration.
There has also been migration between HICs, which is a more recent
occurrence, with skilled workers going from one city hub in one country to
another to do much the same job. This is in the face of the many controls that
have been introduced by HICs in an effort to reduce the amount of illegal
immigration, which was 863 000 in the UK according to one newspaper (2012).
People trafficking is also a problem, with 2744 victims identified by the National
Crime Agency in the UK in 2013.
Of course globalisation in its many aspects has made migration more
possible and the improvements and extent of airtransport networks have played
a major role.
124 Migration
figure
5.24 Total number of foreign-born working age people in the UK, 1993-2013
Forced migration from a Low Income Country (LIC) can in the past be
associated with the forcible removal of some 15 million people from Africa to
work on plantations in the Americas. Even now there is considerable trade in
people trafficking and as a result there are estimated to be between 10 and 30
million slaves in the world today.
The latter years of the last century saw a dramatic increase in the number
of people who suffered internal displacement in their own country. This led to
a tide of 16.7 million refugees (2013) fleeing from political and environmental
upheaval. The 1951 Refugee Convention defines a refugee as someone who
“owing to a well-founded fear of being persecuted for reasons of race, religion,
nationality, membership of a particular social group or political opinion, is
outside the country of his nationality, and is unable to, or owing to such fear, is
unwilling to avail himself of the protection of that country.”
An asylum seeker is someone who has applied for asylum and is waiting for
a decision as to whether or not they are to be regarded as a refugee. The two
terms are very different although they are often confused.
figure
5.25 The advent ofcheap air travel has made migration easier.
Migration
figure
5.26 The departure lounge at Beijing airport, China. Airports can be the point of arrival for many international migrants.
Migration
Estimated number of persons displaced or evacuated from their homes or made
homeless by the threat or impact of a disaster.
Bangladesh
Cyclone Mahasen 1 100 000 evacuated
Arctic Circle
Japan
Typhoon Man-yi 520 000 evacuated
T
Philippines
Typhoon Haiyan Ci 4 095 280 displaced
Tropic of Cancer
Typhoon Trami 1 744 062 displaced
Typhoon Nari ar 405 965 displaced
Niger
>2^ Rainy season floods ;==; 200 961 homeless
Bohol earthquake SU 348 507 displaced
-2» Tropical depression
Equator
Sudan
season floods
319 746 homeless
jfjlr
c
China
Monsoon floods in
13 provinces 1 576 900 displaced
Typhoon Fitow 826 000 evacuated
Lushan earthquake -
223 134 displaced
K 4
2» 694 800 displaced
over 1 000 000
100 000-1 000 000
10 000-99 999
1000-9999
under 1000
no data
Typhoon Usagi ft 586 743 evacuated
India
Monsoon floods in Bihar,
Kerala, Uttarakhand, Assam,
Andhra Pradesh, West
““ Bengal, Uttar Pradesh 1 042 271 displaced
Cyclone Phailin cr 1 000 000 evacuated
Statistics are for 2013.
figure
Tropic of Capricorn
Typhoon Utor 513 000 evacuated
Typhoon Soulik G. 500 000 evacuated
2^. Russia-China floods — 354 000 displaced
Gansu earthquake 226 700 homeless
Vietnam
Typhoon Haiyan 800 000 evacuated
5.27 Disaster-induced displacement worldwide
Estimated number of persons displaced by conflict and violence.
figure
5.28 People internally displaced by conflict and violence worldwide
Migration
The impacts of international migration
The impacts of international migration are felt both in the country of origin
and in the receiving country. These impacts are social and economic, cultural
and political as well as environmental; there is also a temporal element as these
impacts are felt both over the short term and over a longer time frame.
Socio-economic impacts
• Dustmann and Frattini (2013) conducted a study on the fiscal impact of
immigration and found that between 2000-2011 European migrants made a
net contribution of US$31 billion to UK finances, divided between migrants
from the original EU member states, who contributed US$23 billion, and a
further US$8 billion from A8 migrants (migrants from the eight countries
that joined the EU in May 2004). They also found that European migrants
were 43 per cent less likely to be in receipt of state benefits and 7 per cent
less likely to live in social housing. Between 1995-2011 EU migrants in
Britain made a net contribution of US$6.8 billion, non-European migrants
cost Britain US$182 billion, while British citizens were a net cost to Britain of
•
•
•
•
•
US$833 billion.
It is accepted that many migrants are in the UK to do the 3D jobs-dirty, difficult
or dangerous jobs-and as a result migrants are over represented in industries
such as construction, agriculture, hospitality and catering and in household
services.
In some cases migrant labour offsets the declining and ageing population
with a low natural growth commonplace across Western Europe. Examples
are the Turkish migration to West Germany in the 1960s and 1970s and of
Eastern Europeans to France, Spain and the UK.
In 2002 the UK government introduced the Highly Skilled Migrant
Programme to attract the best foreign workers to fill skill shortages in key
areas of the economy.
The Highly Skilled Migrant Programme also attracted workers to do jobs in
areas where vacancies were difficult to fill.
The remittances that get sent ‘home’, which according to the World Bank
will amount to US$685 billion in 2015, help alleviate poverty, provide
investment opportunities and help to strengthen the economy of the home
country.
table
5.4 Asylum claims submitted in major receiving countries, 2013.
Germany
109 600
United States
84 400
South Africa
70 000
France
60 200
Sweden
54 3 00
Malaysia
53 600
Turkey
44 800
UK
23 507
table
5.5 Remittances across the world
US$ million received in 2011
128 Migration
% GDP 2011
I
India
63 663
Tajikistan
31.0
China
62 497
Lesotho
28.6
Mexico
23 610
Moldova
23.2
Philippines
22 974
Samoa
22.5
France
16 379
Kosovo
20.8
table
5.6 UK to Poland remittances
Remittances UK to Poland (US$ millions equivalent)
2004
7276
2005
10 591
2006
13 075
2007
16 153
2008
16 077
2009
12 505
2010
11 658
2011
11578
NOW INVESTIGATE
1
Where do the people in your class come from, where were they
born and where were their parents born? How well do the theories
explained in this chapter apply to the people in your class?
2
Do the theories outlined in this chapter apply to modern day
movements of people?
3
Can you identify any‘internal migration’types of movement of
people where you live? Is the countryside being built on? If the
answer is ‘yes’ to either of these questions, why is this building
taking place?
4
What do the remittance figures shown in Table 5.5 and Table 5.6
tell you?
Migration 129
2030
6
Settlem ent dynam ics
The shape of growth
1950-2030
A Megacity is a metropolitan area with a
total population in excess of 10 million
people. In addition, some definitions set
the minimum level for population density
at 2000 people per square kilometre.
A megacity can be a single metropolitan
area or two or more metropolitan areas
that converge.
131
Settlement dynamics
Changes in rural settlements
Rural settlements have undergone huge changes in character both in HICs and
LICs in recent decades as a result of:
rural-urban migration
urban-rural migration
rural planning policies
the impacts of urban growth
technological change
national government policies.
•
•
•
•
•
•
figure
6.1 Settlement hierarchy
Contemporary issues in rural settlements in the UK
Up until World War I the rural landscape and its many integral parts was
viewed as being uniquely different to the urban landscape. This landscape was
characterised by the following factors:
•
•
•
•
•
•
close-knit community
considerable homogeneity in social traits
family ties much stronger than in urban society
religion more important than in towns
class differences less pronounced than in urban society
less mobility than in urban society.
Since 1918 change in rural areas began to reflect the wider changes in society,
largely as a response to the lack of manpower, and since the Second World War
these changes have continued to gather momentum. As a result the traditional
‘model’ of rurality needed a more flexible approach.
urban built
environment
figure
Settlement dynamics
urban-rural
fringe
6.2 The urban-rural continuum
farming and
deep
commuter zone countryside
remote rural
environments
However other researchers suggest that the question of what is rural is far
more complex than might have been first thought. The complexity has increased
as a result of the changes to the rural economy where, whilst agriculture
remains important, the rural economy is no longer the sole responsibility of
farmers and landowners. Agricultural jobs declined throughout the twentieth
century and this acted as an impetus for rural-urban migration. However
new employers have moved to rural areas and have established themselves as
providers of employment in high-tech industries, light manufacturing and the
Industry LQ is a way of showing how concentrated a
particular industry is in a region compared to the rest of
the country. The higher the LQ, the higher the
concentration of the featured industry in that region.
Location quotient (LQ)
LQ >= 3.0
2.5 <= LQ < 3.0
2.0 <= LQ < 2.5
1.5 <= LQ < 2.0
1.0 <= LQ < 1.5
0.5<=LQ<1.0
0.0 <= LQ < 0.5
no data
Statistics are for 2011.
figure
6.3 Manufacturing employment in Great Britain.
service sector. High-tech industries prefer greenfield sites in attractive locations.
Their workforce is well educated and well paid and because they tend to be fairly
mobile will choose to live in or near attractive locations. This explains the growth
of such industries near or close to Areas of Outstanding Natural Beauty or the
National Parks.
The growth of new industry has attracted new workers to rural areas just
as conditions in urban areas have encouraged a compensatory urban-rural
Settlement dynamics 133
figure
6.4 Two old estate cottages knocked into one home in a village with good access to the M4,
England, UK.
movement of people, aided by increased car ownership and improved transport
accessibility. Second home ownership has also been promoted by transport
access and greater affluence. This growth has both positive and negative
impacts.
Rural gentrification has provided a second life for derelict buildings as well
as providing some iconic housing but these changes often cause resentment
amongst the local population.
Retirement migration, especially into attractive rural areas, is a growing
phenomenon having both positive and negative impacts.
Attempts have been made by government since the Second World War
to restrain this movement of people and the inevitable expansion of small
market towns and villages close to cities. Green belt policies now apply to
major urban areas with housing and services being directed to key villages to
allow these to be provided at hubs rather than being diluted across a number
figure
6.5 Green belts in England
of settlements.
Reinventing rural policy
In OECD countries rural areas account for three quarters of the land area
and house a quarter of the population. Rapid changes in society and in the
economy have led to the need for new strategies for rural development which
take account of the different development needs of rural areas, many of which
are based on the exploitation of specific local resources. For example, the
development of mountain and winter sports are clearly not suitable for all rural
areas.
Three factors are influencing rural policy across OECD countries as new
approaches are explored to address domestic and international requirements.
•
•
•
An increased focus on amenities: the value that society places on natural and
cultural amenities like World Heritage Sites.
Pressures to reform agricultural policy: there is a need to address the
question of farm subsidies, the role of the World Trade Organisation and
international trade in farm produce.
Decentralisation and trends in regional policy: a move from being top-down
to more locally focussed set of policies, involving local stake holders and
with central government having a reduced role.
Settlement dynamics
Canada’s Community Futures Programme actively promotes bottom-up
economic development in rural areas while Finland has, since 1990, had a
multi-year Rural Policy programme. This programme has "broad” policies which
integrate the specific needs of rural areas into the decision making processes of
central government while a “narrow” set of policies target specific rural areas.
The Mexican government has a “micro-region” strategy which adopts a
holistic approach to rural development by co-ordinating policies directed at
263 rural micro regions. Each region has a community centre which, through
a highly participatory process involving all members of the local community,
focuses local priority actions.
Similar programs exist in the UK, in Germany, the Netherlands and through
the LEADER project across Europe as a whole.
Case Study
HiLMARTON: A VILLAGE IN SOUTHERN ENGLAND
The Council for the Protection of Rural England (CPRE) is reported as saying
that nobody should be disadvantaged by where they live but poor rural dwellers
can be disadvantaged in multiple ways. Closures of key amenities such as the
post office can have drastic consequences for the village shop and threats of
closure to village schools add to the problem. The government’s desire to locate
more medical services in polyclinics threatens the existence of the village GP
and the village pub is already in terminal decline.
Hilmarton is a village in North Wiltshire in the North Wessex Downs area.
The village is situated on the A3102 between the towns of Caine and Royal
Wootton Bassett. The parish population peaked at 828 in 1851 but then began
to decline due mainly to fewer labourer inhabitants as farming mechanised and
families sought work in nearby Swindon with its large railway works. The 2011
census listed agriculture in the county as only the fourteenth-largest employer.
Since 1971 greater car ownership has meant that more people can live in
villages. This development encouraged the creation of an executive housing
estate in Hilmarton in the 1970s and by 2011 the population had risen to 745
people.
Hilmarton does have a thriving primary school for 113 pupils, but this is
the only village amenity. To visit the doctor or dentist, to buy stamps, milk or
newspapers the nearest town is three miles away. To buy anything other than
day-to-day items a visit to Swindon or Bath is required some 30-40 minutes by
car or even longer by bus.
European funding to improve the rural economy is channelled in the form of
the Rural Development Programme for England (RDPE) and delivered in a limited
way through LEADER projects. These projects are bottom-up community-led with
public, private and community sectors working together on a range of local issues.
The current programme will concentrate on investment in the rural economy:
•
farming
•
•
•
•
•
micro and small businesses (including farm diversification)
tourism/the visitor economy
forestry
rural services and connectivity
culture and heritage.
figure
6.6 Hilmarton, Wiltshire.
Settlement dynamics 135
Case Study
Mwandama: Contemporary issues in rural Malawi
Malawi has a population of 15.9 million (2011) and a growth rate of 3.33 per cent
(2014), which is well above the total fertility rate (TRF) of 2.2 per cent. Some
3.18 million people live in urban areas but the majority of people live in rural
areas as subsistence farmers. As well as feeding themselves most families grow
tobacco, which makes up 54 per cent of Malawi’s commodity exports along with
coffee, peanuts, cotton and wood products.
Malawi is one of the poorest countries in Africa with around 74 per cent
of people living below the US$1.25 a day poverty line and 90 per cent of
people surviving on less than US$2 a day. The country is ranked 160 out of
182 on the Human Development Index (HDI) and is in the top 15 countries
for deaths as a result of HIV/AIDS, which accounts for a quarter of all
deaths.
Issues related to deforestation, land degradation, water pollution, corruption
and poor governance all contribute to rural poverty and rural-urban migration.
A solution has been the establishment of the Millennium Villages Project (MVP),
which includes the village of Mwandama.
figure
6.7 Mwandama, Malawi, location map.
figure
6.8 Most of Malawi’s population lives in rural areas such as the mountains of the Nyika Plateau.
Settlement dynamics
The Mwandama cluster is located in the south of the country about 24 km
from the town of Zomba between 900-1200 m above sea level. Mwandama sits in
the only region in the world that has seen both a rise in temperature and a drop in
rainfall in recent years, which has led to recurrent famines. The seven villages that
make up the cluster account fora population of 35 000 across 8600 households.
The region is intensively cultivated both by smallholders growing maize,
pigeon peas, cassava and groundnuts, and by commercial estate owners
growing tobacco and maize.
Large privately owned tobacco plantations, which surround the seven villages
in the Project cluster, provide work for many local people at wages of US$0.50
per day, but these plantations have had significant impacts on the development
of surrounding communities. Plantation owners restrict the use of roads to
the villages, and the availability of work gives families an excuse to keep their
children out of school. As a result school attendance rates have historically
been extremely low. However the MVP has brought new classrooms in 14 new
primary schools and meals are provided in primary schools, which helped
increase attendance to 95 per cent in 2011 and decrease the dropout rate by
half. In addition four health centres have contributed to better levels of school
attendance and improved quality of life generally in the area. Other benefits of
the Millennium Villages Project include:
•
•
Increased yields of maize by five times to over 4 tonnes per hectare.
•
A contract with the World Food Programme worth US$47 500 for its
members in 2010.
A mobile bank offering savings accounts and micro loans.
Almost universal coverage for households for improved supplies of drinking
water.
A reduction of one-third in the number of children who suffer from stunting
•
•
as a result of chronic malnutrition, and universal immunisation for measles.
A 400 per cent increase in the numbers of women tested for HIV/AIDS.
The installation of two mobile phone towers to increase coverage in the area.
•
•
Urban trends and issues of urbanisation
Cities first formed after the Neolithic revolution around 8000 BC. This
brought organised farming, which encouraged hunter-gatherers to abandon
their nomadic lifestyles and settle near others who lived by agricultural
production. This in turn led to denser populated areas, thus supporting city
development.
The first true towns developed where the inhabitants began to take on
specialised occupations and where trade, food storage and power were
centralised. It was in the fertile river valleys of modern-day Iraq that the first
cities began to appear. The spread of urbanisation was to take another 3500
years before cities in ancient Greece and Rome were recognised and even longer
before towns in northern Europe could claim city status.
The Middle Ages saw the rapid growth of towns in Europe as trade
flourished but it was not until the mid seventeenth century that the major
technological shock would occur that would start the process to propel the
world into an urban setting. The Agricultural Revolution of the early seventeenth
century freed labour from the land providing the necessary workforce for
the Industrial Revolution, methods of mass production and the urbanisation
that followed.
The Industrial Revolution
Cities of over 100 000 people only accounted for 10 per cent of the population
in England and Wales in 1801. The total population was just under 9 million
and of those nearly 1 million (960 000) lived in London. Areas of high density
Settlement dynamics 137
figure
6.9 World urbanisation, 2014
population were isolated and very small. They were commercial centres
such as the industrial West Midlands, South Lancashire and West Yorkshire.
Whilst the countryside between East Anglia and the West Country was well
populated, embryonic industrial areas in northern and midland England were
growing faster.
Between 1801 and 1851 London’s population grew from 960 000 to
2.7 million - a remarkable concentration of people not replicated anywhere else
in the world. As industrialisation spread so the pace of urbanisation speeded
up. It took 80 years for 30 per cent of the population of England and Wales to
become urbanised but only 66 years in the USA, 48 years in Germany and 36
years in Japan.
In the LICs urbanisation was focused on port cities such as Mumbai and
Kolkata, which grew from the export of textiles and jute, while cities in South
America prospered from the export of coffee from Sao Paulo and sugar
from Recife.
Urban growth spurt in LICs
Research suggests that urbanisation and economic development have
gone hand in hand but in recent years particularly in the LICs economic
progress has lagged behind the rate of urbanisation. Cities in many of these
countries have grown at an alarming rate, outstripping the ability of the city
to cope with its population. In India, predicted to be the fastest growing
economy in 2016 and with some of the world’s largest cities containing
a third of the country’s population, many people live in appalling slum
conditions.
This disproportionate distribution can be explained by the impacts
of globalisation on cities and indeed whole regions being part of the
‘global village’ while other areas remain divorced from it. The influence
138 Settlement dynamics
of Transnational Corporations (TNCs) in focussing activities in one particular
area is clear to see. The growth of a city such as Guangzhou in China is a good
example of where government policy has favoured an urban area rather than
a rural area. Only in recent years has the Chinese government encouraged
industrial development away from the coast to overcome this. An emphasis
on export-driven production creates higher wages and improved standards of
living, drawing rural workers in.
table
6.1 Global city populations
i960
Rank
Population
2008
(millions)
Population
(millions)
1
New York
14.2
Tokyo
36.9
2
London
10.7
Seoul
25-3
3
Tokyo
10.7
Shanghai
24-7
4
Shanghai
10.7
Delhi
21-7
5
Beijing
7-3
Mexico
21.2
6
Paris
7-2
Beijing
21.1
7
Buenos Aires
6.9
Sao Paulo
20.9
8
Los Angeles
6.6
Mumbai
20-7
9
Moscow
6.0
Jakarta
20.0
10
Chicago
6.0
New York
19.9
Urbanisation in Africa
Africa has experienced the highest rate of urban growth of 3.5 per cent per
year over the past 25 years. The African urban population in 2010 was 36
per cent and it is estimated that it will rise to around 55 per cent by 2040.
However urbanisation has not brought with it improvements. Instead it has
resulted in a mushrooming of slums with their associated poverty, insecurity,
crime and inequality. North African countries have benefitted from higher
levels of overseas investment and as a result have fewer slums. Sub-Saharan
Africa on the other hand has a lower urban population (33 per cent) but a
much higher slum dwelling population (65 per cent) and the cities suffer
from a lack of basic infrastructure - 60 per cent of Africans live in areas
where potable water and sanitation are inadequate. Access to three basic
facilities for the population of these sub-Saharan cities are reflected in the
figures below:
•
•
•
access to electricity: 20 per cent
fixed telephone: 3 per cent
mobile phone: 54 per cent (this figure demonstrates the ‘leapfrogging effect’
of using new technology without having had the ‘old’technology).
Most migrants to LIC cities lack a good standard of education and the
necessary skills to join the urban work force immediately. As a result they end
up working in the informal sector, which accounts for 93 per cent of all newjobs
and 61 per cent of all urban employment. Wages are therefore low and irregular,
which is the main reason why migrants gravitate towards the slum housing on
the periphery of cities. As cities have expanded the peri-urban areas have been
built on, destroying natural vegetation and important farmland. People living
in slums also experience unacceptably high levels of water and air pollution and
the associated health risks.
Settlement dynamics 139
figure
6.10 The growth of African cities.
The cycle of urbanisation
Case Study
Suburbanisation US style:
and Tysons Corner
Los Angeles
Los Angeles has always had a love affair with the automobile. As a result the city
and suburbs sprawl over nearly 90 000 sq km in order to house an estimated
14.5 million citizens. This is 120 times the size of Nairobi and results in a
population density of 165 people per sq km rather than the 4850 of Nairobi.
figure
6.11 Tysons Corner skyline
140 Settlement dynamics
Immigration and economic strength have led to the growth of the city and a
series of factors have contributed to the particular suburban form that it has
acquired:
•
•
•
•
•
arrival of the automobile at the same time as economic ‘take-off
availability ofcheap land and cheap petrol
high levels of personal wealth
weak planning legislation
promotion of the ‘suburban dream’ in the media and film industry.
Tysons Corner is on the eastern side of the USA, just outside the capital
Washington DC, and it is an edge city. To qualify as an edge city there are
certain criteria that must be fulfilled:
•
•
•
•
•
it must have been a largely rural area 30 years ago
there must be more jobs than homes
there has to be a ‘single end’ destination, the centre must have shopping,
leisure and entertainment
it must include over 55 000 sq m of retail space
it must include over 464 500 sq m of office space.
Tysons Corner stands at a major highway crossroads and has links into
Washington DC. It has a population of 19 627 (2010 U.S. Census Bureau)
and a population density similar to London at 4600. The influx of high-tech
companies and the building of shopping malls has enhanced its standing as
an edge city. With 100 000 jobs, nearly 232 300 sq m of office space, 3400 hotel
rooms and 230 stores, Tysons Corner is an attractive place to live and work.
Counterurbanisation
Counterurbanisation is the movement of people out of cities, to smaller towns in
the surrounding areas. Since the 1950s this process has been occurring in HICs and
more recently in countries that have experienced rapid industrialisation such as
China. There are a number of reasons for counterurbanisation:
1
The increase in car ownership means people are more mobile. This has led
to an increase in commuting. The growth in information technology (email,
video conferencing) means more people can work from home.
figure
6.13 Derelict docks
figure
6.14 New offices, Cardiff Docks, Wales, UK
Settlement dynamics
2
Urban areas can sometimes be an unpleasant place to live, as a result of
3
pollution, crime and traffic congestion.
Some people move when they retire or when they start a family and want a
4
different environment in which to live.
New business/office/science parks in previously rural towns mean people no
5
longer have to travel to the city centre.
Developments on greenfield sites are often cheaper than the cost of
cleaning up an inner city brownfield sites.
Reurbanisation
Reurbanisation refers to the movement of people back into an area that has
been previously abandoned. Reurbanisation is usually a government’s initiative
to counter the problem of inner city decline caused by pollution, perceived levels
of crime and overcrowding, eurbanisation can be achieved by direct action on
the part of the government or by encouraging developers through the planning
system to improve an area.
Competition for land
Models and arguments developed to describe ‘western’ cities by their very nature
fall short when applied to ‘non-western’ cities. Many of the cities of southern
Africa fall into this category despite many having an ex-colonial heritage.
The cities of this region reflect the rapid urbanisation trends of Sub Saharan
Africa with Angola, Botswana and South Africa reporting in 2010 that some 60
per cent of their population lived in cities, a figure that is estimated to rise to
80 per cent by the middle of the century. This growth, as discussed earlier, had
been fuelled by natural increase, rural-urban migration and the extension of city
boundaries to include peri-urban villages.
Competition for land in African city regions is largely the result of two
differing tenure systems:
•
•
Customary tenure, or community land or masimo, that is not
registered
Statutory tenure of registered land with rights held through a freehold
or leasehold agreement
Competition for land in Maseru - Lesotho
In Maseru, the capital of the southern African country of Lesotho, until 1979 the
usual way of acquiring land was to buy customary land [masimo] from the local
chiefs. Despite this type of transaction being made illegal by the government
in 1979 recent estimates suggest that three quarters of land demand was being
met by the informal purchase of customary land.
Since the early 1980s many of the peri-urban villages have been incorporated
within the city boundaries in an attempt to stop the sub-division of the
customary land into building plots.
An attempt to limit informal development and in order to make land
available for more formal housing the state ‘nationalised’ land and this enabled
the government to set aside land as Special Development Areas (SDAs).
Two projects were started, one in 1980 and another in 1984. At Khubetsoana a
low income housing project financed by the World Bank was established on the
edge of the city. Four years later a mixed income site and service project was set
up close by.
p
Settlement dynamics
Local land owners having received no compensation from the state in
1980 quickly sold their land in 1984, however the plots were ‘illegally’ occupied
and eviction proved difficult when the government came to implement the
project.
Subsequently the government now recognises those occupations in
law which allows for greater security of tenure than would otherwise have
been the case for the occupants. It also means that the owners are more
prepared to invest in developing their land and property than would have
occurred in a previously informal setting. Unfortunately many plots in
the informal settlements have become commercialised resulting in land
becoming even more expensive and inaccessible to the very poorest of
households.
Urban renewal
Greater Noida, with a population of 100 000, is in the Gautam Budh
Nagar district of the northern Indian state of Uttar Pradesh. It lies within
the National Capital Region (NCR) of India’s captial New Delhi which is 30 km
away.
In the early 1980s the government of India realised that the rapid rate at
which Delhi was expanding would result in chaos, so they planned to develop
residential and industrial areas around the capital to reduce the demographic
burden. Before Greater Noida, there were two areas that had been developed
- Gurgaon, across the border from Haryana, and Noida, across the border with
Uttar Pradesh.
Noida’s infrastructure was carefully laid out, but the 1990s saw huge growth
in the Indian economy. Migration to cities like Delhi, Mumbai, Kolkata,
Chennai, and Bangalore exceeded planning estimates. Noida was developed
to accommodate population growth for 20-25 years. The massive population
influx to Delhi, however, caused it to overload within 15 years. The government
of Uttar Pradesh decided to develop another city as an extension to Noida with
better planning. The idea was to create a world-class city. It was planned to be
approximately 25 km from Noida.
Greater Noida is a planned township. Roads are wide with service lanes
for every major road, and all cabling and utilities running underground. It is
planned to have excellent connectivity to the other parts of the region using
Metro, road and rail. Plans to create residential and commercial spaces in the
same region fuelled its commercial growth. Planned IT parks and industries in
this area along with innumerable housing projects are important for providing
employment in this region.
FFFir FFF
figure
6.15 View of Greater Noida
6.16 Galgotias College of Engineering ^Technology, Greater Noida
Settlement dynamics
figure
6.17 Melbourne Docklands
Case Study
Melbourne Docklands
The Docklands area is located on Victoria Harbour in the heart of the city,
close to the Yarra River and immediately southwest from Melbourne’s central
business district. The area was once Melbourne’s largest and busiest port but
by the late 1980s it had become a derelict contaminated industrial wasteland.
The area was a serious source of pollution, which discouraged any major
investment.
The need for industrial quayside locations had declined as this type of
activity increasingly relocated to developing nations such as China. With inner-
city living becoming more popular and Melbourne’s population set to soar,
the Victorian Government saw an opportunity to extend the western edge of
Melbourne’s central business district and reconnect the city to its historical
waterfront. The Melbourne Docklands now:
•
•
•
has almost 10 000 residents and 39 500 workers
attracts more than a million visitors a year
is home to the national headquarters of some of Australia’s largest
companies including Australia New Zealand Bank, National Australia Bank,
•
Medibank Private and Myer
has the highest concentration of top-rated commercial buildings in the
•
•
•
southern hemisphere
is home to 42 public artworks
has 741 marina berths
includes 3.7 hectares of open space.
The Docklands community has also evolved, assisted by the delivery of
community facilities including:
•
•
•
sports courts
a community garden
the state-of-the-art Library at The Dock.
Docklands is still a work in progress. It is one of Australia’s largest urban
renewal projects under construction.
J
Settlement dynamics
Filtering
Filtering is the process by which housing passes from high-income occupancy
to lower income owners and forms a part of suburbanisation. As people
become more affluent they seek to move to new houses in a more pleasant
environment and as they move out so the houses they move from are occupied
by less affluent families. In turn the houses they leave close to the central area
are occupied by people even further down the scale. In this way housing filters
downwards as people take the opportunity to move up the housing scale. This
creates divisions in the city based on wealth and socio-economic class.
Changing accessibility and lifestyle
Suburbanisation and the desire for a suburban lifestyle is a characteristic of
cities across the globe. Both have been made possible by increasing levels of
affluence and because the suburbanites have access to improved transportation.
The situation in Los Angeles is that commuters are willing to spend up to three
hours a day in the car driving to work through polluted air in order to own their
apartment in a child-friendly environment with quiet streets and a pool.
figure
6.18 (a)Traffic congestion in Los Angeles
figure
6.18 (b) Los Angeles apartment
In 2013 ITV News reported that commuters living in and around London
spent an average of 56 minutes a day getting to and from work. The London
Evening Standard in 2015 calculated that for a man in his 40s this figure had
risen to 84 minutes, which equates to 42 days a year! So despite the increased
spend by the individual on access to transport, both private and public, it is
clear in London that more investment in transport infrastructure is required at
significant levels.
According to a survey carried out by the oil company Castrol, Indonesia’s
capital, Jakarta, ranked as the city with the highest number of traffic stops and
starts, with an average of 33 240 per driver per year. Jakarta was followed by
Istanbul, Turkey, with 32 520 stops and starts per year and Mexico City with 30
840 per year. East Java’s Surabaya, Indonesia, was also included in the list as the
city with the fourth-highest stop-start average, reaching 29 880 per year.
The greater use of technology allows people to work flexibly: working from
home or out of the office reduces the time and money spent commuting.
Although the technology exists many employers have yet to be persuaded to
change their attitude towards the old-fashioned nine-to-five routine.
Linfen in China is the most polluted city in the world. The pollution here
is a result of coal mining- the air is loaded with so much burning coal that
most residents are hospitalised for respiratory conditions such as black lung,
chronic bronchitis and asthma. The most definitive proof of excessive coal levels
in the air is the fact that laundry can turn black if hung outside for even a few
minutes.
Settlement dynamics
Mexico City’s pollution problems arise from other factors. In 1992 the
UN described Mexico City’s air as the most polluted on the planet and by
1998 the city had the reputation of being the most dangerous city in the
world for children. Despite more than 10 years of stringent pollution control
measures a haze still hangs over the city most days, endangering the health
of its inhabitants. This situation is a result of industrial growth, a population
boom, from 3 million people in 1950 to over 21 million in 2010, and the
proliferation of vehicles. More than 3.5 million vehicles are now driven through
figure
6.19 Mexico City smog
the city’s streets.
The solution to the problem of urban air pollution is complex but nevertheless
achievable in some small measure. An effective regime of urban planning such
as that in the Brazilian city of Curitiba with its high-speed bus corridors has been
shown to reduce not only car use, but petrol consumption and air quality. Many
cities are now forcing people onto public transport with the introduction of tram
systems, expensive parking costs and the pedestrianisation of central areas. In
south London the tram system not only links outlying suburbs with the centre but
also links in the existing overground and underground train systems, making for
a much more integrated approach to urban transport planning. The application
of technology has allowed passengers to buy smart cards that they can load with
money and then replenish as they ‘spend’each time they travel. This method
offers a slightly cheaper rate than buying individual tickets for each journey. A
further approach has been to make city centres more bike friendly although this
has some way to go in many cities!
Global cities, megacities, world cities
The exceptionally rapid growth of cities especially in MICs and LICs has led to
the creation of megacities - cities with a population of over 10 million people.
In the 1950s this definition only applied to London and New York but by 2011
there were 27 megacities, of which only seven are in HICs. Dhaka and Istanbul
have become megacities as a result of being the capital city of their respective
countries, whilst other cities, such as Osaka and Sao Paulo, have grown as a
result of industrialisation or inward investment from HICs. Global or world
cities are those that have an important function within the global economic
system and as such need not be capital cities, although they often are.
146 Settlement dynamics
Saskia Sassen introduced the term ‘global city’ in her seminal text The
Global City (1991), which described these cities as playing a major role in global
affairs, culture, economics and politics. Along with other academics, Sassen
helped found the Globalisation and World Cities Research Network based at
Loughborough University, which has identified various levels of global city from
Alpha++ to Gamma-, with only London and New York being placed in Alpha++,
the highest category.
Global cities have grown for three main reasons: first, as a result of
demographic changes attracting larger and larger workforces; second, they
have expanded as economic development has gathered pace and with it the
rapid growth of major manufacturing and service centres; and third, these two
growth areas have necessitated growth of key transport networks. Global cities
also attract cultural and social status through tourism and major cultural and
sporting activities, which in turn leads to further investment. Global cities are
often national capitals and as such are magnets for high levels of infrastructural
investment. They are considered to be the engines of growth fortheir countries
and the gateways to the resources of their regions.
The changing structure of urban settlements
Urban structure is a blend of form and function. As towns grew different
functions grouped themselves in the same areas of the town, even in the
same street, such as oral surgeons and dentists in the Frame Street area of
Adelaide, South Australia. The shape of the town, its form, is often a result of the
physical geography of the area, but its ethnic mix and cultural aspects will all
contribute to the urban morphology. In the early years of the twentieth century
geographers tried to find, describe and explain the patterns that existed in
towns. Research on this was done in Chicago by Park and Burgess. Their model
made a number of assumptions on which the concentric zone model (1925) is
based:
•
•
•
•
a uniform land surface
free competition for limited space
equal access to the single city centre
continuing in-migration and expansion out from the centre.
Park and Burgess concluded that these assumptions led to a situation
where the best locations are available to those who can afford them while
the poorest groups of people end up in the worst locations. This leads to
the emergence of different functional zones within the city, which can be
arranged concentrically. In the centre of the model is the central business
district (CBD).
The central business district is the most accessible part of the city and
is dominated by high-end retail and service functions as these businesses
can afford to pay the high rental prices of the area. Surrounding this
central area is the zone in transition. Older housing is subdivided into
flats for poorer immigrants, there is mixed land use and evidence of some
dereliction. The immigrants group in ‘ghettoes’ although as they become
assimilated into the host population they seek to move out to better quality
housing. The zone of working men’s houses is older housing for city centre
manual workers.
The residential zone is occupied by the middle classes, often living in semi­
detached houses, and on the outskirts of the city lies the commuter zone. Park
and Burgess also recognised that within a city there would be ethnic groupings
and in Chicago they identified a Chinatown and Little Sicily.
The concentric rings of the model were however disrupted by features such
as the shoreline of Lake Michigan, the Chicago River, numerous railway lines
and the resistance to change of local communities, all of which were recognised
by these early model makers.
figure
6.21 Downtown Los Angeles, USA.
figure
6.22 Nineteenth-century housing in Leeds, UK.
figure
6.23 Chinatown, San Francisco, USA.
Settlement dynamics
Concentric zone model
Central Business District
Zone of transition
Multiple nuclei model
Hoyt's sector model
Central Business District
Education and recreation
Central Business District
Low class residential
Wholesale, light manufacturing
Mi Heavy manufacturing
Low class residential
Working class zone
Residential zone
Commuter zone
Middle class residential
High class residential
■■ Outlying business district
High class residential
BH Industrial suburb
Industrial
HH Transportation
figure
Middle class residential
Residential suburb
6.24 Urban models
Bid rent theory
Bid rent theory was developed by Alonso in the 1960s and also produced a
model of concentric rings. It is based on the ability of different land users to pay
the higher costs at the centre of a city. Land at the centre is in short supply but
being the most accessible commands a high price, which in turn creates intense
competition between land users wishing to use the same plots of land. The land
use that will earn the most can pay the most and so can locate at the centre:
banks, offices, high-end retail, for example. The land use bidding the lowest will
be consigned to the more peripheral locations. The paradox of poorer sections
of the community living in the expensive centre is explained by the fact that
these sections of the urban population tend to live in much higher densities
and the better-off populace trade the convenience of being close to the centre
against living in large houses on bigger plots of land in the suburbs.
1 - CBD with commerce/retail and offices
2 - Industry/maufactacturing
3 - Residential with highest density nearest centre
figure
148 Settlement dynamics
6.25 Urban bid rent model
For most western cities and for a number of cities in other parts of the world,
the bid rent model now has a number of variations, with ‘spikes’ of activity in
retail, housing and industry occuring at locations both further out and closer in
towards the centre, reflecting the dynamic and changing nature of urban areas
in the twenty-first century.
Hoyt’s Sector theory
Hoyt’s Sector theory (1939) was also developed in the USA and, like Burgess,
Hoyt placed a CBD at the accessible centre of his model. He observed that
as differences in function occurred in the growing city those variations
tended to endure. Low income housing tended to occur in the least favoured
locations while high income housing sought out more favourable locations.
Transport routes, especially rail lines, tended to attract industrial land use
and this had an effect on the development of adjacent housing patterns.
New land developed at the edge of the city took on the function of the
adjoining sector.
Harris and Ullman multiple nuclei theory
Harris and Ullman’s multiple nuclei theory (1945) challenged the idea that
a city developed around a single central nucleus, rather than a number of
separate nuclei. These nuclei might be suburban village centre/s or town
centres that become enveloped as the town spreads outwards. Croydon in
south London is an example of a suburban centre developing as a major
commercial nucleus.
Housing areas would be aligned in much the same manner as the other
models with the poorest members of society close to the industrial areas
and the high earners seeking out those parts of the city with the greatest
environmental benefits.
So far most of the model making had taken place in the USA however the
American city model did not fit the British experience. In 1965 Mann researched
three northern British cities: Huddersfield, Nottingham and Sheffield. His work
was influenced by that of Burgess and Hoyt and the resulting model is very
much an amalgamation of the two ideas. However he importantly included
the influence of the westerly prevailing wind and the effect that this has on
housing in the UK (the westerly wind ensures that the smelly industries are
always on the eastern sides of towns and cities blowing the smell away from
the expensive housing, which is why the workers houses are always on the
east side of a city). It is noticeable that much of the Victorian development in
London took place in the east while the gentry and their estates were largely in
the west.
Limitations of the traditional models of urban structure
The early models of urban structure have a number of limitations when
explaining the modern western city including:
•
•
•
•
•
•
•
They all assume a single central area that dominates the rest of the city.
They largely lack, Mann apart, any consideration of intervention processes by
government policies.
Their main focus is residential land use, which is only one of many land uses.
Very little consideration is given to the physical geography of the city or
historic land uses.
People’s choices and behaviours about where they live are not allowed for.
The models are unable to accommodate issues such as post-industrial decline.
The models do not consider the use of land for unprofitable but socially
desirable uses.
Consequently, while these models ‘fit’ some districts of established cities,
they fail to show the dynamic nature of urban areas and the complexity that is
the city in the twenty-first century.
m squatter areas
suburbs
figure
alien commercial zone
western commercial zone
6.26 Model of a large Southeast Asian city.
Settlement dynamics
EE
Models of cities in Latin America
Much of the research has been in western cities but as cities in the LICs and
MICs have expanded interesting patterns have emerged. Work done by Gilbert
and by Griffin and Ford summarise the features of these cities.
•
•
•
•
•
The CBD now resembles most western cities although originally it would
have been laid out to a strict plan overseen by government officials from
Spain or Portugal.
The high cost housing zone of the rich and high ranking officials also
contains the high value shopping malls.
The industrial areas or areas of disamenity are located along main transport
routes and contain the polluting industries.
Immediately around the CBD is an area of more mature housing where
early slum properties have been improved by their owners.
Beyond this zone is an area of rapid urban expansion, this is the zone of shanty
settlements, (variously called favelas, bidonvilles, barriadas, barrios, villas miseras)
with poor service provision and housing made of a variety of materials.
periferia - older informal
housing (permanent
houses and upgraded
gradually)
CBD-Central
Business District
industry- along
transport routes
high cost
housing- luxury
flats or detached houses
favelas- recent informal
housing (often self-built
housing = poor quality)
figure
6.27 Model of a Latin American city
Urban activities and their location
There are two main sets of factors that will determine the location of most
urban activities: first, the influence of market forces, which will affect the
availability and therefore the price of land within the urban area; and second,
local and national government planning policies and decisions. Such policies
and decisions may well, in certain circumstances, disregard the market if it is
considered that a greater benefit may accrue for the public.
figure
6.28 Hillside/iwe/a in Brazil
150 Settlement dynamics
The manufacturing industry
In the UK and Europe the Industrial Revolution occurred in relatively small
towns and before the age of the car and mass transportation systems and as a
result factories and housing were built next to each other. The twentieth century
has seen the separation of manufacturing and housing as cities have expanded
and developments on greenfield sites have taken place. The disadvantages of
inner city factory sites had become evident and in the period after the Second
World War new suburban sites were identified for manufacturing, which then
moved out into the surrounding rural areas. At the same time there was a
move towards deindustrialisation with former industrialised countries (HICs)
seeing their industries move to lower cost bases in other countries, often LICs.
As a result many industrial cities in the HICs can now be termed post-industrial
cities.
The congested nature of industrial sites and their associated housing
has meant that expansion has not been possible and so the land is often
converted to other uses such as housing. Some large sites do exist from
the nineteenth century but often levels of toxic contamination mean that
they are unsuitable for any use without expensive remediation works. The
only manufacturing that remains in the city is often high value production,
jewellery for instance, as the competition for and the cost of land is so
prohibitive.
In addition restrictive post-war planning has discouraged industry in urban
areas and the decentralisation programmes of many governments has actively
encouraged industry to move to other parts of the country or to unindustrialised
rural areas. Suburban growth has meant that the workforce is closer to any
industry that moves away from the centre.
Retailing
Increased car ownership has played a large part in changes to the mobility of
shoppers and to shifts in the location of shopping areas. With less need to use
public transport high street shopping has suffered greatly as large retailers have
moved to out-of-town locations where they can provide car parking and a huge
retail complex. Some of these complexes are located close to motorwayjunctions
to allow a far greater sphere of influence than would be available to a high
street shop.
Cape Town’s Tyger Valley Shopping Centre is a shopping mall on the outskirts
of the city and is situated just off the Ni, a 12 minute drive from the centre of
the city. Located in the fast growing Tyger Valley business district, the shopping
centre encompasses 275 shops on three levels, a banking mall with bureau de
change facilities, medical and dental facilities and a 10 screen cinema complex.
There is provision of over 5 000 parking bays and a choice of either undercover
parking or free parking.
Gunwharf Quays, in Portsmouth, is a waterfront development on land
released from the naval depot.
figure
6.29 Derelict factory
figure
6.30 Shopping mall in Rio de Janeiro, Brazil
figure
6.31 Gunwharf Quays, Portsmouth, UK
Consisting largely of outlet shops, it combines shopping with recreational
activities, boat trips, a multiplex cinema, nightclub and numerous bars and
restaurants.
The changing central business district
The CBD is the most accessible part of the city. It acts as a focus for the transport
systems feeding in from the suburbs and further afield. Here land values are at
their highest, attracting high-value businesses and functions not found elsewhere
such as government, central banks and the headquarters of multinational and
transnational corporations. Pressure on land encourages vertical development,
the high-rise blocks of Lower Manhattan and the City of London being good
examples, but the CBD is also an area that is constantly changing. In small cities
and towns the CBD may well spread out into residential areas where houses can be
converted into offices for smaller enterprises, or the housing may be demolished to
accommodate new developments. This is known as the area of assimilation, unlike
the area of discard where demolition of old, cramped and unsuitable buildings
takes place.
Decline in the CBD has occurred for the reasons discussed above but
since the mid-1990s government policies have restricted the growth of
large out-of-town shopping centres and encouraged the reimaging of the
city centre. City councils have fostered plans to promote business tourism,
Settlement dynamics
frame
better-off
residential
properties
assimilation zone
autosales
and services
outer
core
residential areas
development
inner core
education
smaller
shops
transport
terminals,
multistorey
car parks
retail stores,
specialist shops,
high-rise office
blocks, commercial
offices (banks)
offices
(insurance,
solicitors), public
administration
theatres
and small
shops
social
services
neglected/
derelict land
discard zone
heavy industry and
poor residential
light
manufacturing
properties
wholesale
services
figure
6.32 CBD under pressure
especially conferences, as well as marketing an image for their city designed
to appeal to international businesses. This has been done by the use of
flagship projects, which are high-profile schemes that subsequently attract
further investment from other companies and developers. Birmingham,
Liverpool, Newcastle and Manchester as well as areas of cities overseas
such as Battery Park in New York and La Defense in Paris have all benefitted
from this approach. The refurbishment of old iconic buildings and the
redevelopment of waterfront sites have also seen a return to the CBD of
residential land uses.
Residential segregation
Residential segregation is common in all cities. Residents with a high
income will have the widest selection of properties and areas to choose
from. Conversely, people on low incomes will be restricted in where they
can live.
Residents from ethnic minorities tend, as we have seen, to group together
for social and cultural reasons into ethnic villages.
The stage of the family cycle also influences where people live, with people
moving several times during their family’s life time. The trend to rent has grown
in recent years in the UK but for many people home ownership remains an
important stage in the family life cycle.
Ethnic minority
percentage
over 40
30-40
20-29.99
10-19.99
0-9.99
no data
Statistics are for 2011.
figure
6.33 Distribution of ethnic minorities in London boroughs
152 Settlement dynamics
Middle-income life cycle
Low-income life cycle
Family home
Childhood
Divided older house
(Rented room/bedsit)
Pre-parenthood
@
Starter home
® (owned)
Family home
® (owned)
Family home
® (owned)
Retirement house
©(owned)
figure
Local authority house
® (1930s)
rented
©Private
room
authority
©Local
inner-city flat
Local authority
©semi-detached house
authority
©Local
semi-detached house
Local authority
©care
home
Child-rearing
Primary-age children
Adolescent children
G rand-pa renthood/elderly
Childhood
Pre-parenthood
Child-rearing
Primary-age children
Adolescent children
Grand-pa renthood/elderly
6.34 Family life cycle in western cities
The management of urban settlements
Only 20 per cent of the population of Malawi is classified as urban and it is one
of the least urbanised countries in Africa - but Malawi is nonetheless one of the
most urbanising counties on the continent with this change taking place at a
rate of 5.3 percent per year. Urbanisation in Malawi has become synonymous
with poverty and slum growth with some 67.7 per cent of the urban population
of the country living in slum conditions. The Malawi City Development Strategy
and Slum Upgrading Programme (CDS/SUP) seeks to improve the lives of
people living and working in the slums and informal settlements in the major
urban areas.
The slum housing problem
Lilongwe is the capital of Malawi and it has been stated that the city does not
have slums as yet but ‘informal settlements’, which are characterised by the
interrelated factors described in the case study below.
Case Study
Mtandire:The slum housing problem
Mtandire is the largest informal settlement in Lilongwe and it is a community
inhabited by poor people with high levels of unemployment. The overwhelming
reason for living in this settlement is employment-74 per cent of people who
live in Mtandire cite work as their reason for being there- and this is reflected
in the gender imbalance, which is 65 per cent male to 35 per cent female. Rapid
urbanisation from rural areas means that 54 per cent of the households rent.
Rented properties are often subject to poor sanitation as there is a lack of
investment in sanitation on the part of landlords.
People draw water from different sources including public water kiosks,
boreholes, shallow wells and local streams. In low income areas the use of the
water kiosk acts as a form of rationing as there is a limit to how much water
a person can carry home. For 29 per cent of families water is available for less
than three hours a day. The use of unprotected sources contributes to an
increasing prevalence of water-borne diseases. Some 78 per cent of the population
walk for up to 20 minutes to get to a water point and one in five people live further
away. An average family uses nine pails of water a day, which cost between USÎ4
and US$8.
A total of 27 per cent of households do not have access to a toilet and
instead use their neighbours’toilets, public toilets, the river or the bush.
Some 91 per cent of families use unimproved pit latrines and a mere
1.6 per cent use flushing toilets with a septic tank connected to a sewer line.
A further 54 per cent of the population do not have a hand washing facility,
figure
6.35 Mtandire, Lilongwe.
Settlement dynamics
which increases the risk of diarrhoeal diseases. Waste collection is intermittent
owing to a lack of accessibility to low income areas so most households burn
their waste. Further challenges faced by the poor in Mtandire include:
•
•
•
•
figure
6.36 Slums on the outskirts of Lilongwe
poor natural drainage
river flooding
settlement accessibility challenges
unattended waste and unmoving drains create a breeding environment for
mosquitoes causing high rates of cholera/diarrhoea and malaria.
The Urban Household Sanitation Improvement Project’s overall goal is to
improve the living conditions of the urban poor. It will achieve this by:
•
facilitating access to sanitation facilities
•
•
•
better sanitation practices
improved personal hygiene and food security
better management of human excrement.
Much is being done to encourage community-led or grassroots solutions,
which are often funded by outside agencies such as the World Health
Organization (WHO), the Bill and Melinda Gates Foundation and the UK
Department for International Development (DFID). Some of the solutions
suggested include the following:
•
•
•
•
•
•
the construction of a drainage system for wastewater and rainwater
the building of a dyke and the planting of trees and grass alongside the
river
the erection of improved foot bridges
installation of protected and adequate water kiosks
the addition of household bathrooms and latrines
training in waste management techniques.
Solving the slum housing problem - the government view
Much of Lilongwe’s housing problem is related to low levels of income, lack of
education and the extensive informal economy, currently employing some
161 000 people. The solution is partly addressed in the 2013 Urban Structure
Plan, which highlights the need of the population to access utilities such as
water supply, sewerage and waste management. The plan recognised that the
previous zoning scheme no longer met the needs of the city.
The plan also recognised that land in the south and east of the city needed
to be zoned to accommodate the urban sprawl. Further urban sprawl is to be
controlled by the preservation of green areas of grassland, forest and open
space.
However limited provision has been made for those who can only afford low
cost housing.
It is planned that by 2030 all residents will have access to piped water and
98 per cent of people will have access to safe sanitation.
Although government and NGOs have made huge investments in Malawi,
these have not led to improvements in the informal settlements. National
figures show that the number of people with access to improved sanitation
in the country is slightly above 50 per cent in the urban areas, whereas almost
91 per cent of households in the informal settlements have unimproved
sanitation. Given that at least 70 per cent of the urban population live here,
these figures paint a gloomy picture of the reliability of national statistics.
Finally, it seems there is little or no investment of human or financial
resources from central government to improve the growing slum situation in
Malawi.
Settlement dynamics
Case Study
The provision of transport infrastructure for a
city: Bogota, Colombia
Bogota has more than 8 million inhabitants and a population density of nearly
4310 inhabitants per sq km. Areas of higher economic status tend to be located
to the north and northeast, close to the foothills of the Eastern Cordillera. Poorer
neighbourhoods are located to the south and southeast and many of them
are shanty areas. The middle classes usually inhabit the central, western and
northwestern sections of the city.
figure
6.37 Bogota, Colombia
figure
6.38 Traffic in Bogota
figure
6.39 Air pollution in Bogota
Transport and pollution controls
At 2640 m above sea level, Bogota experiences terrible air pollution problems. A
recent study reported that 70 per cent of the city’s air pollution problems stem
from automobiles-the city has in excess of 1 million vehicles. Although only a
small number of people own automobiles in the city, traffic is so congested that
it can take over an hour to travel five miles. There is also a large number of small
industries and consequently high levels of air pollutants are detected.
In an attempt to improve air quality a green transport initiative was
introduced - the Transmilenio BRT system - in 2000. Over 1000 buses transport
1.6 million commuters using dedicated lanes across the city. A smartcard system
allows passengers to access transport from elevated platforms and a feeder
system of a further 400 buses and a 300 km network of cycle paths connect to
the main routes. In an attempt to reduce the number of cars on the roads, cars
with certain license plate numbers are prohibited during peak hours, a scheme
known as Picoy placa, which means Peak and [license] plate. Another scheme
reduces the number and size of parking areas to discourage drivers from
bringing their cars into the city.
Despite this Bogota still has poor air quality. However 13 air quality
monitoring stations have been established and a national law passed in 2008
requires fuel distributors to reduce the amount of sulfur in diesel fuels, initially
from 1200 parts per million to 500 and ultimately to 50 parts per million. The
Transmilenio uses low sulfur fuel and is working with the city authorities and
the university on an air decontamination plan to raise air quality.
NOW INVESTIGATE
1
Conduct a traffic survey on a main road leading into the town/city
where you live. You might want to measure noise levels, levels of
pollution (visible and invisible) and numbers of people in each car.
Prepare a report on traffic issues.
2
Investigate where your classmates families have lived. What
conclusions can you reach about rural-urban, intra-urban and
counter-urban movements of people?
3
Using census data investigate the growth of the capital city and
compare this to the growth of other towns within your country.
What conclusions can you draw?
4
For an area known to you investigate the different shopping areas.
How do the differ in terms of services provided, local and national
usage and types and numbers of customers?
Settlement dynamics 155
The belt of land and sea lying between the Tropic
of Cancer and the Tropic of Capricorn is generally
known as the tropical environmental zone.
Climates classified by Koppen as ‘tropical’ are
typical of this belt and include tropical rainforest
climate (Af), tropical monsoon climate (Am) and
tropical wet and dry or savanna climate (Aw).
All tropical climates have relatively constant
temperatures through the year and seasonal
variations are dominated by precipitation.
Tropical Environments
Hb- Af-Tropical rainforest climate
► Am-Tropical monsoon climate
Aw-Tropical wet and dry or
savanna climate
P recipitation
Zonal mean precipitation
(1979 - 2004)
--------- January
--------- February
---------- May
— June
----------October
---------- November
March
--------- April
---------- September
----------August
--------- December
Equator
Latitude
3 Davao (Af)
7
Tropical environm ents
11 Pune (Aw)
157]
Tropical environments
Tropical climates
Global distribution and climatic characteristics of humid tropical and
seasonally humid tropical environments
Tropical environments are located between the Tropics of Cancer and Capricorn,
23.50 north and south of the equator respectively. The Köppen climate
classification distinguishes three different types of tropical climate; rainforest
(Af), monsoon (Am) and Savanna (Aw). The tropical rainforest climate tends to
occur between 50 and io° either side of the equator, although it can extend to
25°north and south of the equator in eastern and coastal areas. For example,
in Mexico tropical rainforest is found along the Gulf of Mexico, the Yucatan
Peninsula and the state of Chiapas. The climate is characterised by average
temperatures of over 18 °C per month, an average of 60 mm of rainfall per
month throughout the year and the absence of natural seasons. In contrast, the
tropical monsoon and savanna climates have distinctive wet and dry seasons.
However, the main difference between the two is that the tropical savanna
climate experiences either less rainfall than the tropical monsoon climateduring the monsoon wet season precipitation totals can exceed 1000 mm per
month - or the savanna tends to have more pronounced dry seasons.
The distribution of the tropical rainforest climate coincides with the I ntertropical
Convergence Zone (ITCZ)-the area where the northeast and southeast trade winds
meet and air rises as the ascending branch of the Hadley Cell. The climate is most
commonly found in Southeast Asia, South America and Central Africa, although
tropical microclimates can be found further afield and not every location in this
equatorial region is dominated by the tropical rainforest climate. Examples of
cities that experience tropical rainforest climates include Kampala in Uganda, Fort
Lauderdale in the USA, Manaus in Brazil and Singapore.
158 Tropical environments
figure
7.2 The general circulation of the atmosphere
The tropical monsoon climate is most commonly found in South and
Central America, although there are regions of South and Southeast Asia,
Africa, the Caribbean and North America that also experience these conditions.
The distribution is controlled by the monsoon circulation, which is a seasonal
change in wind direction. In summer the land heats more rapidly than the
surrounding ocean and the resulting difference in temperature causes air to
flow onshore from the ocean across the land. During winter the opposite occurs
and as the land area cools the winds flow offshore from land to sea. Examples
of cities that experience tropical monsoon climates include Miami in the USA,
Chittagong in Bangladesh and Cairns in Australia.
The tropical savanna climate is typically found towards the outer reaches
of the tropical zone in the continents of Africa, Asia, South America, northern
Australia and southern North America. Examples of cities that experience
tropical savanna climates include Dar es Salaam in Tanzania, Darwin in Australia
and Rio de Janeiro in Brazil.
The role of the ITCZ, sub-tropical anticyclones and monsoons
The ITCZ occurs where solar heating causes the vertical movement of air
through convection and creates a band of clouds several hundred kilometres
wide. On average the ITCZ lies approximately 50 north of the equator, however it
varies seasonally, following the position of the overhead Sun. Due to the ocean’s
ability to retain heat and its subsequent stable temperatures, the position of the
ITCZ is less variable over oceans. In contrast, land temperatures are much more
variable and are affected by altitude and relief, and so the position of the ITCZ
shifts dramatically north and south of the equator over land. For example, over
the Indian Ocean the position of the ITCZ is most pronounced due to the large
Asian continental landmass to the north. The position of the ITCZ is the most
important factor in the migration of low pressure zones and the resulting shift
in seasonal tropical rains. Winds at the ITCZ are very light, which creates calm
conditions known by sailors as ‘the doldrums’.
Tropical environments
Arctic Circle
Sub-tropical anticyclones are areas of high pressure caused by descending air
at the tropopause. The position of high pressure typically lies between 30° and
350 north and south of the equator however, due to the fact that it corresponds
to the descending branch of the Hadley Cell, it alters in response to the seasonal
drift of the ITCZ. The high pressure belt tends to lie over the oceans (particularly
in summer) as the continents are dominated by low pressure due to heating. For
example, two semi-permanent sub-tropical highs are anchored over the eastern
Pacific and Indian Ocean. Sub-tropical anticyclones tend to be large-4000 km
east to west and 2000 km from north to south - and, due to the fact that
temperatures are fairly consistent over this area, pressure gradients are small
and winds are consequently light. Where anticyclones, and thus descending air,
dominate, conditions are arid.
The term ‘monsoon’ is derived from the Arabic for ‘season’ and is used
to describe winds that experience a seasonal reversal. This is a result of
the differential heating of land and sea on a continental scale. Whilst the
monsoon is a feature of climates in several continents, including South and
Central America and Africa, perhaps the most well-known example is India,
which experiences two monsoon seasons annually. The monsoon wet season
typically lasts from June until October. In June the ITCZ extends northwards
to around 30° north as a result of the intense heating of the landmass and so
northern India experiences low pressure. At the same time the surrounding
oceans heat up more slowly and create an area of high pressure off India’s
south coast. Due to the fact that winds blow from high to low pressure,
air moves in a south-westerly direction from the ocean over the Indian
subcontinent. The low pressure draws in the warm, saturated and unstable
air, causing heavy rain to spread across India. The rains start in the south, in
the state of Tamil Nadu, and it takes approximately six weeks for the rains to
reach Rajasthan in the north of the country. Despite the later arrival of the
monsoon rains in the northern regions, the monsoon contributes a greater
percentage of annual rainfall in the north compared to the south of India. For
example, Cherrapunji in northeast India is one of the wettest places on Earth,
experiencing nearly 12 000 mm of rainfall annually. The monsoon rains cool
the Indian landmass causing the temperature differential between land and
sea to reverse. This causes the wind to change direction and become a dry,
north-easterly wind.
The dry monsoon occurs in January where the ITCZ and the sub-tropical
jet stream move southwards. At the same time the landmass around the
33 Tropical environments
Himalayas cools due to the fact that the northern hemisphere is pointing away
from the Sun. This intense cooling causes an area of high pressure in northern
India, whilst southern India experiences low pressure due to the location of
the ITCZ. The winds blow from high to low pressure causing winds which blow
from the north-east over the continent. This results in dry conditions as the air
blows over land.
figure
7.4 Onset dates and prevailing wind currents of the Indian monsoon
Tropical rainforest climate
Singapore is located i° north of the equator and has a tropical rainforest climate
with no distinct seasons. It is characterised by a consistent temperature (27 °C
throughout the year), high relative humidity (the yearly average is 84 per
cent) and abundant rainfall (over 2300 mm per year). The diurnal range in
temperature (difference between daytime and night time) is 9 °C; daytime
temperatures are consistently around 32 °C, whilst night-time temperatures
are 23 °C. April and May are typically the warmest months of the year as they
experience the strongest sunshine and lightest winds, however temperatures
rarely exceed 35 °C (the highest recorded temperature in Singapore was 36 °C,
on 26 March 1998). Whilst the average relative humidity is high, the diurnal
relative humidity is variable. It is at its highest (around 90 per cent) in the early
morning and falls to around 60 per cent by mid-afternoon, although relative
humidity can reach 100 per cent during rainfall events and figures as low as
50 per cent have also been recorded. Rain is abundant throughout the year. The
numberof rainy days per month varies from 11 in February to 19 in November
and December and even though February is relatively dry it still experiences 80
mm of rainfall. It is thought that climate change may have a significant impact
Tropical environments
on Singapore’s climate. The annual mean surface temperature has increased by
0.8 °C since 1948 and rainfall has become more intense in the last decade. Also,
in 2001 Typhoon Vamei, the first recorded cyclone to occur near the equator,
swept north of Singapore killing five people and causing US$3.6 million worth
of damage.
Tropical monsoon climate
Miami, Florida, at 250 north of the equator has a tropical monsoon climate
with hot humid summers and warm dry winters. It is characterised by a more
variable temperature than the tropical rainforest climate (20 °C in January
to 29 °C in August), high relative humidity (the yearly average is 73 per cent)
and high rainfall (around 1500 mm per year), which mainly falls during a
distinct wet season The warm season lasts from May to October with the
JFMAMJ JASOND
7.5 (b) Climate graph
for Miami
figure
warmest temperatures occurring at the beginning of August. During this
period, temperatures vary between 26 °C and 29 °C. The cold season lasts from
December to February, with the lowest temperatures being recorded in January.
During this period temperatures vary between 15 °C and 24 °C. The diurnal
range is 8 °C and this is fairly consistent throughout both the warm and the cold
seasons, although during August it falls to around 6 °C. The tropical monsoon
climate has high average relative humidity of 73 per cent although, in a similar
way to the tropical rainforest climate, diurnal relative humidity is variable.
Relative humidity is 84 per cent in the morning and falls to 62 per cent in the
afternoon. Rain occurs seasonally in Miami. The cold season is also relatively
dry; from November to April the number of rainy days per month hovers
around seven and these months experience rainfall that ranges from 40 mm to
100 mm. During the warm season rainfall is higher, with the number of rainy days
increasing to 17 and average rainfall varying between 135 mm and 260 mm.
Tropical savanna climate
Darwin, Australia, lies 120 south of the equator and experiences a tropical
savanna climate with distinctive wet and dry seasons. Like the tropical rainforest
figure 7.5 (c) Climate graph
for Darwin
climate it is characterised by a consistently high temperature all year round (25 °C
to 30 °C throughout the year) but, unlike the tropical rainforest, the relative
humidity is relatively low (the yearly average is 53 per cent). Diurnal temperature
ranges are similar to both the tropical rainforest and tropical monsoon climates,
averaging 10 °C in June. The savanna climate is seasonal with the dry season
running from May to September and the wet season running from December
to March. During the dry season days are warm and sunny and there is virtually
no rainfall; the average number of rainy days during this period is less than one
and monthly rainfall totals are in the region of a few millimetres. In the 2012
dry season Darwin recorded no rainfall for 147 days. Relative humidity is low, on
average around 40 per cent, but this figure drops to below 30 per cent during
the afternoons. In the wet season the average relative humidity increases to
around 70 per cent. Whilst rainfall does not occur every day, there are around
20 rainy days per month during this period and average monthly totals vary
between 200 and 400 mm. Rainfall totals in Darwin average 1800 mm per
year. However in February 2011,1110 mm of rain fell in one month alone. Since
the beginning of the twentieth century Darwin has seen an increase in its
average temperature of 1 °C, although the first 50 years of the century warmed
at a slower rate than the last 50 years. Temperatures have warmed at night in
particular and this has led to an increase in fires, droughts and floods as a result
of climate change.
Landforms of tropical environments
The formation of characteristic landforms
Tropical environments are characterised by diverse and complex landforms
that are the result of a range of factors including climate, vegetation, geology,
tectonics, scale, time and, increasingly, human impact. The warm and
moist nature of tropical climates means that both mechanical and chemical
Tropical environments
weathering are common; particularly the processes of hydrolysis and exfoliation.
Hydrolysis is a form of chemical weathering that occurs on rocks that contain
feldspar, notably granite. Rainwater (which is typically slightly acidic) changes
the chemical composition and size of minerals in the rock making them less
resistant to weathering. When feldspar undergoes hydrolysis clay minerals are
produced and kaolin, silicic acid and potassium are released. Exfoliation is a
form of mechanical weathering that tends to occur in tropical savanna areas that
experience less moisture in comparison to their tropical rainforest counterparts.
Tropical savanna regions are characterised by a large scale diurnal range in
temperature. Rocks are heated and expand during the day when temperatures
are high and cool and contract during the night when temperatures are
significantly cooler. As rocks are poor conductors of heat, this expansion and
contraction only occurs in the outer layers of the rock causing them to peel or
exfoliate.
figure
7.6 Effects of hydrolysis
figure
7.7 Exfoliation joints in granite.
Laterites (also known as duricrust) are concentrations of iron (ferricrete),
aluminium (alcrete), silica (silcrete) and calcium carbonate (calcrete) found
within the zone of weathering in tropical areas. Calcrete tends to dominate in
tropical regions with low average rainfall (less than 840 mm) whilst ferricrete,
alcrete and silcrete tend to be found in more humid regions. Laterites form
under the surface to a thickness of 1.5 m, where groundwater flow concentrates
iron and aluminium oxides. Laterites are soft whilst in the ground and moist
but, when exposed to the air they harden irreversibly. Laterites therefore have a
vital role in tropical geomorphology forming cap rocks to escarpments, terraces
and mesa and affecting drainage patterns within soils.
figure
7.8 Laterite bricks in a quarry in Koovery, India
figure
7.9 A duricrust inselberg near Dori, Burkina Faso
Tropical environments
figure
7.10 Tor formation
Granite: (deep weathering profiles) tors, inselbergs and bornhardts
Granite is an igneous rock that, by definition, is composed of at least 20 per
cent quartz and 65 per cent feldspar. Granite is widely distributed throughout
continental crust and often occurs as smaller (less than 100 km2) intrusions
known as batholiths. However the warm moist climate of the tropics encourages
hydrolysis, which in turn shapes the landscape to create a range of distinctive
landforms including tors, inselbergs and bornhardts.
An inselberg is an isolated hill (or hills) that stands over a plain; thus, tors
and bornhardts are examples of inselbergs. Inselbergs are best developed in
the seasonal tropics on rocks such as granite and gneiss, which have widely
spaced joints and a high potassium content. The term inselberg is mostly used
to describe an abrupt rise from the plain below, whilst tor (or boulder inselberg)
is used to describe rounded weathered boulders embedded in the bedrock.
Bornhardt (or monolithic domed inselberg) are characterised by steep slopes that
end in a convex upper slope. Inselbergs are relict features, meaning that they
have maintained their relief as the adjacent surrounding landscape has been
lowered. Uluru in south-western Northern Territory, Australia, is an example of a
sandstone inselberg, which rises 348 m above the surrounding desert plain.
Tors (or castle kopjes) are thought to form when joints in the granite are
widened by sub-surface chemical weathering. Where the joints are spaced
widely spherical core stones are formed, shaped by spheroidal weathering
(chemical weathering which is a small-scale form of exfoliation). Where the
joints are closer together, the rate of weathering increases to create either
day-filled depressions or small core stones. The formation of the tor occurs
below the surface and so it is only exposed if denudation occurs, removing
the surrounding sediment. When the tor is exposed chemical weathering
continues to act below the surface, which can lead to the collapse of the tor.
Tors are typically 20 to 35 m in height and have core stones up to 8 m in
diameter. The Jos Plateau rises between 1200 and 1400 m above sea level
and covers 8600 sq km of central Nigeria. It is dominated by Cambrian and
Jurassic granites and Pliocene basalt and is the location of a number of tors.
Bornhardts are dome-shaped outcrops which are common in the tropical
savannas of Africa but can also be found in more humid tropical regions. They
typically are composed of granite or gneiss but can equally be formed from
1. Laterite mesa landscape
2. Bornhardts begin to emerge
2. Bornhardts dominate olain
figure
7.11 Bornhardt formation
Tropical environments
figure
7.12 Kopje, Serengeti National Park,Tanzania
other rocks such as dacite, limestone and conglomerate. Sugar Loaf Mountain
in Rio de Janeiro, Brazil, and Mount Hora in the Mzimba region of Malawi are
examples of bornhardts. Vertical joints are formed in the rock below the surface
to a depth of 35 m during the process of pressure release (where overlying
materials are removed, usually by erosion, which causes the underlying rocks
to expand). It is therefore thought that chemical weathering exploits these
joints to partition the rock into a series of domes. These are then exposed as
the surrounding regolith (loose material) is removed, revealing the bornhardts
below. However there are several alternative explanations including parallel
retreat and pedimentation. Another theory is that of etchplanation. This is a
term used to describe progressive rock decomposition occurring within deep
weathering profiles and suggests the evolution from bornhardt to inselberg
and then to residual tor. This theory takes account of varying periods of deep
weathering, uplift and climatic change.
Limestone: tropical karst (cone karst, tower karst and cockpit karst)
Limestone is a sedimentary rock composed mainly of calcium carbonate.
Most of the grains present within limestone are the skeletal remains of sea
organisms such as coral or foraminifera. Limestone can also include other
materials such as clay, sand or iron oxide, which can cause the rocks to exhibit
different colours when weathered. Karst topography is a landscape formed as
limestone dissolves through the process of solution, although it can also form in
other soluble rocks such as dolomite and gypsum. In tropical regions there are
three major landform features associated with karst scenery; cockpit, cone and
tower karst. The latter two only exist in sub-tropical and tropical climate zones.
Some geographers believe that limestone landscapes evolve from cockpit
(cave systems that have collapsed to leave large valleys with the remaining
limestone forming hills) to cone (more common and less spectacular with
residual cones usually covered in rainforest) to tower karst (spectacular 30-300 m
high towers with bare vertical sides). Others believe that the hydrological and
tectonic conditions that form each type of karst make them quite distinctive. They
suggest that cockpit karst develops in areas of high tectonic uplift where there is
intense vertical erosion by rivers. In contrast, tower karst develops where tectonic
uplift is absent or limited, where the limestone lies in close proximity to other
rocks and where the water table is close to the surface.
Cockpit karst is a limestone landscape pitted with smooth-sided, soil-covered
depressionsand cone-shaped hills. The Chocolate Hills in Bohol Province,
Philippines, are a stunning example of cockpit karst. There are approximately
1500 hills which cover an area of over 50 sq km and are fairly uniform in height,
ranging from 30 to 50 m. It is thought that the hills were formed through a
combination of dissolution of limestone by water (by rainfall, surface runoffand
groundwater) and sub-aerial erosion by rivers following a period of uplift by
tectonic processes.
In Southeast Asia, rounded cone karst hills are termed ‘Fengcong’ when they
cluster together whereas, isolated tower karst, surrounded by flat plains are
termed ‘Fenglin’. The best developed form of these types of karst are found in
Guangxi Province, China where the Li River cuts through the karst scenery. In
its flood plain, fenglin karst is common whereas further away from the river lie
multi-peaked clusters of fengcong karst.
Tower karst tends to be more variable in size than cockpit karst measuring
just a few metres high to over 150 m. They are formed when cone karst
is vertically steepened by water table undercutting (see Figure 7.14). As a
consequence they have steep, almost vertical sides, tend to form isolated
‘towers’ and are characterised by caves and solution notches that form at the
base. Khao Phing Kan and the neighbouring Ko Tapu are examples of tower
karst located in the Ao Phang Nga National Park in Thailand. Since 1998
tourists have been forbidden from approaching the 20-metre-high Ko Tapu
as it is feared that the erosion of limestone that could result may lead to its
collapse.
figure
7.13 Sugar Loaf Mountain, Rio de Janeiro, Brazil
honeycombed
solution hole surface
figure
widened joints
7.14 Tower karst formation
Tropical environments
figure
7.15 Cockpit karst,The Chocolate Hills, Bohol, Philippines
Humid tropical (rainforest) ecosystems and seasonally
humid tropical (savanna) ecosystems
Plant communities: development of climax, subclimax and plagioclimax
Succession is the process of temporal and spatial change in plant communities.
Each stage of succession (or sere) is characterised by a group of species that
have adapted to and alter the micro-environment, thus allowing another
group of species to subsequently dominate. At the beginning of succession
nutrients and organic matter are limited, biodiversity is low, and the organisms
that are able to survive in such harsh conditions (pioneer species) tend to be
small. In late succession, as the ecosystem moves towards climatic climax,
there is more organic matter available and greater biodiversity of species. On
a global scale climate is the dominant factor in determining the location of
biomes (large-scale ecosystems) such as the tropical rainforest. However, in
some areas the distribution of vegetation is controlled by soil type rather than
climate (edaphic control) and, even where climate is dominant, soil type can
affect plant groupings. For example, in savanna regions clay soils result in
forested areas whereas sandy soils result in grassland areas. A plagioclimax is
where succession is prevented from reaching climatic climax due to human
activity such as burning or grazing. Sometimes the succession is prevented
from reaching climatic climax and stops at a stage prior to this, due to some
arresting physical factor such as forest fire or volcanic activity. This is known as
figure
7.17 Sub-climax and plagioclimax
a sub-climax.
The rainforest on Chances Peak in Montserrat had high biodiversity of plants,
insects, lizards and birds. By the mid-1990s, as a result of volcanic activity, the
cloud forest that dominated the summit had been destroyed by acid rain, heat,
dust and gases and the forests in the Tar River valley on the east side had been
destroyed by lahars. Reforestation will only begin to occur when volcanic activity
on Chances Peak is arrested for a significant period of time (studies in Puerto
Rico suggest a period of about 40 years). Pioneer species, such as Cercropia,
are able to tolerate high light intensities and temperatures and their seeds are
easily distributed by birds and bats. Once these pioneer species have become
established they will provide shade, which will allow new shade-tolerant species
to germinate and survive.
33 Tropical environments
primary succession
pioneer species
intermediate species
hundreds of years
figure
7.18 Primary succession
Vegetation characteristics
Tropical rainforest vegetation
The tropical rainforest is the world’s most biodiverse ecosystem but it is also
incredibly fragile. This is because the species that live in rainforests have adapted
to the constant high temperature and humidity and, due to the fact they are
so specialised, their food sources are limited. This means that if deforestation
occurs, it is very difficult for the rainforest to return to its original state. The
Net Primary Productivity (NPP) is the amount of organic material produced by
plants and available to herbivores. It varies dramatically between ecosystems and
is determined by heat, water and nutrient availability, age and the health of the
plant species. The NPP for the tropical rainforest is 2200 g/m2/year compared to
the savanna, which has NPP of 990 g/m2/year. Due to the fact that there are no
seasons in the tropical rainforest trees shed their leaves throughout the year. The
trees are tall and thin with a crown of leaves at the top and buttress roots at the
bottom. Buttress roots serve a dual purpose; they prevent the tree from falling
over and they gather nutrients over a wider area.
Trees in the rainforest broadly grow in three layers. The emergent layer is
composed of those trees that have grown rapidly to reach the sunlight, thus
overshadowing their competitors. Trees are typically between 45 m and 50 m in
height although they can reach 70-80 m on occasion. Species that live in the
emergent layer include the harpy eagle, the sparrowhawk, the vampire bat and
the gibbon. The canopy is composed of trees that reach 25-30 m in height. This
layer is dense and almost continuous and so blocks out 70-80 per cent of the
available light. The fauna is similar to that which is found in the emergent layer
although it is more diverse; the canopy is estimated to be home to a quarter
of all insect species. Epiphytes (plants that grow harmlessly upon other plants)
are abundant in this layer and include ferns, orchids and bromeliads. There are
also lianas (long-stemmed, woody vines) that are rooted in the soil but use the
canopy trees as a vertical support to climb to access the sunlight. The final layer
of trees is the understorey, which receives only about 5 per cent of the available
sunlight, although where the canopy is broken by falling trees the understorey
vegetation is much denser. Plants in the understorey tend to have large
colourful flowers so that the animals and insects that carry their pollen can find
them in the dim light. The high humidity in this layer suits amphibians such
as salamanders and frogs; tree frogs have evolved feet with tiny suction pads
covered with sticky mucus that help them to hold onto branches. Below the tree
layers the forest floor is covered with decaying vegetation, which decomposes
rapidly due to the hot and humid climate.
Tropical environments
figure
7.19 Tropical rainforest, Amazonia, Brazil
Emergent layer: Trees grow rapidly up to
50 m tall to reach the sunlight. This layer is
where most of the mammals and birds live
off the fruit, flowers and leaves.
Canopy layer: this layer is made up of trees,
growing up to between 25 and 30 m tall,
forming a dense canopy. The canopy blocks
out 70 - 80 per cent of the available light.
There are many epiphytes growing in this
layer - plants that grow harmlessly on other
plants. There are also many climbing plants
(lianas) with long-stemmed and woody vines
and long rope-like stems. It is estimated that
25 per cent of all insect species live in the
canopy.
Understorey layer This layer only receives
about 5 per cent of the available light. The
vegetation in this layer is dense with
broaded- eaved plants and large colourful
flowers. Buttress roots help to support the
trees, preventing them from falling over.
At ground level it is very humid and there is a
lot of decaying vegetation, which is broken
down quickly by fungi, insects, moulds and
bacteria. This produces valuable nutrients for
the growing trees, which they access using
their roots.
figure
7.21 Cross section of rainforest
Tropical environments
figure
7.20 Buttress roots in Daintree Rainforest, Queensland, Australia
Savanna vegetation
Savanna vegetation includes a mosaic of grasses, trees and shrubs that
have adapted to survive the dry season. Species are xerophytic (adapted to
drought) with adaptations that include deep tap roots to reach the water
table and sunken stomata on the leaves to reduce moisture loss. Species are
also pyrophytic (adapted to fire) meaning that many trees have a thick bark, a
large amount of biomass (stored energy) below the ground and the ability to
regrow rapidly after burning. Savanna grasses have their growth tissue located
at the base of the shoot close to the soil surface so that burning or grazing
actually encourages its growth. Examples of plant species in the savanna
include the acacia, palm and baobab trees and elephant grass, which can grow
over 5 m tall.
figure
7.22 Acacia savanna,Taita Hills, Kenya
Nutrient cycling: Gersmehl diagrams, soil fertility, energy flows and trophic levels
Within ecosystems nutrients are circulated and reused frequently.
Macronutrients (those used in large quantities) such as oxygen, carbon, hydrogen
and nitrogen and micronutrients (trace elements used in small quantities)
such as magnesium, sulfur and phosphorus can all be absorbed by plants.
Animals eat the plants and take on the nutrients. The nutrients are eventually
returned back to the soil when the plants and animals die and are broken down
by decomposers. All nutrient cycles involve stores and flows between the soil,
litter and biomass, the proportions of which can be shown in the Gersmehl
diagram (Figure 7.23). In the tropical rainforest the warm humid climate results
in a high input of nutrients from weathering and precipitation. The continual
growing season means that most of the nutrients are held in biomass storage;
there are few nutrients held in the litter layer as the breakdown of nutrients
is rapid. Where trees have been removed, precipitation is not intercepted and
nutrients are leached out of the soil store; as a result, rainforest soils are relatively
infertile despite appearances. In contrast, the biomass and litter stores in the
savanna are relatively small as a result of the shorter growing season and fire
respectively. The soils are quite fertile as most of the nutrients are found in this
store so they are not burned or leached out of the system.
Tropical environments
MV
rircles - compartment size proportional
circles - compartment size proportional
to amounts of nutrient stored
to amounts of nutrient stored
rrows- width proportional to amounts
arrows - width proportional to amounts
of nutrient flow
of nutrient flow
figure
7.23 Gersmehl diagram showing nutrient cycling in the tropical
rainforest
figure
7.24 Gersmehl diagram showing nutrient cycling in the tropical
savanna
The main driving force in terms of energy within an ecosystem is
sunlight- it provides the energy required for photosynthesis and drives
the hydrological cycle. The flow of energy can be shown in food chains and
webs, which are the natural systems in which organisms feed on each other
to survive. An organism’s place within that web is the trophic level. There
are four trophic levels; primary producers, primary consumers, secondary
consumers and tertiary consumers. Between each trophic level it is estimated
that there is a 90 per cent loss of energy, which is a result of respiration
and excreta. In the tropical rainforest the primary producer trophic level
consists of ferns, bamboo and moss. Insects, spiders, fish and parrots are
the herbivores that eat the producers; they are known as primary consumers.
The secondary consumers, which eat the primary consumers, are animals
such as bats, amphibians and reptiles. The tertiary consumers are at the top
of the food chain and include snakes and carnivorous mammals such as
jaguars. In contrast, savannas are dominated by tall grasses, which are the
main primary producers, however shrubs and sparse trees such as the acacia
are also found within this trophic level. Primary consumers include giraffes,
antelopes, wildebeest, elephants, rhinos and, in Australia, kangaroos. These
herbivores frequently coexist peacefully, each with their own niche (role
within the ecosystem). Secondary consumers are carnivores such as cheetahs,
jackals, snakes and lizards whilst tertiary consumers include lions, which prey
on other creatures. Scavengers are also important in the trophic systems of the
savanna. Vultures, hyenas and termites form an integral part of the nutrient
cycling system as they break down organic material into smaller pieces so that
it can be eaten by decomposers.
figure
7.25 Factors which influence the formation of soils.
Tropical environments
Soil formation: soil forming processes, soil types and profile characteristics
There are five major factors that influence the formation of soils: parent
material, climate, living organisms, topography and time. Despite the
tropical rainforest
thick leaf litter layer
L
thin humus layer due to
rapid decomposition
O
concentration of iron
and aluminium oxides,
red horizon
B
0
Oz>
similar to A, iron and
aluminium oxides,
clay-rich
parent material subject to
rapid chemical
weathering, clays form
figure
7.26 Soil profile of 3 latosol
fact that tropical rainforests and tropical savannas have vastly different
extents and organisms they both have climates that result in deep
highly-weathered soils. They are also both ferralitic with accumulations
of iron, aluminium and manganese, although a distinction can be made
between the leached ferralitic soils of the rainforest and the weathered
ferralitic soils of the savanna. These soils are formed in ancient shield areas
that are tectonically stable and were unaffected by glaciation during the
Pleistocene. As a result they have had time to develop and are deep (up to
30 m) and infertile.
In the tropical rainforest latosols dominate. It is the general name given
to red soils of the humid tropics which are rich in iron and aluminium.
They cover 7.5 per cent of the world’s total non-glaciated land area and,
despite supporting the richest and most biodiverse vegetation on the planet,
are heavily leached and infertile. The soil is moderately acidic as the rapid
absorption of nutrients by vegetation prevents the soil from becoming more
acidic. However, if forest clearance occurs then the acidity of the latosol
rapidly rises.
In the latosol soil profile the O horizon (humus layer) is very thin due to
intense bacterial activity that rapidly decomposes the dead organic matter
in the litter layer. The next layer down, the A horizon, contains aluminium
and iron oxides that sometimes build up to form a hard laterite layer further
down the soil profile. The B horizon extends deep into the ground and is often
uniform in texture due to the intense leaching the soil experiences. Finally, the
C profile consists of the parent rock of the area. In Brazil the parent materials
Tropical environments
found under latosols range from metamorphic to sedimentary rocks and
these different parent materials cause the latosol to vary in colour from red
to yellow.
In the tropical savanna the seasonal rainfall, high temperatures and
abundant grass-based litter layer result in red earths. These soils are similar
to rainforest soils but tend to exhibit less leaching. During the wet season
precipitation exceeds evapotranspiration, which results in the leaching
of minerals through the soil to a considerable depth. However, during the
dry season evapotranspiration exceeds precipitation and water is therefore
drawn back to the surface through capillary action. This carries dissolved
salts to the surface, creating a hard, cement-like layer called laterite.
Laterite layers tend to occur in soils where the water table is not too far
below the surface and it can leave the lower horizons soft and vulnerable
to erosion.
figure
7.27 Gully erosion in tropical oxisols.
processes
humification
eluviation
oxidation and
dehydration
alternate
oxidation
and reduction
silicification
reduction
weathering
figure
7.28 Soil profile of a ferruginous mollisol found in the savanna.
Tropical environments
Sustainable management of tropical environments
These case studies show some of the threats to (exploitation) and problems
of sustainable management of areas within either the tropical rainforest
ecosystem or the savanna ecosystem, along with evaluation of attempted
solutions.
Case Study
Tropical rainforest ecosystem
Papua New Guinea occupies the eastern half of the island of New Guinea and,
together with a series of offshore islands, is located between o° and 120 south
of the equator. A ridge of mountains, the New Guinea Highlands, runs the
length of the island to an elevation of 4000 m and dense tropical rainforest is
found in the lowland and coastal areas.
4700
A
oJayapura
-AitaPe
r-
Bismarck Sea
Mountain height
(in metres)
■
National capital
°
Other town
= Pipeline
Oil fields
PAPUA
Bougainville
Island
Siew guinea
Kererna
I
Gulf \
of Papua
Strait
Collir
(BayQ
,
D’Entrecasteaux
Islands
a,
AUSTRALIA
figure
C o r a I
Sea
7.29 Papua New Guinea
The area covered by tropical rainforest is 160 930 sq km in total, which is
approximately 75 per cent of the original forest cover. The rainforest is biologically
diverse and home to over 200 species of mammal, 20 000 species of plant,
1500 species of tree and 750 species of bird, of which over half are endemic to
the island. Examples of species include the giant orchid, which has flowers each
10 cm wide, the monitor lizard, which grows to over 2.4 m long, and the buff­
faced pygmy parrot, which, at 11.5 g in weight and 8.6 cm high, is the world’s
smallest parrot.
As well as being a diverse habitat for plants and animals the forests are
also home to the Maisin people. There are approximately 3000 indigenous
people living in Oro province, most of whom live in villages along the south­
western coast of Collingwood Bay. The villagers depend upon the forest for
shifting cultivation (slash and burn) gardens, material for houses and canoes
and hunting for food. Despite a largely traditional and subsistence way of life,
the Maisin are integrated into wider Papua New Guinean society. Anglican
missionaries originally set up schools in the villages at the beginning of the
twentieth century and, as a result, most Maisin adults can communicate in basic
English as well as Tok Pisin (a creole language spoken throughout Papua New
Guinea) and their own Maisin language. Approximately 25 per cent of the Maisin
now live in urban areas elsewhere on the island and send remittances back to
their families. These remittances make up a large proportion of the
local economy.
Tropical environments
figure
7.30 Giant orchid
figure
7.31 Monitor lizard
The Papua New Guinea constitution states that the Maisin people are the
legal owners of their traditional lands. However over the last 20 years they have
been under increasing threat from large scale logging companies. The KiungaAiambak road project, located in Maisin-owned forests in Western province,
was driven by a Malaysian-owned logging company called Concord Pacific.
The project was intended to improve communications and provide benefits to
the local people but between 1995 and 2002 over 600 000 sq m of logs with an
export value of US$60 million were exported to Japan and China yet no road
was built. The exploitation of timber has caused a number of problems for the
Maisin including the loss of biodiversity in the surrounding rainforest, the loss
of a clean water supply through sedimentation, an increase in the spread of
disease due to increased contact with the timber cutters and ecological changes
caused by deforestation.
Palm oil exploitation around Aitape has also resulted in problems for the
Maisin. Most of the palm oil plantations are not for the growth of edible oil
for the local population but instead are destined for the export market. Forest
clearance for the plantations has caused both sedimentation and eutrophication
as a result of soil erosion. The use of pesticides and fertilisers has also
figure
7.32 Buff-faced pygmy parrot
Tropical environments
threatened the nearby Sissano lagoon, killing the coral reef and threatening the
prawn and fishing industry in the area.
Following a court case in 2002, which the Maisin people won, the Papua New
Guinean government has been put under pressure from the World Bank, the
International Monetary Fund (IMF) and the Australian government to enforce
more sustainable practices in their development of the local forests. An example
of a project that has attempted to produce commercial oil in a sustainable way
is the Kutubu Petroleum Development Project funded by Chevron Texaco. The
project is centred on Lake Kutubu, a lake in the Southern Highlands province,
and extends south to the Gulf of Papua through the Kikori River Delta. Flow
lines bring the hydrocarbons to a central production facility and these are then
transported along a 264 km pipeline to a marine terminal in the Gulf of Papua.
A number of sustainable practices have been implemented at every stage of the
process; project pipelines have been buried, spills have been eliminated, waste
has been comprehensively managed and road construction has been minimised.
The World Wide Fund for Nature has also worked with a number of partners,
including Chevron Texaco, to develop a long-term strategy to ensure economic
and environmental viability. Areas of focus include conducting extensive
biodiversity surveys, raising community awareness of the negative impacts of
industrial scale logging, helping local villagers to develop a sustainable fisheries
strategy and establishing environmentally friendly and locally developed
businesses. The project has also worked with the local community to promote
self-reliance in their dealings with both the Papua New Guinean government
and NGOs. Village Development Committees have been established to train
local personnel to help villagers; health workers have provided information on
malaria control and sanitation and agricultural workers have assisted farmers in
improving subsistence gardens.
Case Study
The
savanna ecosystem
The tropical savanna located in Australia covers the northern parts of
Queensland and the Northern Territory, from Townsville in the east to Broome
in the west. This region is located 17° south of the equator with a dry season
lasting from May to October. During this season fires occur which maintain the
ecosystem. The fires destroy those plants that are not resistant to burning and,
as a consequence, the savanna landscape in Australia has very few trees and
shrubs. Two examples of plant that do thrive in the savanna are the jarrah tree
figure
7.33 Jarrah tree
Tropical environments
and kangaroo paw. Jarrah trees usually grow to between 40 and 50 m and have
no branches. They have a lignotuber (large swelling located beneath the soil)
that stores carbohydrates and makes it possible for a young jarrah tree to grow
healthily after a fire. The kangaroo paw is a biennial green and red flowering
figure
7.34 The Eastern grey kangaroo.
plant that thrives in sandy or gravelly soils in previously disturbed or burnt
areas. Plants have also adapted to the savanna climate which experiences long
periods of drought. Trees such as the acacia have long, thin tap roots in order
to reach the deep water table, and many trees do not lose their leaves in order
to conserve water. Trees such as the baobab have thick trunks in order to store
vast quantities of water, typically up to 100 000 gallons.
Marsupials (mammals whose young are born undeveloped) are dominant
in Australia’s tropical savanna. Animals such as the echidna, Eastern grey
kangaroo and possum live in or near the trees for shade, food and water.
Reptiles are also common and estimates suggest that the savanna is home
to between 100 000 and 200 000 adult saltwater crocodiles. This species
of crocodile is the largest of all living reptiles and can reach up to 6.7 m in
length and 2000 kg in weight.
There are a number of threats to Australia’s savanna. Mimosa pigra (mimosa)
is an aggressive shrub that has been present in this area for 100 years. It has
a number of features that make it highly invasive; it grows rapidly, has low
nutrient requirements and its seeds are easily dispersed. As a consequence,
mimosa has turned large swathes of savanna into homogenous shrubland,
which has reduced the diversity of the species present, some of which are
endangered. It can also affect the hydrological regimes of water bodies, which
can increase sediment deposition and, due to the fact that it provides an ideal
habitat for feral pigs, this has led to an increase in these animals, which are
considered pests. In the past few decades much has been learned about the
management of mimosa. As mimosa poses a national threat, a coordinated
National Strategic Plan has been implemented by the Australian government
and Aboriginal agencies from Northern Territory, Western Australia and
Queensland. The plan has four main aims:
•
•
to inform and educate local communities
to prevent mimosa from spreading to new areas
•
•
to develop methods for managing mimosa
to reduce the impact of current mimosa infestations.
There has been progress since the plan’s inception with most new
occurrences of mimosa being reported by the public. Communities are
also becoming more aware that overgrazing and inappropriate fire regimes can
remove the native vegetation, making areas prone to weed invasion.
figure
7.35 Kangaroo paw
Tropical environments
figure
7.36 Mimosa pigra
Another threat has been government-sponsored clearance of the native
vegetation, although only 2 per cent of Australia’s savanna has been removed
compared to 22 per cent of natural forest and woodland. The majority of the
land has been cleared for agriculture, predominantly sheep and cattle, as the
climate is unsuitable for other types of cultivation. However land clearance
disrupts the habitats of native species and makes them more prone to weed
invasion. Land clearance also releases over 1 million tonnes per year of
greenhouse gases into the atmosphere and damages river catchments such
as the River Daly and River Roper. Soil degradation, in the form of increased
erosion and salinity, can also occur, which in turn has a negative effect on water
quality. The Vegetation Management Act (1999) works in Queensland to control
the clearing of native plant species and was amended in 2004 to phase out
large scale clearance. Whilst some small scale tree removal activities are exempt
from the regulations, the remainder must apply to the Department of Natural
Resources and Mines for a permit for permission to clear.
NOW INVESTIGATE
1
Investigate the formation of features of karst scenery, including
limestone pavements, sinkholes, dolines and caves.
2
Investigate how particular plants have adapted to the tropical
savanna climate.
3
Investigate how tropical soils are likely to change in the future if
rates of deforestation and other human activities increase.
Tropical environments
240
250
260
-Congo
--------------------- Israel
------------------------------- Syria
--------- Reunion
Grenada
-------------- Bahrain
Lithuania
-Saint Vincent and the Grenadines
Canada 265 523 km
--------------------- Bru nei
-------- -------Sâo Tome and Principe
Antigua % Barbuda
--------------- Lebanon
Martinique
------- ----------- Georgia
-Virgin Islands (US)
-- -- Djibouti
rtemala
Bulgaria
Samoa
— Comoros
------------------- Mauritius
------------------------------------ The Gambia
----------------------- Latvia
------------------------- Guadeloupe
- Equatorial Guinea
------------------ Suriname
— Albania
----------------- Cyprus
Romania
---------------- Trinidad and Tobago
Seychelles
— El Salvador
__
— Kuwait
■-----------Ghana
French Guiana
Cote d'Ivoire
-------------------- Liberia
------------------------- Azerbaijan
----------- Jamaica
Qatar
Tonga
Poland
—- Puerto Rico
— Uruguay
-------------Cape Verde
Cambodia
----------------- Guyana
------------------------------- Mauritania
---------------------------------------------------- Turkmenistan
Federated States of Micronesia
------------------------ Senegal
Algeria
Kenya
Dominican Republic
----------------------------------Guinea
Sierra Leone
----------------------- — Uzbekistan
--------- Nam bia
Cameroon
----------- Honduras
----------------------------- Netherlands
----------- Nicaragua
Tunisia
Ki ri bati
— Haiti
- Belize
Maldives
_______
Taiwan
—----------Morocco
------------ _ Gabon
------------------------------ Libya
--------------------- -—-—-—— Costa Rica
--------- Marshall Islands
-------------------------------------- Sudan
-------------------------------------------------- Angola
---------------------------------------------------------------- Pakistan
-------------------------------------------------------------------------------- Oman
------ —
- Sri Lanka
---------------------------------------------------- ------- ----------------- Portugal
United Arab Emirates
------------------------ Estonia
------------Nigeria
-------------------------- Vanuatu
Yemen
Guinea-Bissau
-------------------------------------- Bangladesh
----------------------------- Peru
Eritrea
Tanzania
------ Germany
New Caledonia
- South Africa
— - Somalia
North Korea
----------------------------------------------- Kazakhstan
Ecuador
Fiji
Ukraine
Denmark
------------------------------ Panama
---------------- Croatia
French Polynesia
Colombia
Iran
Egypt
Ireland
Venezuela
Mozambique
— Thailand
Spain
Cities of more than 1 million
inhabitants that live within
200 km of the coast
Land area within
200 km of a coast
Canada’s coastline is
four times longer than
Australia’s and eight times
longer than Brazil’s
53% of the
United States
population lives
near the coast
Saudi Arabia
Turkey
- Argentina
------------------------------ Iceland
Italy
— Malaysia
Solomon Islands
Madagascar
The Bahamas
Vietnam
------------ South Korea
— Cuba
Myanmar (Burma)
------------------------------ Greece
------------------------------------------- India
------------- New Zealand
— United Kingdom
Papua New Guinea
Mexico
Sweden
---------- Japan
China
-------Finland
Brazil . ,
Philippines
230
220
210
200
190
Coastal environm ents
170
In China, over
400 million people
live on the coast
Coastal areas comprise
20% of the earth’s surface,
yet contain over 50% of the
entire human population
United States
of America--
44% of the world's population
live within 150 kilometres of
the coast
The coast is the area where landmasses meet the sea
or ocean. Measuring a coastline length is not an exact
science and cannot be precisely determined as the
forces of nature, in particular waves and tides, are
constantly sculpting the coastal zone. The graphic of
costline lengths includes only countries with
coastlines of over 200 kilometres.
120
Russia
-- Australia
—-
Chile
I— Indonesia
179|
60
70
km (thousands)
80
90
100
Coastal environments
Coastal processes
The coastal zone extends from 40 km inland to 320 km offshore, the latter being
the political limit of a nation’s offshore jurisdiction.
Coastal environments are shaped by a range of physical and human factors,
which in turn produce a variety of coastal landscapes.
table
8.1 Factors impacting on coastal environments
Impact
Factor
figure
Lithology
Hard rocks (granite and schist) give rugged coastlines such
as the west coast of Scotland. Soft rocks (clays and sands)
give low flat coastlines such as North Carolina, USA.
Geological
structure
Concordant (Pacific or Dalmatian) coasts occur when the
geological strata run parallel to the coast. Discordant
(Atlantic) coasts occur when the geology runs at right
angles to the coast, as it does in southwest Ireland.
Processes
Erosional coastlines where the coast is retreating rapidly,
as along much of England’s east coast, or depositional
coastlines such as Denmark’s west coast.
Sea level
changes
Interact with other processes and produce advancing
coasts, such as the east coasts of Scotland or the
submerging islands of the South Pacific.
Human
impacts
Where coasts have been modified, for example by
defence works, such as in Japan.
Ecosystem
types
Coral, mangrove, salt marsh, sand dune, shingle and
rocky shores add variety to coastlines around the world.
8.1 Cliff encroachment, Isle of Wight, UK
Shoreline
Coastline
beach
littoral zone
MHWL- mean high water level
MSL- mean sea level
MLWL- mean low water level
backshore
fore­
shore
MHWL
MSL
MLWL
closure
depth
breaker zone
zone of nearshore currents
figure
5j
8.2 The coastal zone
Coastal environments
offshore
zone
Waves
Waves are created by the friction of the winds acting on the surface of the sea.
Deep sea waves, waves of oscillation, are merely surges of energy and are
very different to the waves that break on the shore. This type of wave moves in
circular orbit, which dictates the shape of the wave.
little motion
shallow depth
elliptical paths
below half wave length
shortens wave length
of orbiting water
(depth less than
particles
one-half wave length)
figure
8.3
Types of waves
Waves in the oceans can travel thousands of kilometres before reaching land. The
potential distance waves can travel is referred to as theirfetch and this can influence
wave height and their energy. Wind waves range in size from small ripples to waves
over 30 m high. More generally, a swell consists of wind-generated waves that are
not significantly affected by local wind. Waves that break on the shoreline are known
as waves of translation. Friction with the seabed slows down the base of the wave
causing the wave length, the distance between two wave crests, to shorten, the wave
height, from trough to crest, to increase and the wave fronts to close up. This leads
to the formation of breakers, of which there are three types:
•
•
•
Spilling breakers: are usually found on gentle gradient beaches and steep waves,
which result in the crest becoming unstable and spilling forward up the beach.
Plunging breakers: occur on steeper gradient beaches. These waves develop
an almost vertical front before plunging down as an intact mass of water.
Surging breakers: are found on steep beaches but with waves where the
front and crest remain relatively smooth and consequently the wave runs up
the beach without breaking.
Once the wave has ‘broken’the water surges up the beach as swash while
gravity pulls the water back as backwash giving rise to two basic types of wave
translation, namely constructive waves and destructive waves.
figure
8.4 (a) Spilling breakers
figure
figure
8.4
8.4 (b) Plunging breakers
(c) Surging breakers
Coastal environments
Destructive waves
Constructive waves
wave crests
far apart
gently sloping
wave front
strong swash
pushes material
up the beach
breaking wave
plunges forward
steep wave
gently sloping
beach
Swash is stronger than backwash, so waves run gently up the beach material is carried onto the beach and deposited there.
figure
waves close
together
breaking wave
spills forward
Backwash is stronger than swash, so waves crash onto the beach material is eroded from the coastline.
8.5 Constructive and destructive waves. Constructive waves have a low frequency, 6-8 a minute, and are generated offshore. They are spilling breakers and their
low frequency means the backwash has time to return to the sea allowing the nest wave to retain all its energy. Destructive waves, at 12-14 a minute, are generated by local
winds. They are plunging breakers and the energy transmitted down the beach as a result of the steeper gradient breaks up the beach material.
figure
8.6 Bay of Fundy, Canada
Tides and the tidal cycle
Tides are caused by the passage of and gravitational pull of the Moon and the
Sun on the oceans. The new moon, the start of the 28-day lunar cycle, creates a
low spring tide and the full moon, halfway through the cycle, creates the high
spring tide. Mid-way between these two points when the Sun and the Moon are
at 90° to the Earth neap tides occur.
Other factors also affect the tides: the effects of the Coriolis Force, which
causes moving objects to be deflected to the right in the northern hemisphere
as a result of the Earth’s easterly rotation, the shape and size of the oceanic
basin, offshore geometry and local meteorological conditions. Tides are
generally accentuated in bays and constricted estuaries such as the Bay of Fundy
in Canada, where some of the highest tides in the world are experienced.
The difference between high and low tides is called the tidal range and can
vary from almost nothing in the Mediterranean Sea to the exceptional 15 m tides
found in the Bay of Fundy.
In the Severn Estuary in the west of England the narrowing shape of the
estuary causes water to be rapidly funnelled and rise as the tide makes its way
up the channel, creating the Severn Bore, which can reach over 1 m in height
and move at a speed of 30 km/hr.
The dominance of wave, wind or tide on a coastal environment can produce
a range of coastal landscapes.
table
figure
8.7 The Severn Bore, England, UK
8.2 Coastal landscapes produced by wave, wind and tide
Wave dominated
Beaches
Wind dominated
Sand dunes
Tide dominated
Deltas
Mangroves
Cliffs
Deltas
Mudflats
Shore platforms
Salt marshes
Spits, tombolos
High energy
High energy
Low energy
Storm surge
The main cause of a storm surge is high winds pushing seawater towards the
coast, causing it to pile up there. A smaller contribution is also made from the
low pressure at the centre of the storm ‘pulling’ the water level up by about 1 cm
for every 1 millibar change in pressure. Some intense storm pressures can drop
by as much as 100 millibars below normal resulting in a corresponding rise in
local sea level of 1 m. Strong winds in the storm generate large waves on top of
the surge that can cause damage to sea defences or increase the risk of flooding.
In the case of tropical storms (such as typhoons) there may also be a very large
amount of rain, which further increases the risk of flooding.
Coastal environments
figure
8.8 The devastation caused by Hurricane Katrina USA, 2005.
When Hurricane Katrina approached the coast of America in 2005, it
generated a storm surge of more than 8 m in some areas. The widespread
flooding included almost all of the city of New Orleans where the sea defences
could not cope, resulting in more than 1800 people being killed.
Wave refraction
As waves approach the shoreline friction with the seabed reduces their speed. This
shallowing and reduction in speed causes the waves to be ‘bent’towards that part
of the shore where they are moving slowest. As waves slow down the wave height
increases and they break. This increases the energy released against the headlands
while in the deeper water of the bay the wave crests diverge and release less energy
when they break. On an Atlantic-type coast headlands will be eroded by the high
energy waves and the bays will experience deposition by the low energy waves.
reduced wave energy
refracted
in embayment
z wave fronts
headland
concentration of
wave energy onto
headland
concentration of
wave energy
onto headland
parallel wave fronts
Figure 8.9 Wave refraction
Where refraction does not take place longshore drift occurs. This leads to
a build-up of material along the shore in the direction of the prevailing wind
(called downdrift). The swash of constructive waves move in the direction of
the prevailing wind, taking material up the beach. The backwash of destructive
waves runs at right angles down the beach following the steepest slope and
removing material.
Coastal environments
mb?
figure
8.10 Waves approaching the beach at an angle.
figure
8.11 Oblique waves
Sub-aerial processes
Sub-aerial processes at the coast weaken and break up the cliff making material
available for the erosion processes. Cliff falls provide protection at the foot of the
cliff to reduce briefly the effects of the sea in eroding the cliff.
These processes occur at the coast throughout the year although some are
seasonally more active. A combination of seawater and frost action can be very
active under severe weather conditions. Clays present in cliff formations are
highly susceptible to alternate wetting and drying.
salt weathering and
solution weathering
biological
weathering
freeze-thaw
weathering
figure
table
8.12 Sub-aerial processes
8.3 Weathering from sub-aerial processes
Types
figure
8.13 Differential erosion
Coastal environments
mass
movement
Effects
Biological
weathering
Plant roots, birds, animals and molluscs (piddocks)
burrow into softer rocks allowing water to access the
rock and accelerate chemical weathering.
Freeze-thaw
weathering
Water that has entered jointed rocks freezes,
expands and weakens the rock for further
weathering, mechanical and chemical.
Salt weathering
Rock structures are weakened by the expansion of
sodium and magnesium compounds in jointed rocks.
Slaking or hydration
Some minerals will disintegrate when exposed to
water, weakening the structures around them.
Solution weathering
More chemical weathering, particularly of calciumbased rocks by water. Often found in rock pools
where organisms excrete organic acids.
Erosion
There are three main erosional processes at work on all coasts although the
impact they have will be affected by the lithology of the shore area.
•
•
•
Wave quarrying (hydrostatic pressure) will affect unconsolidated sands and
gravels, cliffs of glacial till and previously loosened materials. The energy of
a wave is proportional to its height and storm waves consisting of hundreds
of tonnes of water have recorded pressures of up to 50 kg/sq cm. The weight
of water traps air against the cliff and pneumatic pressure can help in
weakening jointed rocks.
Wave abrasion or corrasion is the most effective form of wave erosion. The
wave, loaded with materials from sand particles to boulders, hurls itself at
cliff lines causing the greatest effects between the high and low tide levels.
In hard rocks the effect is to smooth the surface whereas in jointed rocks of
alternate resistance the effect is to wear away the softer material leaving the
harder part more prominent and more exposed to erosion.
Wave attrition affects the loose material on the shoreline produced by wave
quarrying and particles will become rounded. Most attrition will take place
in the breaker zone and during the tidal cycle the whole area between high
and low tide levels will be affected.
figure
8.14 Rough sea
Case Study
Erosion at Wamberal Beach, NSW, Australia
Wamberal Beach on the New South Wales coast of Australia, some 50 km north
of Sydney, is part of Gosford City.
Beach materials extend to a depth of 26 m but recent losses of sand have put
the dunes behind the beach at risk. Possible causes of this loss are:
•
•
•
•
longshore transport out to the offshore reefs, which is not returned owing to
the nature of the reef surface
offshore transport during storm events by rip currents
infilling of the lagoon behind the beach
wind, or aeolian, transport when onshore winds are blowing.
/coffs Harbour
■
The southern section of the bay and headland complex is susceptible to
erosional damage during storm conditions. During storm and heavy rain
events the lagoons break out across the beach area at the same time that it is
being eroded and this can exacerbate the erosion that is taking place. Using
surveys done in 1995 and comparing them to today’s figures it seems probable
that over the next 20-50 years the coastline could retreat between 6 and 15
m. The quantity of material that could be lost over the same period could be
between 140 and 345 m3/m. The building of a sea wall in the 1970s has resulted
in coastal squeeze restricting the amount of materials that make their way into
the system.
TarmTOrth<®
NEW SOUTH
WALES
C*
-
o
Jr Port Macquarie
ubbo
^Newcastle
Wamberal Beach
Sydney
Wollongong
erra
Alb
O'
CTORIA
figure
Tasman
Sea
8.15 Wamberal Beach, NSW, Australia
Wave transportation and deposition
Sediment is transported as either bedload or suspended load. Bedload is
moved either in constant contact with the seabed, traction, or in intermittent
suspended contact (saltation). Larger pebbles, shingle and boulderswill only be
moved under storm conditions. Suspended load exists in a sea that is turbulent
or in a strong current where the water is able to support the particles.
Deposition will be governed by the size, weight and shape of the materials
being transported. Some particles, such as clay, will stick together, flocculate,
become heavier and be dropped as a deposit.
Coastal environments
Figure 8.17 Sediment budgets
Sediment cells
Sediment cells or littoral cells are the unit of study when examining and/or
managing coastal processes and their effects in a named area.
The UK coast is divided into a number of sediment cells and around the world
coastal managers use the same methodology. In southern California there are
five cells stretching from the Santa Barbara cell in the north to the Silver Strand
cell on the USA-Mexico border at Tijuana. An important aspect of the study of
sediment cells is the concept of dynamic equilibrium. This is the result of the
inputs, processes and outputs that operate within the cell. A change to one input,
such as the concreting of a crumbling cliff face, deprives the process relying on
that material and as a consequence there is a change to a downdrift landform.
Case Study
The Columbia River sediment cell
The Columbia River sediment cell extends from Tillamook Head in Oregon to
Point Grenville in Washington State, USA. It has four major concave-shaped
barrier beach sections of shoreline separated by the Columbia River and the two
large estuaries of Willapa Bay and Grays Harbor. The inputs to the cell include:
•
•
•
sediment from the Columbia River
winter waves and coastal currents produce net northward sediment transport
summer conditions tend to see onshore sediment transport and
accumulation at relatively high rates.
Changes to the cell
• The construction of entrance jetties at Columbia River and Grays Harbor
had serious implications for the immediate coastline by interrupting the
longshore transportation of sediment, resulting in erosion of the inlets and
•
•
•
•
offshore migration of tidal deltas.
The beaches have grown seaward by many metres per year for several decades.
Jetties have influenced accumulation and possibly erosion patterns on the
beaches over distances of 20 km or more.
Accumulation rates along the coast have slowed dramatically over the past
few decades.
High rates of erosion are occurring along sections of beach that had
previously grown most rapidly.
figure
8.18 Columbia River sediment cell
Coastal environments
•
•
Local erosion sites have either increasing rates or an expanding scale of
erosion along the coast.
Beaches have experienced severe shoreline retreat caused by large
subduction-zone earthquakes.
Longshore drift
Many of a coast’s depositional features are formed by the process of longshore
drift, which transports sand and shingle along the coast.
Waves approaching the coast at an angle will ‘break up’the beach at that
angle but the returning water will follow the steepest path. This pattern repeated
will result in a movement of sediment downdrift, i.e. along the beach. Waves
approaching the coast at an angle of 30 0 seem to have the maximum effect.
Beaches affected in this way are said to be drift-aligned. To slow this process
down groynes are often built. Differing heights of beach updrift and downdrift
are evidence of the presence of this process.
BEWARE
caution/^
BEACH LEVELS
MAY CHANGE
FALLING ROCKS
INCOMING TIDES
figure
8.20 Beach warning signs
figure
8.21 An avalanche fence to stop falling rocks
wind blows waves
towards the beach
sand and pebbles are
transported along the
coastline by waves
waves approach the
beach at an angle
backwash drags the
sand and pebbles
straight back down
the beach
figure
waves break and
swash carries sand and
pebbles diagonally up
the beach
at Hastings, England, UK.
8.19 Longshore drift
Other structures, jetties and breakwaters built to protect harbour entrances
have the same effect of trapping material but also starving downdrift sections
of the coast and exacerbating the erosional process. A major groyne built at the
downdrift end of the beach in Hastings, southern England, in order to retain
the beach at the seaside resort has led to starvation further east and resulted in
major erosional problems and cliffs falls, (see figures 8.20 to 8.22)
Characteristics and formation of coastal landforms
Cliff profiles are dependent on a number of variables:
• Structure-the arrangement of the rocks in the landscape including such
features as strata (layers), dips (angle) and faults (displacements).
•
•
Lithology - the composition of the rock will determine how vulnerable it
might be to weathering processes.
The orientation of the cliff to the prevailing wind and therefore storms and
high energy waves.
8.22 A granite bund to protect cliffs at Fairlight,
England, UK.
figure
Coastal environments
stack
figure
wave-cut
8.23 Headland erosional features on the northeast coast near Sunderland, England, UK.
Wave refraction will focus the waves’ energy on the sides of headlands - any
points of weakness will be exploited and eroded creating first a wave-cut notch,
which in time will enlarge to form a cave. With erosion taking place on both
sides of the headland the cave may eventually be eroded through the headland
to form an arch, which, if it collapses, leaves a geo (a word taken from Old Norse
gja, meaning a ravine) and a stack. The process repeats causing the headland
over time to retreat further.
high tide
mark
jointed
limestone
strata
wave-cut
platform
figure
8.24 A stack and cave on the northeast coast near Sunderland, England, UK.
While the lithology of a cliff is important the structure is the defining factor
when it comes to determining the shape of the cliff profile. If the strata dip
vertically or horizontally then the cliff will develop a steep profile, however, if the
strata dip towards the sea, then shelving cliffs prone to landslides will develop.
Both these patterns will be disrupted if faults are present in the rocks; this may
cause strata of more vulnerable rocks to be lowered into the erosion zone and
undermine the integrity of the surrounding rocks.
Most cliffs are composed of more than one rock type and their relative
resistance to erosion will play a large part in the shaping of the cliff profile and
the rate at which it retreats. Clay cliffs are highly susceptible to collapse as they
retain large amounts of water, which makes them unstable.
Coastal environments
block of softer
rocks lowered
figure
fault
8.25 Fault plane diffs
massive limestone
with master joints
and bedding planes
hard, igneous rock
fault line
sedimentary rocks
dipping towards
the sea
figure
8.26 Varying cliff profiles
figure
8.27 Collapsing day diff
Coastal environments
Coastal platforms
Cliff retreat normally results in the formation of a platform along the coast.
Until recently this has been called a wave-cut platform as it was assumed that
it was the result of wave action. New research has questioned this assumption
and in particular the ability of wave action to create some of the more extensive
platforms found around the coast. It is now believed that because the sea level
has not been sufficiently constant in post glacial times, the last 10-15 000 years,
these features may have other origins.
figure
8.28 Inland effects of collapsed cliff
Deposition
Depositional coastlines are of two major types: swash-aligned and drift-aligned.
Swash-aligned beaches are influenced by constructive wave patterns, which
are also important for building up large beaches. In contrast, drift-aligned
coasts bring in waves at an angle to the shoreline and therefore the waves tend
to transport sediment down the coast, which keeps beaches narrow.
Drift-aligned beaches are associated with spits, bars and tombolos. Swash
beaches are associated with large beach profiles, with dunes and a variety of
berms and ridges.
Beaches
Beaches consist of a variety of materials that are brought in by waves and material
that falls from cliffs. The coarser material is found in the backshore and foreshore
areas as littoral deposits while finer materials, worn down by attrition, are found
in the offshore zone. The beach area is the material between the spring tide low
water mark, LWM, and the spring tide high water mark, HWM.
upper beach
I
J]
Coastal environments
lower beach
___ I___
Most beaches can be divided into three zones: a backshore zone, a foreshore
zone, and an offshore zone. The backshore, above the HWM, is marked by dunes
or a cliff. There may also be a ridge or berm which has been thrown up by storm
waves, sometimes referred to as a storm beach. The edges of these ridges may
be scalloped into cusps due to the action of the swash depositing material and
the backwash drawing out material.
The foreshore is the area exposed only at low tide. The surface may be undulating
with ridges or fulls and troughs, swales, running parallel to the waterline.
Offshore is where the finest material is deposited and where the waves
disturb the seabed this material can be pushed up as offshore bars.
The formation of beaches is the product of constructive waves operating
in a sheltered aspect where they can be supplied by longshore drift with a
plentiful supply of material. Steep destructive storm waves will tend to reduce the
angle of a beach whereas the summer’s constructive waves will increase it
figure
8.30 Seasonal fluctuation in beaches
Sediment size, which affects the rate of percolation, will have an effect on
the beach angle. Coarse grade material, shingle, allows rapid percolation so the
impact of the swash element is unimpeded as a result of the backwash effect being
reduced. This means that deposition will occur. By contrast, sand only produces a
low angle beach as there is far less percolation and much more backwash. These
processes are futher complicated by the fact that particle size will vary across the
beach. At the low water mark particles are constantly being moved so the process of
attrition will be continuously at work and particles will be much smaller as a result.
Localised depositional features
Bars, barrier islands, spits, tombolos and forelands will develop when:
• there is an abundance of material, mainly sand and shingle
• the local geology creates an irregular and indented coast
• deposition is encouraged by the presence of vegetation, which decreases
wave speed and energy
• there are estuaries and/or major rivers.
Offshore bars develop on gently shelving seabeds and are composed of
sand and/or shingle. Waves encounter friction with the sea floor some distance
offshore and the turbulance this creates leads to deposition and the creation of
a bar. The water inside the bar towards the coast, sometimes called a lagoon or
sound, can be much calmer and if fed by rivers then terrestrial deposition can
lead to the development of mudflats and salt marsh.
Spits are commonly found along indented coasts. Material moved by
longshore drift and other currents is moved into a low energy environment
such as a sheltered river mouth or estuary. The long narrow ridge of sand and
shingle that forms is always attached at the updrift, proximal end and at the
downdrift: or distal end it may be curved. This curved effect is the result of
wave refraction or local currents remodelling the sediment to form a simple
straight ridge. Recurved spits develop if this remodelling becomes extensive and
compound recurved spits show signs of widening as they approach the distal end.
Close examination often reveals a number of relict spit features demonstrating
previous extensions of the spit as it grew to its current shape and position.
figure
8.31 Tombolo and white sandy beach, New Zealand.
Coastal environments
figure
8.33 Aerial view, East Head spit
East Head to Pasdam, West Sussex Sediment Transport
figure
8.32 Seasonal flows, Chichester, England, UK
Bars
Bars are ridges of deposited sediment that attach at either end to the mainland.
They usually form when a spit extends across a small bay or irregularity in the
coast. In the Baltic Sea on the north Polish coast these sandy bars or nehrungs
enclose extensive lagoons or haffs.
figure
8.35 The Szczecin Lagoon, on the Germany-Poland
border. Area 687 sq km, average depth 4 m.
Coastal environments
Barrier islands
Barrier islands are naturally formed sandy breakwaters parallel to the coastline.
The eastern seaboard and Gulf coast of the USA has over 300 such islands. At
Cape Hatteras some islands are 20 km offshore while in Florida it is difficult to
recognise that islands actually exist as they are so close to the mainland, with
the resort of Palm Beach actually built on an island.
These huge beaches have been slowly driven onshore during periods of
rising sea levels and, while no single theory can explain the development of
barrier islands, scientists now generally accept the idea that barriers can be
formed by a number of different mechanisms, often acting in concert.
Barrier island systems develop most easily on wave-dominated coasts with a
small to moderate tidal range. Coasts are classified into three groups based on
tidal range:
•
•
•
microtidal, 0-2 m tidal range
mesotidal, 2-4 m tidal range
macrotidal, >4 m tidal range.
Barrier island systems tend to form along microtidal coasts, where they
are well developed and nearly continuous. Along with a small tidal range
and a wave-dominated coast, there must be a relatively low gradient shelf.
Otherwise, sand accumulation into a sandbar would not occur and would
instead be dispersed throughout the shore. An ample sediment supply is also a
requirement for barrier island formation. The last major requirement is a stable
sea level. If sea level changes are too drastic, there will not be enough time for
wave action to accumulate sand into a dune, which will eventually become a
barrier island through accumulation.
The best known example of an barrier island system is the Isles
Dernieres, which was built up along the Gulf Coast over a period of 7000 years
as deltas of the Mississippi. They are now one of the fastest eroding coasts
in the world and are overtopped at least six times a year, most spectacularly
under Hurricane Katrina, which removed the pleasure beach completely. The
combination of subsidence and reduced sediment supply has remodelled the
sediments forming beach ridge complexes and as a consequence the wetlands
behind these barriers have converted to open-water areas.
1978
figure
8.36 Isles Dernieres, Louisiana, USA
Tombolos
Where a ridge of deposits links an island to the mainland it is called a
tombolo.
Chesil Beach extends 25 km from Burton Bradstock on the Dorset coast and
links the Isle of Portland to the mainland. Recent research suggests that this is a
relatively new feature, geologically speaking. Around
18 000 years ago sea levels had fallen by as much as 100 m, meaning that the
English Channel at this point was probably dry. During and immediately after
the last ice age huge amounts of sediment were transported by meltwaters into
the dry English Channel and as sea levels rose this material was pushed onshore
by wave action to form the feature seen today.
Cuspate forelands
Cuspate forelands, also called ‘nesses’ in Great Britain, are triangular-shaped
beach features that vary in size from a few square metres to 250 sq km (for
example, Dungeness in Kent). Some cuspate forelands are stabilised by
vegetation, while others may migrate along the shoreline downdrift.
The foreland at Dungeness was undoubtedly formed by the action of
longshore drift, however it seems likely that sheltered conditions from the west,
river deposition from the streams entering Rye Bay, wave refraction and early
colonisation by vegetation may all have contributed to the formation of this strange
landscape feature.
Coastal environments
figure
8.37 Localised depositional coastal features
coastline forwards
(marsh area only)
■ Shore fort at Lympne
spit changes orientation with
accretion (deposition) to the NE
edge and erosion in the SW. Beach
ridges reflect this movement
figure
8.38 (a)—(d) Development of a cuspate foreland
194 Coastal environments
----------- Present day extent of foreland
I Alluvium
Degraded
cliffline
Sand dunes
Sand dunes will form under certain conditions:
• a reliable supply of sand
• strong onshore winds
• a large tidal range
• vegetation to trap the sand.
Windy sandy beaches are invariably backed by sand dunes because strong
winds transport sand inland as it dries out at low tide. Vegetation will reduce
wind speeds and cause sand grains to be deposited.
Sand dune succession
Sand grains are moved by the wind so the strength of the wind and the
nature of the surface is important. Sand grains will be moved initially
by saltation but uneven surfaces will cause eddying and the speed to
fluctuate and some material may be moved in the air. On the leeward side
of obstructions wind speeds decrease and so deposition will take place. In
order for dunes to stablise vegetation needs to be present. The youngest
or embryo dunes are nearest the sea. Few nutrients are present and as
few plants can tolerate the arid, salty windy conditions they need to be
8.39 Sand dunes and grass vegetation, Wharariki
Beach, New Zealand.
figure
sediment deposited and moved by wind,
wave and tidal action
xerophytic and halophytic (drought and salt tolerant). These dunes therefore
remain largely sand and fairly mobile and are referred to as yellow dunes.
Increasing distance from the sea causes conditions to ameliorate and a
greater number of plant species are able to establish themselves and the
dunes become less mobile as plants bind the dune together; this is the zone
of the semi-fixed dune. Fixed dunes or grey dunes develop as more species
become established and start to provide a humus content to the dune, making
the soil richer and damper allowing pioneer species to be replaced by less
tolerant species of grasses and flowering plants. Between the dunes damp
areas collect known as dune slacks and here marsh vegetation may start
to grow.
Towards the back of the dune system climax vegetation is governed
by the nature of the soil. Calcium rich, alkaline soils provide grasscover
and the presence of broad-leaved trees but more usually the soil
is acidic, which gives rise to a climax vegetation of pine trees and
heather, potentially giving the oldest part of the dune system complex
vegetation cover.
embryo dunes
yellow dunes
blow out
semi-fixed dunes
dune
slack
grey dunes
succession
plagio-climax__
dune heath
plagio-climax
Fixed dune (or grey dune): as time goes on the soil develops and
becomes damper and richer. Lichens, mosses and flowering plants
can grow on the dune. They form a continuous cover over the sand.
Marram grass is replaced by red fescue grass.
dune scrub
climax woodland
vegetation
embryo
dune
semi-fixed du ne
wet dune slack
slack
dune
slack
As the dune system gets older and larger,
water can collect towards the back of a dune.
figure
slack
8.40 Sand dune succession
dune healthland
succeeds grasses and flowering
plants as small trees mature.
These damp hollows are known as dune slacks.
Marsh plants and small willow trees can grow here.
figure
8.41 Sand dune succession
Coastal environments
figure
8.42 A spit at Axmouth, southwest England, UK.
figure
8.43 Mudflats developing behind a spit.
Mudflats and salt marshes
Mudflats and salt marshes develop where there is fine sediment available,
sheltered conditions and low wave energy. The main inputs, which are fine clays
and silts, are transported in suspension by rivers and tides.
The particles flocculate, giving them a greater settling capacity, and once
deposited they are less likely to be entrained into the water flow as larger sand
particles.
Deposition will take place as the tide turns when the water flow and
velocity are at a minimum. As the mud builds up the frequency with which it is
flooded decreases and vegetation can colonise the area to start the process of
establishing a salt marsh environment The presence of plants further slows the
movement of water and allows deposition to take place throughout the tidal
cycle; this process is known as bioconstruction.
figure
8.44 Marsh samphire is a typical pioneer species
along with marsh cord grass. Both of these are halophytic
species, which flourish in marsh conditions.
concave
landward edge
figure
8.45 Salt marsh
196 Coastal environments
Mangroves
Mangroves are a range of species of trees and bushes that have adapted to
living in the coastal swamps and the creeks and estuaries in tropical regions.
There are hundreds of different species of mangrove with each area having its
own distinctive association of plants.
Mangroves are colonising plants and will reclaim muddy areas that can, in time,
develop into much more complex ecosystems.
Although extremely hardy plants a number of factors lead to the degradation
and destruction of mangrove swamps and forest.
In many LICs clearing has taken place in response to a growing population,
the need for building materials and for firewood.
Commercial activities such as prawn farming in countries like Bangladesh
has led to further clearing.
Urbanisation in its many forms - housing, port development and tourist
facilities - has had a major impact.
Pollution from chemical effluent and from oil spills can choke the delicate
root systems starving the plant of oxygen which results in die back.
•
•
•
•
The dense nature of mangrove vegetation makes it a useful barrier for the coast,
absorbing wave energy, holding material together and reducing the impact of
coastal erosion. With their removal many countries have had to invest heavily
in hard engineering projects to protect what has become a vulnerable coastline.
Organisations like ‘Mangroves for the Future’ and ‘Wetlands International’ are
encouraging governments to adopt a more sustainable and holistic approach
with programmes of mangrove conservation and regeneration.
The particular conditions for growth are:
• Brackish water
•
•
Three different types of root system develop in response to the local tidal and drainage conditions.
Between the high water mark and the mid tidal
mark
figure
8.46 (a) Species
growing in anaerobic
figure
Pioneer species will grow closer to the low water
mark
conditions have horizontal
develop aerial roots providing
the plant with oxygen.
roots which send up vertical
shoots to get oxygen.
8.46 (b) Further
inland different species
Sonneratia
figure
8.46 (c) Away from
waterlogged mid and high
tide areas mangroves develop
buttress roots which provide
oxygen and anchor the trees.
Bruguiera
Coral reefs
Coral polyps are tiny, soft-bodied organisms. At their base is a hard protective
limestone skeleton called a calide, which forms the structure of coral reefs.
Reefs begin when a polyp attaches itself to a rock on the sea floor then divides,
or buds, into thousands of clones. The polyp calicles connect to one another to
create a colony that acts as a single organism. As colonies grow over thousands
of years, they join with other colonies and become reefs. Some coral reefs began
growing over 50 million years ago and the Great Barrier Reef off the Australian
east coast is at least 5 million years old.
Global limiting factors
•
Temperature: reef-building corals are rarely found in areas where the water
temperature drops below 18 °C for more than a few days.
•
Water depth: corals can only grow in relatively shallow water with few
growing below a depth of around 90 m.
•
Light: corals need sunlight to support the algae that live within their tissues.
Although corals need nutrients, they cannot thrive in areas where there are
large amounts of nutrients. Typically plankton or seaweeds (macroalgae)
grow to excess in nutrient-rich water and smother the corals, blocking out
the light.
Coastal environments 197
•
Salinity: coral is intolerant of seawater with a salt content of less than 32
•
practical salinity units (psu).
Conditions must support the presence of the zooanthellae (the algae that
provides the coral with food, energy and colour) which exist in a symbiotic
relationship with the coral.
Local limiting factors
• Sediment: corals require clean clear water as any sediment will clog up
their feeding and cleansing mechanisms as well as reduce the light for
photosynthesis required by the algae on which they feed.
• Wave action: being supported by limestone skeletons, corals can survive in
very tough conditions. However, in the strongest storms many corals will be
smashed to pieces.
• Exposure to air: coral cannot survive being exposed to the air for any length
of time and so they always grow below the LWM.
Types of reef
There are four main types of reef, which can be identified as:
• Fringing reef: this is located very close to land and often forms a shallow
•
•
figure
8.47 (a) Fringing reef
•
lagoon between the beach and the main body of the reef.
Barrier reef: this resembles a fringing reef but is located further from the
shore and can be much bigger than a fringing reef. For example, the Great
Barrier Reef in Australia lies 300-1000 m from shore and is 2000 km long.
Atoll: these circular or horseshoe-shaped reefs encircle a lagoon. No
apparent landmass is normally associated with an atoll.
Patch reef: these outcrops ofcoral usually lie within a lagoon.
Origins
Fringing reefs, barrier reefs and atolls are thought to represent stages in coral
reef formation. Charles Darwin first proposed this theory of coral reef formation
in 1842.
figure
figure
3
8.47 (b) Barrier reef
8.47 (c) Atoll
Coastal environments
Step 1: A fringing reef forms first and starts growing in the shallow waters
close to a tropical island.
Step 2: Over time the island subsides and the reef grows outwards. The
distance between the land and the reef increases. The fringing reef
develops into a barrier reef.
Step 3: If the island completely subsides, all that is left is the reef. The reef
retains the approximate shape of the island it grew around, forming
a ring enclosing a lagoon. Darwin speculated that underneath each
lagoon should be a bedrock base- the remains of the original island.
Subsequent drilling into atolls proved this hypothesis to be true.
Two other theories are those of Murray (1872) and Daly’s Glacial Control theory
(1909). Murray believed that the base of the reef was a submarine mountain
consisting of volcanic peaks or wave worn remnants that reached close enough
to the surface for it to be a foundation ofcoral growth. Coral fragments would
accumulate and be cemented into a solid mass. Daly on the other hand favoured
a sea level change mechanism brought about by post-glacial ice melt. He found
evidence of glaciation in the Hawaiian Islands and postulated that the sea would
have been colder and sea levels lower so the coral would have died off. Once
conditions became more favourable to coral growth the new reefs would have
grown on the base provided by the old dead reefs. Recent research done by the
Lamont-Doherty Earth Observatory at Columbia University in New York has
shown that sea level changes around Barbados occurred many times between
70 000 and 250 000 years ago by as much as 30 m in a very short period of time.
All of which lends support the theories of Darwin and Daly. The likelihood being
that no one single process operated on its own.
figure
8.48 Coral bleaching caused by high water temperatures, Indonesia.
Human threats to coral reefs
Data collected by the World Resources Institute suggests that over half of the
world’s coral reefs are at high or medium risk of degradation and in Southeast
Asia this figure rises to 80 per cent Overfishing, industrial pollution and
domestic waste threaten not only the coral but also the fish stocksand marine
environment in general.
Impacts are indicated by events such as coral bleaching. When conditions for
coral growth alter the first noticeable effect is the breakdown of the symbiotic
relationship between the coral and the zooanthellae. This effect is most
noticeable when temperatures increase by no more than 1 or 2 °C and in shallow
waters the potential for this to occur is great. In 1998 extensive bleaching
worldwide resulted in considerable damage to 16 per cent of the world’s coral
reefs. Much of this was due to abnormally high temperatures, in some cases as
much as 4 °C higher at a depth of 20 m.
Reports of global coral health
A global assessment carried out in 2004 by the United Nations Environment
Programme (UNEP) reported that 20 per cent of reefs were damaged beyond
repair. Much of this decline was attributed to climate change, poor farming
practices, overfishing and coastal developments. The report also noted that
recovering reefs were continuing to improve, particularly in the Indian Ocean
and in Australian waters.
In 2010 the World Meteorological Organization (WMO) and the Convention
on Biological Diversity (CBD) released a report outlining the threat to coral
reefs caused by climate change and subsequent coral bleaching, as well as by
ocean acidification. This report highlighted the fact that coral reefs were the
first ecosystem to demonstrate the effects of climate change and that unless
significant reductions in greenhouse emissions took place there was likely to be
a catastrophic collapse of the ecosystem. The report noted:
•
•
•
Increased bleaching and possible extinctions of some species likely to occur
as sea temperatures rise.
Increased ocean acidification reducing the ability of the coral to calcify,
weakening structures and slowing growth.
Increased storm activity leading to damage and erosion along coastlines.
In seawater carbon dioxide becomes carbonic acid, which in turn forms
bicarbonate and carbonate ions. The levels of these are important because they
control the pH of seawater. This is a measure of how alkaline the water is, In
fact, seawater has a relatively stable pH of about 8.3.
Coastal environments 199
Sustainable reef management
Given time and improved conditions reefs can recover, especially from once only
incidents such as a pollution spill, but not necessarily from longer-term stress.
It is important therefore to look for longer-term strategies in order to maintain
reefs.
In 2015 researchers discovered a new species of algae that helps corals to
survive in the temperatures of up to 36 °C found in the coastal water of the
United Arab Emirates (UAE). These temperatures would be expected to kill corals
figure
8.49 Coral that is tolerant of the warm water off the
coast of the United Arab Emirates.
elsewhere. The algae live in a symbiotic relationship with the coral. The discovery
of this new species of algae means that corals might be able to survive increased
sea temperatures, although other threats remain.
In 2015 University of Plymouth researchers highlighted another recent
concern - ocean acidification (OA)- and the effect that it might have on coral.
The rate of acidification has been rapid although so far quite small. On average
the pH measure of acidity/alkalinity at the surface of the oceans has fallen by
0.1 since burning coal for steam power become widespread in the eighteenth
century. The area of concern is the rate at which this is happening because
the oceans are becoming corrosive enough to dissolve many marine plants
and animals. Research conducted around volcanic seeps, where COa naturally
bubbles into the sea, has attempted to determine which organisms survive by
capturing the CO;. Coral reefs are severely weakened as CO; rises and in the
tropics weakened reefs will contribute to increased coastal erosion.
Some organisms can however adapt to the effects of long-term acidification
with soft corals doing particularly well, however transplanting these corals into
waters of pH 7.8 results in them dissolving away. So acidified oceans could end
up with fewer species of crumbling reefs and other species, such as jellyfish
and seaweed, moving in and taking their place. A few species have an outer
protective layer that allows them to survive in acidified waters but their survival
is also reduced by other stress factors.
Rising temperatures and acidification destroys coral and reduces biodiversity.
It is time for governments to reduce emissions and invest in research as these
and other systems are much more resilient when stress levels are reduced.
Increasing diversity
and value of local
economies by
providing fishermen
Establish guidelines of
with better boats
sustainable quotas for all
and on-shore
activities, fishing, diving,
refrigeration
and boat anchorages
Developing alternative
strategies for income
generation to prevent
illegal fishing
Setting up a
programme of research
to monitor and assess
health and impacts of
training to encourage
public support and
any of the improvement
schemes
expertise locally for
better management and
to promote bottom-up
involvement
Developing codes
of conduct for all users
figure
200 Coastal environments
8.50 Strategies for reef management
Sustainable management of coasts
Coastlines present a range of challenges as more people demand to live, work
and holiday there. Consequently the coastal area has become overdeveloped,
overexploited and overcrowded. In the USA half the population lives within
6 km of the sea or the Great Lakes and three-quarters of the population live
within loo km of the coast. In England and Wales Shoreline Management Plans
(SMPs) are designed to ensure a holistic approach to coastal defence by taking
into consideration all the interacting factors that contribute to, or are affected by
such defence schemes (Table 8.4).
table
8.4 Shoreline Management Plan
Defence options
Allow coastal retreat
Do nothing
Improve coastal defences
Beaches on chronically eroding shores can
maintain their natural width as they slowly
retreat landward.
Maintain existing levels of defence
Management options
Cliff stabilisation
Coastal infrastructures, sea walls, paths
Beach cleaning
Pollution, spills
Offshore dredging
Land management issues
Recreational
Coastal defence includes protection from the effects of the sea, both
erosion and deposition, and protection against coastal flooding. Coastal Zone
Management includes all activities within the coastal zone both human and
physical and in dealing with these issues there is great potential for conflict.
Coastal protection takes two forms: hard engineering and soft engineering.
Beach loss eventually occurs in front of a
sea wall where there is chronic erosion.
figure
8.51 Hard engineering and beach loss
Hard engineering
Hard engineering is the use of structures put in place to resist the energy of the
tides and waves. They are expected to resist considerable variation in conditions
and usually require expensive and on-going maintenance. They are nevertheless
effective in permitting the development of the coastline although they can also
have negative impacts upon the shoreline, causing it to narrow, which can lead
to a reduction in biodiversity as habitat is reduced as well as exacerbating the
effects of erosion and sediment movement along the coast. Table 8.5 shows the
main types of hard engineering and their limitations.
Soft engineering
Soft engineering attempts to devise solutions that work with the processes.
These schemes are sometimes less expensive to implement and need less
maintenance. However, they can have a potentially negative impact where
landowners have to give up land and/or property so that a scheme can be
implemented. Table 8.6 shows the variety of soft engineering options and their
limitations.
Coastal environments 201
table
8.5 Types of hard engineering
Limitations
Operation
Technique
Breakwaters
Offshore structures of concrete or rocks that deflect waves
before they reach the shore; the term can also refer to
protective walls near harbours
Tend to deflect waves along new paths,
which may cause scouring of foundations
or erosion elsewhere
Gabions
Metal cages filled with rocks, which can be stacked to build
walls (often 1 m cubes); may also be arranged as a mattress so
that waves can percolate
Metal cage may fail relatively quickly,
spilling contents; if stacked, they may
move in strong waves
Geotextiles
Permeable fabrics that accumulate materials yet allow water to pass
through; modern types (geotubes) are filled with dredged sand
Relatively new and there is limited
evidence of results on a large scale
Groyne
fields
These wooden or rock barriers, sited perpendicular to the
shore, trap and retain drifting sand; repairable; the key is to
get a balance of sand stored and sand still moving
Likely to interfere with the sediment
budget along a coastline, causing deficit
or even starvation downdrift
Revetments
Sloping ramps (concrete, rock or open wooden baffles) to
absorb wave energy; modern versions have large blocks placed
in a finer mix foundation
Despite sloping design, revetments have
similar problems to sea walls; they may
damage foreshore ecosystems
Rip rap
(rock
armour)
Similar to sea walls, but permeable and able to adapt to
change; larger rocks are not easily moved; can look relatively
natural depending on location
Rocks can roll in severe weather or be
under-scoured by backwash; not always
visually attractive and usually expensive
Sea walls
These bulkheads separate land from water, supporting the land
as well as holding back the sea; modern designs can absorb
and deflect as well as resist wave attack; seen as appropriate, if
not mandatory, in promenade and harbour situations
Wave return walls may accelerate beach
erosion due to downward motion of
water and scour at toe of wall; often the
most expensive option both in terms of
capital and maintenance costs
table
8.6 Types of soft engineering
Operation
Technique
Limitations
Beach
drainage
Drainage improvement for swash-aligned beaches
using coarser sand; reduces surface backwash and
gives better beach colour (for beach users)
A new concept not tested fully; will not work
on drift-aligned beaches
Beach
nourishment
Artificial replacement of sand from land or water
(pumped onshore as slurry)
Exogenous (imported) sediments may have
environmental and visual drawbacks
Beach
reprofiling
Economical way to resist erosion by changing the
shape of the beach
‘Scraping’only works in low energy environments;
storms can deconstruct the shape
Cliff drainage
Reduces saturation by piping water out of cliffs and so
prevents landslips
Only applicable to some rock types
Cliff profiling
Slope of cliff face lessened (regraded) to improve
stability (critical angles involved)
Requires detailed research into the geology of
the cliffs
Cliff toe
protection
Blocks placed at cliff foot beneath potential failure sites
Largely a temporary response, as this method
does not halt erosion
Creating stable
bays
Increasing length of bays in an attempt to spread wave
energy along the coast and focus wave erosion on
headlands; protects bays
Not yet tried in Europe; long-term approach
Dune
regeneration
Wind velocity reduced by fences or planting above
beach level to encourage sand deposition; generally
effective if managed properly
Effective only in aeolian environments and
where public access can be controlled
Marsh creation
Planting mudflats with pioneer species like spartina to
increase stability in tidal flow; seem as an affordable
and perhaps sustainable solution
Technique may be jeopardised by an
accelerated rise in sea level if marsh plants
cannot adapt quickly enough
Mudflat
recharge
Similar to beach nourishment but uses cohesive
sediments (for example, in Dutch Polders)
Similar limitations to marsh creation
Rock pinning
Bolting rock layers to prevent slipping along cliff faces
Only applies to some cliffs and does not
prevent wave erosion
Sand
bypassing
Removal and re-injection of sediments into a sediment
cell; used to bypass important harbour breakwater
features, which keep navigation channels clear
Despite common use, the costs are becoming
increasingly prohibitive
Vegetation
planting
Use of planting to stabilise cliffs and dunes (e.g. kudzu
and marram grass)
These fragile environments need careful
management
202 Coastal environments
Case Study
Sand dredging
at
Diani Beach, Kenya
Diani Beach is listed as one of the world’s great resorts. A proposal to extract
5 million tonnes of sand just offshore from the beach has created a furore
locally with tourism stakeholders and local residents. Sand is a vitally important
component of modern society and clean sand is rarely found on land but sea­
based deposits only require washing to remove the salt. The sand at Diani is
required for construction work in and around the port of Mombasa. This project
is seen by the government in Kenya as a major step forward in the development
of the country. Local people, fishermen, tourism managers, environmentalists,
the Kenyan Wildlife Service and marine scientists are not so sure.
The South Coast Residents Association (SCRA) is involved in monitoring the
dredgers working offshore and the effects that the work is having. The SCRA has
found the following:
•
•
•
•
•
Dredging is damaging the reef and adversely affecting the fish stocks.
Coastal mangroves are being killed off; they are an important part of the
coastal defence system.
Changes to the seabed morphology are affecting local currents and tidal
patterns, which in turn increase erosional effects on beaches.
There is potential for the collapse of the tourist industry.
Rubbish and heavy metal contaminants are dumped offshore and are being
brought onto beaches by the tides.
figure
8.52 The location of Diani Beach in Kenya.
Currently (2015) it seems that the Kenyan government appears to be ignoring
these environmental concerns. Locals would like a way to be found to source
the sand from elsewhere and not condemn Kenya’s prized beaches to a slow
death. To make matters worse, sea sand needs to be washed with fresh water,
an equally scarce resource at the coast. However with monies available from
Chinese investors it seems very likely that this project will continue to progress
at the ultimate expense of the beaches of southern Kenya.
figure
8.53 Diani Beach, Kenya
Coastal environments 203
Case Study
Tourism and management issues in EastTimor
East Timor is a ‘new’ tourist destination in Southeast Asia. East Timor’s main
attractions are spectacular coral reefs and their biological diversity. These reefs
are important not just for tourism and the habitat and biological diversity they
support but as the provider of food for the many fishing communities around
the coast.
INDONESIA. Pulau
Flores
Sea
Romang
Banda Sea
Wetar
•
?
INDONESIA
Flores Adonara
'
Larantuka Lomblen
Solor
o Laliki
Manatuto
Pantar
Foho Tatamail
EAST TIMOR
<0
Pante Macassar 9
Gunung Mutis V
2427 S ■
Savu
Ssmau
Huaki \
Set®
HhadeAtauro
Dili
o
<
.»
Kisar
Laute^SLa|a
Baucau
spalos
Viqueque
EAST TIMOR
'
dBesikama
INDONESIA
°KJpang
Timor Sea
EASTTIMOR
figure
8.54 EastTimor
The tourism emphasis has two main strands:
•
Ecotourism, defined by Ecotourism Australia (2006) as “ecologically sustainable
tourism with a primary focus on experiencing natural areas that foster
environmental and cultural understanding, appreciation and conservation”.
•
Pro-poor tourism (PPT), which is defined as “tourism that generates net
benefits to the poor” (UN 2002). These include economic, environmental,
cultural and social benefits. Significantly, pro-poor tourism differs from
sustainable tourism because PPT has poverty alleviation as its first objective,
while sustainable tourism focuses on the environment.
figure
8.55 (a) and (b) Vibrant coral reef in EastTimor.
204 Coastal environments
Specific centres for tourism development have been identified along the
coastal margins at Dili, Manatuto, Baucau and Lautem. A comprehensive list
of objectives has been drawn up by the government to ensure the greatest
benefit for the people of East Timor as they exploit the island’s tourist potential.
Many of these objectives revolve around training in all aspects of the tourism
industry and the provision of infrastructure to support tourism and prevent
indiscriminate development of facilities. The need for local people to be involved
and to benefit economically from tourism has been recognised. Diving and
fishing has to be controlled in order to protect the reefs from damage but also
to ensure that commercial fishing does not suffer adversely. The development
of alternative sustainable coastal-marine livelihoods (such as ecotourism) are
essential for the conservation and protection of the island's unique marine and
coastal ecosystems and biodiversity.
Underpinning all of this is the need for legislation to protect the natural
and complex cultural heritage of the island for future generations. There are a
range of potential negative impacts that could arise from an influx of foreign
tourists and visitors to local communities. The establishment of tourist precincts
that offer enhanced amenities and services could assist in minimising access to
places of cultural or environmental sensitivity. The designation of marine parks
would go some way to protecting the reefs and the coastline and limiting access
to more fragile areas.
NOW INVESTIGATE
1
Describe and explain the formation of tombolos, offshore bars,
barrier beaches and coastal dunes. To what extent can these coastal
landforms be changed by physical processes and human activities?
2
Explain how weathering, rock type and rock structure influence the
erosion and form of coastal landforms.
3
Using examples, explain why different stretches of rocky coastline
produce different landforms.
4
Explain how far the conditions that allow the growth and develop­
ment of coral reefs are under threat.
Coastal environments 205
Natural disaster classification
Extreme Temperature: HeatWave, Cold Wave, Extreme Winter Condition Wildfire: Forest Fire, Land Fire Drought
Mass Movement (dry): Rockfall, Landslide, Avalanche, Subsidence Earthquake Volcano
Flood: General Flood, Flash Flood, Storm Surge/Coastal Flood Mass Movement (wet): Rockfall, Landslide,
Climatological
Storm: Tropical Cyclone, Extra-Tropical Cyclone, Local Storm
Geophysical
Hydrological
Meteorological
Disaster occurrences by continent, 2014
••••••
••••••
••••••
•••••••••
•••••••••
•••••••••
•••••••••
•••••••••
Americas disaster occurrences 72
••••••
••••••
•••••••••
•••••••••
•••••••••
•••••••••
••••••
••••••
••••••
••••••
••••••
Europe disaster occurrences 48
Africa disaster occurrences 34
France
Top 10 countries by total
number of disasters 2014
1
2
3
4
5
6
7
8
9
10
China
USA
India
Japan
Philippines
Indonesia
Mexico
Thailand
France
Nepal
39
20
15
12
12
11
8
8
7
7
Americas people affected, 2014
Mexico
Europe people affected, 2014
Africa
people affected, 2014
2.3 million
77 000 people
6 million people
were affected by climatological disasters
were affected by geophysical disasters
were affected by climatological disasters
1.1 million
were affected by geophysical disasters
2.7 million people
15 000 people
were affected by hydrological disasters
were affected by geophysical disasters
1.3 million
111 000 people
646 000 people
were affected by hydrological disasters
were affected by meteorological disasters
were affected by hydrological disasters
180 000
131 000 people
were affected by meteorological disasters
were affected by meteorological disasters
Serious destruction of a community or an environment
is categorised as a disaster when one of the following
criteria is fulfilled:
Avalanche, Subsidence
Ten or more people are reported dead
One hundred or more people are affected
A state of emergency is declared
There is a call for international assistance
Hazardous environm ents
•
•
•
•
Natural disasters are classified by the climatological,
geophysical, hydrological or meteorological event that
triggered the disaster.
•••
• •••
• •••
Asia disaster occurrences 142
Oceania disaster occurrences 11
Indonesia
Asia people affected, 2014
Oceania
people affected, 2014
31.5 million people
170 people
were affected by climatological disasters
were affected by climatological disasters
2.6 million people
1380 people
were affected by geophysical disasters
;
32.1 million people
80 000 people
were affected by hydrological disasters
were affected by hydrological disasters
26.3 million people
89 000 people
were affected by meteorological disasters
were affected by meteorological disasters
207
Hazardous environments
Hazards resulting from tectonic processes
The global distribution of earthquakes and volcanoes related to plate tectonics
A hazard can be defined as a naturally occurring process that has the potential
to cause damage to property and loss of life. Tectonic or geological hazards
include seismic activity (earthquakes), volcanic activity and tsunami, which
mostly occur in a clear linear pattern.
This pattern is determined by the position of plate boundaries with
collisional and destructive plate boundaries, which result in broad linear chains,
and conservative and constructive plate boundaries, which result in lines of
earthquakes and volcanoes that are relatively narrow (although they can still
exceed 100 km in width). For example, where the continental crust of the Indian
subcontinent is moving northwards into the continental crust of the Eurasian
plate (collisional boundary) a broad belt of earthquakes can be found in the
Himalayas. Volcanoes and earthquakes in broad chains can also be found on the
west coast of South America where the dense oceanic Nazca plate is subducting
(plunging) beneath the less dense continental South American plate (destructive
boundary). Narrow chains of volcanoes and earthquakes can be found in the
centre of the Atlantic Ocean where the North American plate and Eurasian
plate are moving slowly apart (constructive boundary). Similarly, narrow bands
of seismic activity can be found on the San Andreas fault where the North
American plate and Pacific plate are moving past each other in opposite
directions (conservative boundary).
Whilst approximately 85 per cent of seismic and volcanic events occur at plate
boundaries there are also isolated occurrences of these phenomena that do not
conform to this pattern. For example, the Hawaiian hotspot is an example of
intraplate volcanism that is likely to be formed as a result of isolated magma
figure
9.1 Distribution of plate boundaries, volcanoes and earthquakes
208 Hazardous environments
plumes. Outlying earthquakes can also be caused by human activity rather than
naturally occurring processes. For example, groundwater extraction is thought
to have contributed to the 2011 Lorca earthquake in Spain, whilst fracking (the
mining of shale gas by the process of hydraulic fracturing) was linked to an
earthquake in Oklahoma in the same year.
The relationship of hazards to plate tectonics
Temperatures of over 6000 °C in the Earth’s core and the heat released by
radioactive decay of elements in the mantle work together to create convection
currents. This circular motion in the asthenosphere (semi-molten part of the
mantle) results in the movement of the seven major and over 50 minor plates
that make up the Earth’s crust. The rate of movement of the plates is variable
although the average is between 5 and 10 cm per year.
Divergent plates
Where convection currents rise and diverge, tensional stresses are produced
in the crust. Magma (molten rock) rises from deep in the mantle and, as the
upper parts of the mantle begin to melt, fluid basaltic lava erupts to form a new
oceanic crust. The explosivity of volcanic eruptions depends upon the viscosity
and composition of the lava. Basaltic lava has a low silica content (between
48 and 52 per cent) and can reach temperatures of 1200 °C. As a consequence,
the lava is fluid and any gas bubbles that are formed rise to the surface creating
a gentle, effusive eruption. Earthquakes at constructive boundaries tend to occur
as a result of this volcanic activity. They have shallow foci (0-70 km deep) and are
usually submarine so are of minimal hazard to people.
P
A
Active volcano
A
Recent volcanic eruption
between 1965 and 2015
| Major earthquake zone
Major earthquake
between 1965 and 2015
figure
9.2 Plate boundaries; their directions and current rates of movement
Hazardous environments
destructive (convergent)
plate boundary
oceanic volcanic ridge - new oceanic
crust forms pushing the plates apart
depth (km)
the denser ocean crust descends
and the less dense continental crust
remains on the surface
constructive (divergent)
plate boundary
mantle extends
to 2900 km
Melted asthenosphere flows upward as
magma along the volcanic oceanic ridges
and cools to form new ocean floor/
lithosphere. The new lithosphere moves
away from the ridge on top of the
asthenosphere (sea-floor spreading). Where
the denser oceanic crust meets the older,
the oceanic crust back into the
asthenosphere. The edge of the continental
crust is deformed downwards to form an
ocean trench. The time between the
formation of new oceanic crust and its
melting back into the asthenosphere is
commonly 250 million years.
less dense continental crust, gravity pulls
figure
9.3 Plate tectonics
Convergent plates
When plates move together or converge they create either a collisional or a
destructive boundary. If the plates are both composed of continental crust and
therefore have similar densities they will collide, pushing and compressing
sediments from the ocean floor into young fold mountain chains. For example,
the Indian subcontinent first collided with the Eurasian plate approximately
40 million years ago forming the Himalayas. The focus of the earthquake is the
point inside the crust where pressure is released. Significant seismic events,
which typically have a shallow focus, regularly occur in the Indian subcontinent
and include the 2005 Pakistan and 2011 Sikkim earthquakes.
Where two plates of differing densities converge, the denser of the two will be
subducted below the other. This occurs at continental/oceanic margins where the
denser oceanic plate is subducted below the more buoyant continental plate, but
can also occur at oceanic/oceanic margins where the slightly more dense or faster
moving plate will subduct below the other. Friction builds up between the two
plates during the process and is suddenly released, creating both shallow and deep
focus (300-700 km) earthquakes. The heat generated from the friction also causes
partial melting of the crust. This molten rock (magma) rises up through fissures
(cracks) to form volcanoes. Lava at destructive boundaries has a high silica content
(rhyolite, the most viscous type of lava, is composed of over 70 percent silica) and
relatively low temperatures (approximately 600-900 °C). As a consequence this
lava is viscous and gas bubbles, which do not escape easily, build to create highly
explosive eruptions. Lava at destructive boundaries where oceanic and oceanic
plates converge is basic. Approximately 80 per cent of the world’s active volcanoes
occur on destructive boundaries with about three quarters of these, including Mt St
Helens (USA) and Nevado del Ruiz (Colombia), lying on the Pacific ‘Ring of Fire’.
Conservative boundaries
Subduction does not occur at conservative margins and so these are not associated
with active volcanism. However, as two parallel plates move past each other- either in
different directions or in the same direction but at different speeds - friction builds.
210 Hazardous environments
figure
9.4 Conservative plate boundaries in the San Francisco area.
figure
9.5 San Andreas fault, California, USA
figure
9.6 Hawaiian-Emperor seamount chain
figure
9.7 Hot spot volcano cross section
The subsequent release of this energy creates frequent, shallow focus earthquake
events such as the 1989 Loma Prieta earthquake on the San Andreas fault.
Hot spots
Not all volcanic activity occurs at plate boundaries. The Hawaiian Islands, which
can be found over 3000 km from the nearest plate boundary, are a series of
volcanic islands that vary in age and stretch north-west in an arc across the central
Pacific Ocean. It is thought by some geologists that a mantle plume, or ‘hot spot’,
rises from the mantle here. The overlying plate moves slowly across this plume
with volcanoes erupting when they are over the heat source. As the plate continues
on its journey these volcanoes move away from the heat source and become
extinct. The main island of Hawaii is over the hot spot at this moment in time; it
consists of five currently active volcanoes including Mauna Loa and Kilauea.
Earthquakes and resultant hazards
Seismic waves radiate outwards from the focus. There are four types of
seismic waves which travel at different speeds and which can be detected by
seismometers. Waves that travel through the earth are known as body waves and
include P (Primary) waves, which can travel through both solids and liquids at
5.5 km per second, and slower S (Secondary) waves, which can only travel through
solids. Love and Rayleigh waves are surface waves that travel more slowly. The
shaking of the ground caused by these seismic waves and the surface faulting
that occurs are the primary hazards of earthquakes. Surface waves are responsible
for most damage to buildings and structures, which present the greatest hazard
to humans given that buildings can collapse and injure or kill their occupants.
Underground pipes and power cables may also be ruptured resulting in fires
and explosions and infrastructure such as road networks may be seriously
affected. In the 1989 Loma Prieta earthquake about 98 per cent of the economic
losses were as a result of ground shaking and two-thirds of the deaths occurred
when part of the Nimitz Freeway collapsed. Aftershocks, which tend to be of
a lower magnitude than the main tremor but last for longer and occur more
frequently, can sometimes cause more damage than the original quake due to the
fact that structures are already weakened. For example, the 7.1 magnitude Darfield
earthquake occurred near Christchurch, New Zealand, on 4 September 2010 and
injured over 100 people. Whilst there were over 9000 recorded aftershocks which
lasted until early January 2012 the strongest and most devastating occurred on
22 February 2011. This was a magnitude 6.3 event but, due to the fact that the
epicentre was located close to the city of Christchurch and structures had been
weakened by previous shocks, it resulted in the deaths of 185 people.
Hazardous environments 211
earthquake starts tsunami
figure
figure
tsunami
waves spread
9.8 How tsunamis are triggered
9.9 Liquefaction
Secondary hazards (caused by primary hazards) include liquefaction, landslides,
mudflows and tsunamis. Liquefaction occurs where the shaking of the ground
causes unconsolidated and saturated sediments to act as liquids. Building
foundations, underground pipes and sewerage systems can all be destroyed or
severely damaged as they subside. The shaking of the ground can also result in
landslides, rockfalls, mudflows and avalanches on even gentle slopes. The 2010
Chile earthquake had a magnitude of 8.8 and triggered landslides which caused
the loss of approximately 9 per cent of homes in the affected region and over 500
deaths. It also activated a tsunami causing warnings to be issued in 53 countries.
Whilst the tsunami caused localised damage, it also travelled over 17 000 km to the
coast of Tohoku, Japan, where over US$66 million of damage to the fish industry
was recorded. Tsunamis are a result of the vertical movement of the sea floor and,
whilst they can be triggered by volcanic activity and landslides, the majority occur
as a result of seismic activity. Not every earthquake will trigger a tsunami; most
require a magnitude of at least 6.5 and a relatively shallow focus of 50 km or less.
Around 90 per cent of tsunami occur in the Pacific Basin and over a third are
generated in the deep sea trenches off the coast of Japan, South America and the
Aleutian Islands. Perhaps the most devastating tsunami in recent memory is the
Boxing Day tsunami of 2004, which was triggered by a 9.2 magnitude earthquake
off the western coast of northern Sumatra. The Boxing Day tsunami hit 14 different
countries and affected over 5 million people. The 2011 Tohoku earthquake and
tsunami that occurred off the coast ofJapan was also devastating, causing nearly
16 000 deaths and triggering a meltdown of the Fukushima nuclear power plant.
Volcanic hazards; types of eruption and their products
The shape, nature of eruption and hazards presented by volcanoes depend
largely on the viscosity and silica content of their lava. Therefore, very hot
runny lava with a low silica content produces gently sloping shield volcanoes
with associated effusive Hawaiian eruptions, whilst cooler viscous lava with a
high silica content produces steep-sided cone volcanoes with explosive Plinian
eruptions. The strength of a volcano’s eruption is measured by the Volcanic
Explosivity Index (VEI) and is dependent upon the amount of material ejected
in the explosion, the height of the ash cloud and the resultant damage. Typically
effusive Hawaiian eruptions have a low VEI of o or 1, whilst more explosive
Plinian eruptions have a higher VEI of 5 or above.
212 Hazardous environments
Effusive eruptions pose a limited hazard to people; they are usually
associated with lava flows that are spectacular but tend to pose more of a threat
to property than human life. Explosive eruptions, on the other hand, are much
more unpredictable and violent and therefore hazardous. The primary and
secondary hazards associated with volcanic activity are summarised in Table 9.1.
table
9.1 Hazards associated with volcanic activity
Primary (direct) hazards
Secondary (indirect) hazards
Pyroclastic flows (nuees ardentes)
Atmospheric ash fallout
Volcanic bombs (projectiles)
Volcanic landslides
Lava flows
Tsunamis
Ash and tephra fallout
Acid rainfall
Volcanic gases
Lahars (mudflows)
Earthquakes
Jökulhlaups (glacier bursts)
Primary hazards
Pyroclastic flows (sometimes known as nuees ardentes) are mixtures
of hot rock fragments, lava, ash and hot gases that can surge downhill,
reaching speeds of 700 km/h. They are often accompanied by ash
(<2 mm diameter) and tephra (>2 mm diameter) particles that are
created by the explosion of magma or the fragmentation of solid rocks.
figure
9.10 Pyroclastic flow, Soufriere Hills volcano,
Montserrat, Caribbean.
The low-viscosity basaltic magma
results in the easy release of gases.
The eruption is non-violent.
Low-angle volcanic domes or lava
plateaux are the result, e.g. Hawaiian
islandsand Icelandic volcanoes.
(b) Andesitic magma
plume penetrates into the troposphere
The high-eruption columns spread gases
over large distances. As the eruption
wanes there may be collapse of lava
columns and resulting pyroclastic flows
and surges. The eruption of Mount
Pinatuboin 1991 sent a plume oftephra
30 km high into the atmosphere.
(c) Rhyolitic magma
eruption through a
weakness in the flank
of the volcano
dome of solid lava
blocks vertical eruption
the magma fragments
into pyroclastic
materials and gases
figure
lateral blast of great force
The lava dome blocks the volcano so
that the eruption is sudden and violent
through a weakness in the side of the
volcano or in some cases the top to
produce a summit crater called a
caldera. Examples include Mount
Pele, Mount St Helens and Krakatoa.
9.11 (a)-(c) classifications of volcanic eruptions
Hazardous environments
The smallest particles can be ejected into the stratosphere (20-50 km up
into the atmosphere) and can alter global climate patterns, cause breathing
difficulties, cause poorly built houses to collapse or present a hazard to aircraft.
Eyjafjallajokull, a Strombolian Icelandic volcano, erupted in 2010 covering large
areas of northern Europe with ash. As a result 20 countries closed their airspace
to commercial air traffic, disrupting the journeys of over 10 million travellers.
FIGURE 9.12 Ash cloud
figure
9.13 Lahar
Secondary hazards
Lahars or mudflows represent the second greatest volcanic hazard, after
pyroclastic flow. They are caused when volcanic material mixes with water and
then moves rapidly (over 60 km/h) over long distances. Lahars can be triggered
by volcanic landslides. The source of the water can be heavy rainfall, the collapse
of a crater lake or the rapid melting of snow or a glacier (jökulhlaup). This
means that people living in tropical regions such as Indonesia and in glaciated
environments such as Iceland can be particularly susceptible to lahars.
Primary and secondary impacts on lives and property
The effects on lives and property of tectonic hazards can be mitigated by either
modifying the event (by attempting to control lava flows with water sprays
or artificial barriers) or vulnerability (by building earthquake-proof buildings,
carrying out earthquake drills or evacuating residents from high risk volcanic
zones). Clearly, the areas that are most vulnerable and have the highest
number of deaths tend to be the poorer regions of the world although more
industrialised regions tend to suffer economically.
Nyiragongo is a stratovolcano located in the East Africa rift valley on the
border between the Democratic Republic of the Congo and Rwanda. Formed at
a divergent boundary, its lava is low in silica and therefore flows rapidly posing a
danger to life and property. It also emits toxic gases such as sulfur dioxide at a rate
of up to 50 000 tonnes per day, which has the potential to affect human health
and natural environments. Nyiragongo is unusual in that it also has a 500 m
deep lava lake in its crater that can be rapidly drained when cracks appear in its
flanks. In 2002 lava drained from the crater and flows 50 m across and 6 m deep
covered the nearby city of Goma. In total 147 people were killed, mainly from
carbon dioxide asphyxiation and building collapse, and over 120 000 people
were made homeless.
Despite being an effusive eruption, the 2002 event was devastating due to
the Democratic Republic of the Congo’s exposure to the hazard and the people’s
vulnerability. Over half a million people live on the flanks of Africa’s most active
volcano. They are poor and largely depend on subsistence agriculture, 80 per
cent of which was devastated in the eruption. Coupled with this, war has raged
in the area for much of the past decade, which has increased the population’s
vulnerability to the hazard.
Prediction, hazard mapping and monitoring of earthquake and volcanic
hazards and perception of risk
Whilst earthquake and volcanic hazards both present significant risks for
people, volcanic activity in particular can provide significant opportunities. The
attractive scenery encourages tourism, geothermal energy can be generated
and volcanic soils contain minerals that make them some of the most fertile
soils on the planet. It is no wonder that over 500 million people currently choose
to live on or near active volcanoes and that this number is set to grow due to the
dramatic population growth of LICs around the Pacific Basin in particular. Given
the long timescales of the recurrence intervals of volcanic eruptions compared
to relatively short human timescales, many people perceive the benefits of living
next to an active volcano to outweigh the risks. Other factors that may affect an
individual’s perception of risk include their experience (those who have greater
experience of hazards are more likely to adjust to the situation of living in a
hazardous environment), their material well-being and their personality.
Predicting seismic activity is notoriously difficult and there is no current
method of reliable earthquake prediction. However China is developing a
network of Seismo-Electromagnetic Satellites (CSES) as part of their earthquake
Hazardous environments
figure
9.14 Geothermal energy generation
monitoring network. Strong seismic activity can cause anomalies in the Earth’s
atmosphere and magnetic field, which has the potential to be detected by
satellites. Indeed, two days before Japan’s March 2011 earthquake, Chinese
researchers detected abnormal electromagnetic signals in the area using ground
based systems. Given that predicting seismic activity remains a challenge, most
research is concerned with hazard mitigation by assessing the earthquake
hazard and the vulnerability of the population. Volcanoes are easier to predict
as physical changes occur that can be monitored. For example, GPS can be
used to monitor the swell of the surface of the volcano, chemical sensors can
monitor increased sulfur levels and seismometers can be used to record the low
magnitude earthquakes that occur as the magma rises.
Hazards resulting from mass movement
Mass movement and resultant hazards: nature and causes
Mass movement is the movement of surface material due to gravity that occurs
either as a result of natural and/or human activity. These geomorphological
hazards can be classified according to their speed or type of movement; for
example falls, flows, slides and slumps.
The likelihood of a slope failing is a combination of the strength of the
slope and the force that is acting upon it. Most of the time there is a balance
between the stick and the slide forces, however, if this balance is upset by
either increasing shear stress or decreasing the shear strength, then mass
movement will occur. Decreasing the shear strength by increasing the
amount of water in the slope materials is the most common cause of mass
movements. Saturation reduces internal cohesion and friction, increases
pore-water pressure and adds weight to the slope, which is often enough to
figure
9.15 Types of mass movement.
Hazardous environments 215
tall heavy trees add weight to the
slope and may impose high lateral
stresses in strong winds
irrigation of lawns may cause
higher water tables .
slope fill used to create a flat surface
may become saturated with water if
the air spaces have not been
\
squeezed out
vegetation clearance may promote
development of shrinkage cracks
in clayey soils and lead to
increased infiltration of runoff
toe support removed
by excavation
\
downpipe directing
run off from roof into
ground
building adds
weight to slope
increased
weight of‘fill1
on the slope
y ’
infiltration from
effluent irrigation
field
water enters movement
cracks as they open up
rise in groundwater table results
in increased porewater pressure
and reduction in shear strength
on potential failure sürfece
leakage from
underground services
increase in saturation in the unsaturated
zone above the groundwater table
resulting in a reduction in soil cohesion
fluvial erosion may
result in local slumping
and oversteepening of
slope base
\
high groundwater table following
period of prolonged rainfall
relatively low groundwater
table during dry season
percolating water reduces
internal cohesion
figure
soil rock interface or upper
surface of stronger material
9.16 Factors detrimental to the slope stability of a building site.
trigger an event. In addition, removal of overlying material or vegetation can
decompress and loosen sediments. This, combined with natural weathering
processes and the burrowing of animals, can open up cracks that cause the
porosity to increase and allow more water to enter. Increasing the angle of the
slope, particularly at the base, adding weight to the slope through saturation
or building, or shocks from earthquakes can increase the shear stress,
contributing to the likelihood of mass movement.
On 31 January 2015 a landslip at the Harbury cutting between Banbury and
Leamington Spa in the UK caused significant disruption to the Birmingham
to London rail network. This cutting is one of the deepest and steepest in the
country and, until 2006, was heavily forested. Since then, most of the trees
have been removed, which, at first glance, appears to have been the main
cause of the landslip. However, the slope had also been reprofiled to increase
stability and drains installed to reduce saturation; both of these factors suggest
effective management of the slope to reduce the likelihood of failure. It could
also be argued that the removal of the trees was necessary given that large tree
roots can perforate drainage systems, which focuses water at specific points
and makes the slope more vulnerable. Whilst the argument is that poor slope
management is increasing the frequency and severity of mass movement
events, it appears that in the case of the Harbury cutting the situation is
complex and probably not a straightforward consequence of deforestation.
Impacts on lives and property
Whilst mass movement events account for relatively few deaths compared
to other hazards such as earthquakes, flooding and tropical cyclones, they
do account for huge financial losses as a result of damage to buildings and
infrastructure. Since 2000 there have been 12 mass movement events, which
have killed 50 or more people. The most devastating of these occurred in
Kedarnath, India, on 16 June 2013 and was a direct result of the monsoon rains
and the subsequent melting of the Chorabari glacier. An estimated 5748 people
were killed in the flash flooding and landslides that resulted and over 110 000
people were evacuated. Unsurprisingly, these high magnitude, low frequency
events are associated with the unstable steep slopes found on fold mountain
belts such as the Himalayas, the Alps and the Andes.
Mass movement events are the result of hydrological, geological and
atmospheric interaction. As in the example above, the impacts of the landslide
3
Hazardous environments
cannot be separated from the impacts of the heavy rainfall and flooding. This
makes individual assessment of the significance of a mass movement event
problematic.
Increasingly, human activity plays an important role in determining landslide
activity. Whilst careful management of slopes can reduce the risk of failure,
increased urbanisation, particularly in less industrialised areas, has made urban
areas more vulnerable. The development of shanty towns on marginal, steep
and often unstable slopes puts large numbers of people at risk. For example,
official census data suggests that nearly 70 000 people live in Rochinha, the
largest hillside slum in Rio de Janeiro, although unofficial estimates put the
population between 150 000 and 300 000. Part of Rochinha is built on a former
landfill site, which makes the residents highly vulnerable to mass movement
events; in April 2010 over 200 people were killed when higher than average
rainfall saturated the already unstable slopes.
On 13 November 1985 Nevado del Ruiz, a stratovolcano in Colombia, erupted
after nearly 70 years of dormancy. Pyroclastic flows melted the mountain’s
glaciers sending four lahars down the slopes at 50 km/hour. As the lahars
reached the river valleys at the bottom of the mountain they gained in speed,
engulfing the town of Armero. Out of the town’s 29 000 inhabitants, 20 000
were killed and casualties in other towns increased the death toll to 23 000.
Some 5000 people were injured and 5000 homes in 13 villages were destroyed
resulting in over 20 000 refugees. The damages were estimated at US$7 billion,
which equates to about one-fifth of Colombia’s GDP.
Relief efforts were hampered by the soft mud, which was difficult to move
through and up to 4.5 m deep in places. Several of the highways connecting
Armero had been destroyed by the lahars, which meant that it took 12 hours for
the first survivors to be rescued. The main hospital in the town was destroyed,
so survivors were airlifted to makeshift emergency clinics set up in nearby
towns. It was difficult to get antibiotics to all of these clinics and over 150 people
in the clinics died due to infections.
figure
9.19 Glacier at the summit of Nevado del Ruiz
figure
figure
9.18 Rochinha shantytown, Rio de Janeiro, Brazil
9.20 The direction taken by the mudflows after the 1985 eruption.
Hazardous environments
The government was criticised because although a detailed hazard map
was published in the month before the eruption it was poorly distributed and
highlighted pyroclastic flows as the main hazard rather than lahars. Following the
disaster the Colombian government set up the Directorate for Disaster Prevention
and Preparedness to prevent such devastating mass movement events in the
future. This has inspired a warning system for Mount Rainier, an active volcano in
Washington state, USA, which has a similar potential for lahars.
Due to climate change, the glacier on top of Nevado del Ruiz has retreated
dramatically. Nevertheless, melting of only 10 per cent of the glacier by another
eruption could produce lahars with a volume similar to those seen in 1985. Over
500 000 people currently live in the surrounding valleys and their lives would be
at risk should another event of similar magnitude occur.
Prediction hazard mapping, monitoring of the hazard and perceptions of risk
The short-term prediction of mass movement hazards is difficult due to the
fact that the triggers themselves are usually difficult to predict. For example,
landslides are often triggered by earthquakes and volcanoes where the
problems of prediction have already been discussed. Hydrologic triggers, such
as prolonged and heavy rainfall, are easier to forecast but it is difficult to know
which slopes are likely to be affected or exactly when the landslide will occur.
Having said that, the United States Geological Survey (USGS) has published a
series of warning signs that may be observed shortly before a mass movement
event. These include leaning telegraph poles, new cracks or bulges in the ground
and springs occurring in ground that has not previously been wet. Scientific
monitoring can also take place with instruments being used to measure ground
deformation, the expansion of fissures and groundwater pressure.
In the longer term, mass movement events tend to leave distinctive deposits
and geological scars in the landscape and so it is possible to create hazard maps
that show the areas most likely to be at risk. These maps are available for most
parts of the world but are expensive and require technical expertise to produce.
They can be used by planners to make decisions about construction policies or
to determine how slopes at risk can be stabilised. However, in places where the
pressure for urban development is high, the short-term demand for housing
may outweigh the longer-term risk of a mass movement event occurring.
In 2012 researchers investigated the perception of landslide risk in Italy.
They found that people in Italy were more concerned about technological risks
(environmental pollution, car accidents) than natural risks. Of the natural risks,
they were most concerned about earthquakes, followed by floods, landslides and
volcanic eruptions. Geographically, people’s perceptions of risk were influenced
by recent landslide events; for example, in Calabria the perception of landslide
figure
218 Hazardous environments
9.21 Rates of ground deformation or the presence ofcracks can be monitored.
risk was very high but the risk to life and property was moderate. Researchers
attributed this to the number of non-fatal landslides that have occurred in
Calabria in the recent past.
Hazards resulting from atmospheric disturbances
The distribution of tropical cyclones, hurricanes and typhoons
Tropical cyclones, hurricanes and typhoons develop as low pressure systems
over warm tropical oceans. They are large (200-650 km in diameter) storms
with wind speeds that exceed 120 km/hr. Local names for these phenomena
vary with tropical storms being named hurricanes, cyclones and typhoons in
theCaribbean, Indian Ocean and Southeast Asia respectively. Globally, the
spatial distribution of tropical storms is not even; they occur seasonally when
the conditions for their formation are optimum. About 80 per cent of tropical
storms occur around the Intertropical Convergence Zone (ITCZ)- the zone
where two Hadley Cells meet-which meanders between 50 and 150 north and
south of the equator. About half of all storms occur in the Pacific Ocean with
most of these developing off the coast of Japan. Other significant areas of
formation include the seas surrounding Australia (about 20 per cent) and the
Caribbean (about 11 per cent). Tropical storms also vary temporally; the Atlantic
hurricane season is from ijune to 30 November and 97 per cent of hurricanes
occur between these dates. Interestingly, whilst 1 June has been fixed as the start
of the season for decades, the end date has slowly shifted from 31 October to 15
November and finally to 30 November, which is its current position.
Saffir-Simpson Hurricane Scale:
hurricane
category 1
figure
9.22
hurricane
category 2
hurricane
category 3
Distribution of tropical cyclones, 1945-2006
The distribution of tornadoes
Tornadoes are violent atmospheric storms that are usually more intense than
tropical cyclones but much smaller and short-lived. As a consequence they cover
a smaller area than tropical cyclones and relatively little is known about them
in terms of their structure and formation. They are funnels of cloud with winds
Hazardous environments 219
Washington
Maine
Montana
North Dakota
innesota_
O rego i
Idaho
South Dakota
'
New York ■
Wisconsin,/ f
K
_
Michigan
-Rhode Island
Wyoming
,
Nebra:
Nevada
Ohio
Utah
Hampshire
jyiassach u setts
Pennsylvania ' .New Connecticut
_
Jersey
'.Delaware
Illinois
'irgini;
Colorado
California
Missoui
The Enchanced Fujita
Nortl
Caroli i
lahoma
Arizona
isas
irolina
New Mexico
(EF) scale rates the
strength of tornadoes.
The six categories for
the EF scale are listed
below, in order of
increasing intensity.
Number of recorded EF3, EF4 and
Louisiana
EF5 tornadoes per 2470 square miles
Florid;
The wind speeds are
estimated.
EF5 >322 km/h
EF4 267-322 km/h
EF3 218-266 km/h
EF2 178-217 km/h
11-15
5-10
1-4
EFl 138-177 km/h
EFO 105-137 km/h
2470 sq miles is approximately 6397 sq km
figure
9.23
The distribution of tornadoes in the USA from 1950 to 2006.
that exceed 100 m/sec. To be categorised as a tornado they must be in contact
with both the ground and the base of the cumulonimbus clouds from which
they descend. Whilst tornadoes have been observed on every continent, with the
exception of Antarctica, they tend to be found in mid-latitude regions given that
their formation is dependent upon the interaction of contrasting air masses.
However they can also develop from cumulonimbus cloud development around
tropical storms. Around 80 per cent of all recorded tornadoes occur in the USA
with the Great Plains (Oklahoma, Texas and Kansas) having the highest global
frequency of over five tornadoes per year and being named ‘Tornado Alley’.
Tornadoes also vary seasonally, typically occurring in temperate continental
interiors in spring and early summer.
Processes causing the development of cyclones, hurricanes, typhoons
and tornadoes
How do tropical storms form?
Tropical storms need a number of conditions in order to form and develop.
Sea temperatures need to be warm (over 27 °C) to a depth of 60 m, as the
heat given off during condensation provides the energy that drives the storm.
Coupled with this, the low pressure system needs to be far enough away from
the equator that the Coriolis Force (the rotation of the Earth) causes enough
spin in the rising air mass. It needs to be approximately 5-150 north or south of
the equator as if it is too close to the equator there will not be enough rotation
and so the tropical storm will not develop. Conditions also need to be unstable
with a high humidity. There also need to be weak winds active in the upper
troposphere which are strong enough to transport the excess heat away from
the storm but not so strong that the top of the storm system is removed. Given
these very specific conditions it is unsurprising that only about 10 per cent of
tropical disturbances develop into tropical storms.
Typically, tropical storms last several days with the fully developed storm
lasting between two and three days. The storm is self-sustaining provided there
is a supply of latent heat and moisture to give the storm energy. Several factors
can cause storm decay including its movement into colder oceans or land,
which removes the source of heat and/or moisture.
220 Hazardous environments
A fully mature tropical storm has a distinctive cross section with the eye being
central. This area is typically between 5 and 50 km in diameter and is characterised
by the low wind speeds and clear skies associated with the subsidence of air
and adiabatic warming (warming that occurs to a parcel of air without a transfer
of heat to the surrounding air). Either side of the eye is the eye wall, a tower
of cumulonimbus clouds that is formed as a result of intense convection. This
releases the latent heat, which drives the storm and is associated with high winds
(120 km/hr) and torrential rainfall (500 mm in 24 hours). In the outer regions
bands of rising air cause clouds to form, which bring heavy rainfall; there may be
up to six of these cells within the storm structure.
cirrus outflow
descending dry air
warming by adiabatic
compression
high-level
anticyclonic
outflow
cirrus canopy
cirrostratus
deep cumulonimbus
warm
core
altostratus and altocumulus
rapid updraughts
of moist air
cumulus and cumulonimbus cloud
bands spiralling inwards
excessive
turbulence
and violent
winds
calm eye
1
outer
convective
band
4
vertical development
10 000 m -15 000 m
figure
9.24
spiralling rain bands
940 mb
torrential
rain
very high
evaporation
rates
960 mb
converging
warm air
cyclonic
surface flow
980 mb
1000 mb
surface
temperature 27 °C
The structure of a tropical storm.
How do tornadoes form?
Tornadoes require four conditions for their formation; moisture, instability, wind
flow and uplift, all of which tend to occur in mid-latitudes. Here, warm, moist,
tropical air from the equator meets cold, dry air from the poles. They rotate
cyclonically- anticlockwise in the northern hemisphere and clockwise in the
southern hemisphere-due to the Coriolis Force. The most destructive tornadoes
develop from a type of thunderstorm known as supercells. Supercells contain
mesocyclones - low pressure rotations that occur a few miles into the atmosphere.
Tornadoes are typically short-lived, lasting anything from an hour to just a
few seconds. The main parent cloud is capable of spawning a number of smaller
vortices that move with the parent, often twisting across the ground beneath.
Once the tornado comes in contact with the ground it begins to decay and so
may only track a few kilometres (although there have been examples of tornado
tracks extending for hundreds of kilometres).
Hazards from large scale atmospheric disturbances and related dangers
Tropical storms and tornadoes cause multiple hazards with loss of life and
property damage occurring from a combination of storm surges, high winds,
heavy rainfall, flooding and mass movement events.
The majority of deaths (over 90 percent) resulting from tropical storms
are caused by storm surges. As storm surges hit land low-lying coastal areas
Hazardous environments
1 Cold air meets warm air
3 The corkscrew
Warm, moist air from the Gulf of Mexico
moving northwards meets fast-moving
cold air (>25 m/s) from the Rockies or
Arctic air from Canada. As the land
mass warms up during the day, the
warm, moist air becomes unstable and
lifts upwards through the cold air to
form a small low-pressure system called
a mesocyclone. Air from the surrounding
area converges into the cyclone centre.
Cumulonimbus cloud development
occurs with the updraughts of warm air
and develops into a thunderstorm. The
different wind speeds and directions
between the warm and cold air masses
result in wind shears vertically through
the atmosphere.
The corkscrew motion develops further
as the warm air rises and the cool air
descends on the outer edge. The fast
jet stream helps to maintain the
updraught by removing air at high levels,
which enables the fast inflow at ground
level. The rotation may be wide at first
(10 km) with a spin of 55 km/hr, but as
the storm develops the rotation
becomes tighter and faster. A supercell
thunderstorm most favours tornado
development. These have one giant
updraught and strong downdraughts.
There will be thunder and lightning,
heavy rainfall and possibly hail.
jet stream
supercell
thunderstorm
warm air
vortex tubes
2 Putting the twist to
The converging air is def ect&Tby’the
Coriolis =orce into a circular path, and
together with the wind shears results
in air spinning upwards through the
storm. At higher levels, the jet stream
must be fast (>65 m/s) to enable wind
shears to develop at high levels so that
the spinning column of air extends
throughout the troposphere.
figure
evelop near to the rear
edge of the thunderstorm where there
are downdraughts of cold air. The most
common position is in the warm air
mass just ahead of the surface-level
cold front.
9.25 Tornado formation
are particularly vulnerable to the waves that are driven by the strong winds. In
2005 Hurricane Katrina produced a storm surge with waves over 8 m high. The
coast of Mississippi was battered and the surge itself was responsible for killing
over 1800 people. In addition, the influx of seawater can cause extensive salt
contamination, which in turn can damage crop production. The impact of storm
surges depends on a number of physical and human variables. These include the
topography of the coast, the wind strength and the height of the tide (physical)
and the land use, population density, vulnerability and preparedness (human).
Heavy rainfall can lead to severe river flooding, can act as a trigger for
mass movement events and, in conjunction with storm surges, lead to coastal
flooding. These secondary hazards are often as destructive, if not more so,
than the primary event. Whilst rainfall amounts are variable, typical figures are
approximately 100 mm per day. Large areas of standing water coupled with
the warm tropical climate can result in water-borne diseases that can induce
epidemics long after the storm has passed. However, the storms sometimes
bring much-needed precipitation to arid regions. For examplejapan receives
over half of its precipitation from typhoon events.
figure
Hazardous environments
9.26 A storm surge
Hazards from small scale disturbances
Strong winds are a particular hazard associated with both tropical storms and
tornadoes. These can reach 320 km/hr and cause structural damage to buildings
and infrastructure. Crops, particularly tree crops, can be destroyed and loose
debris can become lethal projectiles. Strong winds can also destroy power lines,
hampering communication and disrupting rescue efforts.
Pressure surges associated with the reduction in atmospheric pressure within
the body of the storm also result in coastal flooding. When air pressure reduces
by 1 mb, sea level rises by 1 cm. Therefore, in the centre of a deep depression
with a pressure of 960 mb, sea level will be approximately half a metre higher
than normal (if this is taken to be around 1013 mb). The opposite occurs when
pressure rises.
Primary and secondary impacts on life and property
Hurricane Sandy (also known as ‘Superstorm Sandy’) was the deadliest
hurricane in the 2012 Atlantic hurricane season and the second most costly in
history (after Hurricane Katrina in 2005). A total of 233 people were killed in
the eight countries along the hurricane’s path and estimates of the damage
stand at US$68 billion. Jamaica was the first country to be affected by Hurricane
Sandy. Trees and power lines were damaged and shanty houses were damaged
by the strong winds and flooding. Over 100 fishermen were stranded in
Pedro Cays and over 70 per cent of the island was without electricity. Another
country that was badly affected was Haiti, which was still recovering from the
figure
9.27 A tornado
figure
9.28 Houses in the aftermath of Superstorm Sandy.
devastating earthquake which hit the country in 2010 and the subsequent
cholera epidemic which ensued. Approximately 54 people died and 200 000
were left homeless after four days of intense rainfall that put most of the
southern half of the country under water. A month afterwards the cholera
epidemic returned as a direct result of the storm causing a further 44 deaths
and 5000 infections.
figure
9.29 Superstorm Sandy
Hazardous environments
However, the country that was most devastated by the superstorm was
also the most economically developed - the USA. Twenty-four states were
directly affected and people were killed in nine states, including New York
(49 deaths), New Jersey (10 deaths) and Connecticut (three deaths). Nearly
20 000 flights were cancelled between 27 October and 1 November due to
flooding and other storm-related issues. Two days after the storm hit, 6 million
customers were still without electricity, highlighting the fragility of the ageing
American electricity network, which has been compared to that of other
nations such as Slovenia and Portugal. On a more local scale, Kentucky saw
over 30 cm of snow in the eastern part of the state as Sandy merged with the
Arctic front, and over 100 000 homes were damaged in the Long Island area of
New York.
Prediction, monitoring of large and small scale atmospheric disturbances
and perceptions of risk
Prediction of tropical storms
Tropical storm watches and warnings are two levels of alert issued by national
weather forecasting bodies to coastal areas at risk. Tropical storm watches are
issued when wind speeds are likely to reach 63 km/hr within 36 hours. They are
figure
9.30 Weather balloon
224 Hazardous environments
upgraded to warnings when these wind speeds are likely to occur within 24
hours. Hurricane preparedness can become difficult once the tropical storm has
reached maturity- it takes time to alert communities and to evacuate peopleand so watches and warnings are issued in advance.
The National Hurricane Centre (NHC) in Miami, Florida, is one of the world’s
most developed warning systems. Funded by the US government, the centre
uses data from geostationary satellites and ground-based recording stations to
observe developing storms. The data is then fed into computer models based
on previous events and hurricane paths to estimate the likely track and intensity
of the storm event. The track, in particular, is notoriously difficult to predict,
however it is vital that the data is interpreted accurately for warnings to be given
and for lives to be saved. Too many wrong warnings can induce complacency in
the population and can cause massive economic losses as people are evacuated
unnecessarily.
Evacuation of communities at risk has become more time consuming and
complex as population densities around coastal areas have increased. For
example, it took 24 hours for 1 million people to be evacuated before Hurricane
Katrina hit the city of New Orleans in 2005 and it is estimated that Lower Florida
Keys could take over 31 hours to evacuate given that there is a single highway
and the mainland is over 100 km away.
Prediction of tornadoes
Radar and satellite technology are used to monitor atmospheric conditions
although it is not possible to accurately predict the tornado’s location, path or
intensity. However, using these technologies has resulted in the number of
false warnings of tornadoes falling from 73 per cent to 24 per cent. Given that
the majority of tornadoes occur in the USA, the most developed forecasting
and warning system is the US National Severe Storms Laboratory (NSSL).
The laboratory uses data from weather balloons, satellites, aircraft and surface
weather stations to calculate atmospheric conditions and issue warnings.
Areas of the USA that are regularly battered by tornadoes, such as Oklahoma
and Kansas, have a reduced death rate due to these warnings and subsequent
responses to the hazard. Conversely, those areas that do not experience
tornadoes regularly, such as Ohio and Indiana, have higher death rates due to
the perceived lack of threat.
Sustainable management in hazardous environments
The sustainable management of earthquake zones
Whilst data would suggest that the number of earthquakes appears to be
increasing, more seismometers are being installed each year and so this is a
feature of increased recording and reporting rather than increased incidence.
In any given year there are on average 17 earthquakes of magnitude 6 and
above and one earthquake of magnitude 8 and above. However, with rapid
urbanisation occurring in many LICs people are becoming more vulnerable
to earthquake hazards. More than a third of the fastest-growing cities are in
areas at risk of earthquakes and approximately 1.5 million people were killed
by earthquakes during the twentieth century. Most of these deaths were as
a result of the collapse of unsuitably built or poorly designed buildings. For
example, a magnitude 7 earthquake killed 200 000 people in Haiti in 2010
whilst a magnitude 8.8 earthquake in Chile in the same year killed only 700.
The difference between the two events is that buildings in Haiti were erected
quickly whilst Chile adhered to more stringent building codes.
figure
9.32 A portion of a roof that collapsed in the Haiti earthquake in 2010.
Hazardous environments
figure
9.33 The Skytree tower in Tokyo, Japan - an example of an earthquake-proof building. The tower includes a central shaft made of reinforced concrete, and the
outer tower structure is attached to this central core with oil filled dampers.
226 Hazardous environments
Case Study
Managing
the effects of earthquakes in Japan
Essentially, buildings can be modified in two ways; by making them stronger or by
making them more flexible so that they sway with the shaking ground. Japan is one
of the most prepared countries in the world for earthquakes, having learnt lessons
from the 1995 Kobe earthquake that killed 6400 people. A reassessment of building
regulations followed and many structures are now either built or retrofitted with
deep foundations and shock absorbers, which dampen seismic energy. For example,
the 54-storey Roppongi Hills Mori Tower in Tokyo was completed in 2003 and
built with fluid-filled shock absorbers that slosh thick oil in the opposite direction
of swaying. Another method is to implement‘seismic isolation’technologies that
decouple the main building from its basement so that the structures are not affected
by ground tremors. The 18-storey Sendai MT building, which has such technologies
in place, remained undamaged during the magnitude 9 earthquake that hit the
east coast ofJapan in 2011, despite horizontal displacement of about 20 cm. Despite
such earthquake-proof technologies being in place, nearly 20 000 people died in
the 2011 east coast earthquake in Japan; 90 per cent as a result of the tsunami which
followed. The Fukushima nuclear power plant overheated when power lines were cut
as a result of the earthquake and the back-up generators failed to provide power to
the cooling systems. In addition, communication of the severity of the accident was
poor- meaning that the evacuation of 150 000 residents in the town was slow and
many people were exposed to increased levels of radiation.
Japan, as a rich, industrialised nation with a GDP of US$4.92 trillion (2013), has
the capacity to install or retrofit expensive earthquake-proof technologies to make its
people less vulnerable to the earthquake hazard. Many of the people most vulnerable
to earthquakes globally are those living in poverty; how can they afford to live in ‘life
safe’ buildings that cost 5-10 percent more than ordinary buildings to construct?Japan
possibly has the answer here too as, in addition to their technological accomplishments,
they also have a series of simple and inexpensive management responses to the
earthquake hazard. For example, Japanese children take partin monthly earthquake
drills in which an alarm sounds and children are taught to crouch head-first under
their desks to protect them from falling debris. They are also given the opportunity to
visit earthquake simulation machines to familiarise themselves with the experience of
being in an earthquake. As soon as an earthquake strikes Japan, all television and radio
stations switch to official earthquake coverage. This informs the public of the risks,
including tsunami events that often follow, and enable people to evacuate or retreat to
purpose-built tsunami bunkers if they live on the coast In addition, all offices, schools
and many houses have earthquake kits which include hard hats, gloves, drinking water,
basic medical supplies and enough dry rations to last a couple of days.
figure
9.34 Students practice earthquake drill japan
Hazardous environments
Case Study
The sustainable management of volcanic hazards
in Montserrat
Volcanic regions bring agricultural, mining and tourism benefits to communities
and many choose to live with the risk of an eruption. It is therefore important
to mitigate the risk by managing vulnerability, crises and reconstruction whilst
maximising the benefits of living in a volcanic environment This can be done
both pre- and post-eruption and is most successful if carried out by the local
community rather than by outside agencies.
The island of Montserrat in the Caribbean is a good example of a less
industrialised country and British overseas territory that has failed to manage
its volcanic hazard sustainably. The Soufriere Hills volcano erupted in 1997
and much of the southern part of the island, including the capital Plymouth,
was evacuated and became part of the exclusion zone. The population of the
island, which was 11 000 before the eruption, had dropped to less than 4000
by 1999-
figure
228 Hazardous environments
Exclusion Zone
Central Zone
No admittance except for scientific monitoring and National Security Matters
Northern Zone
Area with significantly lower risk, suitable for residential and commercial
occupation
Residential area only, all resident on heightened state of alert
All resident to have rapid means of exit 24 hours per day
Hard hat area all residents to have hard hats and dust masks.
9.35 Montserrat volcano risk map, September, 1997
figure
9.36 The new airport on Montserrat (John A. Osborne Airport).
A decade later and the population had risen to over 8000; people with skills
in construction were needed to rebuild government buildings, primary schools
and housing in the north of the island. However, by 2009 the population
had fallen to just over 5000, a situation which persists in 2015. There are two
main reasons for this. First, the construction jobs, which were plentiful in the
economic boom, disappeared once the buildings had been completed. Whilst
there remain plans to develop a new capital at Little Bay on the northwest tip
of the island, this will not be completed until 2020. Second, once thejohn A.
Osborne airport had been completed near the village of Gerald's in 2005, the
US and UK government stopped subsidising the ferry that had previously been
the only method of getting to the island. This made it difficult for tourists and
importers to get to the island cheaply and so the number of tourists fell and
the price of basic goods on the island rose. Coupled with this, much of the
aid given in the aftermath of the eruption dried up at about the same time.
The UK gave over US$150 million in aid to the island but this was phased out
from 2002.
In the short term, the management of the Montserrat volcano was relatively
successful. Hazard mapping led to the evacuation and resettlement of much
of the population in the north of the island and, as a consequence, only 19
people lost their lives in the 1997 eruption. However, a local approach to living
Hell's Gate
Silver Hill
k403
Litth ST PETER Yellow Hole
Brades O* >Davy Hill
,
John A. Osborne
(de facto capital)O
Airport
>t John'
JZudjoeheao
Baker Hille
Bunkum Bay) >St Peter's
Lawyers
a Mt
392
Trant’s
Katy Hill
.•'-TranV^
Centre Hills
Old Road
-b/smu
Blu" ^%alem
’Bethel
Harris0
Lee's
Cork Hil
'uitt's
EXdLUSICTNJZpNE^
Bransby
Point
TO*’
Chances
914 k
Plymout
ANTHONY prPc/’S'S
(abandoned a
.756
O'Garra's
Old Fort Pt
figure
9.37 Montserrat 2015
Hazardous environments
with risk was not adopted and so long-term problems, including depopulation
and cultural fragmentation, have emerged which might have been prevented
with a more sustainable approach. Despite the implementation of a sustainable
development plan in 2008 (which will run until 2020) and the fact that volcanic
activity within the Soufriere Hills is currently quiet, the volcano continues to
have a dramatic impact on the population of the island.
Case Study
The sustainable management of areas of mass
MOVEMENT IN MALAYSIA
Malaysia is a country in Southeast Asia which is separated into two similar sized
regions by the South China Sea. Heavy seasonal rains and strong winds caused
severe flooding and mass movement on the east coast of Malaysia at the end of
figure
9.38 Angsana tree
INDONESIA
figure
2014 and into 2015. By the end of 2014,21 people had been killed and over 250
000 had been evacuated; Kelantan was the most devastated state with 14 deaths
and 158 000 people being displaced. Much of the flooding that occurred (up to
a depth of 255 mm) and the subsequent mass movement which happened when
the upper slopes became saturated and failed, was as a consequence of heavy
rainfall coupled with deforestation in upland regions.
Due to the fact that deforestation plays an important role in destabilising
slopes in Malaysia, research has taken place in the state of Pahang to assess
the potential of bio-engineering to manage slopes more sustainably. Bundles
of bamboo and brush were positioned along rills and gullies and, at suitable
sites along contours, geo-structures (constructed from materials including
coir and straw) were positioned and held in place using live stakes of angsana
and ubi kayu (species of fast growing tree). After six months, 93 per cent of
angsana and 75 per cent of ubi kayu stakes had sprouted and taken root.
This resulted in the stabilisation of slopes and a decrease in the likelihood of
slope failure as increased vegetation cover reduces the intensity of raindrops
falling on exposed soil and roots bind the soil together to increase its shear
strength.
In addition, increased sediment was trapped by the geo-structures,
providing ideal conditions for seed germination. After six months there were
77 species of plant established and a year after the study was first implemented
around 75 per cent of the bio-engineered land was completely revegetated.
SINGAPORE
9.39 The land masses of Malaysia, which are separated by the South China Sea.
Hazardous environments
Landslides have not occurred on the plots that have been bio-engineered
whereas control plots, which have not been managed, have seen undercutting of
the slope face.
The cost of the geo-structures is relatively low- US$3000 compared to more
conventional structures such as rock gabions, which cost around US$20 000. Also,
as these areas are remote, transportation and labour costs to install rock gabions
would have been prohibitive. The materials that are required to construct the geo­
structures are available locally and are relatively cheap. Coupled with this, the fact
that they are also non-polluting, visually attractive and require minimal maintenance
makes the bio-engineering of slopes a sustainable management solution.
NOW INVESTIGATE
1
Investigate the role of governments in the management of tectonic
hazards.
2
Investigate the effects of a tropical storm in a less industrialised
country of the world.
3
Investigate an example of a country that has successfully managed
volcanic hazards.
Hazardous environments
North America
Europe
desert;/;.
Very severe
12 080 sq km
Slight to none
310 530 sq km
Moderate
273 720 sq km
Population living in Europe’s drylands
Arid - 600 000
Semi-arid - 28 800 000
Dry sub-humid - 115 100 000
26% of total Europe population
Population living in N. America’s drylands
Arid - 12 800 000
Semi-arid - 53 900 000
Dry sub-humid - 24 300 000
22% of total N. America population
Africa
Very severe
74% desertified
Qtytands 13 423 450 sq
52 550 sq km
South America
Population living in S. America’s drylands
Arid - 6 300 000
Semi-arid - 46 900 000
Dry sub-humid - 33 800 000
30% of total S. America population
Semi-arid- 117 600 000
Dry sub-humid - 109 000 000
40% of total Africa population
Aridity Index
(The rate of precipitation to evaporation)
Drylands are defined as having an
aridity index of 0.65 or less
Hyper-arid <0.05
Arid 0.05-0.20
Asia
More than two billion people live in areas of
the world classified as 'drylands' which are
vulnerable to desertification. Drylands can
become degraded by desertification as a result
of climate variations and human activities
76% desertified
Drylands 15 712 400 sq krn
Very severe
IC
Arid and sem i-arid environm ents
Population living in Asia’s drylands
Arid - 161 600 000
Semi-arid - 500 700 000
Dry sub-humid - 657 900 000
Oceania
39% of total Asia population
Very severe
290 000 sq km
Slight to none
2 958 730 sq km
Desertification
Drylands
Slight to no desertification
Moderate desertification
Severe desertification
Very severe desertification
Population living in Oceania's drylands
Arid - 300 000
Semi-arid - 1 400 000
Dry sub-humid - 5 300 000
25% of total Oceania population
Semi-arid 0.20-0.50
Dry sub-humid 0.50-0.65
233
Hot arid and semi-arid environments
Aridity means lack of rain but more technical definitions look at water balance the balance between the input of precipitation and losses due to evaporation
and transpiration by plants. In general, arid areas have less than 250 mm of
precipitation a year while semi-arid areas receive 250-500 mm a year.
About a third of the world’s surface is classed as arid. Figure 10.1 shows the
distribution of the world’s deserts and Figure 10.2 shows annual rainfall across
the world.
figure
10.1 Distribution of the world’s deserts
234 Hot arid and semi-arid environments
Hot arid and semi-arid climates
Causes of aridity
i High pressure
The most important cause of aridity is the sub-tropical high pressure belt
around latitudes 30° north and south of the equator. This is also called the
Intertropical Convergence Zone (ITCZ). High pressure means air is descending
and is caused by the Hadley Cell (Figure 10.3)-air rises in equatorial regions
and descends in the sub-tropics - and the Ferrel Cell - air rising in the mid­
latitudes and descending in the sub-tropics. When air descends it cannot rain
because rain is always caused by air rising and cooling - cooling causes water
vapour to condense into cloud droplets and rain.
Dry trade winds blow out from the sub-tropical high pressure belt. They are
deflected by the spinning of the Earth and carry dry conditions to the western
sides of continents. Because they are moving towards the equator these winds
are getting warmer and this makes them even less likely to produce rain - air
that is warming cannot rain.
figure 10.3 Trade winds blow from the sub-tropical high pressure belt towards the equatorial low
pressure belt but are deflected to their own left by the spinning of the Earth (the Coriolis Force). They
carry dry conditions to the west side of continents.
2 Continentality
Rain falls when winds move from over the sea, where they have picked up
moisture, onto land, which causes the air to rise somewhat. When air rises
it cools, water vapour condenses into cloud droplets and it rains. So coastal
areas with frequent onshore winds are often wet. However, as the winds move
inland they lose their moisture so places a long way from the sea tend to be dry.
The climates of places far from the sea, such as central Asia, have continental
climates so this process is called continentality.
3 Cold ocean currents
İfan ocean current is cold and the land is hot, then air blowing onshore will
always be warmed by the land. Air that is being warmed cannot rain so deserts
result. The Atacama Desert in South America (Figure 10.12) is adjacent to the
cold Peruvian current and is the driest desert in the world.
4 Rain shadows
When winds are forced to rise over a mountain they cool and produce rain.
However, on the lee side of the mountain the air descends. Descending air will
always be getting warmer and thus cannot produce rain. The Patagonian Desert
on the lee side of the Andes in South America is an example.
Hot arid and semi-arid environments
figure
10.4 Inter-annual rain variability. All arid areas have a very variable rainfall total.
Precipitation
By definition, precipitation levels in deserts are low. But there also tends to be
a big difference between one year and the next-there is high inter-annual
variability (Figure 10.4). What is more there are often spells of dry years followed
by spells of wet years. The Great Plains of the USA had a wet spell in the
1920s and many farmers settled there; this was followed by a long spell of dry
conditions in the 1930s, which ruined them. The soil erosion that followed gave
the area the name ‘dust bowl’.
Recurring droughts in East Africa led to crop failure and food shortages in
1984/5, 2006 and 2011. During the 2011 drought 50 000 to 150 000 people were
reported to have died.
Effective precipitation means the percentage of rainfall that becomes
available to plants and crops. Effective precipitation in deserts is low
because of:
•
•
•
•
figure
10.5 Buried machinery in Dallas, South Dakota,
USA, in 1936. The Dust Bowl ecological disaster extended
from Texas into the northern plains and Canada.
236 Hot arid and semi-arid environments
Rainfall intensity: rain often comes in heavy, short-lived storms. This means
that more rain runs off the surface into streams and less soaks into the soil
where it might otherwise be available for plants.
Evaporation: many deserts experience high temperatures with strong winds
so evaporation rates are very high - effective precipitation is less because so
much rain evaporates very quickly.
Seasonality: rain often comes during one season only.
Impermeable surfaces: desert surfaces are self-sealing and so water cannot
sink in; most rain runs off to streams.
Having said this, very high rainfall totals can be experienced in individual
storms- sometimes as much as the normal annual total in one storm. Because
of the rapidity of the runoff, it is dangerous to live in or near dried-up riverbeds
because of flash floods.
Rainfall in deserts is also highly variable spatially- it may rain in one place
but not in another.
If air is sufficiently humid, fog can form. Namibia in southern Africa, for
example, has 200 days of fog a year because the air is cooled by winds blowing
from the cold offshore sea current.
figure
10.6 Dew irrigation in Lanzarote, one of the Spanish-owned Canary Islands off the west coast of Africa. Rainfall totals are low but the onshore winds
are humid and dew forms on the cold igneous rocks at night. Farmers have created shallow bowls and planted vines in the centre of each. The dew drips down
to the root zone of the vines.
If the air is humid, dew can form. Dew is caused by ground radiating heat
back to space at night; the ground becomes cold and cools the air above it.
Water vapour in the cooled air condenses onto rocks as water droplets, which
run into the ground. In the Canary Islands and Israel this dew is directed
towards the root zone of plants where it irrigates them.
Places which are under the influence of the sub-tropical high pressure belt
all year round are going to be dry all year round. But the world’s pressure belts
move north in the northern hemisphere summer, and south in the northern
hemisphere winter. So places towards the equatorial edge of the sub-tropical
high pressure belt will get rain in summer because they will come under the
influence of the equatorial low pressure belt (ITCZ) in this season. In low
pressure air rises, giving rain.
Places towards the polar edge of the sub-tropical high pressure belt will get
rain in winter because they will come under the influence of the mid-latitude
low pressure belt in this season.
There are, therefore, differing degrees of aridity. Some places are dry
all year, some have some seasonal rainfall. Places that receive seasonal
rain will be semi-arid as opposed to completely arid. Some locations
have especially high temperatures, which reduces the effectiveness of the
precipitation.
Temperature
Diurnal variations in temperature
In deserts the sky is often clear (because air is descending and clouds
cannot form). They will therefore be very hot in the day but very cold at night
because, with clear skies, the ground reradiates the heat back into space. So the
temperature difference between day and night is great- this is called the
diurnal range. Diurnal temperature ranges exceeding 40 °C have been recorded
in Death Valley in the USA.
In coastal deserts the sea acts to cool the temperature during the day so
the diurnal range is much less than inland. In coastal Peru the diurnal range is
11 °C, which is about half of that experienced inland.
Seasonal variations in temperature
The further a desert is from the equator, the greater the difference in
temperature between summer and winter. The reason for this is that places
nearer the equator do not have clear seasons. Deserts further from the
Hot arid and semi-arid environments
equator have cold winters; this is especially true of central Asia but other cold
deserts are Patagonia and northern parts of the North American deserts.
The further a desert is inland, the greater the difference in temperature
between summer and winter. This is because the sea is colder than the land
in summer and lowers the temperatures of coastal places nearby and is
warmer than the land in winter, raising the temperature of coastal areas.
High wind energy
Deserts lack vegetation so winds are uninterrupted and can be especially strong.
Hot winds blowout of deserts because of the high pressure. So, for example,
the Sirocco wind blows north out of the Sahara bringing hot and dry conditions
figure
to France and Italy.
The ground in deserts gets hot during the day (with a maximum temperature
around 3:00 p.m.) and heats the air above it. Hot air is less dense than cooler
air and will rise - a process called convection. The Coriolis Force caused by the
spinning Earth throws the rising air into a spiral and creates a short-lived but
powerful spinning vortex of air called a dust devil.
Larger-scale dust storms are caused by frontal systems where warm and
cooler air have clashed. Cold air is forced up over the warmer air and winds
rotate due to the Coriolis Force. The Sahara Desert is a key source of dust
storms, particularly the Bodele Depression on the edge of Chad where dust
storms occur on average 100 days a year.
10.7 A dust devil in East Africa.
So what is the difference between arid and semi-arid areas?
Arid areas have less than 250 mm of precipitation a year while semi-arid areas
receive 250-500 mm a year. Semi-arid areas are on the edges of arid areas and
they are a transition zone between a dry and wet zone.
Arid areas only attract farmers when there are rivers which were formed
outside the dry zone in a wetter climate and can be used for irrigation, like
the River Nile in Egypt. Semi-arid areas may be suitable for livestock grazing,
especially during a wet spell. In other respects the climates of arid and semi-arid
areas have similar characteristics.
The world’s main deserts
Sahara, Arabia, Pakistan and India
The world’s main deserts are caused by the sub-tropical high pressure belt.
Places in the west are also affected by the cold Canaries current moving down
from the Arctic-the cold air cannot rain because it warms up as it moves inland.
figure
As one moves east, further from the sea, the climate becomes more
continental - hotter in summer, slightly cooler in winter and drier.
10.8 (a) Climate graphs for locations at the
west and east of the Sahara Desert
Caspian*1^
ATLANTIC
OCEAN
j J.
MOROCCO
%
e«n Sea
TUNISIA
'SfRIA
LEBAN0^oS?
IRAN
IRAQ
ALGERIA
,.r Tjarfatra
'
' /WESTERnI
/
"'K
p
Hoggar
SAHARA I
r
Libyan
Desert
S a h
LIBYA
C3*ro
Sinai
PAKISTAN
SAUDI BAH|
EGYPT
QA17
S < QThar
ran - \Desert
INDIA
ARABIA
t^lJbiah^
Desert »
i
MAURITANIA
CHAD
MALI
NIGER
Bodbtb
Arabian
Desert
SUDAN
Arabian
Sea
Lake
\Chad
FASO
2] Sahel area
—► Ocean current
NIGERIA
itta/rttwfd
Wind
figure
10.8 (b)The locations of the Sahara, Arabian and Thar deserts.
238 Hot arid and semi-arid environments
ETHIOPIA
INDIAN
OCEAN
Hot winds blow out of the Sahara, such as the Sirocco to the north and
Harmattan to the south.
The southern edge of the Sahara Desert is called the Sahel zone - a hot, dry
region which has suffered periodic droughts and famines over the past 50 years.
Lake Chad has shrunk considerably since the 1960s, when it had an area of more
than 26 000 sq km, to less than 1500 sq km as a result of water extraction by the
local populations and climatic drought.
There are two great exogenous rivers (they form outside the region but
flow through it): the River Nile in Sudan and Egypt and the River Indus in
Pakistan.
Southern Africa
The southern Africa deserts are caused by the sub-tropical high pressure belt
and the cold Benguela current flowing offshore. The Namib is the coastal
desert, the Kalahari is inland. Humidity is high in the coastal Namib and fog is
common. The cold coastal current also lowers the summer temperatures in the
Namib so that the annual temperature range is only 6 °C.
figure
10.9 Kalahari and Namib deserts
North America
These deserts, where so many cowboy films have been shot, occupy much of
Mexico and the south-west of the United States. They have three causes:
•
•
•
the sub-tropical high pressure belt
the cold Californian current blowing offshore
the Rocky Mountains, which create a rain shadow in the east.
figure
10.10 Deserts of North America
Hot arid and semi-arid environments 239
South America
The Atacama Desert is caused by the cold Peruvian current flowing offshore.
Humidity is often high and fogs are common. In the period June to October a
low cloud forms in the coastal Peruvian desert and this supports vegetation on
hills near the coast.
The Patagonian Desert is caused by the fact that weather systems move west
to east and Patagonia is in the rain shadow of the Andes Mountains.
figure lo.ıı The Atacama Desert is the driest desert in
the world.
figure
figure
10.12 (b) Climate graph for a location in the southern
Patagonia Desert
240 Hot arid and semi-arid environments
figure
10.12(a) Deserts of South America
10.12(c)The rain shadow over the Patagonian Desert
Central Asia
These deserts are caused by the fact that they are a long way inland
(continentality) and in the rain shadow of the Himalayan Mountains
(Figure 10.13). They also experience high pressure in winter and in this season
they are extremely cold - partly because of their latitude, partly because of
high altitude, and partly because of their distance from the warming influence
of the sea. For this reason most of the Central Asian deserts are often
classified as cold or mid-latitude deserts.
figure
10.13 (a) Inland deserts of Central Asia
figure 10.13 (b) Climate graph for a location in
the Gobi Desert
Australia
These deserts are caused by the sub-tropical high pressure belt and, on the
west coast, by a cold ocean current. The eastern mountain range (the Great
Dividing Range) also acts as a barrier to the south-easterly trade winds
and creates a rain shadow effect that accentuates the aridity of central Australia.
figure
10.14 Deserts of Australia
Hot arid and semi-arid environments
Landforms of hot arid and semi-arid environments
Weathering
Weathering is the break-up of rocks. In arid areas weathering tends to be
superficial-confined to the surface - because there is little water. In wetter climates
chemical weathering using water will weather rocks someway below the surface.
Weathering in deserts is also quite selective. Rocks are more likely to be
weathered if they occasionally get wet due to fog, dew or rain, or if the rock is
itself weak because of fissures or joints. So semi-arid areas experience more
weathering than arid areas because they are wetter.
figure
10.15 Exfoliated stones
1 Thermal fracture
Thermal fracture is the break-up of rock caused by heat. Heating and cooling
is a powerful force in arid areas because of the big diurnal temperature range.
The rock expands and contracts with the heating and cooling and this creates
cracks in the rock. If different minerals in the rock have different coefficients of
expansion (expand by different amounts) this too will cause stress and make the
rock break up.
Rocks do not conduct heat well so during the day there is a big contrast
between the temperature of the surface of the rock and layers a bit below
the surface. The surface of the rock expands and breaks away from the inner
layer- a process called exfoliation (Figure 10.15).
Rocks become much hotter than the air- in the Sahara Desert when the
air temperature is 40 °C the temperature of rocks can reach 80 °C. The break-up
of large blocks of rock into smaller blocks is called block disintegration. The
break-up of rocks into fine particles is called granular disintegration.
Insolation weathering (heating and cooling) is much more effective if there is
moisture trapped in rock pores because water expands when heated.
2 Freeze-thaw
There are several deserts at high altitude where the temperature falls below
freezing, such as the Gobi. Water in the pores or cracks of the rock expands
when it is frozen and this can shatter the rock.
3 Salt weathering
Salt accumulates in arid environments for a number of reasons:
• Rocks with salts already in them are chemically weathered, increasing the
amount of salt in the environment.
• Rainwater has salts in it; the water evaporates to leave the salts as a
•
•
•
•
deposit.
Groundwater (water in rocks under the ground) can be drawn up to the
surface by capillary migration: water at the surface evaporates and this
draws up more water from depths that can exceed 3 m. When this water
evaporates at the surface it leaves salts.
Salt left behind as the remains of former lakes or seas.
In sabkhas - coastal salt flats subject to occasional flooding by the sea.
Enclosed (endorheic) drainage basins-rivers that flow into a large basin
and evaporate, leaving salt.
So arid environments have a lot of salts in them and these salts are carried
by water into the pores and cracks of rocks. Here salt crystals grow (salt
crystallisation) and start to break up the rock. Salt crystals can absorb water (a
process called hydration) and this makes them grow, adding pressure. Heating
during the day also causes salt crystals to expand.
4 Chemical weathering
Chemical weathering is the break-up of rocks by chemical changes to their minerals.
It is most likely to occur where moisture is available. Oxidation, for example, is when
irons in rocks take up additional oxygen and turn to rust. Hydration is when a rock
like calcium sulphate takes up water and expands. Chemical weathering is limited
in arid areas because of the lack of water. Where it is found it is slow and limited to
areas that experience dew, fog or occasional rainfall.
Hot arid and semi-arid environments
Erosion and deposition by wind
Wind erosion is powerful in deserts because:
• the surfaces lack the three things that tend to bind soils together- moisture,
•
•
clay and organic matter
there is little vegetation to slow the wind down
winds are often very strong.
Arid areas will experience more wind erosion than semi-arid areas because they
have less moisture and organic matter in the soil, and have less vegetation.
There are two types of wind erosion:
• Abrasion - the impact of particles hitting other rocks.
• Deflation - loose particles are picked up by the wind and carried away.
Sand particles are carried by the wind. Large grains roll along the surface
(traction or surface creep), middle-sized grains jump along in hops (saltation)
and the lightest particles are carried in the wind in suspension (Figure 10.16).
prevailing wind
Suspension zone
mushroom rock/
rock pedestal
1 m
Saltation zone
0.1 m
little abrasion above
1 m as sand grains
rarely lifted this high
maximum abrasion in this
zone as sand particles hit the
rock with energy
limited erosion near the
base as coarse sand is
not lifted into the air
Surface creep
figure
10.16 Desert sediment transportation and its effect on erosion.
Wind-sculpted rocks
Zeugen are mushroom-shaped rocks that have been eroded by the abrasive
action of windblown sand. The undercutting effect is concentrated near
ground level, where sand movement is greatest. Zeugens tend to form in areas
of horizontal rock strata when the lowest bed is relatively weak (Figure 10.16).
Yardangs are wind-abraded ridges of rock (Figure 10.17) that range in size
from very small to huge. Yardangs are formed in tougher rock when the softer
rock around is removed by the wind. They can be of many shapes but are
typically three or more times longer than wide, and when viewed from above
resemble the upturned hull of a boat: facing the wind is a steep rounded face
that gradually gets lower and narrower toward the lee end.
To the south-east of the Tibesti Mountains in central Sahara are yardangs up
to 200 m high and many kilometres long. They are aligned with the prevailing
wind and this is regarded as proof that they are the product of wind erosion
(Figure 10.18).
Deflation hollows are simply hollows carved out of weaker parts of the rock
by the wind. The Quattara Depression in Egypt now lies 128 m below sea level
and an estimated 3335 km3 of material has been excavated by wind.
figure
10.17 Yardang landscape
Hot arid and semi-arid environments 243
figure 10.18 Yardangs, dunes and lakes south-east of the Tibesti Mountains in the Sahara Desert. The image shows an area approximately 11 km by 9 km. The dark
surface of water is divided by linear orange sand dunes and rocky yardangs. The map shows the location of the image.
Sand dunes
Sand covers about a quarter of the world’s deserts. Where the area of sand is
large it is called a sand sea or an erg. Ergs are deposited by the wind and can
move forward overtime.
Sand dunes vary in shape and size according to the supply of sand, the
strength and direction of the wind, the amount of vegetation and the shape
of the ground surface. So different types of dune are found in different places
(Figure 10.20). Dunes are largest where there is a big supply of sand, such as in
the mountain basins fed by alluvial rivers in Central Asia.
Types of sand dunes
Dunes formed at right-angles to a dominant wind direction:
• Barchans are small crescents formed where the supply of sand is limited.
Where there is more sand these dunes join up to form barchanoid ridges
(Figure 10.19).
• Akle dunes - long sinuous ridges formed when there is plenty of sand
- they are similar to barchanoid ridges. Akle dunes are common in the
western Sahara.
Dunes formed by multi-directional winds:
• Seif dunes - straightish ridges running parallel to the wind that are caused
by either two main wind directions (Figure 10.20) or by helical-roll vortices
•
figure
10.19 A barchanoid ridge in the Sahara Desert, Libya.
(Figure 10.21).
Star dunes - dunes in the shape of a star.
Dunes formed by obstacles:
• Nebkha-a small dune where sand is dropped in the shelter of the lee of a bush.
• Wind-shadow dune - formed in the lee of a hill.
• Lunette - small dune formed in the lee of a deflation hollow.
Erosion and deposition by water
There are three types of rivers in arid areas:
• Exogenous: rivers which were formed in wet areas outside the desert but
flow across it, such as the River Nile in Egypt, which is created by heavy rain
•
•
in the Ethiopian Highlands.
Endorheic: rivers that flow into inland lakes, such as the River Jordan
flowing into the Dead Sea bordered by Jordan.
Ephemeral: rivers that only flow after rain. When rain falls in arid areas it often
comes as heavy, short-lived storms. So many months or years of drought are
followed by a sudden storm with large quantities of water moving very fast
across the surface carrying large amounts of sediment with it- a flash flood.
Hot arid and semi-arid environments
barchans
wind-shadow dune
figure
10.20 Types of sand dune
Water in rivers is known as stream flow but much water takes the form of
sheet flow, which means it flows evenly over land as runoff.
When it rains in deserts the runoff is great because little water sinks into
the ground - it just runs off downslope. The reason for this is that there is so
little vegetation that the ground is not broken up by plant roots or animals.
There is little humus (dead vegetative matter), which would make the soil
more permeable. Because the soil is exposed to beating raindrops it becomes
compacted. Fine material (fines) is broken off and lodges in pore spaces in the
soil, further reducing permeability.
When water runs off in deserts it carries a great deal of sediment with it.
Figure 10.23 shows why in semi-arid areas there is enough rain to cause erosion
but not enough to support the vegetation that would prevent erosion.
Wadis
A wadi is an ephemeral river (it is dry much of the time). The river channel has
steep sides and is filled with alluvium because of the abundant sediment carried
by the runoff. The channel is often braided - it breaks into several branches.
In south-western USA wadis are called arroyos. They develop fastest in soft rock.
Arroyos can cut as deeply as 20 m into the valley floor, are often wider than 50 m
and can be hundreds of kilometers long. The rapid widening and deepening of
arroyos has been a costly nuisance in south-western USA since settlement began
in the mid 1800s and it is still the case that roads can be suddenly cut off by them
(Figure 10.22).
Canyons
Wadis form in lowland areas. If the landscape is more mountainous then
canyons form - deep gorges like the Grand Canyon have been cut by rapid
runoff carrying rocks, which help to erode the canyon further (Figure 10.24).
Hot arid and semi-arid environments
roll vortex
alluvial plai
deflated surface
figure
10.21 (a) and (b) The formation of a seif dune by roll vortices.
figure
10.22 Arroyo, New Mexico, USA
Salt lakes and playas
A salt lake is a landlocked body of water that has a concentration of salts
(typically sodium chloride) and other dissolved minerals that are higher than
most lakes. When a salt lake dries out it becomes a playa. Both may be formed
in one of three ways (Figure 10.25):
•
•
•
figure
Tectonically, by the collapse of rocks down faults, as happens in Death Valley,
California, or by folding, as we see at the Chott el Djerid in Tunisia.
By solution (dissolving) of the underlying limestone rock.
By wind erosion of soft rock-this is a deflation hollow.
10.23 The relationship between erosion rates and
rainfall totals.
Hot arid and semi-arid environments
If you dig a pit in a playa you find layers left by each storm - clay,
silt and salts. The evaporated water often leaves salt on the surface.
figure
10.24 The Grand Canyon, Arizona, USA
(a)
(b)
Tectonic - collapse down fault lines
Solution - dissolving of soluble rocks
(c)
Deflation - wind erosion
10.25 Formation of depressions in arid areas: (a) tectonically, (b) the solution
of limestone, and (c) wind deflation.
figure
figure 10.26 The Racetrack Playa in Death Valley National Park,
California, USA.
Hot arid and semi-arid environments
Because playas are so flat they are often used for land speed record attempts,
such as the Bonneville Salt Flats speedway at Salt Lake City, Utah, USA.
The extensive playas in south-western USA are fossil lake basins of the
Pleistocene pluvials, the geological epoch that ended about 11 700 years ago.
Along The Gulf coast of the Arabian Peninsula are low-lying salt flats
called sabkhas. They are occasionally covered by high tides or rainstorms but
much of the time they are just above high-tide level. They are 30 km wide in
places and are growing over time. Sabkhas are formed from salt deposited by
the sea and from water drawn up from just below the surface by evaporation
- evaporites.
Alluvial fans
At the point where the gradient of a river suddenly lessens (such as at the foot
of a mountain) the river slows down and loses energy. As a result the river
drops the large volume of sediment it has been carrying and this creates an
alluvial fan.
The size of the fan depends on the volume of water and the rock type. Easily
eroded rocks form larger fans.
Pediments
A pediment is a gently sloping rock surface covered by gravel. Pediments are
common in deserts and have two main causes:
figure
10.27 Alluvial fan, Greenland
1
2
The retreat over time of a hillslope - a process known as pedimentation.
Water accumulates at the junction of the mountain and the plain and deep
weathering occurs at this point. The weathered materials are removed by
water and wind over time and the mountain front retreats (Figure 10.29).
Rivers swing from side to side and erode the surface - a process known as
lateral planation.
figure
10.28 Buttes in Monument Valley, Arizona, USA.
248 Hot arid and semi-arid environments
(a) Parallel slope retreat
scarp recession
Stage 2 - Erosion strips away weathered rock to reveal inselbergs
figure
10.29 Inselberg formation
Inselbergs
An inselberg is an isolated steep-sided hill. In south-western USA they are called
mesas and buttes. Mesas are flat-topped pinnacles with steep sides formed in
horizontally banded rock that have become isolated from an adjacent plateau;
buttes are a smaller version of the same thing. Inselbergs can form in either of
two ways:
1
2
By slope retreat as described above - when a pediment retreats it leaves an
inselberg. The steep slope of the inselberg is called a scarp so this is called
scarp recession.
Ina previous climatic period the area was warm and wet. Chemical
weathering attacked the joints of rocks underthe ground leaving areas with
wide jointing less affected. Subsequent erosion stripped away the weathered
rock leaving the areas with fewer joints standing as inselbergs.
figure
10.30 Inselbergs in Namibia
figure
10.31 Piedmont zone, Iceland
Piedmont zone
‘Piedmont’ means ‘at the foot of the mountains’. In deserts the piedmont zone
is sometimes called a bajada. It is a gently sloping surface at the foot of the
mountain covered in loose sand, gravel or scree and washed by intermittent
stream torrents. The piedmont zone contains playas, salt lakes and inselbergs.
Equifinality
You may have noticed that several of the landforms described above, such as
desert depressions, pediments and inselbergs, have more than one possible
cause. This is called equifinality - several explanations are equally possible.
Hot arid and semi-arid environments 249
Past climates and landforms
You might have noticed that several times already we have referred to landforms
beingthe product of a different climate. This is true of inselbergs, which may be
formed by weathering in hot and wet conditions.
Wet periods in climate history are called pluvials. There was a pluvial
in the Sahara 12 000 to 5000 years ago, for example, and 18 000 years ago
in south-western USA - both in a period known as the Pleistocene. Evidence for
these wetter conditions takes many forms:
•
•
•
•
•
Ancient shorelines which show that lakes used to be much larger than they
are now, such as Lake Chad on the southern edge of the Sahara.
River valleys that were clearly cut by rivers which no longer flow, such as the
south-eastern Sahara.
Fossilised soils which can only be formed in wet conditions, such as laterites
in large parts of Australia.
Animal and plant remains in areas where such fauna and flora could not
survive today, such as the remains of rats in south-western USA.
Evidence of previous human occupation, such as Roman grain production
in parts of Tunisia that are now desert.
There is also evidence of stronger winds and drier conditions in the past:
there are large areas of sand dunes in modern deserts which have become
stable, not least in the Sahara and southern Arabia. The fact that they have
become stable- they are no longer forming or moving- suggests that they
were formed in the Pleistocene when wind speeds were stronger and, in some
areas, there was even less rainfall than today. These stable dunes gradually erode
over time or become vegetated.
In western USA there is evidence of colder conditions in the past in the
existence of relict frost screes - slopes of rock shattered by climates colder than
today.
Soils and vegetation
Soils
Desert soils (aridisols) have a number of distinctive characteristics:
1
2
3
4
figure
10.32 Soil erosion, southern California, USA
5
6
figure
10.33 The arid Sahara has a low density of
biomass.
250 Hot arid and semi-arid environments
Because there is little moisture there is little chemical weathering of the
rocks so the soils are thin and lack the soil horizons (layers) of soils in wetter
climates.
There is little vegetation so there is little humus or biomass in the soil
(rotting vegetable matter), often below 3 per cent of the total.
They have a low clay content because minerals are not broken down to such
small sizes by chemical weathering.
They are salty for the reasons given on page 242. This creates three problems:
• A high concentration of sodium salts causes deflocculation (dispersal)
of the soil particles; in a good soil the particles stick together in small
lumps but a deflocculated soil becomes impermeable and the air
necessary for plant growth cannot penetrate.
• Salts prevent plants from absorbing water into their roots.
• Salts are poisonous to many plants.
The surfaces are impermeable (do not admit water) because the beating rain
on bare surfaces compacts them. Fine material breaks off and is washed or
blown into the pores of the soil, blocking them. As mentioned in 4, sodium
salts in the soil cause the soil structure to collapse.
They are stony because finer particles are blown or washed away, leaving
only the stones. Sometimes stones are forced up from below the surface by
wetting and drying or freezing and thawing. Stone pavements, called reg or
hammada in North Africa, are a hard impermeable surface composed of rock
fragments set in sand or clay.
7
Hard crusts called duricrusts form. Salts are leached down from the surface
to lower horizons or move up from the water table by capillary action. The
commonest types of duricrusts are calcrete, formed from calcium carbonate,
or gypcrete formed from calcium sulphate. Duricrust is a hard rock band at
or below the surface that makes root development in plants difficult
Soil erosion
Soil erosion is closely linked to desertification (see page 252). It is caused by the
same combinations of drought, over cultivation, overgrazing and cutting down
of trees. However, at this point let us note that soils in arid areas are especially
vulnerable to erosion for a number of reasons:
•
•
•
•
Soils are loose because they lack clay, humus and moisture.
There is a lack of vegetation that would otherwise bind soils, shelter them
and protect them from beating raindrops.
Rainfall, when it comes, is often intense.
Wind speeds are often strong.
figure 10.34 Barrel cactus is the most common plant
found in deserts across the world. Its height can be
anything between i and 10 m.
Soil erosion strips off the top layer of soil, which is often the most fertile part.
The sediment is blown into rivers and irrigation canals, potentially blocking
them and causing flooding. Roads and crops become buried in loose sediment.
Vegetation
The main characteristics of arid zone vegetation are:
• a generally low biomass - in other words, not much grows
• a low range of species types
• adaptation to drought and salt
• limited nutrient cycling - the movement of plant nutrients from the ground
into the roots of the plant and back to the soil again when the plant dies or
sheds leaves. Nutrient cycling requires water if it is to be efficient
Plants need water for a variety of reasons. Water is needed to support plant
tissue growth. Plant nutrients in the soil are dissolved in water and water is the
medium by which they enter the plant. Water is needed for photosynthesis and
for the plant to regulate its temperature by transpiration - the evaporation of
water vapour through plant cells.
Deserts have a low biomass. The biomass of a tropical rainforest, for example,
is 250 000 kg per hectare, that of a dry steppe only 5000 kg per hectare, but the
biomass of a hot desert may be only 500 kg per hectare.
figure
10.35 Aloe Ferox, a succulent plant, in southern Africa.
figure
10.36 Rose of Jericho - an ephemeral plant
figure
10.37 Wild palm trees, Morocco
Adaptations of plants to aridity
Plants adapt to arid conditions in a number of ways.
Xerophytes are plants designed to resist drought. Their leaves are small (to
reduce the amount of water lost by transpiration), or spines and thorns have
replaced leaves altogether. They are waxy in order to retain water. Bark is thick
to prevent the plant collapsing when it dries out. Roots are deep or spread out
laterally at shallow depths over many square metres. Some plants, such as the
cactus, aloe and prickly pear, store water in their leaves, roots and stems and
they are known as succulents. Some plants die-back in the dry season. These
plants are called ephemerals and their seeds lie dormant during the dry period.
Phreatophytes have deep tap roots that can reach down to the water table,
such as date palms. They commonly grow near lakes, stream channels or springs.
Halophytes are tolerant of salt. Some are able to prevent the entry of salts
or they can excrete the toxic salts onto their leaves. Some avoid salt by growing
in the rainy season when salt concentrations are less. Date palms can grow in
saline groundwater.
Desert vegetation is generally sparse but grows in greater densities wherever
there is more moisture, such as in hollows, at the bottom of slopes or in dry
valleys (which are sometimes moist under the surface). There are fewer plants
where the surfaces are impermeable or on shifting sand dunes.
Hot arid and semi-arid environments
Adaptations of animals to aridity
Animals adapt to arid conditions in a number of ways.
Behavioural adaptations:
• Birds and I arger animals can avoid the hottest and driest seasons by
migrating to cooler or wetter areas.
• Many desert animals animals, such as rodents, snakes and invertebrates, live
in caves or burrows to avoid heat.
• Many desert animals are nocturnal - they only come out at night when it is cool.
•
Sand snakes move by side-winding, which means only a small part of the
body is in contact with the hot sand. Lizards assume an erect position when
running, keeping their bodies off the ground.
Morphological and anatomical adaptations:
•
In mammals desert fur coats are short and well-ventilated to allow sweat to
evaporate directly from the skin.
•
In the ostrich the bare head, throat, legs and abdomen allow for cooling.
•
•
Long legs keep the body separated from the extreme temperatures on the
ground.
Sand-dwellers have evolved to survive in dunes, for example fleshy footpads
in camels and scaly fingers in lizards.
Physiological adaptations:
•
They maintain their water balance by maximising water intake and/or
•
•
•
•
•
minimising water loss. Camels and wild asses, for example, can drink large
quantities of water in a very short time.
In coastal deserts animals obtain water by licking fog-drenched rocks.
Herbivores, such as eland and oryx, obtain water from the foliage of the
shrubs they eat.
Many desert animals are extremely tolerant of dehydration.
Camels and elands can reach body temperatures of 44 °C with no harmful
consequences.
Like ephemeral plants, smaller desert animals can evade drought by
entering into a dormant phase; grasshoppers survive dry spells in the form
of eggs or pupae.
Desertification
Desertification means the spreading of desert conditions. It applies, therefore,
to semi-arid areas on the edge of deserts (Figure 10.40) and implies that
where natural vegetation or crops used to grow, now they don’t. Desertification
figure
10.38 Desertification and soil erosion caused by
overgrazing.
Hot arid and semi-arid environments
can be caused by both climate change and by the behaviour of people living there.
The climate is always changing in response to changes in the output of
heat from the Sun, the movement of continents by continental drift, volcanic
eruptions and mountain building. We know that areas of the globe that were
once wet are now dry and that other areas that were dry are now wetter.
A large-scale, drought-induced famine occurred in Africa’s Sahel region
(the area on the southern edge of the Sahara Desert) from February to August
2010 - one of many famines to have hit the region in recent times (Figure 10.39).
Although the causes of the drought are disputed, the Atlantic Multidecadal
Oscillation (AMO) theory states that sea surface temperatures in the North
Atlantic warm and cool in a 70-year cycle and affect rainfall in Africa: an AMO
warm phase increases summer rainfall over the Sahel, while a cold phase reduces
it. So cold sea temperatures might be associated with drier conditions and
desertification.
Another theory is that the 2010 drought was caused by air pollution
generated in Eurasia and North America. The pollution changed the properties
of clouds over the Atlantic Ocean, disturbing the monsoons and shifting the
tropical rains southwards.
Droughts are not a new phenomenon. Following the fall of Carthage in
146 BC the Romans colonised a large part of North Africa. Between that point
and the sixth century AD this area became the ‘granary of Rome’ by growing
wheat. In subsequent centuries the average rainfall decreased and much of the
land turned to semi-desert. Human causes of desertification include:
i
2
Sahel precipitation anomalies 1900-2013
Increasing numbers of people due to declining death rates and high birth
rates and over cultivation of the land as a result. The increase in population
means more food is needed. Cultivation is extended into dry lands previously
used for livestock grazing. If the land is cultivated without fallow (periods of
rest) or fertilisers, the soil fertility will fall and eventually become barren.
Overgrazing by animals - animals eat all the natural plant life and this
creates soil erosion. Goats and camels, in particular, can eat the woody
portion of plants and this kills the plant - they are browsers (they eat various
parts of plants) as opposed to sheep and cattle who are grazers - they mainly
eat grass. Overgrazing is caused by:
figure
•
•
•
3
4
5
increases in herd size due to population growth
a decrease in available grazing land because of increasing areas of crop
cultivation
settling of nomads in restricted areas by governments wishing to tax
and control them; this means that instead of grazing over wide areas the
settled nomads are restricted to keeping their livestock in smaller areas.
10.39 Annual rainfall as a deviation from the
average in the Sahel. There was an unusually wet period
from 1950 until 1970, which encouraged farmers to move
into the area, followed by extremely dry years from 1970 to
1990. Rainfall in the period 1990-2010 was also below the
average and year-to-year variability was high.
Poverty-farmers are forced to cultivate and graze livestock in vulnerable
areas in order to have sufficient food for their families.
Salinisation due to badly managed irrigation. If irrigated fields are poorly
drained they become waterlogged and the surplus water evaporates, leaving
poisonous salts. If irrigation canals are badly lined water will leak out causing the
water table to rise; if the water table rises to within 2-3 m of the surface water
can be drawn up to the surface by capillary rise and evaporate, leaving salts.
Deforestation - cutting down trees for fuel results in increased wind speed
and increased runoff, both of which cause erosion.
figure
10.40 Desertification vulnerability
Hot arid and semi-arid environments 253
Sustainable management of hot arid and semi-arid
environments
Case Study
Rajasthan,
northern
India
Rajasthan is a densely populated semi-arid area in India partly occupied by the
Thar Desert. Because of overcultivation and overgrazing much of the land lacks
agricultural value and dunes have shifted into previously farmed areas. The Thar
is characterised by high velocity winds, huge shifting sand dunes, high diurnal
variation of temperature, intense solar radiation and high rates of evaporation.
The desert only receives 10-500 mm of rainfall every year, 90 per cent of which
falls between July and September. The sandy soils have a rapid water infiltration
rate, poor fertility, low humus content and high salinity. Actions taken in recent
years to counter desertification include:
•
figure
10.41 Sand dunes advance onto farmland,Thar
Desert, India.
•
•
•
•
•
•
•
•
•
Planting trees as windbreaks, including varieties of Prosopis and Acacia.
These trees can be grown on poor soils and yield food, fodder, fuel and
building timber.
Fencing dunes to keep out livestock.
Fixing parallel strips of brushwood into the dunes to stabilise them.
Planting cover crops to protect the soil in between the times when the main
crop is grown.
Inter-cropping: planting crops afterthe main crop has been harvested in
order to fully protect the soil.
Putting cut vegetation on the soil (mulch) in order to improve its capacity to
retain moisture and improve fertility.
Planting along contours in order to reduce the flow of water or loose soil downhill.
Scientists from the Central Arid Zone Research Institute (CAZRI) have
successfully developed and improved dozens of traditional and nontraditional crops such as Ber trees (like plums) that produce much larger
fruits than native plants and can thrive with minimal rainfall.
Planting new high-yielding grass varieties for desert livestock. These grasses,
besides contributing to the development of good rangeland in the Thar
Desert, have significantly helped to stabilise the sand dunes.
Damming eroded gullies as soon as they start to appear.
Measures to control desertification in Rajasthan have been partially
successful but with a population of 70 million the area still faces growing
pressure from population growth and the over-exploitation of fodder (for
livestock) and fuel wood.
Case Study
The Mojave
desert: an arid area in a
HIC
The Mojave Desert in southeast California and southern Nevada in the United
States is the driest of America’s deserts. Rainfall is very low and temperatures
in summer can rise to 54 °C. Much is at high altitude where extremes of
temperature - high and low- are common and winds can be strong.
There is little agriculture, mainly alfafa (a fodder crop fed to cows) which is
irrigated by water from the California Aqueduct, a 640 km network of canals,
s Hot arid and semi-arid environments
tunnels and pipes built between 1963 and 1997 which take water from the Sierra
Nevada mountains and the valleys of north and central California to the south.
The main land uses in the Mojave Desert are recreation, tourism and military.
Las Vegas (population 2 million) is a city based on gambling and entertainment.
Three National Parks were created in 1994- Death Valley National Park, Joshua
Tree National Park and the Mojave National Preserve-and these attract many
visitors. Tourists also come to see the ghost towns left behind by nineteenth
century miners digging for silver and gold.
There is a large military presence. The Marine Corps are based at Twentynine
Palms, and the Edwards Air Force Base is used for testing fighter aircraft.
Mojave Airport is a long-term storage centre for large airplanes because of the
combination of the very dry climate (which preserves the aircraft from corrosion)
and hard ground for parking the aircraft. Inevitably there is a conflict between
the military, tourists and the natural environment and the US government has
to achieve a balance between the needs of each.
The main sustainability issue has been the adverse impact of millions of
tourists on the natural environment. Activities including hiking, mountain biking,
horse riding, camping, hunting, trapping, rock climbing and off-highway vehicle
(OHV) recreation. The designation of the three National Park areas protects them
from development but huge areas of public land are the responsibility of the
US Bureau of Land Management and in recent years they have designated large
parts for use by off-road vehicles. However, research showed that the off-road
vehicles compact the ground surface so reduced the infiltration capacity and
increasing runoff- which causes erosion and flooding. The vehicles damage
vegetation and small mammals and tyres cause erosion directly. When it rains
water is channeled into the ruts created by wheels leading to gully formation.
A US pressure group, the Center for Biological Diversity, has taken action to force
the Bureau of Land Management (BLM) to alter its policy, producing research to
show the impact of off-road vehicles. In 2009 a court declared a proposed extension
of the areas accessible to off-road vehicles illegal because of the damage being done
to air quality, soils, plants and animals including the endangered Mojave fringe­
toed lizard. The judge described the Mojave environment as ‘extremely fragile, easily
scarred, and slowly healed.’The BLM is now required to place signs on all off-road
vehicle routes which are legal to use, monitor to determine if illegal vehicle use is
occurring, and provide enforcement to prevent illegal use.
Native American Indians were forced out of the area in the nineteenth
century. The 1994 California Desert Protection Act requires the Secretary of
the Interior to ensure that American Indian people can have access to land for
traditional cultural and religious purposes. Upon the request of an Indian tribe or
religious community, the US government must temporarily close specific areas to
the general public to protect the privacy of these cultural and religious activities.
Another pressure on the area is the advent of renewable energy projects- solar
and wind farms-which were specifically promoted under the 2010 California Desert
Protection Act. The United States is keen to reduce its dependence on fossil fuels
and it was felt that the Mojave Desert-a sunny and windy area - needed to play
its part. The military are being encouraged to set up renewable energy projects on
those parts of their land which are unused but already damaged by previous use.
The bill also established endangered species mitigation zones and requires
developers proposing to develop private lands to contribute money to a fund
that would be used to better manage habitat for desert tortoise and other
endangered or threatened species.
The military, renewable energy development, recreation and the natural
environment co-exist in an uncomfortable relationship, but one which is
managed by law.
figure 10.43 Joshua Tree National Park, Mojave Desert,
California, USA
NOW INVESTIGATE
1
Investigate the specific causes of aridity in one continent of your choice.
2
Which is the more important cause of desert erosion -water or wind?
3
To what extent are desert conditions created by humans?
4
Choose one area of semi-desert and explore the methods used to
combat desertification.
Hot arid and semi-arid environments
.A*
Cereal production 2011
In low-income countries (LICs)
cereals (rice, wheat, millet or maize)
constitute a large part of daily
sustenance. In medium-income
countries (MICs) and high-income
countries (HICs) cereal consumption
is moderate but substantial.
(tonnes)
World 2 341 974 936
Africa
153 653 049 6.6%
10.1*
6.1*
1.5*
North America
466 402 454 19.9%
Brarf^'2*
Argentina 32.7%
Paraguay 3.5%
Rest ofS America 14.6%
South America
148 597 802 6.4%
China 42.3%
Asia
1 067 997 362 45.6%
India 22.0%
Indonesia
5.8%
Rest of Asia 29.9%
Russia 19.7%
Europe
France
464 566 768 19.8%
Graine
12.1%
msny 9,o%
P°'’ndi.7*
Oceania
40 757 501 1.7%
%
^4.
Continental values are the percentage of the world total
Country values are the percentage of their continental total
13.7%
USA, France and Australia, (where
production exceeds regional demand),
are the largest exporters of cereals.
Cereal exports 2011
(tonnes)
World 384 730 039
1]
Production, location and change
Africa
5 734 911 1.5%
North America
114144 404 29.7%
Paraguay 4.9%
South America
Rest of
6 America 6.1 %
50 334 256 13.1%
Thailand 21.5%
India 18.9%
Asia
Vietnam 13.7%
54 177 035 14.1%
Pakistan 13.4%
Kazakhstan 11.096
Turkey 6.8%
China 4.896
Rest of Mia
franco V**
Europe
136 340 709 35.4%
Russ'3
■nel°'8*
yjwarn
Oceania
23 998 723 6.2%
»3*
•J*
6*
257
11
Production, location and
Agricultural regions
□
Hign mountain pastures under extensive
sheep, beef and dairy cattle
Wet mountain pastures and hay
O meadows under beef and dairy cattle
Landscapes of permanent grassland in
| small fields with hedges under mainly
Agricultural systems and food production
Factors affecting agricultural land use
Agricultural land use is affected by a range of factors that combine to create the
farming landscape that makes certain regions of the world so identifiable. These
factors can be:
sheep, beef cattle and some dairy
and floodplain pastures under
□ Wetlands
mixed livestock farming
Mediterranean rangelands (sheep, goats)
□
and permanent crops (olives, vines)
□
diverse cropping and livestock
figure
Mixed farming areas of small-scale
ii.i Agricultural regions of France
258 Production, location and change
•
•
•
•
physical
economic
political
socio/cultural.
Physical factors
The physical landscape of France allows a range of agricultural practices, from
rearing livestock to growing grapes. Some regions have difficult physical
environments, such as steep shaded slopes and high limestone plateaux, and
despite advances in all aspects of'arming technology, from genetically modified
(GM) seeds to improved machinery, these areas remain at the margins of
production. While being strongly influenced by the physical environment, farm
production may have more to do with the political and socio/cultural influences
of a region.
The agricultural regions of France reflect the physical geography and climate
of the country. Climate is a key influence on crop growth, as each crop requires
critical temperatures, rainfall and growing season. This is particularly true for
the growing of vines for wine making or viticulture.
table
ii.i Climatic conditions for viticulture
Ideal climatic conditions for viticulture (grape vine cultivation)
Sunshine
1300-1500 hours of sunshine in the growing season
Frost
At least 200 frost-free days
Rainfall
690 mm throughout the year, mainly winter and spring
Rain at other times can cause problems
Temperature
Winter 3 °C, Summer 22 °C
Soil type and fertility are also critical as they provide the necessary
conditions for root development. Locally, slope can be very important. In the
case of viticulture, south-facing slopes in cooler regions mean that the vines
receive a greater intensity of the Sun’s rays, with sunshine falling at an angle
perpendicular to the hillside; whereas in parts of the south of France growers
sometimes use north-facing slopes to protect the vines from too much
sunshine. Slopes also ensure good groundwater drainage.
Production, location and change 259
Climatic conditions play a role when damp weather or high winds damage
plants, causing mildew or allowing the spread of disease. Water is a vital
ingredient in the agricultural process. In many parts of the world irrigation,
artificial watering, is practised. Using rain-fed systems as well as reservoir
systems irrigated farming accounts for 70 per cent of total global water
consumption in any year. In India the figure rises to 90 per cent and in regions
where irrigation is vital any break in the supply can prove disastrous. The
ongoing drought in California, since 2010, has depleted groundwater and
reservoir supplies and by 2014 meant that the Central Valley was projected to
have lost about US$810 million in crop revenue. It was estimated that about
1732 sq km, or 5 per cent of irrigated cropland, was likely to go out of production
in the Central Valley, Central Coast and Southern California.
Economic factors
Economic factors include the cost of growing a crop and the price received in
the market place. While costs generally rise market prices can fluctuate from
year to year and from day to day. Production costs will include investment in
machinery, specialist buildings and equipment in addition to labour costs. In
recent decades there has been a trend in HICs for farm numbers to decrease
and the size of farms to increase. Large farms benefit from economies of
scale especially through mechanisation and automation. Small fields can be
amalgamated into larger fields, which makes the use of machinery more
efficient and operations such as sowing and fertilising produce less wastage.
Larger farms can also purchase and market in bulk and thus outcompete small
farms.
A further consideration of economic factors is the application of agro-technology.
There are a series of key dates in the development of technology, from the invention
of the seed drill by Jethro Tull in 1733, to the GPS-guided tractor and the 24 000 litre
bulk tanker of today.
Agro-technology is increasingly vital for a country’s food security
and more and more technology transfers are taking place to regions of
the world where food security is a major issue. Many of these countries,
especially in sub-Saharan Africa, although dependent upon their agricultural
system actually have a system that cannot adequately feed their people. The
majority of small scale farmers lack access to new technologies, finance and
specialist support.
In HICs agriculture has become capital intensive and more industrialised
especially with the production offish, poultry and some livestock. Capital
intensive farming has certain common factors that apply to most operations.
Capital intensive farming is characterised by very large units that invest massively
in mechanised and automated systems, make maximum use of IT systems,
and employ fewer, but highly skilled workers. Extensive use of fertilisers,
pesticides and herbicides ensures maximum production and allows the land
to be used intensively year after year. These farms are often owned by large
TNC (Transnational Corporations) food companies and are vertically integrated,
meaning the farm grows, packages and sells the crop. Dole owns plantations
and canning facilities and has the marketing power to bring pineapples from
plantations in the Philippines to consumers worldwide. The British company Fyffes
uses the same integrated system for growing, ripening and marketing bananas.
Political factors
The production of food and the issue of food security gives governments a keen
interest in agriculture. Consequently, much of an individual farmer’s decision
making will be influenced by government policies. In countries where there is a
command economy, such as China, there is even more control of farming and
the influence of the government is very strong.
In Europe following the Second World War agriculture was in chaos.
Food shortages existed which led in 1945 to famine conditions in Germany
and the Netherlands and food rationing well into the 1950s. The Treaty of Rome
(1957) sought to remedy this situation and to increase food production as quickly
260 Production, location and change
as possible and so established the Common Agricultural Policy (CAP). This
aimed to:
•
•
increase productivity
ensure that farmers have a 'fair’ standard of living
•
•
•
keep prices steady for agricultural products
maintain regular supplies for the markets
ensure reasonable prices for consumers.
CAP has always been a contentious policy, with some regions receiving a
disproportionate level of subsidy compared to others and environmentalists’
claims that damage has been done to species-rich habitats.
Socio/cultural factors
Change in agricultural practice is often slow and where farms are handed
down from parent to child/children the practice of growing particular
crops or keeping particular livestock becomes an important tradition. In
LICs these factors take on a significant role, often owing to the fragility
of the circumstances in which the farming community works. Shifting
cultivation is one such traditional system practised all over the world,
often in difficult locations such as in forests or on hillsides.
Land tenure and land rights
Farmers may be owner-occupiers or tenants who pay rent to a
landlord. In most European countries owner occupation is now
the norm, which is the reverse of the situation in the nineteenth
and early twentieth centuries. However in many parts of the world
sharecropping is a common form of tenure. In this system the
landlord provides the capital inputs, seed, equipment, fertilisers and
so on for which they receive 50 per cent of the harvest as rent.
In some LICs land is often given as part of a bride’s dowry,
which can have the effect of further reducing the size of an already
small workable farm.
The main concern is the gender imbalance that exists when it
comes to ownership of land by women - in many LICs this is only
now being addressed as countries look to develop economically.
Kenya’s new constitution appears to represent gains for the women
of the country. The constitution promises the right to own property
to “every person”, ensuring “equitable access to land” and “security of
land rights" but without mentioning women or acknowledging their
historical landlessness.
Although increasing numbers of women have access to land
to farm, the question of whether they own the land in their own
name remains an issue across much of the less developed world.
Agricultural systems
Agriculture in its many parts, from individual smallholdings in
Southeast Asia to the vast cattle stations of Australia, all operate
in a similar way. They all exist to make a ‘profit’ and in order to do
that they need to have access to a range of inputs, such as labour,
energy, seeds and fertilisers. Profit will accrue if the harvest sells
for more than the inputs cost. Figure 11.4 shows the complexity
and interrelated nature of the farming system.
At the heart of the model is the decision making process of
farmers and how that is influenced by various factors. These factors
may alter in the light of government policy, climatic changes and
a farmer’s own experience. The system is therefore dynamic in
nature and always fluctuating.
Agriculture can be divided into three broad types as a consequence
of the variation of inputs, which in turn gives rise to the variation in
types across the globe.
figure
11.3 Sharecropping farm system
output
loss to the system,
along with natural
outcome
hazards such as
drought, hail and
action
figure
disease
negative feedback:
disequilibrium is
increased (stagnation
and decline)
114The agricultural system
Production, location and change 261
Subsistence and commercial farming
Subsistence farming supports about a quarter of the world’s population. It
comprises smallholdings, with cultivation taking place in difficult environments
where the risk of crop failure is high. As a result most families are poor or very
poor as they produce food to satisfy their own needs with an occasional surplus
to sell. Pure subsistence farming is now extremely rare.
Output however is high with intensive use being made of family labour.
Subsistence farmers are also very knowledgeable about the local conditions
and the crops that will thrive in those conditions. The farmers will grow a range
of crops to ensure that if one crop fails the harvest is not lost completely, and
which also provides for a varied diet, ensuring the maintenance of the soil’s
fertility. Where the climate becomes too extreme for sedentary farming nomadic
systems may become more prevalent. Nomadic systems are found in countries
such as Niger and Mali.
Commercial farming is the dominant type of farming in HICs and in some
MICs. It is large scale and makes the best use of the technological advantages
available to the farmer. The farms tend towards specialisation as this allows
economies of scale to operate, often on a global scale. In order to supply
these specialist markets European and American companies have established
plantations to supply tea, coffee, and fruit such as bananas and pineapples.
Commercial farming includes the raising of livestock, grain production and
market gardening to produce flowers, fruit and vegetables.
figure
11.5 Polytunnels in Almeria, southern Spain
figure
11.6 Planting padi, China
Production, location and change
Extensive and intensive farming
These terms refer to the relationship of the inputs to one another. Extensive
farming is practised where capital and labour inputs are low in relation to the
amount of land being farmed, so parts of the prairies of Canada, the steppes
of Russia and the shifting cultivation of the forests of central Africa fall under
this heading. Intensive farming where labour inputs are high and the land area
is small would include wet rice cultivation in Southeast Asia and the intensive
production of flowers and vegetables under glass in southeast England and
Almeria in southern Spain.
Arable and livestock farming
Arable farming is the growing of crops either intensively or extensively. The
main requirement is a fairly flat landscape and high quality soil. Livestock
farming is usually practised in less favourable areas with colder, wetter, steeper
and less fertile soils. This type of farming can be intensive or extensive, or
pastoral nomadism. Mixed farming is a combination of both types of farming,
where farmers grow crops and raise stock. In HICs, such as the UK, this is often
done so the crops and animals complement each other. In LICs mixed farming
is a formula used to spread the risk of harvest failure and plan against food
shortages.
Case Study
An
in
extensive pastoral system:
Livestock rearing
Australia
Extensive livestock rearing makes Australia the world’s third largest exporter
of cattle. The largest farming property in both Australia and the world is Anna
Creek Station (farm) in South Australia, one of 16 properties owned and run by
the Kidman Company. At 24 000 sq km, Anna Creek Station is larger than Israel.
The main physical input is the extensive semi-arid areas over which the
cattle graze.
Human inputs tend to be low for the extent of the area covered by the
stations. The processes are grazing, breeding and checking for disease. The
outputs are the live animals, mainly young animals for export, and meat.
Statistics are for 2011.
Border Rivers and
Maranoa Balonne
Burdekin
Burnett Mary
Cape York
Condamine
Desert Channels
AUSTRALIA
Avon
Northern
Agricultural
Rangelands (WA)
South Coast
South West
Swan
The total number of cattle is
28 506 169
50 130
104 763
1 059 866
310 051
470 792
71 502
Adelaide and
Mount Lofty Ranges
Alinytjara Wilurara
Eyre Peninsula
Kangaroo Island
Northern and Yorke
SA Arid Lands
SA Murray Darling Basin
South East (SA)
1 230 340
1 432 424
902 248
141 794
551 106
1 739 691
2 715 515
138 237
933 292
425 991
Fitzroy
Mackay Whitsunday
Northern Gulf
South East(QLD)
South West (QLD) 609 581
Southern Gulf 1 593 268
Wet Tropics 198 387
q
892
22 676
20 637
61 373
235 209
161 437
659 097
Border Rivers-Gwydir
Central West
Hawkesbury-Nepean
Hunter-Central Rivers
Lachlan
Lower Murray Darling
652 793
777 559
151 743
569 125
489 495
31 186
Murray 418 972
Murrumbidgee 576 775
Namoi 659 110
Northern Rivers 941 324
Southern Rivers 232 842
Sydney Metro 6777
Western 202 052
CAP. TER.
Corangamite
East Gippsland
Glenelg Hopkins
Goulburn Broken
Mallee
North Central
North East (VIC)
Port Phillip and
455 666
125 036
928 242
591 774
13 141
311 590
TASMANIA
211
•»-629
405 286
309 640
Westernport
West Gippsland 780 672
Wimmera 48 812
figure 11.7
*
North (TAS) 291 776
North West (TAS) 340 872
South (TAS) 56 562
Distribution of cattle in Australia
Production, location and change 263
With a national herd size of around 42.7 million cattle the industry involves
over half the farms in Australia with exports taking 70 per cent of the production
to over 100 countries.
Cattle are reared under a range of climatic conditions although dairy
production is located in coastal areas where pasture growth generally depends
on natural rainfall.
Drought is a major concern for cattle farmers and a great deal of effort is
put into managing pasture to ensure herds survive. The so-called Millennium
drought, the ‘Big Dry’, was recognised as the worst recorded. It lasted from 1995
figure
11.8 Cattle on the Anna Creek cattle station,
South Australia.
until late 2009. Farmers have become more conscious of water management
and conservation, particularly after the government imposed limits on how
much water could be drawn from groundwater supplies.
Farming issues
Some of the other issues facing agriculture in Australia are: low soil fertility,
weed infestation, global warming caused by climate change, and biosecurity
(the destruction of natural vegetation and habitats from overgrazing). Since
European settlement at least 54 species of birds and mammals are known to
have become extinct.
Case Study
An
intensive arable system:
in the UK
Market
gardening
Location
Much of Sussex is given over to mixed arable and livestock farming, sheep
on the chalk hills and cattle on the low clay vales. However to the west of the
county where the coastal plain widens towards Chichester there is an area of
hyper-intensive arable farming. Why? First, this area receives 1400 hours of
sunlight every year. Second, the area receives 775 mm of rainfall every year.
Third, the land is flat, allowing for mechanised practices. Finally, the soil is a
fertile sand-silt loam underlain with water retentive brick-earth soils, which
create a high water table.
Crops and one farm
Langmeads Farms in West Sussex grow all their crops in rotation to ensure the
maintenance of the soil quality.
table
11.2 Order of crop rotation
Year 1
| Lettuce
Year 2
First wheat
Year 3
Potatoes
Year 4
| Wheat
Years
Maize
Year 6
| Peas
The first wheat crop benefits from the fertilisation of the soil for the lettuce
grown in the previous year. Potatoes then ‘clean’the soil as they require deep
ploughing and harvesting, which helps remove weeds and mixes the soil layers
up. The maize in year five reintroduces some organic content to the soil. A crop
of peas or maybe barley will be planted in fields that for some reason have got
out of sequence. Much of the maize goes to an anaerobic digester locally to
make electricity and the rest is used for silage or cattle feed. The lettuce, and
more recently herbs, are the most intensively cultivated crops. In an advanced
health conscious society such as the UK with an increased emphasis on a healthy
diet, lettuce has become a main ingredient. One farm supplies all the major
Production, location and change
supermarkets as well McDonalds, KFC and a number of other fast food outlets.
This, along with herb growing, is a hyper capital-intensive operation. A new
fully automated glass herb growing facility currently being built near Chichester
will cover over 8 ha, with a packing house the size of three football pitches,
costing in the region of US$30.4 million. The crops can be grown, packaged and
delivered across the UK on a daily basis.
Lettuce and soft fruits are grown in polytunnels or under fleece to prevent
the wind and the rain from damaging the crops and to allow the germinating
plants a better chance to establish strong growth.
The labour force is mainly contract workers from Eastern Europe with a small
number of permanent staff in managerial roles. To ensure a year-round supply
to their customers, the organisation has operations in Spain, France and Italy.
Issues arising from the intensification of agriculture and the extension of
agriculture
Since the end of the Second World War there have been huge advances in
agricultural production thanks to the use of mechanisation, fertilisers, pesticides
and herbicides, greater and more effective use of irrigation methods, and the
advent of high-yielding varieties of seeds.
Mechanisation has resulted in farmers having a strong incentive in the UK to
remove centuries-old hedgerows. By 1990 over half of UK hedgerows had been
removed and with them the habitats and biodiversity that contributed to the
make-up of the traditional countryside.
Intensification can also lead to land degradation through the use of
chemicals, which can have deleterious effects ultimately on food production and
on the environment.
Soil erosion
Soil erosion usually occurs as a result of the removal of the protective vegetation
cover. Tropical forest removal can exacerbate erosion when the surface is
exposed to torrential tropical rain. In marginal areas overgrazing can result
in the scant vegetation being stripped off, followed by the soil drying out and
being removed by wind erosion and surface runoff. Friable soil types are likely
to be more at risk, as in China where the loess soils in the Yellow River Basin are
lost at the rate of 100 tonnes per hectare every year.
Soil erosion has become the major environmental problem in China. The
Yangtze River Basin loses 2.24 billion tonnes of soil per year, which damages
67 000 ha of farmland (Figure 11.10). The effects of soil erosion mean that
almost 100 million people will lose the land they live on within 35 years if
erosion continues at the current rate.
Salinisation
In semi-arid and arid areas, salinisation is a serious problem and it affects
7 per cent of the world’s land area. This occurs when transpiration from plants
and evaporation exceed the amount of incoming precipitation in regions
where the water table is close to the surface. The presence of salts is harmful
to many plants and yet the cause, although natural, can be made worse by
man’s efforts to increase food production. Irrigation without proper drainage
can raise the water table locally and by capillary action salty water is drawn to
the surface.
In South Australia salinisation is a problem in all principal agricultural
areas, with 3700 sq km affected. At current rates, this is expected to increase
by 60 per cent by 2050. It is expected to cost the state around US$37.3
million per year in lost agricultural profit, and is expected to taint more
than 20 per cent of groundwater to levels above those safe for human
consumption.
figure 11.9 Soil damaged by salt deposits, which has been
caused by using the wrong type of irrigation.
Production, location and change
figure
ıı.ıo Soil deposition in the Yangtze River. Soil erosion is a major environmental problem in China.
Desertification
Desertification describes the effects human activity and climatic processes
have on a landscape reducing it to desert-like conditions. Often resulting
from the overgrazing of semi-arid pastures, the results are irreversible.
Desertification takes place in drylands and some 15 per cent of these may
already be degraded: representing about 9 million sq km. Over 250 million
people in more than 100 countries are directly affected by desertification and
more are at risk. In Africa 66 per cent of the total land area is classified as arid
or semi-arid.
Global Assessment of Human-induced Soil Degradation (GLASOD) was
established in 1990 to assess the status of human-induced soil degradation.
There has been no further study on a global scale.
figure
11.11 Effects of desertification
Production, location and change
The Green Revolution
The Green Revolution refers to a series of research and development and
technology transfer initiatives occurring between the 1940s and 1960s that
increased agricultural production, particularly in the developing world. Norman
Borlaug is credited with saving over a billion people from starvation with a
process that involved the development of high-yielding varieties of cereal grains.
This was supported by an expansion of irrigation infrastructure, modernisation
of management techniques and the distribution of the hybridised seeds,
synthetic fertilisers and pesticides to farmers. First trialled in Mexico, it was not
until 1961, with India on the brink of famine, that the Punjab region was selected
fortrials of a new rice called IR8, developed by the International Rice Research
Institute (I RRI). IR8 rice produced more grains of rice per plant when grown
with certain fertilisers and irrigation. Studies showed that IR8 rice yielded about
5 tonnes per hectare with no fertiliser, and almost 10 tonnes per hectare under
optimal conditions: 10 times the yield of traditional rice.
In the 1960s rice yields in India were about 2 tonnes per hectare; by the
mid-1990s, they had risen to 6 tonnes per hectare. India became one of the
world’s most successful rice producers and is now a major rice exporter,
shipping nearly 5.4 million tonnes in 2013.
However there are criticisms. Punjab is now witnessing the serious
consequences of intensive farming using chemicals and pesticides. A study
has underlined the direct relationship between indiscriminate use of these
chemicals and increased incidence of cancer in this region. Environmental
activist Vandana Shiva has written about the impacts in Punjab and claims that
the reliance on heavy use of chemical inputs and monocultures has resulted in
water scarcity, vulnerability to pests, and incidents of violent conflict and social
marginalisation.
In 2009 a study was undertaken which revealed that in 50 Punjabi villages
incidences of chemical, radiation and biological toxicity were widespread.
The success of IR8 has not been repeated in Africa, probably the one
continent that needs it most. This failure has been attributed to various
factors including; widespread corruption, insecurity, a lack of infrastructure,
and a general lack of will on the part of African governments. Nevertheless
environmental factors, such as the availability of water for irrigation and the
high diversity in slope and soil types in any given area, are also reasons why
success has been so elusive.
Production, location and change 267
A recent programme in western Africa has attempted to introduce a new
high-yielding ‘family’ of rice varieties known as New Rice for Africa (NERICA).
NERICA varieties yield about 30 per cent more rice under normal conditions,
and can double yields with small amounts of fertiliser and very basic irrigation.
However the programme has been beset by problems and the only success has
been in Guinea, where it currently accounts for 16 per cent of rice cultivation.
The management of agricultural change
The three sub-Saharan countries of Mali, Burkina Faso and Niger are ranked in
the Human Development Index at positions 176,181 and 187 respectively with
scores of 0.407, 0.388 and 0.337. They are all critically short of food particularly
during the dry season, which in some years can last for 12 months.
In 2006 Alliance for a Green Revolution in Africa (AGRA) was established to
trigger an African Green Revolution. The intention was to transform the existing
agricultural system of small scale farmers into a highly productive, efficient,
competitive and sustainable operation able to ensure food security and lift
millions of people out of poverty. By 2020 AGRA’s aspirational objectives are to:
•
•
•
reduce food insecurity by 50 per cent in at least 20 countries
double the income of some 20 million smallholder farmers
put at least 15 countries on the path to achieving and sustaining a Green
Revolution.
Low soil fertility in the first place and the impact of continuous cultivation of
the same crops leading to inevitable soil exhaustion are the main reasons for low
yields. In order to remedy this, AGRA set up the Soil Health Programme in 2008.
Drought in 2010 left 7.1 million people hungry in Niger as crops withered
and livestock died, although a simple farming method -fertiliser micro­
dosing- could have averted the crisis.
“I planted two fields with millet, sorghum and cowpea”, says Mahamoudou
who farms in a village in Niger. “In the first field, I used microdose tech­
nology and in a second one I used the traditional method - broadcasting
fertiliser at the same time as sowing the seed.”
The results were obvious. In the microdose plot yields of sorghum were
three times those in the traditional field; 1550 kg/ha as opposed to only
550 kg/ha.
Even if they use fertiliser, most farmers in Mali, Niger and Burkina Faso just
throw handfuls of it across a newly sown field. This is a traditional method but
most of the fertiliser is wasted, the granules falling nowhere near the newly
sown seed. Add to this the fact that the soil is sandy so what nutrients there are
in the fertiliser are quickly leached out before the crops can access them. In Mali
fertiliser costs US$1.65 per kilo, which is four times the average world price, so
farmers only buy small amounts. Farmers in Mali only use about 5 kg of fertiliser
per hectare and consequently crop yields are disappointingly low.
Microdosing overcomes these problems by putting the fertiliser right
beside the plant where it is most needed and most effective. The process
usually takes two people - one person to make a small hole and a second
person to drop a capful, or ‘three finger pinch’, of fertiliser into the hole
followed by the seed. Microdosing can then be repeated once the seeds have
germinated.
Production, location and change
figure
11.13 Microdosing
Using this method has meant Mahamoudou has tripled his harvests and has
increased his wealth.
"When I started microdosing in 2000 I had only two sheep. Now I have
20 sheep, 20 goats, 2 cattle and 10 donkeys", he says.
Another farmer had harvested 3 tonnes of maize from a plot he had been
microdosing against the traditional broadcast method, which only yielded 2 tonnes
per hectare, and a plot with no fertiliser that yielded a meagre 800 kg/ha. So with
limited investment there is a greater yield, which allows the farmer and his family
to use the harvest for subsistence and the rest he can ‘bank’ and use the money to
undertake activities such as raising livestock or diversifying into other crops.
Table 11.3 shows the extent of the project’s influence in two countries and the
potential effect that it will, and is, having on daily life in the region.
In low rainfall areas field trials show that 32 kg/ha of microdosing produces
increased yields of millet compared to the traditional broadcasting of three
times as much fertiliser. In areas with higher rainfall totals similar results were
achieved for sorghum. In Burkina Faso some 45 000 farmers have adopted
microdosing and in Mali the area under millet, sorghum and cow pea has
increased by nearly 50 per cent. The number of households using the technique
in 2010 was 60 942- two years later this had risen to 119 918, which is an
increase of 100 per cent.
Low pressure drip irrigation is also a very successful agricultural method
used to increase yields - it only takes ten minutes to switch on a drip kit. Water
is supplied directly to the roots instead of the entire plant. The water is pumped
from boreholes using solar power.
Production, location and change 269
table
11.3 Microdosing project highlights
Mali
Burkina Faso
Microdosing
2819 demonstration plots
22 413 field demonstrations
440 farmer schools
11 210 farmers trained in fertiliser microdosing
57 338 farmers benefited
72 farmers’ organisations holding farmer field schools
45 000 farmers adopted technology
25 860 farmers trained in integrated soil fertility management
20 500 farmers trained in microdosing
Yield increases of 33-47 % compared to no fertiliser
393 field days with 57 338 farmers
206 farmer field days with 9642 farmers (34 % women)
Broadcasts reached 366 000 farmers
133 broadcasts on regional radio and six FM stations
Inventory credit
58 warrantage warehouses set up
1150 tonnes of grain stored in 43 stores
158 committee members trained
FCFA 72 million (US$144,000) lent to 1077 farmers
FCFA135 million (US$280,000) lent to 3470 farmers
(51 % women)
Input supplies
36 fertiliser dealerships set up
43 dealerships set up
584 tonnes of NPK and urea fertilisers used in field
demonstrations
76 897 farmers (30 % women) bought 94 850 minipackets and
34 255 50-kg bags of fertiliser
3470 farmers (51 % women) benefited
figure
11.15 Successful drip irrigation crops, Africa
Another method to counteract poor yields during drought is known
as bioreclamation of degraded lands. The exhausted soils of the Sahel are
replenished using rainwater storage methods and the replanting of indigenous
trees and crops. In the dryland tropics, such as Niger, indigenous plants
and crops are hardy natural survivors that are adapted to tolerate drought
figure
11.16 Cow peas, now a successful crop in Mali
where microdosing is used.
conditions.
Finally the ‘warrantage’ scheme allows farmers to borrow against their
harvest. This means that farmers can sell their harvest when the price improves
but in the meantime are able to invest in their farm by diversifying, repairing or
merely clearing existing debts.
The long-term effects of all these interrelated schemes seem to bring
benefits but are not yet fully understood. Much more research is needed to
examine the impact on the soil in the long term and further work is needed to
develop simple tools to help and reduce the labour intensity of the microdosing
technique.
Production, location and change
Manufacturing and related service industry
Geographers recognise two types of manufacturing activity: Fordist industries
and flexible industries. Prior to the 1970s most manufacturing in the advanced
economies was Fordist, named after the assembly line techniques pioneered by
Henry Ford in the USA in the 1930s. These industries have declined and modern
industry uses more flexible production techniques such as having a smaller
workforce that can multitask.
Factors influencing industrial location
All industrial activity can be viewed using a spatial system approach. Each industry
and indeed each firm within that industry will be located according to the decision
making processes of entrepreneurs and the importance they attach to the two sets
of factors intrinsic to all industries - physical factors and human factors.
figure
11.17 Palm oil processing in Indonesia.
figure
11.18 The Aluminium de Dunkerque plant in France.
table
11.4 Factors influencing the decision making process
Physical factors
Human factors
Climate
Capital
Energy
Government policy
Raw materials
Labour
Transportation
Markets
Site
Quality of life
Production, location and change
Raw materials
Some industries such as sugar refining, oil refining and aluminium smelting
use raw materials directly and are known as process industries. Raw materials
lose weight during the manufacturing process and process factories are
located near their raw materials. Cocoa production loses considerable weight
in the processing of cacao pods and as a result much of the processing takes
place close to the areas of production, such as at the port site of Tema, Ghana.
Similarly the processing of palm oil takes place close to the areas of production
in Indonesia and Malaysia.
In many industries technology has reduced the amount of raw material used
figure 11.19 Coal transporters at Gezhouba Dam on the
Yangtze River, China.
in manufacturing and so the need for proximity to them has been reduced. Where
this is not the case and raw materials are still required in large quantities tidewater
locations are favoured so that bulky materials can be brought in, often from
overseas in bulk carriers, which are then unloaded at these break-of bulk points.
In the case of the Aluminium de Dunkerque smelter, on the north coast of
France near the port of Dunkerque, the proximity of the nuclear power station at
Gravelines just down the coast is as important as the presence of the deep water
terminal for importing the bauxite raw material.
Markets
Where goods are sold will have an important influence on where a factory might
be located. If the cost of getting a finished article to market is high then it
makes sense to locate the manufacturing base near the market. Where transport
costs can be reduced then factory location can be much more flexible. Similarly
if the industry depends on being able to react quickly to changes in demand or
fashion then market locations might be considered over more remote sites.
figure
11.20 Total oil facility, Dunkerque, France
Energy
The Industrial Revolution in the UK relied almost exclusively on coal, a pattern
that has been repeated across the globe as industrialisation has spread, and as
a result most industrial towns grew up on or near to coalfields or at a port site
where coal could be easily imported. At first canals, then railways and, much
later, roads transported the coal to the factory and the finished products to
market. Investment in plant was massive so even when local supplies of coal
were supplanted by ‘new’ electricity, factories stayed where they were, a situation
known as industrial inertia. This is why steel making persists in Sheffield, in
South Yorkshire, despite the original reason for steel manufacturing being
located there (the presence of coal fields) having long since disappeared.
The twentieth century saw a switch in energy sources to the electricity grid and
oil and gas pipelines. This change in sources has made energy a ubiquitous resource
rather than the localised factor it was two hundred years ago. While some industries
remain dependent on energy supplies, many other industries can locate almost
anywhere as they are no longer dependent on localised energy supplies. They have
become footloose industries, their location reliant on factors other than energy.
figure
11.21 Coal transportation, Yangtze River, China
Transport
As transport technology has improved the issue of transport costs has diminished
as a major factor influencing industrial location. Two types of cost remain: fixed
costs or terminal costs and line haul costs. Fixed costs relate to the cost of
maintaining terminals as well as the cost of the transport system itself. Line haul
costs are the actual costs of moving the goods, wages and fuel costs. High fixed
costs required at terminals often have low line haul costs as goods are moved
by pipeline or by water. Airtransport however has high fixed and high haul costs
and consequently only high value or perishable goods are shipped by air.
figure
11.22 Perishable flowers awaiting transport
Production, location and change
Land and climate
At the start of the industrial age factory owners were able to build almost wherever
they pleased as long as land was available at the right price. In the nineteenth
century textile factories were often built over several storeys, whereas today
factories are often single-storey with associated storage space and car parking.
In the modern age a disinclination to have industrial areas anywhere within
the built-up zone has led to factory estates beyond the suburban fringe, often on
greenfield sites. Figure 11.24 shows the new Rolls Royce facility in Sussex rising
from a field of oil seed rape. In Ghana, for example, the establishment of the
480 hectare Export Processing Zone at Tema has led to the location of numerous
industries including cocoa processing, seafood canning and printing.
Climate can also play a role in the location of businesses: afterthe
Second World War California attracted industry with its mild Mediterranean
climate and cheap land. Stanford University began encouraging graduates
to stay in California instead of leaving the state and to develop the
high-tech region in the area now known as Silicon Valley. As a result
California is regarded as a world centre for the technology, engineering, and
aerospace industries. The specific climate of a region may determine the
crops that can be grown and this influences the location of the processing
plants if there is considerable weight loss during the processing phase,
and especially if these crops are to enter the world trade markets, like palm
oil and sugar.
Labour
Labour costs still make up a sizeable proportion of manufacturing costs. Labour
costs can be wage rates or unit costs. Wages are high in HICs and lower in LICs
and as a result many TNCs have located in low wage cost countries. Initially
TNCs moved to South Korea, Taiwan and Singapore but as wages rose in these
countries they relocated to Thailand, Indonesia and, since the 1990s, to China.
The labour cost as part of the production of an Apple iPad is a mere 2 per cent.
More important than wage rates are the unit labour costs, which relate wages to
output or productivity-the productivity level of workers interests industrialists,
not simply what they have to pay. Low wage areas may mean low productivity
and so high unit costs.
Labour quality is also important especially as automation has replaced many
manual jobs in manufacturing. Toyota chose to locate their factory in Derby,
UK, not because of high unemployment levels but because there was a history
of engineering in the area. Skilled workers are vital to the prosperity of R 8< D
(research and development) companies involved in high-tech industries for
whom innovation is everything. These sorts of companies will locate where there
are a disproportionate number of highly skilled workers, for example Silicon
Valley in California.
Low wage costs should encourage investment but the benefit of lower labour
costs is offset by the fact that during a recession labour costs are also falling in
other countries.
Capital
A major influence on the location of an industry are the two types of capital
available to an entrepreneur-financial capital and fixed capital. Financial capital
is the money (funds) available for investment. One important characteristic of
this type of capital is its mobility. Companies and their financial supporters
invest in areas where profits are high and disinvest where profits are low. This
may vary regionally within a country and is reflected in the problems in getting
investment in northeast England, unlike the ease with which investment is
attracted in the southeast. Internationally investors will shy away from areas
where the potential for conflict exists, preferring instead a more stable financial
environment.
Fixed capital, plant and machinery is immobile and another reason for an
industry to persist in an area, creating industrial inertia. This occurs when
companies are reluctant to write off valuable fixed assets so long as they remain
profitable. The Ruhr region in Germany and Liege in Belgium all retain steel
industries as it would be costly to transfer the fixed capital investments of
the steel industry to less costly sites. These regions have all acquired a skilled
workforce, a reputation for high quality and the necessary transport links to
ensure that the locations remain profitable.
figure
11.23 Nineteenth-century textile mill, Lille, France
11.24 The new Rolls Royce facility, located on a
greenfield site, Sussex, UK.
figure
figure
11.26 Pacific Quay, Glasgow
Production, location and change
25
------ labour costs per hour
------ wage costs per hour
other costs per hour
QI, Q2, Q3 and Q4 are quarters 1 to 4 of each year
-10
8888888888888888888
figure
11.27 UK Index of Labour Costs, 2001-2014
External and internal economies and diseconomies of scale
External economies and diseconomies of scale are the benefits and costs
associated with the expansion of a whole industry and result from external
factors over which a single firm has little or no control.
External economies of scale include the benefits of positive externalities
enjoyed by firms as a result of the development of an industry or the
whole economy. For example, as an industry develops in a particular region,
such as the car industry in the West Midlands, UK, an infrastructure of
transport communications will develop, which all industry members can
benefit from. Specialist suppliers of lighting, brakes and windscreens
may also enter the industry and existing firms may benefit from their
"I don't want your wallet, I want venture capital."
figure
11.28 Venture capital is important to a business.
proximity.
External diseconomies are costs that are outside the control of a single
firm and result from the growth of a specific industry. For example, negative
externalities may arise as resources become exhausted, especially primary raw
materials, for example coal and iron ore.
Internal economies and diseconomies of scale are associated with the expansion
of a single firm.
Five types of internal economies of scale can be identified:
• Technical economies are the cost savings a firm makes as it grows larger,
and they arise from the increased use of large scale mechanical processes
•
•
•
•
and machinery.
Purchasing economies are gained when larger firms buy in bulk and achieve
purchasing discounts.
Administrative savings can arise when large firms spread their
administrative and management costs across all locations needing only one
set of accountants for its separate enterprises.
Large firms can gain financial savings because they can usually borrow
money more cheaply than small firms.
Risk bearing economies are often derived by large firms who can bear
business risks more effectively than smaller firms.
Internal diseconomies of scale may include:
• Large firms may suffer from poor communication because they find it
difficult to maintain an effective flow of information between their various
•
•
operations.
Coordination problems also affect large firms with many departments and
divisions and a workforce numbering into the tens of thousands.
Low motivation of workers in large firms is a potential diseconomy of scale
that results in lower productivity, as measured by output per worker.
274 Production, location and change
figure
11.29 Steel works, Liege, Belgium
Government policy
Government involvement in industrial matters will largely depend on the
political system of the country in question. A command economy, such as
China, is where the government, rather than the free market, determines what
goods should be produced, how much should be produced and the price goods
will be offered for sale.
In the rest of the world although the state does intervene for socio­
political and economic reasons, locational decisions are made by individual
firms and are governed by profit and loss. In the UK Labour governments
tend to be more involved whereas with Conservative (Tory) governments
such state involvement is less likely. Government regional policy is often
guided by the need to solve other socio-political problems and not just
those of industry, such as high unemployment rates, urban dereliction and
decentralisation.
Industrial agglomeration and linkages
Agglomeration or external economies is the grouping together of industries
and economic activities in close proximity. The result, as has been seen, can
be organisations benefitting from economies of scale by sharing costs and
transport systems. Factors that might lead to the creation of diseconomies
of scale, such as increasing traffic congestion, might well lead to companies
deglomerating. Intrinsic to this idea are the contacts and flows or linkages
between companies when they are close to each other. There are four types of
linkage. Figure 11.31 shows the sort of links that could encourage companies to
agglomerate.
figure
11.30 Economies of scale
Production, location and change 275
(a) Vertical (or simple chain) linkages
(b)
The raw material goes through several successive processes:
An industry relies on several other industries to provide its
component parts:
newsprint
•
------------------------------------------ .----------------
brakes------------------gearboxes--------------
pulp
—
mill logging
Horizontal (or simple origin) linkages
car assembly
plant
electrical equipment
tyres --------------------radiators---------------
•
(c) Diagonal linkages
(d) Technological linkages
An industry makes a component which can be used subsequently in
several industries:
watches and clocks
A product from one industry is used subsequently as a raw
other industries:
«------------steel
steel
processed
------------ ►
processed
wire
into
-------------►
into
------------- ►
washers, nuts
and bolts
figure
car industry
domestic appliances
repair workshops/garages
material by
nails
screws
cable
electrical
wiring
11.31 (a)—(d) Linkages
Industrial estates
The thinking behind the development of the industrial estate in the UK goes
back to the period between the two world wars when industry was being
encouraged to move out of inner city locations to ‘new’ purpose-built areas in
the suburbs or on the edges of built-up areas. Benefits included:
•
concentrated purpose-built infrastructure leading to reduced costs per firm
•
•
•
•
attraction for new industries with infrastructure already in place
separation of residential and industrial land uses
localised environmental controls suiting the industry in the area
companies located on these estates were eligible for grants and loans from a
variety of regional development policies from central government.
Export processing zones
Variously called free trade zones, special economic zones and free ports, export
processing zones (EPZs) are defined as zones with special incentives to attract
foreign investors in which imported goods undergo some degree of processing
before being re-exported. The table below shows the rapid growth of the
number of EPZs in an ever-increasing number of countries.
table
11.5 The development of export processing zones
1975
2002
2006
93
116
130
176
845
3000
3500
n.a.
n.a.
22.5
43
66
- China
n.a.
n.a.
18
30
40
- other countries
with figures available
0.8
1.9
4-5
13
26
Physical factors
1986
Numbers of
countries with EPZs
25
47
Number of EPZs or
similar zones
79
Employment
(millions)
1997
The formal and informal sectors of employment
The concept of the informal sector was introduced into international usage in
1972 by the International Labour Organization (ILO), which defined informality
figure
11.32 Worldwide formal and informal employment
276 Production, location and change
as a way of doing things characterised by:
•
•
ease of entry
reliance on indigenous resources
family ownership
small scale operations
•
•
•
labour intensive and adaptive technology
skills acquired outside of the formal sector
unregulated and competitive markets.
•
•
A World Bank report further identified two types of informal sector activities,
which can be described as follows:
i
2
Coping strategies: casual jobs, temporary jobs, unpaid jobs, subsistence
agriculture, multiple job holding.
Unofficial earning strategies (illegality in business).
figure
11.33 A street seller in Beijing, China.
The informal sector has a number of advantages and disadvantages for the
people who are involved. On the plus side it provides jobs thereby reducing
unemployment and, most importantly, underemployment, although the jobs
are low-paid and job security is poor. The informal sector also encourages
entrepreneurial activity and helps alleviate poverty. The World Bank (2010)
estimates that the size of the informal labour market varies from an estimated
4-6 per cent in high-income countries to over 50 per cent in low-income
countries. During economic downturns these numbers rise.
The informal sector also improves the condition of the poor, especially
women, giving an opportunity to earn some money that will help improve their
lives and the lives of their families. These jobs are often concentrated in and
around the CBD or close to tourist sites.
The formal sector, on the other hand, usually comprises employees with
recognised income sources for paying income taxes based on a 38-hour regular
wage job.
figure
11.34 Street food seller, Bangkok,Thailand
Production, location and change
The management of change in the manufacturing industry
Case Study
A
new country:
Bangladesh
This area of Asia has always been a prosperous region but under British rule
East Bengal became a largely agricultural area producing primary goods for
processing and export. Partition in 1947 and the creation of India and Pakistan
caused serious disruption to the economic system. The Pakistan Five Year
Development Programme was based heavily on industrialisation but the largest
part of the budget went to West Pakistan, leaving the resource-scarce East
Pakistan reliant on imports, resulting in the now largely agrarian economy of
East Pakistan going into decline.
By independence in 1971 Bangladesh was one of the least industrially
developed countries among the populous nations of the world. Bangladesh
consumed only one-fifth of the electricity and one-third of the steel of their
Indian neighbours. Many external markets had been lost and although there
was a large workforce it was undertrained, underpaid, largely illiterate, unskilled
and underemployed. The war for independence had crippled what transport
infrastructure there was and the country was still coming to grips with the
damage and death caused by the cyclone of 1970.
In the mid-1970s, with substantial help from India, the USA and the USSR,
the Bangladesh government turned its attention to the development of new
industrial and economic capacity. This involved a programme of nationalisation
that, far from galvanising the economy, led to further stagnation and
inefficiencies. Subsequently the government allowed greater scope to the private
sector, a policy that still continues. However inefficiency in key areas of the
public sector meant growth was restricted until well into the 1980s. In 2003 the
International Monetary Fund (IMF) approved a loan of US$390 million and the
World Bank a further US$536 million to support the government’s economic
reform programme up to the year 2006.
There have been a number of ongoing structural weaknesses in Bangladesh
that have held back progress:
•
•
•
•
•
•
•
•
•
•
the inefficiency of state-owned industries
widespread political and bureaucratic corruption
economic competition, relative to the world
serious overpopulation, which cannot be absorbed into the agricultural
sector
widespread poverty
frequent cyclones and floods (1987,1988,1998, 2007)
political instability
poor infrastructure
insufficient power supplies
the slow implementation of economic reform.
However progress is being made and the economy has shown considerable
improvement in encouraging foreign direct investment (FDI) by:
•
•
•
cooperating with foreign companies to explore and exploit oil and gas
deposits in the Bay of Bengal
constructing natural gas pipelines and power stations
distributing cooking gas across the country.
Progress at last?
It is now perhaps more accurate to describe Bangladesh as a Next Eleven
emerging market, along with countries such as Egypt, Indonesia, Iran, Mexico
and Vietnam or as one of the Frontier Five, with Nigeria, Peru, Vietnam and
278 Production, location and change
figure
11.36 Collapsed factory at Rana Plaza, Dhaka, Bangladesh
Oman. An emerging market is a country that has some characteristics of a
developed market but does not meet the standards required to be a developed
market. This includes countries that may be developed markets in the future
or were in the past. The term frontier market is used for developing countries
with slower economies than ‘emerging’. Bangladesh stands in a prime location
to develop as a regional transportation hub and focal point for the South Asian
Association for Regional Co-operation (SAARC), the Bay of Bengal Initiative for
Multi-SectorTechnology and Economic Cooperation (BIMSTEC), the Association
of South East Asian Nations (ASEAN) and the countries around the Indian Ocean.
Bangladesh’s pro-capitalist population helped the country experience a
growth rate of 6 per cent in the 10 years between 2004 and 2014 (projected to be
6.5 per cent in 2016). Much of Bangladesh’s industry is export-orientated, with
a textile industry second only to China in terms of size. Other key industries
include ceramics, electronics, pharmaceuticals and shipbuilding. The soils in
Bangladesh are extremely fertile, being located on the vast deltaic deposits laid
down by the three great rivers, the Ganges, Brahmaputra and Meghna, that flow
into the Bay of Bengal, which also means that agriculture and the processing of
products are important industries.
The textile industry accounts for some 80 per cent of Bangladesh’s exports
(2009) but this is an industry where there is increasing unrest and demands for
improvements. While some textile and ready-made garment (RMG) factories are
modern, well equipped and well managed, the garment trade remains plagued
by accusations of low wages and unregulated working conditions-as was seen
in the Rana Plaza factory collapse in April 2013, which killed 1100 workers.
In 1993 a Child Labour Deterrence Bill forced an estimated 50 000 children
into an unregulated informal sector. Although conditions are not ideal the work
is financially more reliable than some other sectors, is less degrading than street
prostitution, and the wages enable women in particular to invest in their future
Production, location and change
as well as giving them money to spend and save. Money sent as remittances
helps the extended family in the home village and there are other benefits
beyond those of an economic nature. Women working in the garment industry
marry later, have fewer children and achieve higher levels of education, allowing
them to progress.
Vision 2021
In 2008 the Bangladesh Awami League won the general election with a
manifesto titled Vision 2021. This was to be the policy by which the country
would become a MIC and poverty would be completely eradicated by 2021,
which is the year of the country’s golden jubilee. The slogan ‘Digital Bangladesh’
proclaimed how, with the use of computers and the efficient application
of technology, the election promises of education, health, jobs and poverty
reduction were to be achieved.
Vision 2021 relies on changing attitudes in a patriarchal society to achieve the
empowerment of women and the granting of equal rights. The ultimate goal
is to improve the overall lifestyle of all people regardless of class and position.
Some seven years on from the election government departments are still using
paper-based systems and there have been serious issues of computer data
security, such as the release of the personal details of employees in a number of
government institutions.
Nevertheless the private IT industry continues to expand and in 2010 there
were over 300 firms who were registered as members of the Bangladesh
Association of Software and Information Services (BASIS). This growth has
occurred for a number of reasons:
•
•
•
a growing pool of locally available ICT skills
increasing confidence in the talent of the pool by global consumers
a clear move away from the labour-intensive style of production industries.
The fact that English is the second language in Bangladesh and it is the
international language of business and trade makes the country an attractive
proposition for ‘off-shoring’ of software development and ICT services. The
Japan International Co-operation Agency (J ICA) ranked Bangladesh ahead of all
other Asian countries, including India and China, for offshore competitiveness
as a result of the companies that now flourish there, such as Walton
motorcycles, Jamuna Oil Company and Grameenphone.
The Bangladesh government has drafted a new industrial policy, which includes
stimulus packages for special economic zones aimed at the export market and
incentives for any future foreign direct investment. This is similar to the Chinese
economic model of the 1990s. Companies who invest in areas that are lagging
behind industrially will receive tax breaks on any imported capital machinery
or plant. Indeed foreign entrepreneurs will be offered five-year visas and even
citizenship if they invest sufficient funds, and might be invited to run loss-making
state industries with an emphasis on local market orientated industries.
What does the future hold for Bangladesh?
The website Economy Watch (2015) reports steady growth in the economy of
Bangladesh. Remittances from the Bangladeshi diaspora play a large role in the
generation of foreign exchange and with poverty levels falling and literacy rates
rising the future looks promising. Continued FDI in all sectors of the economy
is encouraging, shipbuilding is growing rapidly with full order books and the
ship breaking industry employs over 200 000 workers. Bangladesh recently
overtook India in clothing exports worth US$3.12 billion (2014).
But labour unrest in the RMG industry has continued with demands for
better wages and improved working conditions. Consequently some sweater
factories are reported to have automated to overcome the problem of worker
unrest. A manual knitting machine needs one operator and can produce a
maximum of five garments a day. On the other hand an automatic machine,
figure
11.37 Protesting textile workers
Production, location and change
also operated by a single operator, can produce about 30 garments a day. Many
owners are buying expensive automatic machines in order to remain cost
competitive in the long term.
How the Bangladesh government continues to respond to workers’ demands
will determine how much progress the country makes towards its Vision 2021
in the coming years. At present the government’s apparent unwillingness to
engage with the mechanisms required for change suggest that Vision 2021 is
unlikely to have been achieved by 2021.
NOW INVESTIGATE
1
Investigate the contribution that agriculture makes to the economy
of the country you live in. What changes have taken place in the last
25 years and what changes are likely to occur in the future?
2
Investigate the types of companies that are located in an EPZ of
your choice. What locating factors will have been important to
attract these companies to the EPZ?
3
Investigate the issues of soil erosion in a country of your choice. What
measures are being implemented to reduce the effects of soil erosion?
4
Desertification affects huge areas and millions of people.
Investigate the measures being taken by governments and NGOs in
a country of your choice to reduce this problem. How successful do
you think the measures are likely to be in combatting the problem?
Production, location and chang<
281
C02 emissions from comsumption of fossil fuels
CO2 emission values are those calculated
from the burning of fossil fuels and
include emissions produced during the
consumption of solid, liquid and gas
fuels, plus those produced during the
flaring of gas.
u<z
UK Netherlands
498 9
239.6
66
Belgium
1399.6
CO2 emissions from the consumption of petroleum 2012
World
32 310.2
flaring of natural gas 2012
Energy regions of the world
Eurasia
Europe
Middle
East
Germany
788.3
12
Environm ental m anagem ent
Europe
Poland
289.5
Asia
Oceania
Africa
4263.3
Turkey
296.9
Kazakhstan
224.2
Russia
1781.7
Uzbekistan
123.2
Ukraine
290.4
Eurasia
2672.0
South Korea
657.1
Japan
1259.1
China
8106.4
Taiwan
307.1
Pakistan
146.9
Vietnam
131.7
India
1830.9
Asia $ Oceania
14 435.8
Thailand
290.7 Singapore
208.0 Malaysia
198.8
Indonesia
456.2
Australia
420.6
Algeria
133.9
Egypt
206.3
Emissions
CO2 Emissions 2012
(million tonnes)
>5000
South Africa
473.2
Africa
1205.7
1000-5000
500- 1000
300-500
200 - 300
100-200
10- 100
0.1-10
Countries with emissions
< 100 are not named.
---------- 1
283
Sustainable energy supplies
Renewable and non-renewable energy resources
Fossil fuels - natural fuels such as coal, oil and gas that have been formed from
the fossilised remains of living organisms-and nuclearfuel, such as uranium
and plutonium, are non-renewable. This means that there is a finite supply that
will eventually become exhausted. Current estimates suggest that oil may run
out by 2050, gas by 2060 and coal by 2090. Conversely, renewable energy can
be used indefinitely. Typically these forms of energy, which include hydroelectric
power (HEP), biomass, wind, solar, geothermal, tidal and wave power, cause less
environmental pollution and are more sustainable.
Currently, non-renewable resources dominate global energy; in 2013
87 per cent of energy consumption was from fossil fuels, with nuclear making
up a further 4 per cent. Since the invention of the internal combustion engine
in the seventeenth century, infrastructure and transport systems have relied on
fossil fuels and these are therefore in continual demand. However, this position
is unsustainable and the global energy mix needs to be transformed so that
there is more balance between renewable and non-renewable energy.
Factors at the national scale affecting demand for and supply of energy
Clearly, on a national scale, different countries have vastly different populations
and levels of economic development so there are huge variations in energy
demand and supply. China, with a population of over 1.3 billion people,
consumes approximately 5.5 billion megawatt hours per year (MW.h/yr) of
figure
i2.i Smoke stacks at a coal-burning power plant.
figure
12.2 The Green Evolution - moving from fossil fuels to renewable sources of energy.
284 Environmental management
electricity. Afghanistan, with a population of just over 30 million people,
consumes 231100 MW.h/yr. There is a loose positive correlation between GDP
and energy demand - the USA consumes 25 per cent of the world’s energy and
has a global share of GDP at 22 per cent-although climate can also have an
impact. However, growth in energy demand is particularly intense in newly
industrialising countries such as India and China. The energy policy of a country
can also have a significant impact on demand; if a country focuses on efficiency
and sustainability, demand in renewables may increase, yet if an industrialising
nation concentrates on building power stations, this may result in an increase in
demand for non-renewable energy.
On the other side of the equation, there are also national variations in supply
that can be explained by a range of physical, economic and political factors.
Physical factors affecting the supply of energy include the fact that deposits of
fossil fuels are only found in a limited number of locations and that renewable
sources of energy are often natural and therefore require suitable conditions.
For example, solar power requires a large number of days per year with strong
sunlight, tidal power requires a very large tidal range, wind power requires high
average wind speeds throughout the year and HEP requires high precipitation,
steep-sided valleys and impermeable rock. Also, the associated infrastructurelarge power stations, for example - requires vast areas of flat land and
geologically stable foundations in order to be developed.
Coupled with specific physical factors are a series of economic factors
affecting supply. Exploitation of resources is often an economic consideration,
with the most accessible, and therefore lowest cost, areas being developed first.
These are likely to be onshore rather than offshore in the case of fossil fuel
deposits and close to major transport and electricity transmission routes in the
case of HEP. In countries that are less industrialised foreign direct investment is
often required for the development of energy resources. In addition, as energy
prices can be volatile, when prices rise companies are more likely to increase
spending on exploration and exploitation.
Finally, political factors at both a national and global scale can affect the supply
of energy. For example, international agreements such as the Kyoto Protocol
(2008-12)- an international climate change agreement- can have a significant
impact on the way in which nations organise their energy; low-sulfur coal is likely
to be favoured over high-sulfur coal as it is more likely to comply with legislation
regarding power station emissions. Currently 31 countries operate nuclear power
stations, although only France, Belgium, Hungary and Slovakia use them as
their primary source of energy. However, any country wishing to develop nuclear
energy requires permission from the International Atomic Energy Agency (IAEA).
Environmental management 285
figure
i2.4Îurbines generating renewable energy from the wind.
It is not only non-renewable sources of energy that are affected by political
factors, for example a potential HEP scheme that draws its water from a river
that crosses national political boundaries may require agreement from the other
countries that share the catchment Also, on a national scale, governments may
insist that energy companies produce a certain proportion of their energy from
renewable sources, which may significantly affect supply.
The balance between different sources
Perhaps the most significant factor in energy supply is resource endowmentthe level of energy resources a country can exploit. Generally, those countries
with a high resource endowment tend to be more prosperous than those
who lack domestic energy resources and rely heavily on imports. However,
resource curse theory suggests that this is not always the case with some
countries, particularly those with an abundance of non-renewable energy
resources, growing more slowly economically than those without a high
resource endowment. There are many explanations for this including the
volatility of prices on the global market, the decline in the competitiveness of
other economic sectors, government mismanagement and weak and ineffectual
exploitation of the resources. It is therefore clear that the physical presence
of resources themselves does not constitute a ready supply- capital and
technology in particular are required to exploit these resources.
Developments in technology have increased our ability to exploit resources.
For example, the Newjersey Institute ofTechnology has developed solar
cells that are so thin they can be embedded into paints and located in places
previously unsuitable for solar panels. Also, Advance Turbine Systems (ATS)
have increased the height of their turbines, which can boost their efficiency
286 Environmental management
by about 20 per cent. Yet it is not only renewable energy that has seen
such developments. Oil and gas deepwater drilling is on the rise with over
3400 deepwater wells in the Gulf of Mexico alone and hydraulic fracturing or
‘fracking’ has become a controversial method of extracting shale gas. Research,
development and implementation of these new technologies requires vast
amounts of capital - each fracking well costs between US$8 million and
US$12 million dollars - and so MICs/LICs are limited in their exploitation of
energy resources.
Environmental impact can also be a factor in the exploitation of energy
resources; people are generally well informed about the environmental impact
of energy sources and can influence government policy. The use of hydraulic
fracturing in the UK is a case in point. UK Onshore Oil and Gas (UKOOG)
carried out a survey in 2014 and found that 57 per cent of the UK population is
in favour of fracking. However, Greenpeace criticised the lack of independence
of the survey and highlighted environmental issues associated with the process
such as groundwater contamination and increased seismicity. To date, Members
of Parliament have rejected a fracking moratorium although an outright ban
has been pledged on fracking in National Parks and 13 conditions must be met
before fracking can take place in the UK.
figure
12.5 Fracking protesters in New York.
Trends in the consumption of fossil fuels, nuclear power and renewables in
MICs and LICs
The amount of energy used globally has been rapidly increasing in recent
decades as a result of both the growing global population and the increased
national wealth and living standards of countries such as China and India.
In 1990,102 569 terawatt-hours (TWh) of energy were used globally, of which
81 % were from fossil fuels, 6 % were from nuclear power and 13 % were
from renewable sources. By 2008 global energy use had increased by 22 % to
143 851 TWh and all three energy sectors had increased; fossil fuels by 24 %,
nuclear by 5 % and renewables by 21 %.
figure
12.6 The fracking process
Environmental management 287
250
figure
History
2015
Projections
12.7 World energy consumption outlook
Oil
Nowhere in the world is the contribution of oil to energy consumption less
than 25 per cent It is the main source of energy in North, South and Central
America and Africa and accounts for approximately 50 per cent of energy use
in the Middle East. The pattern of production is very different to the pattern of
consumption; consumption grew by 1.4 million barrels per day in 2014 whilst
production grew at a slower rate of 550 000 barrels per day. The Middle East
accounted for about 48 per cent of all proved reserves (down from almost
60 per cent in 2008) and 32 percent of all production, with over 13 per cent of
global production in Saudi Arabia alone.
Coal
Coal is the main source of energy in the Asia Pacific region but does not feature
strongly in the energy mix of the other world regions. Europe and Eurasia, Asia
Pacific and North America each have a fairlyeven spread of proved coal reserves
(35 %, 32 % and 28 % respectively) although China dominates production with
47 % of the global total. Consumption is also dominated by the Asia Pacific region,
which consumes over 70 % of the global total; China alone consumes over 50 %.
Natural gas
Natural gas is the main source of energy in Europe and Eurasia and a close
second to oil in the Middle East but it does not feature highly in the energy mix of
the Asia Pacific region. Production of natural gas increased from 3066 billion m3
in 2008 to 3369 billion m3 in 2013. There is a stronger correlation between the
consumption and production of natural gas than there is for oil, which is mainly
due to the different ways in which the fuels are transported. Therefore, as well as
being the two biggest producers of natural gas, the USA and Russia are also its
two largest consumers, using 22 per cent and 12 per cent respectively.
Nuclear power
Nuclear power is not currently available in the Middle East and it makes the
smallest contribution to most of the other world regions. Several European
countries, including France, use nuclear power as their primary source of
electricity and some countries, including China, South Korea and India are
expanding production; India aims to have 25 per cent of its electricity produced
by nuclear power by 2050. The USA is the biggest consumer of nuclear power,
consuming about 33 per cent of the global total.
Hydroelectric power (HEP)
HEP dominates renewable energy production with the ‘big four’- China,
Canada, Brazil and the USA - producing nearly 55 per cent of the total. However,
because HEP requires very specific physical conditions, most of the optimum
locations are already in use and so further development is limited. Costa Rica
23
Environmental management
generated 100 per cent of its energy from renewable sources for the first 75 days
of 2015; this is the first time a country has managed to power itself for so long
without the use of fossil fuels. Excellent infrastructure and unusually heavy
rainfall at the end of 2014 enabled Costa Rica’s four hydroelectric power stations
to work efficiently, allowing it to achieve this milestone.
Wind power
Wind power is growing rapidly as a renewable energy source; doubling in
capacity every three years. Wind power capacity in 2014 was 336 gigawatts (GW),
accounting for around 4 per cent of global energy usage. This rapid growth is a
result of the decreasing costs of wind technology relative to other conventional
energy sources.
Biofuels
Biofuels are fossil fuel substitutes that can be made from a range of crops
including oilseeds, corn and sugar. The USA is the biggest biofuel producer with
44 per cent of the global market, followed by Brazil with 24 per cent. Ethanol
fuel stations are available throughout Brazil and carmakers have developed
a range of‘flex’ cars that run on any blend of ethanol and gasoline. Biofuel
production in some European and Asian countries is growing rapidly; the UK
saw an increase of over 50 per cent between 2012 and 2013 and India saw an
increase of 42 per cent over the same time period.
Trends in LICs
There is considerable variation in the rate of energy growth in LICs, which is
largely due to variations in both economic development and population growth.
It is usually the highest income groups who have access to electricity; globally,
2 billion people lack access to household electricity. In addition, biomass
accounts for over 90 per cent of total energy consumption in most LICs.
Trends in MICs
MICs are increasing their energy demand at the fastest rate. For example,
China accounts for one-third of global growth in energy demand since 2000
figure
12.8 Global energy consumption, 2012
Environmental management 289
figure
12.9Trans-Alaska Pipeline
(although its consumption per person is still significantly behind that of the
USA). Much of this demand is satisfied by fossil fuels, which have a significant
impact on greenhouse gas emissions; MICs accounted for nearly 50 per cent of
global CO2 emissions in 2013, a figure that is increasing every year.
Trends in HICs
Deindustrialisation and greater energy efficiency mean that increases in energy
demand in HICs have remained fairly modest, indeed some countries, such as
Sweden and Norway, have seen decreases in energy demand of over 5 per cent.
The environmental impact of energy production, transport and use at local
and global levels
The environmental impact of burning fossil fuels and other man-made
causes of global warming have been much debated. As energy insecurity has
increased, so energy companies have had to exploit technically difficult and
environmentally sensitive areas. For example, the Trans-Alaska Pipeline (TAP)
snakes 1280 km over the Alaskan permafrost from Prudhoe Bay in the north to
Valdez in the south. TAP delivers 20 per cent of US domestic oil production and
crosses three mountain ranges and over 800 rivers. More than 675 km of the
pipeline is above ground; the oil travels through the pipeline at 82 °C, which is
enough to melt the permafrost and cause subsidence and leaks (although the
design has taken this into consideration). The pipeline has also been designed
to take account of the diverse wildlife of the area. Caribou migrate seasonally
and so the pipeline is elevated by at least 3 m in over 500 locations so that they
can have clear access through the pipeline corridor.
Ironically, the melting of sea ice in the Arctic as a result of global warming
is opening up the region to further exploration. The United States Geological
Survey (USGS) estimates that over 25 per cent of the world’s undiscovered oil
Environmental management
and gas reserves are likely to be found in the Arctic regions, whilst other surveys
suggest as many as 200 billion barrels of oil may be available, which is over
twice the amount of oil found in Kuwait. Most environmentalists oppose the
exploration and exploitation of the Arctic and argue that the environmental
consequences of an oil spill would be serious in such a vulnerable and unique
environment.
The Deepwater Horizon oil spill near the Mississippi River Delta, USA,
provides an example of how energy production has the potential to result in
devastating environmental impacts. An explosion on the Deepwater Horizon oil
rig occurred on 20 April 2010 resulting in an oil spill of over 4.9 million barrels
of oil over the course of 87 days. Around 180 000 sq km of the Gulf of Mexico
was affected, home to over 3300 species. Many of these species were directly
affected by the oil - of 32 dolphins caught off the coast of Louisiana in 2013 over
half were dead or dying- and there are concerns that the oil could remain in
the food chain for generations.
figure
12.10 Deepwater Horizon oil spill
The management of energy supply
Case Study
China’s electrical energy strategy
In 2009 China overtook the USA as the world’s top energy user, a position which
it had held for more than a century. What was particularly startling about this
fact was that only 10 years previously China’s consumption was about half that of
the USA. This growth can mostly be explained by China’s rapid industrialisation,
its large population and its growing middle class.
In 2011 China's energy mix was dominated by coal (69 %), followed by oil
(18 %), HEP (6 %), natural gas (4 %) and other renewables (1 %). Given China’s
reliance on fossil fuels it is also unsurprising that in 2007 China also overtook
the USA as the world’s biggest emitter of COj it released 8715 million metric
tonnes in 2011. However, China’s 12th Five-year Plan (2011-15) built on its
predecessor by ensuring more sustainable growth and investing in environment
protection industries. Whilst estimates in.2007 suggested that China was
building new power stations at the rate of two every week, in recent years they
have replaced many of their older power plants with more efficient technologies.
Estimates suggest that these ‘cleaner’ power plants have an efficiency of up to
44 %, meaning that carbon emissions are cut by a third.
figure
12.11 China’s primary energy production and consumption, 1980-2009
Environmental management 291
Coal
China has plans to build over 360 new coal-fired power stations over the next
few years. Most of these will be built in the east of the country with 60 per cent
concentrated in the six provinces of Inner Mongolia, Shaanxi, Gansu,
Ningxia, Shanxi and Hebei. However there is concern that these provinces
only account for 5 per cent of water resources - coal power stations are water
intensive because water is needed to cool generators and create steam - where
competition for water from agriculture and industry is already high.
Petroleum reserves
As well as developing energy from coal, China is following the USA and Japan
in developing strategic petroleum reserves. In 2007 the Chinese government
announced that there would be an expansion of reserves so that by 2020 it
would hold approximately 209 million barrels (the equivalent to 90 days of
figure
12.13 Workers in a Chinese coal mine.
292 Environmental management
figure
12.14 Rooftop solar water heaters in Hubei.
consumption). Most of these reserves will be held in government-controlled
facilities located in Liaoning, Shandong and Zhejiang provinces.
Renewable energy
China is also the world leader in renewable energy production and this sector
is growing more rapidly than both its fossil fuel and nuclear power capacities.
In 2013 China generated a total of 378 GW from renewables, mainly from HEP
and wind power, and was producing as much energy from water, wind and
solar energy as France and Germany combined by 2014. Longer-term estimates
suggest that by 2050 China will be producing 30-50 per cent of its energy from
fossil fuels; the remaining 70-50 per cent will be produced from renewables.
This is due to the finite nature of fossil fuel reserves meaning that all countries,
not just China, will have to switch to renewable sources.
Wind power
China’s large landmass and long coastline provide suitable conditions for
wind power generation in particular. Estimates suggest that it has a potential
2400 GW capacity on land and a further 200 GW capacity offshore. The Gansu
Wind Farm Project, currently under construction in the desert of western Gansu
province, is likely to become the world’s largest single generator of wind power
when completed. At an estimated cost of US$17.5 billion it should generate
approximately 20 000 MW by 2020.
The National Energy Council (NEC)
Since 2010 the NEC has been responsible for drafting the country’s energy plan
and ensuring energy security. The NEC is overseen by the Chinese Premier, Wen
Jiabao, and has implemented a range of policies to encourage and promote
renewable energy. These include the ‘Golden Sun’ programme, which provides
financial subsidies, technological support and market incentives to promote the
development of the solar power industry.
Environmental management 293
Case Study
TheThreeGorges Dam,China
The Three Gorges Dam is the world’s largest electricity generating power plant
and the greatest producer of hydroelectric energy; it overtook Brazil’s Itaipu
Dam in 2014 by producing 98.8 TWh as opposed to Itaipu’s 87.8 TWh. Spanning
the Yangtze River at Sandouping in Hebei province, the dam was completed
and fully functional on 4 July 2012. The dam took 18 years to construct and cost
US$26 billion.
The dam is over 2 km long and 100 m high and houses 32 turbines with
a capacity of 700 MW each. The capacity of the plant is 22 500 MW. As well
figure
12.15 Satellite image oftheThree Gorges Dam
as generating massive amounts of electricity it is also hoped that the project
will expand the Yangtze River’s shipping capacity and reduce the likelihood of
flooding. Water levels upstream have risen by 90 m, which has had the effect
of transforming the river rapids into a lake, allowing ships to function in this
stretch of river. Downstream an estimated 10 million people will be protected
from flooding as the dam provides additional flood storage.
One key objective of the dam is to reduce China’s dependence on coal. The
plant provides electricity to two cities, including Shanghai, and nine provinces. It
was hoped that, when fully functional, it would provide about 10 per cent of China’s
power, although on average it supports less than 2 per cent. However, at full
capacity the Three Gorges Dam reduces coal consumption by 31 million tonnes per
year, which in turn avoids over 100 million tonnes of greenhouse gas emissions.
Erosion and tremors
There are two hazards that make the dam vulnerable. First, over 80 per cent of the
land surrounding the dam is eroding and depositing about 40 million tonnes of
sediment into the Yangtze Ri ver every year. This is trapped behind the dam and
so areas downstream are likely to be starved of sediment, making them more
vulnerable to flooding and reducing aquatic biodiversity. Second, the dam sits
on a seismic fault and the area is prone to earthquakes and landslides. In the first
four months of 2010 there were 97 significant landslides and in May 2009 around
50 000 cubic metres of material plunged into Wuxia Gorge. In addition, the dam
itself is also under threat from seismic activity. Between June 2003 (when inundation
of the dam reservoir began) and December 2009 there was a 30-fold increase in
seismic events compared to the pre-dam period. Seismic activity appears to increase
when operators increase or decrease the water in the reservoir rapidly and whilst
figure
12.16“hree Gorges Dam location map
Environmental management
figure
12.17 A panoramic view of the Three Gorges Dam.
most of the tremors were of relatively small magnitude (under 2.9 on the Richter
scale), there have been examples of earthquakes reaching 4.1 on the Richter scale.
Relocation and cultural loss
Despite the great potential of the Three Gorges Dam there was much opposition to
the project. A total of 1.24 million residents were relocated from the area that was
to become the dam’s 1045 sq km reservoir (an area larger than Singapore!). Many
of these people have had to move more than once and approximately 140 000 have
been relocated to other provinces. Also, much of the resettlement has been to land
more than 800 m above sea level where temperatures are cooler and the soil is less
fertile. Other criticisms relate to aesthetics and the destruction of cultural sites.
The flooding of the 600 km-long reservoir raised the level of the water by over
90 m and over 1300 archaeological sites were consequently flooded. Whilst efforts
were made to move cultural and historic relics as they were discovered, some have
inevitably been destroyed as they could not be moved given their size, location
or design. For example, many of the hanging coffins on the Shennong Stream
Gorge’s limestone cliffs have been lost or destroyed, although one was found
around 10 km west in the Yangtze River and is displayed in a nearby Daoist temple.
figure
12.18 Hanging coffins
figure
12.19 An abandoned bunker near Chernobyl,
Environmental degradation
Pollution: character, causes, solutions
Environmental degradation is the deterioration of environmental quality through
the increase of pollutants (in the land, air or water) and other processes such as
improper land use and natural disasters. The nature of pollution, in particular,
means that its impact may spread beyond local areas and cross international
borders. For example, in 2011, 25 years after the nuclear meltdown at Chernobyl,
Ukraine in 1986, 355 Welsh farmers were still affected by the fallout that had
covered most of Europe. Also, recent research has suggested that forest fires in
Ukraine and Belarus may release further radiation. Tree leaves pick up radioactive
ions that are then returned to the soil when the leaves die. Whilst health risks and
environmental impacts are generally greatest immediately around the source of
pollution - Pripyat (the location of Chernobyl) is an abandoned city- and decrease
with distance, atmospheric conditions can complicate this pattern. It is therefore
possible to map the externality gradient and field, where the externality is a cost
(or benefit) that affects a party who did not choose to incur that cost (or benefit).
The vast majority of chemicals are toxic, meaning that at a certain dosage they
can damage plants and organisms. Industry and vehicles are major sources of
pollutants that can have significant health and environmental effects. For example,
Ukraine.
Environmental management
sulfur dioxide causes respiratory and cardiovascular illnesses and can lead to acid
rain, which damages lakes, rivers, trees, buildings and cultural relics.
Levels of pollution have generally declined in more industrialised countries.
This has been a result of investment into the research and development
of green technologies to reduce pollution, the implementation of strict
environmental legislation and the relocation of the heaviest polluters
(usually heavy manufacturing industry) to emerging market economies. The
environmental Kuznets curve suggests that after a certain stage of economic
development in a country the level of pollution it causes will decline.
The type and amount of pollution is often dependent on the level of
economic development of a country. In LICs primary industry is dominant and
therefore pollution is often related to activities in agriculture or mining. With
industrialisation, manufacturing industries, energy production and transport
become the major polluters; although within countries the distribution is
uneven and focused on large urban industrial zones. Many newly industrialised
countries, including India and China, are at this stage and have seen major,
large-scale pollution events such as the Bhopal disaster (1984) and the Harbin
explosion (2005). More industrialised countries have seen deindustrialisation,
which has generally resulted in a reduction in pollution, although pollution from
transport has often increased.
Demand and supply of water; issues of water quality
Water is the world’s most essential resource and yet for 40 per cent of the
world’s population lack of water is a constant threat and one that is getting
worse. Demand for water is doubling every 20 years and sometimes, in places
where there is enough water, it is wasted or polluted. In less industrialised
countries water-borne diseases kill 840 000 people per year and over 750 million
people - one in nine of the world’s population - lack access to safe water.
UN estimates suggest that two-thirds of the global population will
experience ‘severe water stress’ by 2025. A country is judged to experience water
stress when the supply of water falls below 1700 m3 per person per year, whilst
water scarcity occurs when the supply of water falls below 1000 m3. Water stress
and scarcity are likely to limit social and economic development, threaten food
supplies and cause conflict between neighbouring drainage basin countries.
Africa, South Asia and the Middle East are likely to be particularly severely
affected; Yemen, Jordan and Israel are withdrawing 15-30 per cent more water
from aquifers than is being replenished.
Arctic Circle
Tropic of Cancer
Deficiency
Areas can only support
vegetation that is
drought-hardy. Areas
that have a long period
of less than normal
precipitation may lose
their natural vegetation.
0- -1000 mm
over-1000 mm
Surplus
Areas have enough water
to support a wide variety
of vegetation. Cropscan
be grown without irrigation.
over 1000 mm
0- 1000 mm
figure
12.20 Water deficiency and surplus
296 Environmental management
Physical water scarcity occurs when demand for water is greater than a
region’s ability to provide the water needed for its population. Water scarcity
is associated with arid and semi-arid areas where high temperatures and
Cup of tea
evapotranspiration rates are coupled with low precipitation. Economic water
scarcity exists when a population does not have the funds available to utilise an
adequate supply of water.
Millennium Development Goal 7-to ensure environmental sustainabilityaimed to halve the proportion of the global population without improved
drinking water between 2000 and 2015. As of June 2014 this target was expected
to be met in Northern Africa, Eastern, Southeast and Southern Asia, Latin
America and the Caribbean. However, sub-Saharan Africa and Western Asia
have seen insufficient progress and Central Asia has seen a deterioration in
access to water.
The concept of virtual water-the amount of water used to produce food
or other products and which is embedded within the item - is becoming
increasingly important. For example, one orange requires 62.7 litres of water in
its production. Therefore Israel, a water-scarce country, discourages the export
of oranges to prevent vast quantities of water being exported to other parts of
the world. Global trade in virtual water has been estimated at 2320 billion m3
per year-a flow equivalent to 29 Nile rivers.
Factors in the degradation of rural environments; overpopulation, poor
agricultural practices, deforestation
Rural environments supply the vast majority of the world’s food and are home
to most of its forested land. These areas have been rapidly degraded, mainly due
to overpopulation as a result of population increase and subsequent pressure on
land. Five main causes of unsustainable agricultural practices and degradation
have been identified by the UN; policy failure, rural inequalities, resource
imbalances, unsustainable technologies and trade relations.
The industrialisation of agriculture has also had a significant impact on
rural ecosystems, particularly in LICs. Large-scale capital intensive farming
of livestock, poultry, fish and crops has spread, particularly since the Green
Revolution, and is a consequence of the globalisation of agriculture. In order
to make each stage of the food production process more economically efficient
there has been vertical integration where a single centre controls all stages of
production and merchandise. Large agricultural companies need to increase
their share of the market and reduce costs in order to be more competitive.
Consequently, agricultural land in LICs has come under the control of TNCs
figure
litres per
y / 250 ml cup
of black tea
One apple
1 AÇ
litres per
J 150 g apple
Bowl of rice
HF A
V
litres per
100 g bowl
Cup of coffee I One orange
Potatoes
Potato chips
290““»“ 1040 f“p"
figure
12.21 Examples of virtual water
12.22 Salt affected soils in Colorado, USA. Salts, dissolved in the soil, rise through the soil due
to capillary action and are deposited at the surface and at the base of the fence post. This process is
called salinisation.
Environmental management
figure
12.23 Overgrazing leads to soil erosion and desertification. This is the process where previously fertile land becomes desert.
either directly or indirectly. Practices on these farms involve a high level of
mechanisation and heavy use of fertilisers, pesticides and herbicides, all of
which have a significant impact on the environment
In the short and medium term these agro-industrial practices are
economically profitable but in the long term they are environmentally
unsustainable. Approximately one-third of the world’s farmland is currently
affected by salinisation, erosion or desertification, deforestation and air
pollution; a decline in biodiversity and the long-term health of farm workers are
further concerns associated with the increase in agro-industry. There are also
fears that the poorest households suffer as they are forced onto more marginal
land by large-scale logging, ranching, mining or agricultural operations.
Nigeria has seen some of the highest deforestation rates in the world. In
the first five years of the twenty-first century the country lost over 55 per cent
of its primary forest, the equivalent of approximately half a million hectares per
year. Much of the land is being cleared for logging, timber export, subsistence
agriculture and the collection of wood for fuel, which remains a significant
problem in Western Africa. As a result of this deforestation Nigeria’s average
temperature increased by 1.1 °C in the period 1901-2005 - the global temperature
increase over the same period was 0.74 °C. During the same period annual rainfall
totals in the country fell by 81 mm. These features combined have led to rapid
desertification in rural regions, particularly in the north of Nigeria; to date over
351 000 hectares of fertile land have been lost, equivalent to 0.6 sq km per year.
Factors in the degradation of urban environments: urbanisation, industrial
development, inadequate infrastructure
Urbanisation is the process of population shift from rural to urban areas.
Urbanisation has resulted in the physical growth of urban areas, particularly
in less industrialised countries. Between 1970 and 2000 over 58 000 sq km
of land was urbanised, mainly in India, China and Africa. The UN estimates
gŞ Environmental management
figure
12.24 Deforestation in the mountains of British Columbia, Canada.
that by 2050 approximately 86 per cent of MICs and 64 per cent of LICs will be
urbanised. The impacts are largely irreversible and include loss of farmland,
fragmentation of habitats and the associated loss of biodiversity, and the
alteration of localised climates.
Urbanisation in Kaduna Metropolis, Nigeria, has resulted in inadequate
infrastructure as development, particularly of waste management, cannot keep
pace with rapid population growth. For example, there has been widespread
dumping of non-biodegradable rubbish in urban drains and streams that has
blocked channels and caused flooding.
Industrial development, particularly rapid industrial development, has
been instrumental in developing countries economically. However, it has also
increased the range and scale of environmental issues in urban areas. Half of
the world’s most polluted cities in 2014 were in India, with Delhi having the
highest concentrations of airborne particulate matter (PM). Other cities with
high concentrations were located in Pakistan and Bangladesh. China had no
cities in the top 20 having waged a ‘war on pollution’that has reduced their
levels of PM 2.5 (the diameter in microns of the particles most damaging to
human health) to 56 (compared with Delhi’s 153).
Even though China has managed to curb industrial air pollution in urban
areas it continues to battle with the disposal of waste. From 2005-10 Beijing
collected an average of 3900 tonnes of rubbish per day more than it had capacity
to deal with. China’s waste management companies favour incineration rather
than landfill as a means of dealing with the problem. In 2003 approximately
2 per cent of all of China’s waste was incinerated. Ninety new incineration plants
are due to be opened by late 2015 and China hopes to increase its incineration
rate to 40 per cent by the same date.
Environmental management
figure
11.25 The 20 most polluted cities in the world (with the highest levels of PM 2.5).
Constraints on improving the quality of degraded environments
Despite attempts to improve the quality of degraded environments there are
numerous constraints that make this a challenging process. For example, it
is estimated that, globally, over 100 000 people per day move from rural to
urban areas. Many of these people live in slums on marginal land where waste
management infrastructure is minimal (or non-existent) and the environmental
conditions can deteriorate rapidly.
Poor knowledge coupled with poor management by either local or
national governments can make improvements difficult to implement. For
example, in Southern African countries destructive and poorly conceived land
tenure policies have replaced traditional ways of managing the environment.
This has been exacerbated by civil wars in the Democratic Republic of the
Congo, Mozambique and Angola, which have seen resources plundered
and rendered large areas of land unusable due to land mines and destroyed
infrastructure.
In addition, many degraded environments require substantial investment
both in terms of institutional and technical costs. For example, integrated river
basin management, water pollution reduction programmes and rural road
maintenance all require high technical and institutional costs that are often
beyond the financial means of many LICs. Also, often these solutions take
time to yield results and financers may withdraw support if results are not as
expected over the short term.
The protection of environments at risk: needs, measures and outcomes
Individual environments at risk of land degradation can be assessed in
terms of their needs, measures and outcomes. Needs are defined as the
strategies that need to be implemented to reduce environmental degradation
without destroying the livelihoods of the local population. Measures are the
policies and practices that can be implemented in order to achieve these
outcomes. Outcomes are a measure of the success of the strategies. Degraded
environments often cross international borders and so effective cooperation is
required between countries to protect vulnerable areas.
300 Environmental management
figure
12.26 Rapid rural-to-urban migration leads to the growth of slums.
Whilst most scientists and conservationists agree that nowhere is completely
untouched by human activity, some governments have designated Wilderness
Areas where the environment is protected by law and human activity and access
for outsiders are completely banned. For example, there are 12 Wilderness
Areas in the Sami native region in Northern Finnish Lapland. These have been
designated to prevent land degradation as well as to protect the livelihoods of
the Sami population. Therefore, activities such as reindeer husbandry, hunting
and taking wood for use within the household are permitted as long as these
activities remain sustainable.
Other areas are designated as National Parks and whilst different countries
define these in different ways, they all limit human activity and development
and serve to educate people on the conservation of the natural environment.
According to the International Union for Conservation of Nature (IUCN) there
are 6555 designated National Parks across the world, the largest of which is
Northeast Greenland National Park. Established in 1974 and expanded in 1988,
at 972 001 sq km the Northeast Greenland National Park is larger than all but
30 of the world’s countries. It has no permanent resident human population
although approximately 40 people, mainly scientists, are present seasonally.
Environmental management 301
figure
12.27 Reindeer in Finnish Lapland
In many areas it is necessary to sustain sizeable populations and rates of
economic activity and when this is the case strategies to promote sustainable
development need to be implemented. For example, in Cambodia shifting
cultivation has degraded the land causing the local population to migrate,
find other forms of employment or occupy other plots of land illegally. The
country therefore needs to ensure sustainable agricultural practices; their aim
is to achieve this on 20 per cent of agricultural land by late 2015. This will be
achieved by: promoting land reform so that local people have greater land
security; improving the government’s land use policy; creating an action plan
for sustainable agriculture (particularly organic agriculture); and integrating pest
management and environmentally sustainable technology.
The management of a degraded environment
Case Study
Darfur
Darfur is a region in western Sudan. The eastern half of Darfur is covered with
flat plains and low sandstone hills (known as goz). The goz is a challenging
environment for people to inhabit; water sources are scarce and pockets of
population can only survive where there are reservoirs or boreholes. To the north
of the goz lies the Sahara Desert. Despite the region’s aridity it is able to support
fertile pasture and arable land in places.
Wadis - or valleys - are another feature of Darfur’s physical geography;
particularly in the West. During the wet season the wadis flood and flow
hundreds of kilometres into Lake Chad. Much of Western Darfur is covered
with infertile sandy soil, which is difficult to cultivate. However, small
areas of forest do manage to grow here and animals are able to graze the
vegetation.
Whilst Darfur is predominantly a flat, arid plateau, the Marrah Mountains
rise up in the centre of the region; volcanic peaks that rise above 3000 m. Here,
there is a small area of temperate climate and a source of water.
302 Environmental management
h
;
land relief in metres
R
Hadjer Momou
P/at
1450
%
___ over 1000
_ 500-1000
___ 200-499
| 0-199
1311
Massif Ennedi
ouaıi' Bao
wadi or
watercourse
marsh
1189
Iriba
Arada
Ouadi Hût
Massif
1060 r ,
A
Biltine
Guereda;
du Kapka
'>Am-Zoer
Ifenat
Jebel Teljo
A
M a r r a 1954
Kutum
Djedaa<
Fasher
Oum-Hadjer
a Jebel Marra
Mangal
Mong<
Sodiri
Abeche
Wad Banda
Am-Dam
Abu
Zabad
1360
’Goz-Beida
Bitkine
-îe Massif
Nyala
du Guera
Babanusa
de Garar
Am Timan
El Muglad
CENTRAL
AFRICAN
REPUBLIC
figure
12.28 Darfur, Sudan
figure
12.29 The highest point of the Marrah Mountains.
Environmental management
Darfur’s environment is generally resource poor and suffers from high natural
variability and unpredictability but it is human activity that, over the last three
decades in particular, has led to the intensification of farming, grazing and
deforestation. Population growth in the region has been dramatic. In 1973 Darfur’s
population was 1.3 million but by 2008 this had increased more than five-fold to
7.5 million, 52 per cent of whom were 16 or younger. Over the same period the
native administration system has been eroded, populations have migrated to
more fertile areas, and political instability and violence have increased.
The war in Darfur
The war in Darfur officially began in February 2003 when the Sudan Liberation
Army (SLA) and thejustice and Equality Movement (JEM) began fightingthe
government of Sudan, which they accused of oppressing Darfur’s non-Arab
population. Although there are several origins of the conflict-which continues
to rage to the present day- access to water and land disputes between seminomadic livestock herders and sedentary subsistence farmers have been partly
to blame. The conflict has resulted in the destruction of crops and water sources
and the restriction of livestock migration, which has caused local overgrazing
and the destruction of trees and rangeland. Livelihoods that are thriving in the
context of the conflict, such as brick-making and charcoal-making, are placing
unsustainable demands on the area’s natural resources.
The UN estimates that 2.8 million people have been displaced as a result of
the conflict and many Internally Displaced Person (IDP) camps have been set
up around agricultural market towns, degrading the land and affecting prime
farmland. There are likely to be long-term repercussions on the livelihoods
figure
12,30 IDP camp near Nyala, South Darfur
304 Environmental management
figure
12.31 A burned and looted village in Darfur.
of both the host and the displaced populations. When reconstruction takes
place the demands on forestry will be considerable; a single family compound
requires between 30 and 40 trees to be planted, which amounts to planting
12-16 million trees if all internally displaced persons return home.
The UN Darfur 2007 work plan
Sustainable Resource Management (SRM) has been suggested as an
appropriate planning framework for the humanitarian response in Darfur. This
equates to a ‘do-no-harm’ to the environment philosophy and requires that the
use of resources be kept within the limits of renewable supplies. The UN Darfur
2007 work plan is outlined in Table 12.1.
Attempts have been made to integrate the environment into relief efforts with
a number of key recommendations being made to specifically improve forestry
and water resource management. The rate of deforestation is considerable and
table
12.1 UN Darfur 2007 work plan
Strategic priorities
Environmental responses
The provision of basic humanitarian goods and
services (food, health, nutrition, shelter and
non-food items, water and sanitation) to avoid
serious threats to health.
•
Environmental resources are essential to the provision of these itemswoodfuel, construction materials, water etc. SRM is the framework for
ensuring the relief effort is not undermined by resource depletion.
To increase the safety of the population by
promoting respect for human rights and the
rule of law, and strengthening responsive
•
The safe collection of environmental resources is a key protection issue. As
these resources are depleted, collection becomes more remote and more
dangerous. SRM makes resources more secure and improves protection.
•
Community environmental governance is an important component of
inter-community relationships, which in turn are important to rebuild the
rule of law.
•
Land tenure is crucially linked with the distribution of environmental
resources. Recording and protecting resources and assets will facilitate
dispute resolution at a local level.
•
Coping strategies are dependent on a sustained and therefore a
well-managed resource base.
•
Livelihoods have to be sustainable; this means that they must be
supported to reverse Darfur’s natural resource depletion.
•
A coordinated approach to introducing new technologies for energy and
construction is also essential.
protection interventions.
To promote, encourage and support coping
strategies and livelihood potential in order
for the beneficiaries to become increasingly
self-reliant
Environmental management
E
has a massive impact on the IDP camps and undermines Darfur’s agricultural
recovery. It is recommended that a strategic study should assess the amount
of forest lost, establish a management plan for the humanitarian context and
develop a plan for recovery. Addressing resource depletion in conjunction
with livelihoods would tackle the causes of degradation as well as its impacts.
Short term economic independence brings advantages but it is important that
livelihoods that undermine sustainable resource management are avoided.
Therefore, priority should be given to replanting shelter belts and protected
forests lost during the crisis.
DARFUR
saving
AFTER 10 YEARS
fh
000 000
people helped
10 568
children attend one of our
48 child friendly centres
across the region every week
0 82 000
O A Ö
families given
9
seeds and tools
Over
300 000
trees planted
across our sites
figure
figure
12.33 Measuring groundwater depletion
Environmental management
we have helped people with:
nutrition
health promotion
food security
getting access to clean water
sanitation and improving hygiene
community building
development education.
12.32 The impact of Tearfund (a UK relief and development charity) in Darfur.
Water security has been diminished as over-abstraction of groundwater
has occurred at IDP camps. However, without accurate measurement of the
amounts being abstracted, the resources cannot be managed and the risks
are unmitigated. The camps at El Fasher have suffered particularly with severe
groundwater depletion, although other camps with large populations and
complex local geology include Kalma, Mornei and Kass.
It is suggested that in order for SRM measures to be successful, the
community needs to be effectively governed to manage both social impacts
and natural resources. The rebuilding needs to be robust enough to face the
inevitable challenges of future droughts and the ongoing effects of population
growth and climate change.
NOW INVESTIGATE
1
Investigate the energy mix of a country of your choice. How has it
changed over time? How is it likely to change in the future? Can
you explain this pattern of energy use?
2
Investigate an example of a significant pollution event. Outline the
character, causes and solutions of the example you research.
3
Investigate a Wilderness Area or a National Park. How has this area
been managed to prevent land degradation?
Environmental management 307
China
China, 2014
Exports
2342 billion USS
Imports (billion USS)
Exports (billion USS)
France
Poland
Russia
Switzerland
Switzerland
China
UK
Netherlands
Netherlands
USA
Spain
UK
USA
Italy
Spain
Belgium
Italy
China
Belgium
_______ ____________ Germany
Germany
50
100
150
100
50
0
Imports (billion USS)
Exports (billion USS)
Netherlands
Sweden
China
Italy
Japan
Poland
Norway
Spain
France
Italy
Russia
USA
UK
USA
France
China
UK
Belgium
Belgium
Germany
Germany
150
50
100
0
100
50
Exports (billion USS) Imports (billion USS)
UK
Italy
Spain
Belgium
China
Ireland
France
Switzerland
Netherlands
Germany
USA
100
50
Exports (billion USS)
Ireland
Spain
Norway
Italy
Belgium
France
Netherlands
USA
China
Germany
100
Imports (billion USS)
Imports
2408 billion USS
USA, 2014
Export and Imports
Percentage
Imports
1958 billion USS
Germany
SSBHiirto over 10.0
Belgium H
■■■■ 5.0-10.0
Poland BHHHM
Russia
Belgium
Poland
Switzerland
0.0-4.9
Austria
UK
Global interdependence
" '
Italy
USA
France
China
Netherlands
France
100
150
0
50
Exports (billion USS)
50
100
150
Imports (billion USS)
Japan
Netherlands |
Russia
Malaysia H
Indonesia
Australia |
Malaysia
Indonesia fl
Qatar
Germany fl|
South Korea
Singapore H
Thailand flH
UAE
Saudi Arabia
Australia
USA
China
150
100
50
0
Exports (billion USS)
50
100
150
Imports (billion USS)
200
e:
Importing and exporting of goods and
° S’services is one of the biggest contributors
[= o-o
to global interdependence. The main graphic
w “ >3
on this spread shows the interdependence
S_3 o
of a selection of the world’s biggest trading
şr
o’
c
nations. Some are net exporters and others
are net importers.
The individual country graphs show each
country’s main trading partners in 2014.
*
South Korea
Brazil |
Mexico |
Russia H
Indonesia
UAE
Kuwait
India |
Germany
Indonesia |
Australia
Vietnam H
Qatar
Saudi Arabia
Japan H
USA
Japan
China H
China
150
100
50
0
50
100
Exports (billion USS)
Imports (billion USS)
USA
India
Belgium
Brazil |
France
Saudi Arabia
Netherlands
South Korea |
UK
Germany |
South Korea
UK|
Germany
Japan
Japan
Mexico
Exports
1623 billion USS
Canada
Mexico
Canada
350
China
300
250
200
150
100
Exports (billion USS)
50
0
50
100
150
200
250
300
Imports (billion USS)
350
400
450
500
309
Trade flows and trading patterns
Visible and invisible imports and exports
Trade can be defined as the exchange of goods and services for other goods and
services that someone else possesses or for a monetary sum. The use of money
as a medium of exchange has allowed trade to be conducted in a manner
that is much simpler and effective compared to earlier forms of trade, such as
bartering. In 2013 the world’s nations exported nearly US$18 trillion worth of
goods and services.
The origins of trade can be traced to prehistoric times with traders shipping
goods around the Mediterranean 4000 years ago - the Ancient Greeks and
Egyptians traded as far away as Britain. The Romans too, traded goods from the
corners of their empire. In the sixteenth and seventeenth centuries ships from
the mercantile nations of Europe such as Britain, France, the Netherlands and
Spain sailed the world’s oceans colonising new lands and setting up trading
posts.
This trading system remained in place until the 1960s where the colonies
(normally LICs) exported primary produce, often in the form of agricultural
produce or mineral ores, to the colonial powers in Europe (or the USA/Canada)
who exported manufactured goods such as automobiles or locomotives. This
system of trade evolved when many of the colonies gained independence from
the 1960s onwards. Since that time there has been a major change in world
trade, brought about by changes in a new world order, technology and the
formation of trade blocs.
The term ‘import’ comes from the word ‘port’, as goods were usually
transported on boats to other places. Countries normally import goods that
cannot be produced as efficiently or cheaply domestically. They also import
raw materials and commodities that cannot be produced in that country either
because they have been exhausted or were never found there, for example many
countries have to import oil.
Exports as
% of GDP
Net importer
Net exporter
Imports
Exports
0.5
USS (trillions)
figure
13.1 World trade in 2014
310 Global interdependence
USS (trillions)
Imports as
% of GDP
Exports are a function of international trade where goods produced in one
country are shipped to another country for future sale or trade that adds to the
producing nation’s gross output. Many of the largest TNCs operating in HICs
will earn a large percentage of their revenue from exports to other countries.
Economies grow by selling more goods and services and a country’s foreign
policy may be underpinned by the need to promote trade with another nation
or group of nations.
The difference between a country’s imports and exports is known as the
balance of trade. A country has a trade deficit if it imports more than it exports;
on the other hand, if a country exports more than it imports, it is known as
a trade surplus. Trade can further be identified as visible and invisible trade.
Visible trade involves the exchange, or the import and export, of actual goods,
while invisible trade involves the transfer of non-tangible goods and/or services,
including business and financial services such as banking and insurance,
tourism and intellectual property and patents.
Global inequalities in trade flows
As transportation and technology has improved, global trade has increased and
governments have relaxed restrictions, partly as a result of lobbying from TNCs
that earn huge profits. In most countries global trade now accounts for many of
the goods or services bought or sold.
Previously, governments often restricted international trade based on
mercantilism, which maintained that countries were all competing to
maximise their stores of gold. Governments imposed tariffs to restrict imports
and promoted exports in order to sell their goods to buy more gold. In the
nineteenth century some countries, including the United Kingdom, replaced
mercantilism with free trade.
figure
India imports-top 10 trading partners
India exports - top 10 trading partners
Statistics are for 2012-2013
Statistics are for 2012-2013
13.2 India’s trade with the rest of the world. Much of India's trade with the rest of the world is dominated by oil products. This is likely to rise as the
country becomes highly developed and demand increases.
Global interdependence
In free trade orientation, governments do not limit imports by imposing
tariffs or promoting exports with subsidies. Since the Second World War
nations have reduced tariffs on imported goods and currency restrictions on
international trade. Despite this move to free trade, many countries still have
trade barriers remaining in place such as import quotas, taxes, and various
means of subsidising domestic industries, and all of these measures hinder
trade.
As global trade has increased, governments have addressed the issue of
trade regulation that originates or ends outside their jurisdiction. Formerly,
governments regulated international trade through bilateral treaties negotiated
between two nations. But as trade has become more global and complex, trade
negotiations have expanded to include more countries. Now, trade is regulated
in part by worldwide agreements governed by the World Trade Organization
(WTO). Although most countries in the world are members of the WTO and free
trade exists between many countries, the WTO has not entirely eliminated tariffs
and other barriers to trade between some countries. Many countries are also
members of trade blocs, where groups of countries such as the European Union
(EU) allow free trade among member countries and occasionally allow trade with
countries they have agreements with, such as South Africa.
Some independent nations have negotiated trade agreements with their own
interests at heart in a form of protectionism. Some protectionism is employed
by most nations, either through subsidies or tariffs to protect essential
industries, such as food or steel production.
table
13.1 The world’s leading exporters in 2013. World trade is dominated by China. China surpassed
the USA as the world’s leading exporter in 2010.
Country
Rank
Exports
US$2 210 000 000 000
1
China
2
United States
US$1 575 000 000 000
3
Germany
US$1 493 000 000 000
4
United Kingdom
US$813 200 000 000
5
Japan
US$697 000 000 000
6
France
US$578 600 000 000
7
Netherlands
US$576 900 000 000
8
South Korea
US$557 300 000 000
9
Russia
US$523 275 000 000
10
Italy
US$474 000 000 000
(Source: CIA World Factbook)
Factors affecting global trade
Global trade is affected by many different factors, some historical but mostly
economic and environmental. Some countries are endowed with minerals due
to their geology; the presence of coal enabled North West European countries
to become net exporters of goods in the nineteenth century, while more recently
many countries in the Middle East have been able to become wealthy through
the presence of gas and oil.
Locational advantage enables some places or even nations to dominate trade.
Historical factors enabled industrial centres to develop, such as Sheffield in
the UK or Pittsburgh in the USA. The presence of coal, iron ore and limestone
enabled these locations to become centres of the steel industry. More recently,
the concept of locational advantage has seen foreign direct investment
(FDI) take place in Newly Industrialised Countries (NICs) and LICs through
Transnational Corporations. They take advantage of proximity to raw materials,
cheap and abundant labour, relaxed tax regulations and environmental laws as
well as locations that are close to large markets.
312 Global interdependence
Transnational Corporations make decisions based on future profits and
therefore tend to avoid countries that are unstable due to endemic corruption,
weak governance and periodic overthrows of the governing bodies. For these
reasons, the MICs/LICs such as Haiti, Honduras and much of sub-Saharan
Africa are beset with risks for TNCs and so receive very little FDI.
Historical factors are also very important in global trade links. Prior to
joining the European Economic Community (now the EU) in 1973, the United
Kingdom traded almost exclusively with its former empire. Agricultural produce
such as wheat from Canada, sugar cane from the Caribbean, fruit from South
Africa and lamb from New Zealand were traded for manufactured goods such
as agricultural equipment, vehicles and military hardware produced in the UK.
Although this trade is no longer as important, as the EU has become the UK’s
major trading partner, it is still a significant part of the UK’s trade, making up
around 10 per cent of both the UK’s imports and exports.
Canada
Sweden
Netherlands
Russia
South Korea
$8.5 billion
$34.5 billion
$6.2 billion
Japan
$6.4 billion
$6.5 billion
$6.7 billion
Trade agreements between countries are treaties that allow two or more
countries to trade without hindrance so goods and services can move freely between
their borders without taxes or tariffs. In some trade agreements, such as the EU,
free movement of labour and capital is also allowed. These groups of nations
are sometimes known as trade blocs. Examples of trade blocs include the North
American Free Trade Agreement (NAFTA), the Association of South East Asian
Nations (ASEAN) and the Caribbean Common Market (Caricom). The General
Agreement on Tariffs and Trade (GATT) is outlined in detail in the next section.
Some trade blocs practise protectionism where imported goods produced
outside of the bloc are subject to tariffs or import quotas. An example of this
is the car industry in the EU. Cars imported from countries such as Japan are
subject to import tariffs. However, since 1992 and the advent of the Single
European Market,Japanese manufacturers can avoid import restrictions by
producing cars within the EU made from locally manufactured components.
Changes in global markets have revolutionised patterns of world trade since
the 1990s as the emergence of NICs has led to a shift in manufacturing and
consumption patterns worldwide. China and other Southeast Asian nations have
become centres of manufacturing, which has led to global shift (see Chapter 14
for more detail). This in turn has led to huge growth in trade between countries.
More details can be found in Chapter 14.
Global interdependence
The World Trade Organization (WTO)
The World Trade Organization is an international body whose mission is to
promote free trade by persuading countries to abolish import tariffs and
other barriers to trade. It has become closely associated with globalisation and
meetings of the WTO often spark protest by anti-globalisation protesters. The
WTO is the only global agency that determines the rules of international trade.
Its remit is to supervise free trade agreements, settle trade disputes between
governments and organise trade negotiations.
The decisions it makes are legal and binding, with every member country
abiding by its decisions so, when the US and the EU are in dispute over bananas
(see text box) or aircraft, it is the WTO that intervenes. The WTO can enforce its
decisions by imposing trade sanctions against countries that break the rules.
figure
13.5 World Trade Organization members, 2015
Global interdependence
The banana wars
The ‘banana wars’ were the result of a six-year trade dispute between the
USA and the EU. The USA complained that an EU agreement giving banana
producers from former European colonies in the Caribbean special access to
European markets broke free trade rules. In fact, only 7 percent of Europe’s
bananas actually come from the Caribbean as American TNCs control the Latin
American banana crop from countries like Ecuador, Costa Rica and Colombia
that supply over 60 per cent of the world’s crop. These countries supply 75 per
cent of the EU market and the USA itself does not export bananas to Europe.
Despite this, the USA filed a complaint against the EU with the WTO
and, in 1997, won. The EU was instructed to alter its rules.
Since 1975 each Caribbean country has had a quota of bananas, enabling
them to sell directly to Europe. The EU hoped that this would help the
economies of poorer Caribbean LICs to grow, without dependence on
overseas aid. The effect of this deal has been to protect banana farmers in
the Caribbean from competition from Latin America, whose bananas are
cheaper because they are grown on large-scale mechanised plantations run
by giant US-based conglomerates such as Chiquita, Dole and Del Monte.
After the WTO ruling, the American government argued that free trade in
bananas had not been restored, despite the EU maintaining that it had changed
its rules. The USA retaliated by imposing 100 per cent import duties on European
products, covering everything from Scottish cashmere to French cheese.
The US government have long championed free trade and see state
support of agriculture as practised by the EU through the Common
Agricultural Policy to be anti free trade. The American government is also
lobbied by powerful TNCs that dominate the Latin American banana industry.
The EU favoured imports from former European colonies, with no duty
imposed on bananas from former colonies in Africa, the Caribbean and the
Pacific. However, the EU charged duties on bananas from other countries.
It was this policy that the USA disputed.
In December 2009 the EU and USA reached agreement at the WTO in
Geneva for the EU to gradually reduce its tariffs on all imported bananas by
35 per cent by 2017.
figure
13.6 Banana plantation, Costa Rica
Based in Geneva, the WTO was founded in 1995, replacing the General
Agreement on Tariffs and Trade (GATT). GATT was started in 1948 when 23
countries signed an agreement to reduce customs tariffs and make trading
easier. The WTO is much more powerful than GATT, which regulated trade in
merchandise goods, whereas the WTO also covers trade in services such as
telecommunications, banking and intellectual property rights. Large trading
nations such as China and Russia have only joined the WTO recently as they
have looked to boost their own trade.
The WTO meets every two years when negotiation on global trade deals take
place. These are known as ‘trade rounds’ and are aimed at reducing barriers to
free trade. A General Council is in charge of the day-to-day running of the WTO;
it is made up of ambassadors from member states who arbitrate on countryagainst-country trade disputes.
The WTO has been criticised in many quarters, especially by people worried
about the impacts of free trade and economic globalisation. Opposition to the
WTO centres on four main areas:
1
2
3
4
The WTO has too much power so it can make nations change laws and
regulations by declaring these to be in violation of free trade rules.
The WTO is run by the HICs for their benefit and does not address the
problems of LICs, such as HICs not fully opening their markets to products
from LICs.
The WTO has little interest in the impact of free trade on workers’ rights,
child labour, the environment and health.
The WTO has no democratic accountability as its dealings on trade disputes
take place behind closed doors.
Global interdependence
Supporters of the WTO argue that it is a democratic organisation whose rules
were written by its member states (many of whom are democracies), and who
also elect its leadership. Furthermore, by expanding world trade the WTO helps
to raise living standards around the world.
The nature and role of FairTrade and the Fairtrade Foundation
The Fairtrade Foundation is concerned with introducing better prices, suitable
working conditions and fairer terms of trade for farmers and workers mainly in LICs.
It supports the development of th riving farming communities that have more control
over their futures, as well as protecting the environment in which they live and work.
It does this by marketing and merchandising FairTrade products. This approach
benefits small-scale farmers, who are usually amongst the most marginalised groups
globally, enabling them to trade rather than rely on aid to to live sustainably.
FairTrade works in different ways; for some products, such as coffee, cocoa,
cotton and rice, the Fairtrade Foundation only supports small-scale operations.
Working through democratic organisations like cooperatives the foundation
offers farmers the guarantee of a stable income to plan for the future. For other
products such as bananas, tea and flowers, the foundation supports plantations
through companies that employ large numbers of workers on estates. Standards
differ from other plantations by protecting workers’ rights through healthy
and safe working conditions and other measures that would be found in HICs.
Employers also have to pay wages that progress towards living wage benchmarks.
For most FairTrade goods, the foundation pays a minimum price that covers
the cost of sustainable production for that product in the region. Producers
receive the market price if the market price for that product is higher than the
FairTrade minimum price. This protects farmers from fluctuations in the market
for the products they grow thus ensuring a regular and stable income.
Farmers are also paid a FairTrade premium and it is up to them how
they use it. The premium is the additional sum of money paid on top of the
minimum price that farmers and workers receive and can be invested in social,
environmental and economic development projects to improve businesses and
communities. In reality, it means investment in education, transport infrastructure,
health, water and sanitation to provide an improved environment to live in.
Although the Fairtrade Foundation works with a range of stakeholders, 50 per
cent of the enterprise is owned by producers representing farmer and worker
organisations. As a result, they are involved in decisions on overall strategy, use
of resources, setting prices, premiums and standards.
Arctic Circle
Tropic of Cancer
Equator
figure
13.7 Countries where FairTrade producers are located.
316 Global interdependence
FairTrade coffee
Around 125 million people worldwide depend on coffee for their livelihoods.
Coffee is the most valuable and widely traded tropical agricultural product.
Twenty-five million smallholder farmers produce
80 per cent of the world’s coffee, but many of them fail to earn a reliable
living from coffee.
Coffee is a commodity that suffers from economic expansion and
contraction. Global production varies from year to year according to
weather conditions, disease and other factors, resulting in a market that
is inherently unstable and characterised by big fluctuations in price. Price
volatility has consequences for those who depend on coffee for their
livelihood, making it difficult for growers to predict their income for the
coming season and budget for their household and farming needs. Many
farmers live close to the poverty level.
The coffee supply chain is complex as beans pass through the hands of
growers, traders, processors, exporters, roasters, retailers and finally the
consumer. Many farmers have little idea of where their coffee goes or what
price it ends up selling for. The more lucrative export of green coffee beans that have been processed ready for export and roasting - is only
an option for farmers if they can form cooperatives, purchase processing
equipment and organise export or hire a contractor to carry out these
processes for them.
The Fairtrade Foundation started in response to the dire struggles of
Mexican coffee farmers following the collapse of world coffee prices in
the late 1980s. In 2011-12 FairTrade certified coffee farmers earned an
estimated US$45 million in premiums that were invested in farmer services
and community projects.
FairTrade products sold by one British
supermarket chain:
Bananas
Sugar
Tea
Roast and ground coffee
Cotton goods such as underwear and
T-shirts
Cut flowers
Pineapples, grapes and citrus fruits
Herbs and spices
Nuts
Drinking chocolate
Chocolate bars
Wine
Case Study
FairTrade
coffee in
Central Vietnam
Cud Lie Mnong Fairtrade Agriculture Cooperative is located in Cu Mgar, in
the central highlands of Vietnam, at an altitude of between 500 and 600 m.
The region has fertile soils suitable for growing Robusta coffee (the most
popular variety). Farmers also produce rubber, pepper and tea. The area under
cultivation for coffee is around 434 000 hectares, which is about 80 per cent of
Vietnam’s total production.
In 2008 Dakman (a coffee processing and export company) started work on
improving the quality of coffee from the producers in the area. They provided
training on a Common Code for the Coffee Community Association (4C) and
GAP (Good Agriculture Practice) before helping farmers from the area set up
a cooperative producer group. In 2009 they received Fairtrade Foundation
certification and now have 84 producers with around 4 hectares of land each for
growing coffee.
Coffee sales have provided the infrastructure (fuel for water pumps and
fertilisers) to improve coffee production. Annual production capacity of Robusta
green beans is around 350-400 tonnes.
The Fairtrade Premium Cooperative has been used for other projects that
have helped improve quality of life for farmers. These include the construction
of a coffee storage warehouse and administrative offices, community
development projects and support for members to help them increase
productivity.
(Source: Fairtrade.co.uk)
figure
13.8 Cu Mgar location map
Global interdependence
International debt and international aid
The causes, nature and problems of debt at the national scale
The debt of poorer countries has long been recognised as being the single
largest obstacle to human development Problems arise because of the huge
amount of debt that LICs owe to HICs. Debt has forced sustainable human
development, security and political or economic stability to be limited in many
of these poor countries. This has been allowed to occur for a number of reasons.
Colonialism
After independence many newly-independent nations came to be governed by
the elite who had been government officials under the former colonial rulers.
Usually these governments (though they adopted new constitutions, held
elections, and claimed to be democratic) continued to rule their territories as
if independence had not occurred. Some sided with the capitalist West, while
others aligned with the Soviet bloc as old colonial economic patterns remained
largely unchanged.
Agriculture and mining had been important to the former colonies and
remained so with limited investment made to improve the efficiency of these
industries. Large sums of money were borrowed from Western banks to invest
in industrial development, while massive public works projects were undertaken,
such as the gigantic dams at Aswan in Egypt and Akosombo in Ghana. In
many cases the supposed benefits of these investments were squandered by
the ruling elite (usually supported by a Cold War superpower). This was known
as sovereign debt. The borrowed money was often spent on arms to bolster
ruling regimes and on sheer consumption, such as the sumptuous palace of
Rashtrapati Bhavan (Figure 13.9). Little of this money was spent on developing
the vast majority of the population in terms of health or education.
During the 1970s and 1980s events combined to show how economically
interdependent today’s world is- and severely intensified the plight of the LICs.
figure
13.9 Rashtrapati Bhavan, the Indian Presidential Palace. This palace was built by the British before Independence in 1947. It was taken over and modernised by
the newly-independent nation at huge cost.
Global interdependence
First, the oil crisis of 1973-4 caused a sudden sharp rise in oil prices affecting
LICs in two ways:
1
2
The increased oil prices meant LICs needed to borrow more.
The massive profits made by the Organization of Petroleum Exporting
Countries (OPEC) and oil companies generated by high oil prices were
deposited in banks, which were eager to loan them to someone. Loans to
sovereign nations were thought to be very safe and so they took place.
As a result LICs were put further in debt and most loans were at variable rates
of interest that could be increased if bank rates increased, as they did during
financial crises.
The rising price of oil led to a period of high inflation globally and banks
in HICs raised interest rates. Inflation was replaced by a severe worldwide
recession, causing more problems for the indebted LICs. Higher interest rates
increased the cost of borrowing and the recession reduced demand for export
goods produced by LICs, thereby increasing the need for new borrowing, often
at much higher interest rates.
As a result many LICs, especially in South and Central America and Africa,
spent as much as 50 per cent of their income from exports on servicing their
debts by paying interest to overseas banks.
Since the 1990s, under the auspices of the International Monetary Fund (IMF)
and the World Bank, a new class of poor nation has emerged - Heavily Indebted
Poor Countries (HIPCs). The HIPC Initiative was launched in 1996 to ensure
that no country faces a debt burden it cannot manage. Since then multilateral
organisations and governments have worked together to reduce to sustainable
levels the external debts of the most heavily indebted poor countries.
A reappraisal in 1999 allowed the Fund to provide better debt relief to HIPCs,
strengthening links between debt relief and poverty reduction. In 2005 the HIPC
Initiative was supplemented by the Multilateral Debt Relief Initiative (MDRI) to
help accelerate progress toward the United Nations Millennium Development
Goals (MDGs). The MDRI allows for 100 per cent relief on eligible debts by three
multilateral institutions-the IMF, the World Bank, and the African Development
Fund (AfDF)-for countries completing the HIPC Initiative process.
Negotiations between the IMF and indebted poor countries for restructuring
of debt takes place continuously. New loans or conditions are granted if the
country adopts structural adjustment programmes that make governments
undertake austerity measures designed to control inflation, limit government
corruption and scale back public services. Often these measures worsen economic
situations that were already quite bad and are unpopular with the population. The
HIPCs are in a hopeless position regarding foreign exchange-they need to keep
their economies running and have to export whatever they can and even, in some
cases, have to deprive their people of food and medicine. Much of this export
revenue has to be used to service debt.
Many HIPCs are producers of primary products such as cocoa, coffee
and rubber and have to export to gain foreign exchange. As a result, they
are vulnerable to the fluctuations of world market prices. During worldwide
recessions demand for commodities decreases, cutting income to HIPCs and
forcing them into negotiating new loans.
Many organisations and individuals advocate excusing HIPCs the debts they
owe as, in all probability, they cannot be paid back and they cause unnecessary
suffering to people who did not arrange the debts in the first place and have
gained little benefit from the borrowed money. However, the international
financial community is reluctant to consider writing this debt off as this could
lead to bankruptcy on a national level and another world financial crisis to rival
that of 2008. Even amongst some HICs large debts have resulted in financial
crises, such as those experienced in the PIGS countries (Portugal, Ireland,
Greece and Spain), with the crisis in Greece enduring much longer than in the
other three countries.
Global interdependence
figure
13.10 Gugulethu, Cape Town, South Africa. Around a third of Cape Town’s 3.8 million people still live in apartheid-era townships. Many of these townships
are on the Cape Flats, such as Gugulethu. Around half of Gugulethu’s population of 100 000 live in shacks. Some improvements have been made, such as access
to electricity.
Odious debt
Odious debt is debt that has resulted from loans given to dictators and
repressive governments in order to maintain order or to build new presidential
palaces or similar buildings. Iraq built up considerable debts while underthe
rule of Saddam Hussein, while in South Africa after the elections of 1994 the
new government under Nelson Mandela was saddled with the debts run up by
the previous apartheid regime, which totalled over US$11 billion. As a result,
health and education services suffer and there is a lack of investment in services
such as utilities in South Africa so that the debts can be repaid.
Many countries that were, or still are, developing have odious debt run up by
previous governments. These countries include Argentina, where taxpayers are
paying debts accrued by the military junta in the 1980s. Kenya, Congo, Uganda,
Haiti and Nicaragua (where the odious debt is over five times the country’s total
GDP) are all considered to be paying off odious debts.
Debt cancellation is the only way in which these countries can rid themselves
of debt and go on to develop and prosper.
Mismanaged lending
Further debt resulted from mismanaged spending and lending by the West in
the 1960s and 1970s. In the 1960s the USA spent more money than it actually had,
which resulted in ‘quantitative easing’(the printing of more dollars). Oil-producing
countries such as Saudi Arabia were pegged to the dollar as this was the currency
oil was traded in, and were affected as the value of the dollar decreased.
In 1973 the oil-producing countries put up oil prices and earned large
amounts of money that were deposited in western banks. Interest rates started
320 Global interdependence
to plummet as inflation rose - resulting in more lending by banks to prevent
a financial crisis. Many of these loans went to countries led by western-backed
dictators, resulting in little benefit for most of the people living there.
In 1982 Mexico defaulted on its loan repayments and the IMF and World
Bank stepped in to help Mexico and other nations facing similar problems.
The IMF introduced structural adjustment policies to ensure debt repayment.
The poor suffer the most as a result of structural adjustment. Loans to LICs are
repaid in currencies that are stable and do not experience wide fluctuations,
such as the US dollar. LICs, on the hand, have weak currencies that are often
the subject of significant fluctuations in exchange rate, leading to further debt
crises as the value of their currency declines against stronger currencies. The
introduction of structural adjustment policies due to advice from the IMF leads
to cutbacks in spending in areas such as health and education to help repay
loans. This leads to reduced development and a downward spiral that brings
further poverty to the poor.
The debt crisis and debt relief
From the 1990s various countries had financial crises at various times such as
in Southeast Asia in 1997 and Brazil in 1999. These crises were often caused by
short-term commercial bank debt and/or securities market investment. In the
case of the Southeast Asian crisis, the private sector (not the public sector) was
the main culprit. Banks, non-banks and corporations over borrowed and foreign
banks and private investors over lent. Huge capital outflows and severe currency
speculation often accompany these crises.
Some heavily indebted poor countries - many of them in sub-Saharan
Africa - could not escape from the debt trap even with repeated structural
adjustment programmes and debt rescheduling. Some of them sought debt
relief several times, or more. They continue to suffer from economic stagnation
and the burden of heavy debt even today. It was clear that their problem was
insolvency and that their economic prospects were bleak- a new approach had
to be taken to stimulate development.
At the same time as the HIPCs Initiative was launched the World Bank
introduced a new development approach for poor countries called the Poverty
Reduction Strategy Paper (PRSP) (1999).
The PRSP was drawn up by individual countries and the World Bank to
provide measures and a timetable for poverty reduction. According to the World
Bank, poverty reduction strategies should be:
•
•
•
•
•
driven by individual countries to promote national ownership of strategies
through the participation of the population
focused on final outcomes that will benefit the poor
recognise the multi-faceted nature of poverty
involve partnerships of government, domestic stakeholders and external
donors
appreciate that poverty reduction is a long-term goal.
By 2015 well over 50 countries had reached the PRSP completion point (this
means they had complied with the World Bank poverty reduction strategies
for a period of three years). In July 2005 the countries attending the G8
Gleneagles Summit pledged full cancellation of debt owed to the International
Development Association (World Bank), the IMF and the African Development
Fund to countries that reach the completion point of the HIPC Initiative.
Reaching the completion point of the PRSP also results in debt cancellation.
Some opponents of debt relief strategies argue that they do little to
help the poor - especially in those LICs blighted by corruption. Others
argue that countries will run up further debts in a misapprehension that
one day these debts will also be cancelled. Many LICs use the money they
gain access to to enhance the wealth of the richest in those nations, many
of whom will spend or invest this money in HICs. It is felt that money
would be far better spent in specific aid projects that will relieve the poor,
particularly in rural areas.
The origins of the World Bank and the
International Monetary Fund
Just before the end of the Second World
War representatives of the Allied powers
met at Bretton Woods, a resort in New
Hampshire, USA. The meeting set up
a new world monetary system using
the ideas of economist John Maynard
Keynes. The United States adopted a
gold standard and agreed to exchange
its currency for gold at the rate of US$35
per ounce. Other nations either adopted
the gold standard as well or pegged their
currency value to that of the US dollar,
with minor adjustments permitted. This
enabled trade to take place among the
allies and the newly-rebuilt economies of
West Germany and Japan after the war.
Two major international financial
institutions were set up as part of the
Bretton Woods agreements-the World
Bank and the International Monetary Fund.
Although both organisations have most of
the world’s nations as members, they are
headquartered in Washington DC and the
USA and its allies effectively govern their
policies.
The World Bank was set up to lend
funds to MICs/LICs and has loaned
more than US$330 billion. The majority
of these loans have failed to achieve
their objectives and are unlikely ever to
be repaid. In the 1980s the World Bank
began to make so-called ‘structural
adjustment’ loans to developing
countries to restructure bad debts and to
introduce unpopular austerity policies.
The IMF was set up to monitor
international currency exchanges and
to make short-term loans to nations
experiencing short-term problems
meeting their balances of payments.
In recent years the IMF has expanded
its functions into areas that overlap
the mandates of the World Bank - for
example, it has made large loans to bail
out countries in the European Union such
as Ireland and Greece.
Global interdependence 321
Eradicate
extreme
poverty and
hunger
figure
Achieve
universal
primary
education
Promote
gender
equality
and empower
women
Reduce
child
mortality
Improve
maternal
health
Combat
HIV/AIDS,
malaria and
other diseases
Ensure
environmental
sustainability
A global
partnership for
development
t+T«
13.11 The Millennium Development Goals
The Millennium Development Goals (MDGs) and poverty
The UN Millennium Summit (2000) adopted ambitious social targets to be
achieved by 2015, which were called the Millennium Development Goals. One
of these goals was to halve the ratio of people in absolute poverty between 1990
and 2015. For the goals to be attained, the World Bank’s PRSP was going to be
used (hence the link between World Bank and UN policies). The World Bank’s
economists estimated that achieving the MDGs would require an additional
US$4O-6o billion dollars of Overseas Development Aid (ODA) per year (doubling
the current level of global ODA). The EU promised to increase its ODA to 0.39
percent of GNP (Gross National Product, amounting to about US$7 billion)
while the USA committed to add US$15 billion over three years for the benefit of
MICs/LICs engaged in 'good practice’. But in the financial crisis suffered by the
HICs from 2008 onwards many countries cut their ODA budgets drastically.
The Sustainable Development Goals (SDG) were introduced in 2015 by the
United Nations to replace the MDG that expired at the end of 2015. The MDGs
have not been entirely successful as over a billion people are still living in
poverty on less than $1.25 a day.
There are 17 SDGs with 169 individual targets; they will run until 2030. The
The SDGs have a much wider scope than the MDGs with aims to eradicate
poverty, protect the environment and ensure prosperity for all. Further details
can be found here:
http://www.un.org/sustainabledevelopment/sustainable-development-goals/
Aid
Aid (also known as Overseas Development Assistance (ODA)) is the assistance
governments, non-government organisations (NGOs), businesses and
individuals of one country give to the people of another country to help reduce
poverty and achieve sustainable development.
Different kinds of aid
Relief aid is often known as humanitarian aid and its purpose is to save lives,
reduce suffering and respect human dignity. Relief aid is normally employed
after events such as natural disasters or humanitarian crises such as civil wars
or famine. Also known as short-term aid, relief aid is generally administered by
NGOs such as Medecins Sans Frontiferes or the Red Cross.
Development aid (also known as international aid, overseas aid or foreign
aid) is financial aid given by governments and other agencies to support
economic, environmental, social and political development Development aid is
different to humanitarian aid as it is long term and concentrates on alleviating
poverty, rather than on a short-term response to a disaster.
Tied aid is foreign aid that must be spent buying products from the donor
country that provided the aid or in a group of selected countries. HICs will
provide a bilateral loan or grant to a MIC/LIC but mandate that the money be
spent on goods or services produced in the selected country. Examples of this
include money given by the UK to fund the building of a hydroelectric dam on
the Pergau River in Malaysia (1991) with money from the UK foreign aid budget.
The Malaysian government bought around £1 billion of arms from the UK. As a
result, the UK Government’s rules on ODA were changed to make it illegal for
tied aid to be given.
Global interdependence
Bilateral aid is assistance given by a government directly to the government
of another country. This is usually the largest share of a country’s aid. Bilateral
aid is often directed according to strategic political considerations as well as
humanitarian considerations.
Multilateral aid is assistance provided by governments to international
organisations, such as the World Bank, the United Nations and the International
Monetary Fund, that is then used to reduce poverty in developing nations.
The impact of aid on receiving countries
Aid is often regarded as being too generous or wasted on corrupt recipient
governments, despite the good intentions of donor countries. In reality, both
the quantity and quality of aid have been poor and some donor nations have
had little regard for what the money has been spent on.
In 1970 the world’s HICs agreed to give 0.7 per cent of their GNI (Gross
National Income) as official international development aid every year. Since
that time, despite billions given each year, HICs have rarely met the promised
target. For example, the USA is often the largest donor in dollar terms but ranks
amongst the lowest donors in terms of meeting the stated 0.7 per cent target.
Furthermore, aid often comes with a price of its own for developing nations.
•
•
•
•
Aid is sometimes wasted on conditions that the recipient must use
overpriced goods and services from donor countries (tied aid).
Most aid does not actually go to the poorest people who need it the most.
Amounts of money given in aid are dwarfed by the protectionism practised
by HICs that denies market access to MICs/LICs and their products, while
HICs use aid as a lever to open the markets of MICs/LICs to their products.
Large projects or massive grand strategies often fail to help vulnerable
people as the money is often embezzled.
Overseas development assistance
Some people (including NGOs and social activists) say that ODA should be
given in grants rather than in loans, which worsen the debt burden problem.
Others believe that ODA should only be given to LICs and MICs should not
receive official aid since they can attract private funds - India, for example, was
receiving ODA from the UK in 2014 despite having implemented an ambitious
space programme. Countries such as the USA believe that ODA should be
given only to poor countries with ‘good governance’(this is called the selectivity
argument) because money given to countries with bad policies and institutions
will be wasted. For these countries advice, not money, should be given.
To reduce transaction costs, for example fact-finding missions, reports,
meetings, administration etc., aid programmes need to be coordinated
among all donors. Common funds should be created to which all donors
contribute, thereby avoiding overlap and duplication and ensuring the money
reaches the people who need it most. Japan follows an approach where since
the needs of each country are different and each donor has its comparative
advantage, it is neither necessary nor desirable to unify all aid programmes and
implementation.
The role of non-governmental organisations (NGOs)
Non-governmental organisations have become quite prominent in the field of
international development in recent decades. But the term NGO encompasses a
vast category of groups and organisations.
The World Bank defines NGOs as “non-profit organisations that pursue
activities to relieve suffering, promote the interests of the poor, protect
the environment, provide basic social services, or undertake community
development.”
NGOs encompass a wide variety of groups, ranging from corporatefunded research associations to community groups, grass-root activist groups,
development and research organisations, advocacy groups, operational,
emergency/humanitarian relief focused groups, and so on.
Global interdependence 323
Since the mid-1970s, the NGO sector in both HICs and MICs/LICs has gone
through massive growth. Around 15 per cent of total overseas development
aid is distributed through NGOs, which is possibly as much as US$10 billion
a year. There could be as many as 30 000 national NGOs working in LICs and
the number of smaller scale community-based organisations number in the
hundreds of thousands.
NGOs can be criticised despite the good they do. For example, in non­
emergency situations some food aid groups deliver food from HICs to MICs/
LICs for free, or virtually free, which ends up undercutting local producers,
thereby having a negative effect on local farmers and the economy of the
country. In addition, many NGOs working in the area of population-related
issues can do more harm than good due to misunderstandings about
overpopulation and family and community structures in those societies.
Many NGOs have religious roots and are therefore seen as a moral thing
to support. Sometimes this aid has limited impacts due to the way it is
administered. Aid has often led to excessive dependency or reliance on aid
rather than helping nations move away from aid. The aftermath of colonialism,
corruption, conflict, rebuilding and developing often requires outside
assistance. The form of assistance that would be preferred is one that allows the
recipient, especially the rural poor, to help themselves, along the lines of the
age-old quote: “Give a man a fish; you have fed him for today. Teach a man to
fish and you have fed him for a lifetime.”
The development of international tourism
Reasons for and trends in the growth of tourism
Tourism is the world’s largest income earner and was worth US$1.5 trillion in
2014. Tourism has become a global leisure activity as can be seen in Figure 13.12.
There were 1.13 billion international tourist arrivals in 2014, which represents
growth of 4.4 per cent over the previous year.
Over the past 50 years tourism has experienced continual growth to become
one of the fastest growing economic sectors in the world. Tourism is closely
linked to development and is now a key driver of socio-economic progress in
many LICs.
Capital raised from tourism activities equals the revenue gained from other
economic sectors such as oil exports, food products or vehicles. Tourism is one
of the major players in international trade and one of the main income sources
for many countries at various stages of development.
This global spread of tourism in HICs has produced economic and
employment benefits and a valuable source of foreign earnings that help negate
trade deficits.
Figure 13.13 shows the last 60 years of tourist growth, increasing from just
tens of millions in 1950 to 694 million in 2004. The continued dominance of
Europe as a destination saw over 40 per cent of world tourists visit Europe in
2014, while large numbers continue to visit East Asia and the Americas.
figure
13.12 The economic value of tourism in 2015.
324 Global interdependence
Estimates
figure
13.13 Tourist arrivals, 1950-2020
Tourism generates huge amounts of wealth and employment for countries
at all stages of development. The reliance on tourism as a source of income
varies across the globe and can be measured as a percentage of GDP in many
countries. Most Caribbean countries get at least half of their GDP from tourism
and France, Spain, the USA, China, Italy and the UK are amongst the most
visited countries in the world.
table
13.2 International tourist arrivals
Rank
|
Country
Arrivals in 2014 (millions)
% change since 2013
1
France
83-7
0.1
2
United States
74-8
6.8
3
Spain
65.0
7-i
4
China
55-6
2-9
5
Italy
48.6
1.8
6
Turkey
39-8
5-3
7
Germany
33-o
4.6
8
United Kingdom
32.6
5-0
9
Russia
29.8
5-3
10
Mexico
29.1
20.5
(Source: United Nations World Tourism Organization (UN WTO))
World tourism
Some key figures:
• 10 per cent of GDP
• 1 in 11 direct, indirect and induced impact jobs
• US$1.5 trillion in exports
• 6 per cent of the world’s exports
• grown from 25 million international tourists in 1950 to 1133 million
tourists in 2014
• 5-6 billion domestic tourists
• 1.8 billion international tourists forecast for 2030.
Global interdependence
Many HICs dominate the income earned by tourism (Table 13.3).
table
13.3 International tourism revenues
Income in 2014 (USS billions)
Country
Rank
% change since 2013
177.2
2-5
Spain
65.2
4-2
China
56.9
10.2
1
United States
2
3
4
France
55-4
-2.3
5
Macao (China)
50.0
-1-9
6
Italy
45-5
3-7
7
United Kingdom
45-3
10.3
8
Germany
43-3
5-o
9
Thailand
38.4
-8.0
10
Hong Kong (China)
38.4
-1.4
(Source: United Nations World Tourism Organization (UN WTO))
Tourism has grown over the last half century for a number of reasons.
1 Advances in travel technology: The advent of the jet engine and wide-bodied
jets has meant that travel to distant lands is now no longer the preserve of
the very rich. Budget airlines such as Easyjet and AirAsia and their use of
regional (and therefore accessible) airports have brought the price of air
fares down and this has increased traffic volumes even in NICs.
2 Disposable income: Salary rises and the price for essential goods such
as housing, food and clothing has fallen in relative terms in most HICs.
Families now have two income earners as the role of women has changed in
many countries leading to increased wealth, the birth of fewer children and
3
4
5
high levels of personal mobility.
Changing lifestyles: Shorter working weeks, flexible working hours, longer
holiday entitlement, increasing life expectancy and earlier retirement in
HICs and MICs has led to more people taking holidays.
Changing types of holiday: The availability and type of holiday has
increased - mass tourism and package holidays have opened up markets to
large numbers of people. Extreme tourist destinations and ecotourism have
risen in popularity.
The media: Increased exposure to the media, especially TV and the internet,
leads to the popularity of some destinations increasing.
Tourism growth can be negatively affected by events such as civil unrest.
After the Arab Spring uprisings in Egypt in 2010 visitor numbers at Red Sea
resorts, hundreds of miles away from Cairo, declined. Terrorism too can trigger
similar drops in tourist numbers. After Bali was bombed it suffered a severe fall
in tourist numbers and global tourist numbers fell after the 9/11 and 7/7 terrorist
attacks. Acts of terror in Morocco in 2011 and Tunisia in 2015 saw foreign
nationals advised by their governments not to travel to those countries for fear
of similar events occurring again. The banking crisis of 2008 also hit tourist
numbers as people had less money available to them fortravel.
The impacts of tourism on the environments, societies and economies of
tourist destinations
While tourism has many positive economic outcomes, it can also have
undesirable impacts. Tourism is a complex industry involving numerous
stakeholders (sometimes with conflicting interests) that requires significant
resources, which can lead to damaging impacts.
326 Global interdependence
Negative impacts from tourism occur when the level of visitor numbers
exceeds the environment’s ability to cope with this increased use. Uncontrolled
tourism poses potential threats to many natural areas around the world. It can
lead to varying impacts such as soil erosion, pollution, discharges of sewage into
the sea, natural habitat and biodiversity loss and increased vulnerability to forest
fires. It often puts a strain on water resources and can force local populations to
compete for the use of other critical resources.
The environment
One of the criticisms of the development of tourism is the impact it has on
the natural environment. These impacts include overuse of natural resources,
pollution, landscape degradation and threats to biodiversity.
The tourism industry generally overuses water resources for hotels,
swimming pools, golf courses and personal use of water by tourists. This
can result in water shortages and degradation of water supplies, as well as
generating a greater volume of wastewater that needs disposal. In drier regions,
such as the Mediterranean, the issue of water scarcity is of particular concern.
Golf tourism has increased in popularity and the number of golf courses has
grown massively but the construction and use of golf courses depletes fresh
water resources. Golf courses then require an enormous amount of water every
day, which can result in water scarcity.
The development of tourism and other recreational facilities has led to
greater pressure on resources as well as landscapes. Deforestation caused by
land clearance for tourist developments has a negative impact also. In Nepal,
a country that is badly affected by the impacts of deforestation, each tourist on
trekking vacations can consume up to 5 kg of firewood per day.
Tourism can cause the same forms of pollution as any other industry: air
emissions, noise, solid waste and littering and the release of sewage, oil and
chemicals. In areas with high concentrations of tourist activities and appealing
natural attractions waste disposal is a serious problem and improper disposal
can be a major despoiler of the natural environment- rivers, scenic areas and
roadsides. Cruise ships in the Caribbean are estimated to produce more than
70 000 tonnes of waste each year. Some trails in the Peruvian Andes and in
Nepal frequently visited by tourists have been labelled the Coca-Cola Trail and
the Toilet Paper Trail.
Construction of hotels and other facilities often leads to increased sewage
volumes, which in turn leads to polluted seas and lakes surrounding tourist
attractions damaging the flora and fauna. Sewage runoff causes serious damage
to coral reefs because it stimulates the growth of algae, which cover the filter­
feeding corals, hindering their ability to survive. Sewage pollution can also
threaten the health of humans and animals; according to the United Nations
Environment Programme around 85 per cent of the sewage discharged into the
Caribbean is untreated.
Often tourism fails to build facilities that are in keeping with natural features
and indigenous architectural styles. Large, dominating resorts of different
designs can look out of place in any natural environment and may clash with
the local buildings. A lack of land-use planning and sympathetic building
regulations in many destinations has facilitated sprawling developments along
coastlines, valleys and scenic routes. This includes the tourism facilities as well
as infrastructure such as roads, employee housing, parking, service areas and
waste disposal.
Attractive landscape sites, such as sandy beaches, lakes, riversides and
mountaintops, are often species-rich ecosystems. Typical physical impacts of
tourism include the degradation of such ecosystems.
The ecosystems most threatened with degradation are ecologically fragile
areas such as alpine regions, rainforests, wetlands, mangroves, coral reefs and
seagrass beds. The threats to and pressures on these ecosystems are often
severe because such places are very attractive to both tourists and developers.
The building of alpine-style ski resorts has led to many environmental issues
such as habitat and biodiversity loss, soil erosion from the preparation of pistes
Global interdependence 327
(ski-runs) and over-use of water resources to manufacture artificial snow when
natural levels are low.
Development of coastal facilities such as marinas can cause changes in
currents and coastlines, leading to the destruction of habitats such as coral
reefs and mangroves. Coral reefs are especially fragile marine ecosystems and
are suffering worldwide from reef-based tourism developments. Evidence
suggests a variety of impacts to coral result from shoreline development, for
example, increased sediment in the water, trampling by tourists and divers, ship
groundings and anchoring, pollution from sewage, overfishing and fishing with
poisons and explosives that destroy coral habitats. The Maldives, in particular,
face many of these threats as well as rising sea levels due to climate change.
Tourists using the same trail over and over again trample the vegetation
and soil, which eventually causes damage that can lead to loss of biodiversity
and other impacts. Such damage can be even more extensive when visitors
frequently stray off established trails. In many British and Irish upland areas
trampling is a perennial problem, especially where visitor numbers are large.
The economic impacts of tourism are well documented in terms of its
contribution to a country’s GNI, the number of people it employs, and the
overall wealth it brings but its impacts on local economies are often overlooked.
Economic impacts
Unlike some of its environmental impacts, tourism’s economic impacts are
mainly considered to be beneficial. These are:
Often tourism projects are subject
to conditions that allow for positive
environmental impacts. These include
planting of trees and landscaping to
minimize the visual impact of any
development. Environmental protection
programs such as building using energy­
efficient and non-polluting construction
materials, sewage systems and energy
sources allows the tourism industry to
develop in a sustainable way.
The Grupo Punta Cana resort in the
Dominican Republic, was designed to
conserve the natural habitat of Punta
Cana. Ten thousand hectares of land was
designated a nature reserve and native
fruit tree garden, including 11 fresh water
springs surrounded by a subtropical
forest where many species of unusual
Caribbean flora and fauna live in their
natural habitat. A trail leads from the
beach through mangroves and lagoons
of fresh water past dozens of Caribbean
flora and fauna species and can be
explored by tourists. Parts of the reserve
that had been deforested in the past have
been replanted. Other environmentally
protective policies have been put into
effect at the resort, such as programs
to protect the offshore barrier reefs and
the recycling of wastewater for use in
irrigation of golf courses. The resort has
also established a biodiversity lab run by
an American university.
328 Global interdependence
•
•
•
•
•
•
•
the generation of foreign exchange
the creation of new job and employment opportunities
the stimulation of trade, income and entrepreneurship - especially in the
service and small business sectors
the provision of new infrastructure, which is then available for non-tourism
uses
increased regional development- particularly in isolated rural areas
greater tax revenue, which permits greater government spending or reduced
taxes on other activities
the impact of the multiplier effect (see page 330).
In many LICs tourism is often in the control of overseas companies in the
form of resorts and hotels, which employ local people in low paid work as
domestic staff such as chambermaids and waiters. Management positions are
usually held by foreign nationals, who are often from HICs. These resorts import
food and drink products from HICs as their guests demand familiar tastes. This
can impose extra costs on host countries by requiring them to import these
items for resale to the visitors. This is especially so with small island economies
that do not produce locally what the tourists want- not just the food and drink
brands that the visitors prefer but also luxury purchases such as jewellery and
photographic equipment. Local producers grow foodstuffs, for example salad
crops, that are familiar to tourists at the cost of growing food for locals.
Tourism can be a useful tool for the alleviation of poverty and given careful
management can be part of the Poverty Reduction Strategy Paper for the
poorest LICs - many LICs use tourism as a way of raising revenues in order to
relieve their foreign debts.
At the same time, there are many negative consequences to consider.
These are:
•
•
•
•
•
•
leakages of expenditure out of the local economy
increased imports
opportunity costs
displacement effects
over-dependence on tourism
inflation and higher land values
•
seasonality issues
•
•
over-reliance on expatriate labour
problems over foreign capital investment
Social and cultural impacts
The social and cultural impacts of tourism are ‘people impacts’concerning
the effects on people in host communities from their direct and indirect
associations with tourists. These can include commodification, where local
traditions such as rituals, festivals and dress become entertainment for
tourists. Some rituals are performed daily, which reduces their significance
for local people. Tourists demand souvenirs and local craftsmen may be
forced to mass produce goods for the tourist market, making these goods
less authentic.
Another impact is standardisation, where tourists expect to see familiar
facilities in unfamiliar surroundings such as fast food outlets from their
own countries. Because tourism involves mixing between people who would
otherwise not meet, cultural clashes can take place as a result of differences in
cultures, ethnicity, religion, values, lifestyles, languages and levels of prosperity.
In LICs there is likely to be a growing distinction between the 'haves’ and ‘havenots’, which may increase social and sometimes ethnic tensions. In resorts in
countries such as Jamaica, Indonesia or Brazil, tourism employees with annual
salaries of US$1500 spend their working hours in close contact with guests
whose yearly income is well over US$100 000.
Tourists in countries where there are strict rules regarding dress or the
consumption of alcohol often disregard or are unaware of these standards,
ignoring the prevalent dress code, appearing half-dressed (by local standards)
in revealing shorts, skirts or even bikinis, sunbathing topless at the beach or
consuming large quantities of alcohol openly.
The attitude of local residents towards tourism development may unfold
through the stages of tourism. Initially visitors are made welcome, but apathy,
irritation and potentially antagonism may lead to anti-tourist attitudes growing
among local people.
Jobs in the tourism sector often involve long hours, unstable employment,
low pay, little training and poor chances for qualification. As a result many
children are recruited to work. Adults and children are coerced into becoming
sex workers with little chance of being able to escape this life. The growth of
mass tourism is also often accompanied by increased crime. The presence of
a large number of tourists with a lot of money to spend, and often carrying
valuables such as smart phones and expensive watches, increases the attraction
for criminals and brings with it activities such as robbery and drug dealing.
Another impact is acculturation where cultures mix and eventually become
similar-the culture of the resort area is often influenced by Western culture.
Tourism can contribute to positive developments, not just negative impacts.
It has the potential to promote social development through employment
creation, income redistribution and poverty alleviation. Other potential positive
impacts of tourism include:
•
•
strengthening communities
facilities developed for tourism can benefit residents
•
•
revaluation of culture and traditions
encourages civic involvement and pride.
Tourism’s environmental and socio-cultural impacts are usually considered
to have a number of positives to offset some of the negative effects but they
may not always be able to do so at the same level of advantage that tourism’s
economic impacts can.
Carrying capacity
The concept of carrying capacity is used widely in geography, with varying
definitions. Basically it is the ability or capacity of an area to deal with the
numbers and demands of visitors who use an area. The World Tourism
Global interdependence 329
Organization (WTO) proposed the following definition of carrying capacity in
1997:
“The maximum number of people that may visit a tourist destination at
the same time, without causing destruction of the physical, economic,
socio-cultural environment and an unacceptable decrease in the quality
of visitors’ satisfaction. This is based on the idea that any geographical
system has certain limits or thresholds. These thresholds, when exceeded,
may affect permanently not only physical components of an environment
like soil or water, but human ones too such as culture and quality of life.”
Figure 13.14 is a model of carrying capacity. It may be used to show changes
over time for one location and different locations at one time. It is often linked
to the product life cycle where stages of development have differing levels of use
with resulting different carrying capacities.
Saturation or carrying capacity
zone may be altered by
management of either people
or site. Effectively the limits of
acceptable change. Could have
number of
differing lines for physical,
people/use
Over capacity leads to decline in people if
management cannot increase resilience.
However this may not establish equlibrium
if geographical system too damaged.
figure
13.14 Carrying capacity
The multiplier effect
Tourism creates jobs in the tertiary sector and also encourages the growth of
jobs in the primary and secondary sectors of industry. This is known as the
multiplier effect, which in its simplest form is how many times money spent by
a tourist circulates through a country’s economy. Money spent in a hotel helps
to create jobs directly in the hotel but also creates jobs indirectly elsewhere.
The hotel, for example, has to buy food from local farmers, who may then
spend some of this income on fertiliser or clothes. Demand for local products
increases as tourists buy souvenirs, which increases secondary employment. The
multiplier effect continues until the money eventually ‘leaks’from the economy
through imports - the purchase of goods from other countries.
Leakage
Leakage is where capital exits an economy or system rather than remaining
within it. A lot of tourism income does not remain in the host country but leaks
back to the HICs. This may be because a western TNC owns the hotel or because
food, drink or other supplies demanded by tourists have to be imported from
overseas.
The World Bank estimates that 55 per cent of international tourism income in
LICs leaves the region due to foreign-owned airlines, hotels and tour operators
or payments for imported food, drink and supplies. In some countries, notably
in the Caribbean, the figure for leakage can be as high as 80 per cent and
leakage is 70 per cent in Thailand. Even in the Mediterranean, two-thirds of
the income from tourism is controlled by less than 10 tour operators based in
northern Europe.
330 Global interdependence
The Tourism Area Life Cycle (TALC or Butler) Model
In geographical terms a model is a simplification of reality. The purpose of
the Butler Model is to look at the way that tourist resorts grow and develop.
The tourist industry, like all industries, is dynamic and constantly changing.
Therefore, the Butler Model is a way of studying tourist resorts and seeing how
they change over time and in relation to the changing demands of the tourist
industry. These changes can then be compared to the predictions, as shown on
the model (Figure 13.15). The Butler Model breaks down tourist development
into six distinct stages.
1
2
3
4
5
6
Exploration stage
A settlement is ‘explored’ or ‘discovered’ by a small number of people (early
innovators). They are attracted by primary tourist attractions that could be
natural or cultural. At this time, tourism has no economic or social value to
local residents and there are no secondary tourism attractions.
Involvement stage
Local residents become involved in the tourism industry as secondary
tourism facilities such as guest houses develop. The resort develops a
‘tourist season' and transport infrastructure often improves as a result of
government involvement.
Development stage
Tourists now exceed the local population during the tourist season. More
tourists attracted by increased publicity have led to the building of new
infrastructure such as hotels, restaurants, shops and other attractions to
cater for the influx of tourists. Many of these new facilities are no longer
controlled by local people and companies from outside of the resort take
over. Local people do not approve of the physical changes to the resort that
they are are experiencing.
Consolidation stage
The growth of tourism begins to slow down but actual visitor numbers
exceed the number of locals. As the resort’s economy is now dominated by
tourism, the resort is well marketed and hotels belonging to international
chains are widespread. There is now a well defined recreational business
district catering for tourists. Local people are often discontented with, and
opposed to tourism.
Stagnation stage
The popularity of the resort is short-lived as visitor numbers have reached
a peak and the carrying capacity of the resort may have been exceeded.
Tourists have become bored with the resort now its initial appeal has waned.
Little of the original settlement remains and it receives negative publicity
about its appearance and clientele so people go on holiday elsewhere.
Falling tourist numbers cause the resort to go out of fashion and leads to
economic decline and the under-use of tourist facilities. This leads to the
eventual closure of businesses and unemployment rises.
The Final Stage
In the original tourist resort model, Butler supplied 5 possible different
scenarios
a
b
c
d
Successful redevelopment leading to new growth
A modest growth in tourist numbers
Stabilisation caused by a reduction in tourist capacity
A gradual decline in tourist numbers caused by overuse of resources and a
lack of investment
e
A rapid decline of tourist numbers caused by catastrophic events such as war.
This was further modified in to two possible stages:
6a) The Decline Scenario The resort is unable to compete with other and
often newer resorts as tourism facilities are replaced by non tourism
facilities. Hotels are closed and are converted into retirement homes or
flats for local people. The visitors change from being holidaymakers to
day-trippers as the area becomes down-trodden and much maligned.
figure 13.16 Blackpool, a popular resort in the North West
of England, UK, has rejuvenated itself in recent years.
Global interdependence
6b)
The Rejuvenation Scenario Alternatively, the resort could rebrand by
reinventing itself opening new facilities or adopting a particular niche
market. This could come from an injection of capital from central of
local government. This would see visitor numbers rise.
Many have academics have criticised the Tourism Area Life Cycle model as
many resorts have not followed the pattern shown. Some resorts seem to go out
of fashion and become undesirable while others continue to sustain their visitor
numbers without any sign of going in to decline.
Case Study
The Butler Model: Majorca
Majorca fits the Butler Model well in so far as it has gone from boom to bust
in around halfa century. In the 1960s Majorca was in the discovery stage- it
received less than half a million tourists per year. Employment was dominated
by the primary sector in mainly fishing and agriculture. Visitors were attracted to
unspoilt beaches, picturesque villages and an unpolluted sea, even though the
infrastructure of roads and public services was poor and there were few hotels.
By 1970 Majorca entered the growth and development stage as there was a
rapid increase in tourist numbers, which was encouraged by the government,
with 3 million tourist arrivals. Majorca had become a popular package holiday
destination for Northern Europeans. Employment shifted from agriculture
to tourism-related work such as construction, jobs in hotels, cafes and shops.
This led to the building of large hotels, apartment blocks and villas, many of
which were built without proper planning. Some road improvements took place
but again without proper planning controls, which led to severe congestion.
Farmland was lost due to development and this led to environmental issues such
as natural habitat loss as well as the pollution of the beaches and the ocean.
In the 1980s Majorca reached the success stage of the Butler Model. Tourist
arrivals rose to 7.5 million leading to resources like water being overused. Up to 70 per
cent of the population worked in tourism and the local economy was dominated by it
Tourist developments blighted the landscape and locals grew resentful of the tourists.
The stagnation stage began in the 1990s as the number of tourist arrivals
began to decline. Unemployment rates rose above 30 per cent as bars and cafes
closed due to lack of customers. Older resorts began to look rundown and resorts
like Magaluf gained a poor reputation. Only high-class hotels gained approval to
be built. There were attempts to clean up beaches and new public parks, gardens
and nature reserves were opened to try to attract some ecotourists.
In the 2000S new facilities such as a new airport terminal were built along
with upmarket hotels to try to rejuvenate Majorca. During the recession from
2008 visitor numbers slumped to only around 6 million but by 2013 they had
figure
13.17 Majorca location map.
reached record numbers of over 9 million.
figure
332 Global interdependence
13.18 Magaluf, a popular resort in Majorca, Spain, has seen a decline in visitor numbers.
Recent developments in tourism
The last few decades have seen a rise in many people’s relative prosperity in
HICs and the demand for international travel has increased. The development of
transport technology-jet aircraft and high-speed rail in particular-have fuelled
this demand. This boom has been aided by internet sales of tourist services
where would-be tourists can surf the web in search of their dream holiday for a
bargain price. Table 13.4 looks at recent trends in tourism.
figure
13.19 The Albert Dock in Liverpool with its heritage and cultural
connections is a top visitor attraction for tourists on city breaks in Liverpool.
table
figure 13.20 The Birkenau Gate, Auschwitz, a former Nazi Concentration Camp.
‘Dark’ sites like these have been become popular destinations for tourists in
recent decades.
13.4 Recent developments in tourism
Trend
Explanation
Sustainable tourism
Sustainable tourism takes into account the ecological and socio-cultural carrying capacities of the
destination and involves the community in tourism development planning to mitigate some of the
negative economic and social impacts of‘mass tourism’.
Ecotourism
Ecotourism involves responsible travel to fragile, pristine and protected areas in a low-impact fashion
and usually is small in scale. It helps educate the traveller and provides money for conservation
projects. Ecotourism directly benefits the economic development of local communities. It also
fosters respect for different cultures and for human rights.
City breaks
City breaks involve a short stay in a city or region with significant historical or cultural connections.
Tourists take advantage of low cost airlines and often stay in budget hotels. City breaks are particularly
popular in Europe, with destinations such as Rome, Paris and Liverpool widely visited.
Home stays
Tourists swap homes in different countries to cut down on the cost of holidays, especially in long
haul destinations. This form of holiday has been promoted by travel/accommodation booking
companies such as Couchsurfing and Airbnb.
Pro-poor tourism
Pro-poor tourism seeks to help the poorest people in LICs. It involves small-scale projects in
local communities and attempts (by Ministries of Tourism) to attract large numbers of tourists to
previously rarely visited areas.
Medical tourism
Medical tourism involves patients visiting countries for medical procedures. Costs are lower and
regulations differ (compared to Western countries) in Southeast Asia, India and Eastern Europe, and
all of these regions/countries are popular medical tourism destinations.
Dark tourism
Dark tourism involves visits to ‘dark’ sites such as battlegrounds, scenes of horrific crimes or acts of
genocide, for example Nazi concentration camps such as Auschwitz in Poland.
Doom tourism
Also known as 'Last Chance Tourism’, this involves travelling to places that are threatened, such as
the ice caps of Mount Kilimanjaro or the coral of the Great Barrier Reef, before it is too late.
Global interdependence
The management of a tourist destination
Case Study
Ecotourism
in the
Galapagos Islands
The Galapagos are a small chain of islands belonging to Ecuador; they are located
in the Pacific Ocean, 1000 km from the west coast of South America. The Galapagos
Islands are famous because they have been isolated from the rest of the world for
hundreds of thousands of years and this has allowed their animals, flora and fauna
to evolve in unique ways. Around 90 per cent of the islands are designated as a
national park and the area was the first UNESCO World Heritage Site (1979).
a,Genovesa
Island
PACIFIC
OCEAN
Baltra
Island
Fernandina
Island
Co Azul
1689
Isabela
Island
Puerto o
Villamil'
Puerto0
Ayora
Tortuga
Island
Floreana
Island
figure
San Cristbbal
Island
Santa Cruz
Island
O
Santa FĞ
Island
Puerto
Baquerizo
Moreno
Espanola Island
13.21 The Galapagos Islands
In recent years there has been a rapid expansion of the tourism industry;
there is growing demand for ‘specialist’ tourism to visit protected natural areas.
Regrettably, this increase in demand for tourists to visit protected areas has
begun to have negative impacts.
Background
In the late 1950s just a few tourists - mainly adventure tourists from HICsvisited Ecuador. In 1969 the cruise ship Lina A began to offer tours to the
Galapagos Islands - this was the start of the tourist boom.
In 1974 the Ecuadorian government formed a national body to improve
tourism within the country, to regulate activities in the tourism sector such as
travel agencies and hotels, and to provide incentives for investment in tourism.
In 1984 a Master Plan forTourism was introduced. The plan outlined priorities
for tourism development but tourism in Ecuador was poorly promoted at that
time and lacked high-quality hotels.
These investments and projects initiated by the tourist board have greatly
increased the number of people and amount of money flowing into the
Galapagos. This influx has, however, been a source of conflict as the impact
of increased tourism on the Galapagos Islands has been social, economic and
environmental.
334 Global interdependence
225
At the national level income is generated for the national park system
through entrance fees to the Galapagos. Until 1993 foreigners paid (US$)
80 cents per person for admission, while Ecuadorians paid (USS) 40 cents. The
government realised that visitors were grossly under-taxed and has since raised
the admission fee to US$100 for foreigners and US$50 for Ecuadorian nationals.
This income goes to the national park service to be distributed among all
Ecuadorian parks. The Galapagos National Park receives the biggest portion of
the admissions income, about 50 per cent of the total, which is over
US$20 million in most years. Roughly 25 per cent of the funds for the Galapagos
go to finance its tourism programme, which includes operational costs for ticket
sales, park guards and patrol boat operators.
The impacts of mass tourism
Over the last 20 years Ecuador has taken advantage of the economic potential
of the Galapagos. Tourism, which generates nearly US$500 million a year, is a
potential growth industry for debt-ridden Ecuador. As a result of tourism, the
GNI of the Galapagos Islands province is the highest in Ecuador. Income is
generated through the many Ecuadorian travel agencies that offer trips to the
Galapagos, while the people employed in tourism on the islands originate from
all parts of Ecuador. Boat trips and dive schools are an important source of
income.
While capitalising on the growth of tourism, the government has also
imposed strict guidelines. However the rise of tourism has led to increased
immigration from the Ecuadorian mainland as many people see the
employment opportunities in the Galapagos as a route to a better quality of
life. The rising population is increasing the pressures on the already meagre
resources of the islands, including fresh water and seafood. The local population
has increased from 6000 to about 25 000 official residents and around 6500
seasonal migrants in the last 25 years. The population is growing at a steady rate
of 6 per cent per year.
As tourist numbers and inhabitants in the Galapagos have increased, so have
the number of airports from one to three. Airline flights and the number of cargo
and cruise ships have increased in frequency too, bringing with them the possible
threat of oil spills. Increases in the number of airline routes and more ships
visiting could potentially bring invasive species - possibly the greatest threat to
the archipelago. Feral pigs, dogs, cats and goats provide the biggest threat to the
endemic species of the Galapagos because many of these species have no natural
predators.
The inhabitants of the islands have contributed to its ecological demise
through their entrepreneurial endeavour. They have turned remote fishing
Global interdependence 335
villages into strips of discos, restaurants, hotels and shops selling converted
plants and animals as souvenirs. Local divers have devastated black coral
formations, an endangered species, turning it into jewellery items that are
popular among tourists.
Although the seas around the Galapagos Islands have been a protected
marine reserve since 1986, illegal fishing continues, particularly for sharks, as a
result of close cooperation between Ecuadorian, Japanese and Korean interests.
The demand for shark fins has deadly results as the nets used to trap sharks
catch all kinds of animals, including Galapagos penguins, dolphins, Galapagos
cormorants, sea lions and sea iguanas. Immigrants from the mainland who now
live on the islands to work in tourism have little knowledge of conservation; they
figure
13.23 The Marine Iguana - a species unique to the
Galapagos.
dump rubbish overboard so animals such as turtles eat discarded plastic sacks,
and they catch lobsters when they are carrying eggs or are too small, which
leads to overfishing. The Charles Darwin Research Centre has documented a
number of cases where the local population has killed giant tortoises fortheir
meat.
Traditionally the islands have had more international than national visitors.
Visitor numbers peaked in 2011 with around 185 000 tourist arrivals and around
two-thirds of these were foreign nationals. Most tourists to the islands do not
stay in one of the local hotels but immediately transfer to a cruise ship. These
cruise ship tours usually last from three days to two weeks and, depending on
itinerary, visit between five and 11 islands. To minimise negative impacts the
park service has designated 45 approved visitor sites around the archipelago.
Tourists are required to stay on marked pathways at most sites and must be
accompanied by a trained naturalist guide. Many trails go through nesting
colonies of sea birds, such as the blue-footed booby, flightless cormorants, gulls
and frigate birds. Tourists often make the mistake of startling the birds when
attempting to get close, causing them to fly from their nests and leaving an
egg or chick exposed. A newly hatched booby chick will die within 30 minutes if
exposed to the equatorial sun.
The Galapagos Islands have a small number of native species, most of which
are endemic. Around a third of the native plant species (which number less than
600), are found only here, while 57 species of reptiles, animals and birds are also
only found in the Galapagos. Among these species are the Marine Iguana, the
Humboldt Penguin (the only species of penguin found in the tropics) and the
Galapagos Cormorant (which has lost its ability to fly due to a lack of predators).
Also, uniquely to the Galapagos, some species are found only on a single island
with a nearly identical but distinct species on a neighbouring island, for example
various types of finches.
figure
13.24 The Galapagos Tortoise. In the absence of predators, they can live to over 100 years of
age and measure nearly 1.8 m in length.
3
Global interdependence
One of the major threats to native species is that some tourists have started
feeding wild animals. Some animals have become reliant upon being fed and
when the extra feeding was curtailed by the Park Service these animals were
unable to locate their natural food sources. Although it is strictly forbidden to
leave rubbish on the islands or in the surrounding waters such disposal still
occurs - including the emptying of sewage tanks by tourist ships right into the
water.
Enforcement officials are unable to keep pace with the influx of visitors and
immigrants and the damage they do. In 1998 a Special Law for Galapagos was
introduced but, like much of the legislation designed to protect the islands, it
has been poorly enforced.
In 1987 the government imposed a restriction of 25 000 visitors a year
visiting the Galapagos but this figure has never been enforced. As Ecuador is
unable to disregard the lure of the tourist dollar and with leakage amounting to
55 per cent of all tourist revenues returning to HICs, the government has tried
to maximise the amount of money made from tourism on the islands.
Uncontrolled tourism and population growth were among the 15 issues
identified by UNESCO’s World Heritage Committee when it recommended
that the Galapagos Islands be placed on the list of World Heritage in Danger.
Recently attempts have been made by the tourism industry to modify tourism
regulations in a way that would have undermined the participatory management
system and reduced the authority of the Ministry of the Environment in
Galapagos.
The economic wellbeing of the Galapagos Islands is compromising the need
for conservation of the unique ecosystems that exist there. The government
of Ecuador sees the Galapagos as a valuable source of revenue but it will only
remain so as long as its uniqueness is preserved.
NOW INVESTIGATE
1
Investigate the patterns of trade of a commodity such as copper
or soya beans. Which countries are the largest producers and
consumers? What is the value of the trade and how has this
changed?
2
Investigate the role of a non-governmental organisation (NGO) in
providing aid in a LIC. How does the NGO use the aid in a chosen
location? What criticisms are there of the NGO’s work in the
location you have chosen?
3
Investigate the development of a tourist location. How has the
location grown and possibly declined? To what extent does the
growth of the location reflect the Tourism Area Life Cycle
(Butler) Model?
Global interdependence 337
GDP (Gross Domestic Product) is the total value of goods
and services produced within a country in a year, not
including its income from investments in other countries.
GDP is an important economic indicator as it attempts to
capture the state of a country’s economy in one number.
The growth or decline of a region’s GDP over time can
measure the success or failure of economic policies and
can be used to determine if an economy is ‘in recession’.
Estonia
Sweden
Norway
$522bn
Iceland
$15bn
$25bn
$580bn
Finland
S267b"
Latvia
$31bn
UK
$2678bn
Denmark
Netherlands
$337bn
$854bn
Lithuania
$46bn
Ireland
$232bn
Belgium
$525bn
Poland
Belarus
S526bn
S98bn
Germany
$3730bn
Lux
$60bn
France
S1839bn
$2806bn
$6bn
Portugal
_
Romania
Moldova
$192bn
Austria
Andorra
Monaco
$3bn
$7bn
Switzerland
Hungary
$685bn
$133bn
S.M.
$8bn
Bulgaria
$54bn
Slovenia
$2bn $48bn
Serbia
Croatia ^bTtosovo
$227bn
Italy
B$H
Liecht
Lux
Mont
S.M.
$16 768bn
$188bn
$428bn
Spain
$1393bn
Ukraine
$98bn
$209bn
Liecht
Canada
Slovakia
Czechia
(Czech Rep.)
$7bn
S58bn
$2149bn
Europe
Bosnia and Herzegovina
Liechtenstein
Luxembourg
Montenegro
San Marino
Georgi.
$16bn
S18bn $X
Macedonia
A..
(F.Y.R.O.M.)
Albania'
Malta
Turkey
$822bn
S13bn Sllbn
$10bn
Cyprus
Greece
$242bn
$24bn
Syria
$35bn
Tunisia
Israel
S47bn
A8(B
Dom.
Dom. Rep.
S.K.N.
S.V.G.
The Bahamas
Cuba S8bn
$34t
$104bn
Libya
Algeria
$75bn
$209bn
Lebanon
$47bn
$1259bn
r
$8bn, $61bn
Belize
S2bn
Jamaica
.___ _ Honduras S14bn
$5Xn
*’b"
$6bn
The Gambia
Trinidad fit Barbados
Tobago
$4bn
Venezuela $24bn
«71b" Guyana
Guinea- Guinea
Bissau $7bn
Slbn Sierra
Leone
$13bn
Nigeria
$515bn
$48bn Benin
$8bn
Togo
$2bn $29bn $4bn
Cote
Liberia d'Ivoire
Suriname
$378bn
$5bn
S3b
Ghana
Ethiop
$5bn
S3bn
Colombia
Eritn
Chad
$10bn
Burkina Faso
$0.8bn
S0^bnS°-7bnSlbnrt.
$55bn
Niger
$7bn
Cape Verde Senegal
$15bn
$2bn
$0.5bn
Costa Rica
Sudan
Mali
$llbn
Slbn
$0.7bn
Dom.
$50bn Panama
S40bn
$255bn
Mauritania
■»W
Sau
Arat
$748t
Egypt
$7’b" Haiti'Dom. Rep.
Mexico
Jordi
$292bn
Morocco
N America
Antigua and Barbuda
Dominica
Dominican Republic
St Kitts and Nevis
St Vincent and the Grenadines
Cameroon
CAR.
$2bn
South
Sudan
$12bn
$30bn
Uganda
Eq. G.
$19bn
SSoTome
£ Principe
Ecuador
$0.3bn
$94bn
$26bn
Gabon
$17bn
D.R.C.
Rwanda
$33bn
$8bn
Brazil
Peru
$200bn
C.A.R.
D.R.C.
Eq.G.
Ken^
$541
Burundi
Congo
$3bn
$14bn
$2244bn
$46b
Tanzania
Africa
Central African Republic
Democratic Republic of the Congo
Equatorial Guinea
$45bn
Angola
$122bn
Malawi
$5bn
Zambia
$22bn
Bolivia
$31bn
Mozambiq
Zimbabwe $16bn
Namibia
$13bn
Paraguay
$13bn
Botswana
$15bn
$29bn
Eswatini.
(Swaziland)
.
. $4bn
Lesotho
Chile
South
Africa
$277bn
Uruguay
Argentina
$612bn
SS6bn
$366bn
$2bn
Europe
US $19 547
billion
North America
US $20 394
billion
Asia
US $27 294
billion
14
South America
US$4300
billion
Econom ic transition
Africa
u->*2344
billion
Oceania
US$1760
billion
TOTAL GDP 2013
Russia
$2097bn
Kazakhstan
$224bn
Mongolia
rbaijan
$12bn
74bn
Uzbekistan
tenia
$57bn
)bn Turkmenistan
$42bn
Kyrgystan
North Korea
$7bn
$15bn
Tajikistan
$9bn
Japan
$4899bn
>6 bn
Iran
Afghanistan
South Korea
$22bn
$493bn
$1305bn
China
$9181bn
uwait
Pakistan
Bahrain
.76bn
N'f1
$225bn
$33bn
Bhutan
S18bn $2bn
Qatar
Bangladesh
$202bn
$154bn
Laos
UAE
$402bn
$1938bn
Oman
Yemen
India
Myanmar
$llbn
$63bn
$80bn
Thailand
$420bn
$35bn
Vietnam
$171bn
>outi
bn
Cambodia
Philippines
$15bn
$272bn
Marshall
Islands
$0.2bn
Kiribati
Sri Lanka
Palau
$67bn
$0.2bn
tmalia
Malaysia
ilbn
Maldives
$312bn
$0.2bn
Brunel
$16bn
Micronesia
$0.3bn
$3bn
Singapore
Nauru
$296bn
$0.2bn
Seychelles
$lbn
Indonesia
Papua New
Guinea
$868bn
S15bn
East Timor
$5bn
Tuvalu
Solomon
Islands
$0.04bn
$lbn
oros
Sbn
Samoa
$0.7bn
Vanuatu
$0.8bn
agascar
Ibn
Mauritius
$12bn
Fiji
$4bn
Country GDP, 2013
Tonga
$0.4bn
Australia
$1531bn
Country
GDP 2013 total
US$ billion
New Zealand
$189bn
339
Economic transition
National development
Employment categories or sectors
All occupations in every location in the world can be classified according to four
different employment categories or sectors:
•
•
•
•
Primary sector: The acquisition of raw materials from land and sea. This mainly
includes mining, quarrying, extraction of oil and gas, farming, forestry and
fishing. In the LICs a large proportion of the population is traditionally involved
in this sector, often in subsistence agriculture.
Secondary sector: The manufacture of raw materials into finished goods.
This includes industries such as electronics, vehicle manufacture and
the construction of buildings. It can also include the manufacture of
components that are used by other manufacturing industries.
Tertiary sector: The provision of services to both business and the public.
This can include retail, the distribution of goods, transport, education,
national/local government and the armed forces.
Quaternary sector: The supply of information and expertise. Technology is
used in this sector by highly qualified specialists who research and develop
products. Research is often conducted in areas such as biotechnology,
aerospace and automotive engineering and information technology
including banking/finance and the creative industries. This sector is often
referred to as the knowledge economy.
The quaternary sector has only been recognised in the last half century as, prior
to 1970, it was often included as a part of either the secondary or tertiary sectors.
Since 1948 the UK government has used a more detailed classification of
five employment sectors; manufacturing, services, agriculture and fishing,
construction, and energy and water. The role of quaternary is not recognised
within the five sectors.
table
14.1 UK sectors of employment
Sector
Percentages of UK workforce (2011)
Manufacturing
9%
81%
Services
Agriculture and fishing
1%
Construction
8%
Energy and water
1%
The chain of production
The chain of production covers all stages of the process from raw materials to
the consumer. Table 14.2 shows each stage and the processes that occur in each
employment sector. At every stage specialists will be involved in research and
development to improve processes and make them more efficient. This is the
quaternary sector.
table
14.2 The chain of production
Primary stage
Farmers, fishers,
miners, foresters etc.,
growing, producing,
harvesting, extracting.
340 Economic transition
Secondary stage
Transport of raw
materials.
Manufacturers
processing, making
and constructing
goods.
Tertiary stage
Transport of product,
storage and other
intermediary services.
Distributors, retailers,
e.g. shops, cafes, selling
goods.
figure
14.1 Chain of production for food
How employment structures vary between countries
HICs
High Income Countries are usually referred to as post-industrial societies
because much of their secondary industry has declined for a number of reasons.
Many different types of industry have moved to lower cost locations such
as Newly Industrialised Countries. This is because companies search for
the cheapest locations to manufacture and assemble components so lowcost labour-intensive parts of the manufacturing process are shifted to the
developing world where costs are substantially lower. The manufacture of
electronics in particular has moved to countries such as China as manufacturers
such as Apple and Nokia look to mass produce smart phones and tablets
through outsourcing to third parties-factories that can produce items at a
much lower cost than in HICs. This change is called global shift.
Outsourcing has also occurred in the tertiary sector as some companies have
moved their call centre and other functions to NICs such as South Africa and
India - countries where English is widely spoken.
Increased mechanisation in some manufacturing industries, such as vehicle
manufacture, has led to fewer workers being employed; certain functions such
as paint spraying can be carried out far more efficiently and safely using robots.
As a result of these factors employment in HICs is now dominated by the
tertiary sector. Primary industry, such as agriculture, is now highly mechanised
leading to fewer people being employed. The quaternary sector is rapidly
increasing in importance and recent estimates put quaternary employment in
the UK as high as 10-15 per cent of all workers.
NICs
The global shift of manufacturing has seen employment in the secondary sector
in newly industrialising countries increase rapidly over the past 40 years. NICs
attract FDI from Transnational Corporations that wish to take advantage of lower
Economic transition
land costs, wage rates and a business environment that is more favourable than
in HICs. This leads to more jobs for local people.
In addition, a favourable business environment leads to local entrepreneurs
creating companies that can become large in both the secondary and tertiary
sectors. Research also becomes important as the quaternary sector develops.
Investment in manufacturing and services often leads to a more efficient primary
sector. Investment in agriculture leads to increased mechanisation and farming
takes place on a commercial scale, which employs fewer workers. The country
transitions into a more industrialised, urban economy where manufacturing and
services are an important part of the economy. They are alternatively known as
'newly industrialising economies’ or ‘advanced developing countries.’
In the 1970s and 1980s examples of newly industrialised countries included Hong
Kong (now part of China), South Korea, Singapore and Taiwan-the original ‘Asian
Tigers’. Examples in the late 2000s included Brazil, China, India, South Africa (along
with Russia these countries are known as the BRICS), Mexico, Indonesia,Turkey
(known as the MINTs with the addition of Nigeria) and also Malaysia, the Philippines
and Thailand. Economists often disagree over the classification of these countries.
LICs
Less economically developed countries rely heavily on the primary sector both for
employment and their economy. Most people working in the primary sector are
subsistence farmers. In Malawi, one of the poorest countries in the world, around
80 per cent of the working population is involved in agriculture that only contributes
around 30 per cent to GDP. Manufacturing (mainly the processing of agricultural
produce) and services make up the other 20 per cent of the workforce, however
these workers contribute nearly 20 per cent and 50 per cent of GDP respectively.
Employment in mining is usually well paid but dangerous work as health
and safety regulations are lax. Fishing and forestry are important areas of
employment but are often in the informal sector. In both NICs and LICs the
informal sector is important to the economy. The informal sector can be:
1
Individuals working in businesses that do not employ many people and who
2
do not deduct tax from their wages.
Workers and persons helping their household business who are unpaid and
do not pay tax.
These workers can include subsistence farmers, street and beach vendors or
people providing a service, for example shoe shiners or sex workers. In South
Africa around 10 per cent of the workforce are employed in the informal sector,
not including those who are subsistence farmers.
Many LICs are reliant on resources that are the product of the primary sector
(primary products). Over 50 per cent of Malawi’s exports are tobacco, while 64 per
cent of neighbouring Zambia’s exports are made up of copper and cobalt, both of
which are vital raw materials in the electronics industry. China is a major export
market with over 40 percent of Zambia’s copper and cobalt production going there.
Reliance on a single commodity makes many LICs vulnerable to fluctuations
in world markets. If the price of a valuable export commodity such as copper
falls, then a country such as Zambia has less money to spend on health,
education, defence and other things that are important to maintaining living
conditions for its population.
table
14.3 Employment structures in countries at different stages of development
% employed
in primary
sector
% employed
in secondary
sector
% employed
in tertiary
sector
UK(HIC)
1.0
18.0
81.0
South Africa (BRICS)
Country
342 Economic transition
7-2
19.6
72.6
Malaysia (NIC)
13-2
43-6
43-4
Mozambique (LIC)
77-0
8.0
15.0
How employment structures change
As countries develop they transition from pre-industrial to industrial and then
to post-industrial economies and the employment structure changes to reflect
this. The Clark-Fisher Model (Figure 14.2) shows this process occurring with the
decline of the primary sector, the rise and fall of the secondary sector and the rise
in importance of the tertiary and quaternary sectors. LICs such as Mozambique
and Malawi are in the pre-industrial phase, with small proportions of the
population employed in manufacturing or services, while NICs such as Malaysia
or Indonesia are in the industrial phase, with manufacturing providing the most
employment. HICs such as the UK and Germany are in the post-industrial phase,
with employment in the service and research sectors dominant, small numbers
of people employed in agriculture, and declining employment in manufacturing.
In 1841, most
people worked in
(T) manufacturing
followed closely
by services and...
...by 1881 the
percentage
■yi
of workers in
services overtook
those working in
manufacturing.
In 1841, over one in
(T) five workers worked in
agriculture and fishing...
figure
14.2
From 1961, the
gap between
services and
manufacturing
started to
widen and at a
faster rate than
previosly...
...and in 2011,
over eight in
every 10 workers
yj were in the
service industry
with less than
one in 10 within
manufacturing.
...until in 2011 less than
one in 100 people in
work were employed in
agriculture and fishing.
...at every census the
yj percentage of people
working in this industry
declined...
The Clark-Fisher Model
Figure 14.3 shows that in 1841 more than one in five workers (22 per cent)
were employed in the primary sector. This sector has been in steady decline over
the last 170 years and is currently the smallest sector in England and Wales. In
2011 less than one in 100 employed people (1 per cent, 0.2 million people) were
employed in this sector.
2011
Manufacturing
Services
Agriculture $ fishing
Construction
Energy $ water
100
80
figure
60
14.3
40
20
0
0
20
40
Percentage of workforce in each sector
60
80
100
Employment changes in the UK, 1841-2011
The way people work has changed dramatically in the past 50 years as
globalisation has allowed the world to be increasingly inter-connected. A shorter
working week for most people combined with longer annual holidays and the
development of computers has radically changed the way that people work.
More recently the internet has changed the way businesses can communicate
and has enabled the service industries to expand and grow. TNCs that span
continents can communicate and operate more easily. Some companies also
now exist solely on the internet, which has changed the way companies do
business and the effect they have on industries. As technology has developed
and changed classifications of industries have had to also develop and change
to accommodate jobs that previously did not exist. New working practices such
as teleworking (working from home) allow flexibility in the workplace, though
this has had less of an impact than originally predicted.
Economic transition 343
Global inequalities in social and economic wellbeing
What is development?
The definition of development is complex but is generally accepted as an
improvement in people’s wellbeing or quality of life. For it to be development,
the improvement must be permanent and could include change in social or
economic systems. Generally, geographers perceive development to have an
impact on health and wealth in less developed countries. The following factors
can often limit rates of development in LICs:
i
2
3
4
5
Climate-related disease - many LICs, especially those with tropical climates,
unfortunately suffer from diseases that thrive in hot humid conditions,
such as dengue fever and malaria. People who contract these diseases are
incapacitated and cannot work or may even die, which limits development.
A lack of natural resources-countries with few natural resources start off at
a very low economic base and find it hard to create products that can sell in
world markets.
Resource curse theory - this is a theory that states if a country has one very
valuable resource all the efforts of the country are put into the exploitation
of that resource. That limits the potential development of other industries
and if the resource is in the hands of a minority unscrupulous ruling elite
then the profits are not shared amongst the people of the country.
Being landlocked with hostile neighbouring countries - although this has
a political element to it, countries that have no access to the sea are at the
mercy of their neighbours. If a country is surrounded by ‘bad neighbours’
that expect huge payments to allow goods to be transited, or are engaged in
regular conflict, development can be held back.
Climatic hazards such as hurricanes and drought are more likely to strike
some countries than others. In the poorest countries a drought can have a
devastating impact on development. The 2011-12 Horn of Africa famine that
affected Ethiopia, Eritrea, Kenya and Somalia had long-term impacts. As well
as weakening people from hunger and thirst, many of these countries had
to deal with a refugee crisis, which diverted valuable resources away from
other development objectives.
How is development measured?
Development can be measured in a variety of ways. One of the most traditional
ways was by measuring a country’s wealth through indicators such as the Gross
Domestic Product (GDP), which is a measure of all the goods and services
produced by a country over a year. This measure has largely been surpassed by
Gross National Income (GNI). GNI measures income received by a country both
domestically and from overseas either from exports or from companies from
that country located in other countries. In some respects GNI is quite similar
to Gross National Product (GNP), which measures output from the citizens and
companies of a particular nation regardless of whether they are located within
its boundaries or overseas.
Usually GDP, GNP and GNI are expressed as a figure per person - the
total sum divided by the number of people living in that country. This enables
comparisons to be made between different nations as populations and the
amount of money made vary greatly. However, there are further limits as the
cost of living varies between countries. One would assume that an item sold in
one country would cost the same in another if the currency of that country were
to be converted. Countries in the EU, for instance, are much more expensive to
live in compared to countries like India or Thailand, so GNI Purchasing Power
Parity (PPP) is used to take account of the differences in the cost of living.
Economists use various indices, for example the iPad Mini Index, to compare
these differences in living costs (Figure 14.4).
Economic transition
Switzerland
France
Poland
Germany
Ireland
Portugal
Austria
New Zealand
UK
Finland
Belgium
Luxembourg
Netherlands
Spain
Denmark
Norway
Italy
Brazil
South Korea
Sweden
Hungary
Mexico
Indonesia
Philippines
Singapore
Czechia (Czech Rep.)
United Arab Emirates
Taiwan
Vietnam
Australia
USA
Hong Kong (China)
China
Thailand
Turkey
Canada
Russia
Japan
Malaysia
-50
figure
14.4
figure
14.5
-25
0
25
Percentage difference in cost compared to USA
50
The iPad Mini Index
Gross National Income (PPP), 2011
Economic transition
table
14.4 GNI (PPP) US$ per person, top 10 and bottom 10 countries
Top 10 countries
Bottom 10 countries
Qatar
123 860
Eritrea
1180
Macao (China)
112 180
Togo
1180
Kuwait
88 170
Guinea
1160
Singapore
76 850
Mozambique
1040
Brunei
68 090
Niger
910
Norway
66 520
Burundi
820
Luxembourg
59 75°
Liberia
790
UAE
58 090
Malawi
760
Hong Kong (China)
54 260
Democratic Republic of the Congo
680
USA
53 960
Central African Republic
60
Table 14.4 shows the Gross National Income per person in US$ (adjusted for
Purchasing Power Parity) in the 10 highest and 10 lowest countries in the world.
These figures do not tell the whole story as average figures are shown and
in many nations there is a massive disparity between the richest and poorest
in society. The United Arab Emirates (UAE) is a good example. Despite the
average figure for GNI (PPP) per person of just over US$58 000, there are huge
disparities between the indigenous Emiratis who make up around 17 per cent
of the population and the immigrant population, many of whom come from
the Indian Subcontinent and the Philippines. The immigrant population work in
service sector jobs such as domestic service, tourism or construction. Many of
these jobs are low paid and the workers live in overcrowded barracks or, worse
still, tented settlements on the outskirts of the main cities of Sharjah, Dubai and
Abu Dhabi. The Emiratis, on the other hand, live in luxury housing paid for by
the state and drive high-end vehicles.
figure
14.6 Dubai-a city of massive contrasts between rich and poor.
Economic transition
table
14.5 Measures of development related to population and health
Measure
Explanation
Growth rate
This figure expressed as a percentage is calculated by subtracting the crude death rate
from the crude birth rate. LICs tend to have high growth rates and HICs tend to have low
growth rates.
Life expectancy
The average age a person can expect to live to. Life expectancy is generally higher in HICs.
Infant mortality rate
The number of infants (under the age of two) dying per 1000 live births. Infant mortality
rate is lower in HICs. The UN uses the child mortality rate (under the age of five) as this
enables a better comparison to be made.
Maternal mortality rate
The number of maternal deaths during childbirth per 1000 live births. Again, this is lower
in HICs with good health systems.
Fertility rate
The average number of children per woman (aged 15-49). The fertility rate is lowest in
HICs.
Number of persons per doctor
This figure is used to compare health services. A lower number of people to doctors is
expected in the developed world.
Calorific intake per person
The number of calories consumed per person per day is a comparison often made to
compare HICs, MICs and LICs.
table
14.6 Measures of development related to education and economics
Measure
Explanation
Adult literacy rate
In most HICs the adult literacy rate may be close to 100 per cent. In some LICS the figure may only be
around 50 per cent as many women cannot read. This often occurs in traditional Islamic societies.
School enrolment
This can vary in different measures and may include education to the end of primary school (ages
11-12) or to the end of secondary school (ages 16-18).
Number of cars
per 1000 people
A measure of the wealth of a country- the more cars owned, the wealthier the country. Similar
measures can include the ownership of televisions or internet usage.
Energy usage
The wealthiest countries use more energy per person.
Governments also vary in how they spend the money they raise. Some
nations spend vast sums of money on weapons rather than on health and
education. Other nations, such as Cuba, invest their money in health and
education systems that are the envy of the developing world.
As well as the measures above other indicators, which are usually related to
population, health and the economy, are used to compare development between
nations.
The Human Development Index
The United Nations introduced the Human Development Index (HDI) in 2008 as
a way of measuring development for each country in terms of a combination of
socio-economic indicators (not just economically). The HDI is a composite index
and uses selected indicators to show human wellbeing or deprivation. Three key
indicators used are:
•
•
•
Life expectancy.
Education - adult literacy and combined primary, secondary and tertiary
educational enrolment.
Standard of living-this index represents data averages for each country
and combines them into a single figure, the HDI, whose maximum possible
value is 1. In 2014 Norway (1st) had an HDI of 0.944; Niger(i8yth) had an
HDI of 0.337.
Disadvantages of the Human Development Index
Statistics issued by national governments are good for making socio-economic
comparisons but there are differences within countries that are not obvious.
Many figures are averages hiding how wealth is distributed between people or
regions. In many LICs there are differences between rural and urban areas and
between the experiences of men and women.
Economic transition 347
table
14.7 Human Development Report, top 10 countries, 2014
HDI
rank
Country
Human
Development
Index (HDI)
Life
expectancy
at birth
(years)
Mean years of
schooling
Expected years
of schooling
Gross National
Income (GNI) per
person (2011 PPP
US$)
1
Norway
0.944
81.5
12.6
17.6
63 909
2
Australia
0-933
82.5
12.8
19-9
41 524
3
Switzerland
0.917
82.6
12.2
15-7
53 762
4
Netherlands
0.915
81.0
ii-9
17-9
42 397
5
United States
0-914
78.9
12-9
16.5
52 308
6
Germany
0.911
80.7
12.9
16.3
43 049
7
New Zealand
0.910
81.1
12-5
19-4
32 569
8
Canada
0.902
81.5
12-3
15-9
41 887
9
Singapore
0.901
82.3
10.2
15-4
72 371
10
Denmark
0.900
79-4
12.1
16.9
42 880
table
14.8 Human Development Report, bottom 10 countries, 2014
Country
HDI
rank
Human
Development
Index (HDI)
Life
expectancy at
birth (years)
Mean years
of schooling
Expected
years of
schooling
Gross National
Income (GNI)
per person
(2011 PPP US$)
178
Mozambique
0-393
50.3
3-2
9-5
1011
179
Guinea
o-392
56.1
1.6
8-7
1142
180
Burundi
0.389
54-1
2.7
10.1
749
181
Burkina Faso
0.388
56.3
1-3
7-5
1602
182
Eritrea
0.381
62.9
34
4-1
1147
183
Sierra Leone
0-374
45-6
2-9
7-5
1815
184
Chad
0.372
51-2
1-5
7-4
1622
185
Central African Republic
0.341
50.2
3-5
7-2
588
186
Democratic Republic of
the Congo
0.338
50.0
3-1
9-7
444
187
Niger
0-337
58.4
1-4
5-4
873
348 Economic transition
figure
14.7 Countries classified according to their human development, Human Development Report, 2014
Average life expectancy in Peru is 73 years but in remote rural areas it can be
much lower, especially in those areas blighted by poverty. Ninety-five per cent of
men are literate but the figure for women is only 84 per cent In rural areas
88 per cent of men and 63 per cent of women are literate.
In the same way, statistics do not always indicate differences between rich
and poor. Peru may be seen as a middle income country but some of its citizens
are very rich indeed. By contrast, a ‘rich’ country such as the USA has some
citizens who are comparatively very poor. It is also difficult to measure quality of
life using things such as feelings of contentment, a sense of belonging, cultural
richness, freedom of speech, the position of women, freedom from oppression
and the state of the environment.
The Human Poverty Index (HPI) is an indication of the standard of living in
a country and was developed by the United Nations to complement the HDI. It
was first reported as part of the Human Development Report in 1997.
Stage 5 - High mass consumption
Stage 2 - Transitional stage
- Preconditions for take off
Stage 1-Traditional Society
Time ----------- ►
figure
14.8 The development pathway (Rostov/ Model)
Economic transition 349
The HPI focuses on what people need to live, such as healthcare, safe water
and plentiful food. These things are used to show variations in quality of life
between one LIC and another. In the HPI a high value equates to greater
poverty.
Stages of development
The Brandt Report (1980) identified the distinction between the richer countries
of the ‘North’ and the poorer countries of the ‘South’. In general, countries
north of the Brandt Line were developed and those south of the Brandt Line
were developing. This distinction oversimplifies the situation - there are many
stages of development and the development pathway (Figure 14.8) can be seen
as a continuum in how some countries become developed at different speeds
while others do not.
The development gap
The geography of the development gap is more complex than a simple NorthSouth divide as suggested by Brandt as Latin America has HDI levels similar
to eastern Europe. China’s HDI and some other countries in Southeast Asia
have relatively high levels but South Asia has a concentration of levels generally
below 0.6. Levels in the Middle East are relatively high but not in countries such
as Yemen, Syria and Iraq. The picture for Africa is very complex - countries in
North Africa and Southern Africa have reasonable HDI levels but regions like
West Africa have the lowest levels of all.
The development gap also equates to global inequality. Currently around
2.8 billion people live on under US$2 per day (‘moderate poverty’) while
some 1.1 billion people live on less than US$1.25 per day (‘extreme poverty’).
Overtime a greater proportion of wealth has concentrated in the hands of
the richest 20 per cent of people compared to the poorest 20 per cent of
people.
development
energy generated in
core by exploitation
of resources
social justice
equal opportunities
life expectancy
quality of life
birth/death control
satisfaction
outer strands may
also be seen as the
outcomes of
development
mobility
outer strands are
an integral part of —►- personal wealth
development
core
culture
freedom of speech
identity
demographic
social
democratic government
environmental
change
conservation
sustainability
cultural
environmental
political
figure
14.9 The development cable
350 Economic transition
cross-section
reveals
state/level/stage of
development
The globalisation of economic activity
According to the Financial Times globalisation can be defined as the integration
of economies, industries, markets, cultures and policy-making around the world.
Globalisation describes a process by which national and regional economies,
societies and cultures have become integrated through the global network of
trade, communication, immigration and transport.
Initially globalisation was primarily focused on trade, foreign direct
investment and international capital flows. More recently the term has been
expanded to include a broader range of areas and activities such as culture,
media, technology, socio-cultural, political and even biological factors such as
climate change.
Global trade has grown enormously since the Second World War with
international trade in manufactured goods growing an estimated 100 times
from US$95 billion to nearly US$19 trillion in the 60 years since 1955. Much of
this rise has been since the collapse of communism in 1990-trade volumes
have risen by 3.5 times since then and this has been both a primary cause
and effect of globalisation. This has been due to a number of factors - the
liberalisation of world trade through the formation of the World Trade
Organization and the global shift in manufacturing to newly emerging
economies.
Central to this rise in trade has been the use of the shipping container,
which has made international supply chains more intricate and inclusive.
This has helped to accelerate industrialisation in emerging economies such
as China. Trade links have enabled developing economies simply to join
existing supply chains rather than build an entire industry from the ground up.
China dominates container traffic. It is estimated that around 26 per cent of
container traffic originates in China and 97 per cent of all containers are made
in China.
table
The World Trade Organization (WTO)
The World Trade Organization is an
international body that deals with the
global rules of trade between nations.
Its main function is to ensure that trade
flows as smoothly, predictably and
freely as possible. Some organisations,
especially TNCs, believe that the WTO is
great for business. Others believe that the
WTO has the potential to undermine the
principles of democracy and make the
rich much richer.
Containers by numbers
•
14.9 World’s busiest container ports
Rank
Port
Millions of TEU (2012)
1
Shanghai, China
2
Singapore
31-7
3
Hong Kong, China
23.1
4
Shenzhen, China
22-9
5
Guangzhou, China
17.7
6
Busan, South Korea
17.0
7
Ningbo-Zhoushan, China
16.8
8
Qingdao, China
14-5
9
Dubai, UAE
13-3
10
Tianjin, China
12.3
11
Rotterdam, Netherlands
11.1
12
Port Klang, Malaysia
13
Kaohsiung, Taiwan
•
34-5
•
•
•
•
•
10.0
9.8
14
Hamburg, Germany
8.7
15
Antwerp, Belgium
8.6
16
Los Angeles, USA
8.1
17
Dalian, China
8.0
18
Tanjung Pelepas, Malaysia
7-5
19
Xiamen, China
7-1
20
Jakarta, Indonesia
6.2
•
•
•
•
Containers come in various lengths
- 20 feet (approx. 6.1 m), 36 feet or 40
feet - but the width and height are
the same for all - 8 feet wide, 8 feet
tall. This facilitates standardisation in
transportation and storage.
There are 17 million shipping
containers in the world. At any
one time between 5 and 6 million
shipping containers are in transit on
ships, trucks and trains.
In total, containers make around 200
million trips a year.
There are 90 000 ocean-going cargo
ships.
Each ship expects to operate 24 hours
a day for about 280 days a year.
The world’s biggest container ships
have 109 000 horsepower engines
that weigh 2300 tonnes.
Shipping is responsible for 18-30 per
cent of all the world’s nitrogen oxide
(NOx) pollution and 9 per cent of the
global sulfur oxide (SOx) pollution.
One large ship can generate about
5000 tonnes of sulfur oxide (SOx)
pollution in a year.
70 per cent of all ship emissions are
within 400 km of land.
85 per cent of all ship pollution is in
the northern hemisphere.
Shipping is responsible for 3.5-4 per
cent of all climate change emissions.
Note: TEU = Twenty-foot Equivalent Unit, which is the standard size of a container.
Economic transition 351
figure
14.10 The world’s largest container ship in Rotterdam, Netherlands
However, globalisation is much more than just trade. In the last 20 years the
breadth and depth of links between nations and between regions has grown
enormously. Communication costs have declined dramatically allowing easy
daily contact using the internet and telephone, enabling the outsourcing of IT
and other services, to India for example, and the rise in global work teams.
Another important element of globalisation is immigration. The International
Organization for Migration estimates that there are two hundred million
migrants around the world today. Migrants leave MICs/LICs for HICs,
particularly for the USA, Canada, Australia, the UK and the rest of Europe.
Though there are tensions at times in Europe and elsewhere, this immigration
has changed the face of the regions where migrants have made new lives.
At a different level of society a global elite of entertainers, sports players
and entrepreneurs are able to move freely between the largest global cities
influencing those who live there.
Transportation is another factor in globalisation - today we see a much more
interconnected world than in the past. The transportation of people and goods
has increased substantially in the last few decades with massive growth in the
aviation industry thanks to the inception of low cost airlines and the growth of
‘hub’ airports such as Dubai. In 2013 there were over 36 million flights worldwide
carrying a capacity of around 3 billion passengers; this figure is likely to rise over
the next 20 years allowing increased commercial and personal connectivity.
figure
14.11 Dubai International Airport- one of the world’s busiest airports.
Economic transition
Globalisation also comes in the form of cultural globalisation. Western culture
in the form of brands and entertainment in particular has spread throughout the
world. This process has been two-way; India, an emerging economy, has seen its
cuisine and culture, particularly Bollywood films, travel all over the globe.
Political globalisation is when government action takes place on a global
level and responsibilities such as the welfare of citizens and economic growth
are acted upon by an international political body, for example the European
Union. Governments typically served the citizens of their own nations but now
the world is much more globally connected these decisions are taken on a
larger stage. The UN, for instance, is viewed as the world’s peacekeeper to solve
disputes between countries.
Foreign direct investment (FDI)
Foreign direct investment is investment from one country into another
(normally by TNCs rather than governments). FDI involves establishing
operations or acquiring tangible assets by purchasing or setting up
income-generating assets in a foreign country.
FDI is not just a transfer of ownership as it usually involves the transfer of
factors complementary to capital, including management, technology and
organisational skills. There are five types of FDI:
•
•
•
•
•
Horizontal FDI: where the company carries out the same activities abroad as
at home, for example Toyota assembling cars in both Japan and the EU.
Vertical FDI: when different stages of activities are added abroad.
Forward vertical FDI: where the FDI takes the firm nearer to the market, for
example Toyota acquiring a car distributorship in America.
Backward vertical FDI: where international integration moves back towards
raw materials, for example Toyota acquiring a tyre manufacturer or a rubber
plantation.
Conglomerate FDI: where the TNC acquires an unrelated business abroad,
for example Toyota acquiring a soft drinks company. This is the most
unusual form of FDI as it involves attempting to overcome two barriers
simultaneously- entering a foreign country and a new industry. This leads
to the analytical solution that internationalisation and diversification are
often alternative strategies.
FDI can also take the form of greenfield entry or takeover.
• Greenfield entry means starting an operation from scratch as Honda did by
building a factory on the edge of Swindon in the UK.
• Takeover means the acquisition of an existing foreign company, for example
Tata’s acquisition ofjaguar Land Rover from Ford. Foreign takeover is often
covered by the term ‘mergers and acquisitions’ (M8<As) but internationally
mergers are relatively rare (they account for less than i per cent of all foreign
acquisitions).
The New International Division of Labour (NIDL)
The NIDL is defined in the Oxford Dictionary of Geography as the global division
of labour associated with the growth of TNCs and the deindustrialisation
of the advanced economies. The most common pattern is for research and
development to take place in more economically developed countries and for
production to take place using cheap, less skilled labour in less economically
developed countries. The impacts of the NIDL have been uneven: between
nations, where some benefit more than others; and within nations, where core
regions have profited at the expense of the periphery.
Economic transition 353
Economists regard the NIDL as an inevitable outcome of globalisation.
Previously under the ‘old’ international division of labour, until the 1970s,
LICs were incorporated into the world economy principally as suppliers of
raw materials, especially mineral ores and agricultural products. However,
as developing economies become absorbed into the world economy, more
production shifts to these economies.
This has led to global shift, where production processes are relocated from
HICs such as the USA,Japan and the EU, to MICs and NICs in South and
Eastern Asia (for example China, Vietnam and Malaysia) and Latin America.
TNCs take advantage of improving transport links and advances in
information and communications technology. From the 1950s to the late 1990s
the developed nations’ share of world manufacturing output declined from
95 per cent to 77 per cent, while the developing nations increased their share of
manufacturing from 5 per cent to 23 per cent.
The resultant division of labour across continents closely follows the Brandt
Line where the North - with 25 per cent of the world’s population - controls
80 per cent of the world’s income while the South - with the remainder of the
world’s population - has access to 20 per cent of the world’s income.
Factors affecting the growth and spatial structure of Transnational
Corporations (TNCs)
ATNC is a large company with subsidiaries, operations or manufacturing
bases in more than one country. TNCs have grown by buying up foreign firms
in mergers and acquisitions, for example Cadbury and Oreo are owned by
Mondelez International, an American food TNC that was formerly known as Kraft.
Much of the manufacturing conducted by TNCs is subcontracted (outsourced) to
third parties, which makes it hard to regulate working conditions.
TNCs link together groups of countries through the production of
goods (most manufacturing TNCs are ‘assembly industries’). They also forge
connections between people in different countries by shaping common patterns
of consumption.
There are now well over 60 000 TNCs and they control around 25 per cent
of the world’s economy and employ around 1 per cent of the world’s workforce.
In order to make more money, TNCs operate in a way that involves controlling
production. Many TNCs control the whole production and sales process, which
figure
14.12 Land Rover Defender-a vehicle produced by
the Indian company Tata.
keeps down costs. They expand their production so that they can produce items
for less and therefore make more profit.
TNCs also grow larger and more powerful by acquiring the opposition - either
taking over or merging with competing companies (see FDI). Ford, for instance,
moved up-market by buying Jaguar, Volvo and Land Rover and a share of Mazda.
They sold Jaguar and Land Rover to the Indian conglomerate Tata as they didn’t
make large profits from the two brands, something that Tata have managed since.
Outsourcing
TNCs outsource many of their operations. Outsourcing is the sub­
contracting of manufacturing and other services to low cost locations such
as China and India. This means the TNC can make even larger amounts of
money as it doesn’t have to pay high wages in rich countries. Many TNCs
outsource the design of software to Indian-based software designers in
Mumbai and Bangalore-the Indian equivalent of Silicon Valley.
Call centres are often outsourced by British companies such as British
Telecom, British Airways, Sky TV and Aviva to countries such as India and
South Africa. Sporting goods manufacturers like Nike, Reebok and Le Coq
Sportif outsource the manufacture of sports shoes and clothing to factories
in Indonesia, Bangladesh and Vietnam.
The sales of the world’s largest TNCs can be greater than many middle or
low income nations. Apple has sales similar to the GNI of an oil-rich state such
354 Economic transition
as Nigeria (US$469 billion), while Toyota’s sales were greater than the GNI of
Portugal (US$222 billion) in 2013.
TNCs are accused of exploiting host countries by paying workers low wages,
avoiding paying corporation taxes and conducting industrial processes that
might be illegal in their own countries. However TNCs bring FDI to nations,
which allows workers to contribute tax revenues to the governments of those
countries and stimulates the growth of local services. Further benefits can be
even more widely felt when a TNC sources its parts locally within a trade bloc.
Other criticisms come from the social and cultural impacts TNCs may have
on host nations through the exploitation of workers. Mattel, Inc. is one of the
largest toy companies in the world with sales of approximately US$6.48 billion
in 2013. It is home to such brands as Barbie, Fisher-Price, Hot Wheels and
Matchbox. Mattel has company-owned or controlled facilities in many countries
including China, India, Indonesia, Malaysia, Mexico and Thailand.
In 1997 Mattel announced the establishment of their Global Manufacturing
Principles (G MP), which is a code of conduct that covers all of Mattel’s own
production facilities and those of its primary manufacturers around the world.
Mattel’s management wanted the company’s products to meet its global quality
standards regardless of the location of manufacturing; they also wanted its products
to be made under humane conditions and for all workers engaged in producing
goods for Mattel to be treated in accordance with national laws and customs.
Many TNCs however have very poor records on pollution and worker safety.
They have been accused of trying to wrongly economise with both safety and
pollution in order to keep costs down. An American company, Union Carbide,
was responsible for a chemical leak in 1984 in the Indian city of Bhopal that
killed over 3000 people and injured half a million more.
table
14.10 Composite index of the World’s largest TNCs ranked by sales, 2014 (Forbes 2000)
Rank
Company
Headquarters
Industry
Sales
(billion
US$)
Profits
(billion
US$)
Assets
(billion
US$)
Market
value
(billion
US$)
1
Wal-Mart Stores
United States
Retail
476.5
16.0
204.8
247-9
2
Volkswagen Group
Germany
Automotive
261.5
12.0
446-9
119.0
3
Chevron
United States
Oil and gas
211.8
21.4
253.8
227.2
4
BP
United Kingdom
Oil and gas
379-2
23.6
305.7
148.8
5
Citigroup
United States
Banking
94.1
13-4
1883.4
145-1
6
Apple
United States
Consumer
electronics
173.8
37-0
225.2
483-1
7
HSBC
United Kingdom
Banking
79-6
16.3
2671.3
192.6
183.3
8
Bank of America
United States
Banking
101.5
ii-4
2113.8
9
Toyota
Japan
Automotive
255-6
18.8
385.5
193.5
10
Royal Dutch Shell
Netherlands
Oil and gas
459-6
16.4
357-5
234.1
11
PetroChina
China
Oil and gas
328.5
21.1
386.9
202.0
12
Bank of China
China
Banking
105.1
25-5
2291.8
124.2
13
Wells Fargo
United States
Banking
88.7
21-9
1543-0
261.4
14
General Electric
United States
Conglomerate
143-3
14.8
656.6
259.6
15
Exxon Mobil
United States
Oil and gas
432-4
32.6
346.8
422.3
16
Berkshire Hathaway
United States
Conglomerate
178.8
19-5
493-4
309.1
17
JPMorgan Chase
United States
Banking
105-7
17-3
2435-3
229.7
18
Agricultural Bank of China
China
Banking
136.4
27.0
2405-4
141.1
19
China Construction Bank
China
Banking
121.3
34-2
2449-5
174.4
20
ICBC
China
Banking
148-7
3124-9
215.6
42-7
Economic transition 355
Case Study
The global spatial organisation and operation of
oneTNC: Toyota
The Toyota Motor Corporation was first established in Japan in 1937. In 1959
Toyota opened its first overseas plant, which was in Brazil. By 2004 the company
was the third-largest manufacturer of automobiles in the world and by far
the largest in Japan, producing one vehicle every few seconds! It had 12 plants
and 11 subsidiary companies in Japan and 51 manufacturing companies in
26 countries from the USA to India; it employed just over a quarter of a million
people worldwide. Toyota sold nearly 6.72 million vehicles, from mini-vehicles to
large trucks, in over 140 countries.
The automotive business makes up over 90 per cent of the company’s
total sales. The remaining 10 per cent of Toyota's operations include
telecommunications, prefabricated housing (including earthquake-resistant
designs) and leisure boats. Toyota, like many other TNCs, has realised the
importance of creating a good public image and using environmentally-friendly
practices and is famous for its Toyota Production System, which has a main
goal of eliminating waste. This has enabled Toyota to reduce pollution and
production costs. Toyota’s two factories in the USA have achieved ‘zero landfill
status’ as Toyota sells or gives away all waste products to companies that recycle
the waste.
Toyota in Europe
Toyota has been selling cars in Europe since 1963. Since 1990 it has invested
over US$7 billion in Europe and currently employs over 90 000 people in
its 9 manufacturing plants, spanning seven countries, and various retailing
subsidiaries. Toyota has a policy of globalisation in adapting its vehicles to meet
the specific needs of Europe's many varied customers.
When Toyota decided to set up a plant for its expanding market in Europe to
avoid tariffs and quotas as a result of the introduction of the single European
market in 1992, it chose the UK. The UK had an excellent skilled and flexible
workforce, a strong tradition of engineering and vehicle manufacturing and
favourable working practices. The UK also had a large domestic market for
Toyota cars, reliable industrial transport links to customers and 230 British- and
European-based supply partners. Ease of integration and communication was
facilitated by the use of English as a common language (English is the second
language in Japan).
In 2001, a new factory new Valenciennes on the border of France and
Belgium began producing the Yaris car model, followed a year later by a new
factory in Poland building transmissions.
In 2002, Toyota opened a factory in Adapazari, near Istanbul in Turkey,
producing the Corolla and Verso models, most of which are exported to
European countries and beyond. Toyota opened a diesel engine plant in JelczLaskowice, Poland that began operating in 2005, at the same time as a new
vehicle manufacturing plant in Kolin in the Czechia that produces the Aygo
model in conjunction with Peugeot and Citroen. In 2007 Toyota's expansion
in Europe continued with the opening of a plant in St Petersburg in Russia
producing the Camry model. Toyota also produces minibuses in Portugal.
Around two-thirds ofToyotas sold in Europe are manufactured there.
Worldwide, Toyota operates 54 factories in 20 different countries and
has joint ventures with other manufacturers in seven more. Many of these
factories are in emerging markets but also include 16 factories in Japan and
seven in the USA.
356 Economic transition
Factors in the emergence and growth of Newly Industrialised Countries (NICs)
Newly Industrialised Countries are nations whose level of economic development
rank them somewhere between the developing and developed world.
Characteristics of NICs
NICs share similar characteristics to LICs but tend to be moving towards freer
and stronger developed export-led economies; they can be said to be emerging
markets.
Some common attributes seen in NICs include: increased economic
freedom, increased personal liberties, transition from agriculture to
manufacturing, the presence of foreign TNCs, strong foreign direct
investment and rapid growth in urban areas due to migration from rural
areas.
Emerging markets are broadly defined as nations in the process of rapid
growth and industrialisation. Often these nations are changing to an exportled economy with a growing working age population. Emerging markets can
be identified by the Morgan Stanley Capital Investment (MSCI) Emerging
Markets Index, which currently includes 23 countries. Table 14.11 identifies these
countries.
table
14.11 Emerging markets, 2015
Latin America
Asia
Africa
Europe
Brazil
China
Egypt
Czechia
Chile
India
South Africa
Hungary
Colombia
Indonesia
Poland
Mexico
South Korea
Russia
Peru
Malaysia
Greece
(Czech Rep.)
Philippines
Taiwan
Qatar
Thailand
Turkey
UAE
These characteristics of emerging markets include:
• Transitional economy: emerging markets are often in the process of moving
from a closed economy to an open market economy.
• Young and growing population: emerging markets often have younger
populations that can lead to long-term growth in the economy by replacing
ageing workers and consumer goods. However, younger populations can
also lead to an increased risk of political instability and can be more mobile
than older populations.
• Underdeveloped infrastructure: emerging markets are usually in the early
stages of building infrastructure. Government spending can be high and at
the cost of other areas of the economy.
• Increasing foreign investment: emerging markets usually see strong foreign
direct investment, which can be a good sign of anticipated economic growth
ahead but can also lead to economic expansion and contraction.
Economic transition 357
What’s in a name?
In 2ooijim O’Neill, chief economist of Goldman Sachs, coined the
acronym BRIC to represent the four fastest growing emerging markets Brazil, Russia, India and China. These countries were joined by South Africa
in 2010. These countries represent almost 3 billion people, or approximately
40 per cent of the world’s population. The five nations have a combined
nominal GDP of US$16 trillion, which is equivalent to approximately 20 per
cent of the gross world product, and an estimated US$4 trillion in com­
bined foreign reserves.
In 2005 Goldman Sachs decided to expand BRIC to include 11 more coun­
tries that it dubbed the Next Eleven, or N-11. These countries include Bang­
ladesh, Egypt, Indonesia, Iran, Mexico, Nigeria, Pakistan, Philippines, South
Korea, Turkey and Vietnam.
In 2009 HSBC began promoting CIVETS, a term first coined by The Economist
to include Colombia, Indonesia, Vietnam, Egypt, Turkey and South Africa.
In 2011 the MINTs emerged; these include Mexico, Indonesia, Nigeria and
Turkey. These four countries are expected to experience rapid economic
growth by 2020.
Industrial growth in some LICs and NICs and de-industrialisation in MICs
In recent years manufacturing in NICs has increased and manufacturing in
HICs has decreased due to global shift. In the last few decades many countries
that have traditionally relied on primary products have seen a massive growth
in their manufacturing industries (NICs). This has led to a rapid increase in
de-industrialisation in HICs such as the UK and Germany where there was a
long history of manufacturing.
The increase in worldwide affluence has driven higher consumption
and consequently production in many areas of the world and has led to
massive levels of overseas production to satisfy global demand. These new
manufacturing hubs are located nearer to emerging markets in order to extend
global reach as companies need to maintain competitive advantage. The
introduction of less restrictive markets has allowed TNCs to stretch their profit
margins, which has resulted in increased drive for development in LICs.
Deindustrialisation
Deindustrialisation is a long-term process of change in the employment of
industrial nations. This is normally a fall in the contribution made by the
manufacturing (secondary) sector to national output, employment and income.
In countries such as the UK and France this included steel and ship building.
This can be measured in a number of ways:
•
•
•
A falling share of manufacturing in total national output (GDP)
A falling share of industrial employment in total employment
A declining share of UK manufactured exports in world trade
In the UK, the share of total GDP taken by manufacturing has declined from
23 per cent in 1989 to just under 19 per cent in 2000 to just 9 per cent of the labor
force by 2011- a real decline over 1.2 million workers since 1989.
358 Economic transition
Regional development within countries
Disparities in social and economic development within countries
Huge contrasts in wages, employment or educational opportunities and access
to healthcare among local, regional and national populations are common.
Even in the USA, a country renowned for equality, there are disparities between
rich and poor. In 2005 the U.S. Census Bureau estimated that the top 5 per
cent of wage earners earned over 30 per cent of all US income. Oxfam recently
declared that the combined wealth of the 85 richest people in the world
was equal to more than the wealth of the poorest 3.5 billion people in the world
The most commonly used measure of inequality is the Gini coefficient,
which is a measure of statistical dispersion intended to represent the income
distribution of a nation’s residents. A Gini coefficient of o would mean perfect
equality, where everyone has the same income. A Gini coefficient of 100 means
maximum inequality (for example, where only one person has all the income
or consumption and all others have none). This can also be shown using the
Lorenz curve that is a graphical representation of the cumulative distribution of
wealth or income.
The USA has a Gini coefficient of around 40 - a figure that is very similar to
Cameroon, while Germany has a Gini coefficient of around 30- a figure matched
by Pakistan. Many sub-Saharan nations have figures over more than 50 including
South Africa with 63 (the world’s highest) while most MICs have a figure between
30 and 40. Afghanistan has the lowest Gini coefficient, which is 27.
In Organisation for Economic Cooperation and Development (OECD)
countries the average income of the richest 10 per cent of the population is
about nine times that of the poorest 10 per cent. Turkey, Chile and Mexico have
seen inequality fall but in the latter two countries the incomes of the richest are
still more than twenty-five times those of the poorest.
In emerging economies, such as China and India, strong economic
growth over recent years has helped lift millions of people out of absolute
poverty. However the benefits of economic growth are not evenly distributed
and rates of income inequality have risen further. Of the most dynamic
emerging economies only Brazil has managed to reduce inequality but the gap
between rich and poor is still much larger than that of the countries of the OECD.
Cumulative percentage of population
figure
figure
14.13 The Lorenz curve (hypothetical)
14.14 The Gini coefficient, by country according to the World Bank, 2014
Economic transition 359
The concept of core-periphery
Within countries, both core and peripheral regions can be found. Even in the
most developed countries there are wealthy core regions where much of the
investment takes place, often this is found around the capital city. For much of
the UKs recent history, there has been a North-South Divide with the richest
region of the country, London and the South East dominating the peripheral
north regions such as Scotland, Wales and the North East. In Italy, the richer
north overshadows the poorer region of the south - the ‘Mezzogiorno’ in terms
of investment and industrial output.
In many African nations, the core is usually around the ports and capitals
founded by the former colonial powers e.g. Lagos in Nigeria and Accra in
Ghana.
In Argentina, there is a striking North/South economic divide, with the
southern regions south of the capital Buenos Aires much more prosperous than
the regions to the north of the country. Santa Cruz, one of the most southerly
provinces has a GDP per capita 15 times greater than Chaco, close to the border
with Brazil ($30,496 and $2,015 respectively). The economy of the south is based
on the mining of precious minerals and energy production, while the north is
reliant on agricultural produce, though tourism is an increasingly important
industry in the south.
Government incentives have been important for Argentina’s most southerly
and remote province, Tierra Del Fuego, in reducing the impacts of regional
disparities. Tax incentives have been in place since the 1970’s to encourage
the location of manufacturing industry. Foreign Direct Investment (FDI) is
important as South Korean TNC Samsung is a major employer producing TVs,
DVD players and cell phones in the city of Rio Grande.
All the countries of the world can be divided into two categories - the ‘core’
and the ‘periphery’. The core includes all of the major world superpowers (both
economic and military) that also own much of the world’s wealth - the so-called
‘switched-on’ places. The periphery are those countries that do not possess
much wealth and have largely been by-passed by globalisation - the so-called
‘switched-off ’ places.
360 Economic transition
Core-periphery theory is generally understood to be that as prosperity
increases globally most of the growth is experienced by a ‘core’ region of rich
countries despite having a smaller population than those in a ‘periphery’ of
poorer nations.
Physical and political barriers prevent the poorer nations of the world from
having a greater say in global relations than HICs as global institutions in
particular favour the wealthy. The wealth disparity between core and peripheral
countries is extreme, with 15 per cent of the global population enjoying 75 per
cent of the world’s annual income.
Dependency theory
The origins of this world structure came about through dependency theory.
From the seventeenth century onwards capitalist European countries such as
Britain and the Netherlands exploited the peripheral countries like South Africa
through colonialism and imperialism. Raw materials were obtained from the
periphery, often through slave labour, and were sold by companies set up by
the colonial masters to countries in the core where they would be consumed or
manufactured in products and then sold back to the periphery.
Supporters of dependency theory believe that centuries of exploitation have
damaged the colonised countries and left them a long way behind, making it
difficult for them to compete on equal terms in the global market. Colonial
powers established political regimes during reconstruction after the Second
World War and in the lead up to independence. In many peripheral nations the
language of their colonial masters remains the official language, long after their
independence. Governments in peripheral nations sometimes practice policies
better suited to the core regions. Intra-governmental organisations such as the
IMF and the World Bank may also impose restrictions that do not provide the
ideal course for the periphery.
The core-periphery model can also be found at a country or regional scale.
Many countries have distinct core and peripheral regions. The UK has a NorthSouth divide - the South East of England is significantly richer in GDP terms
than the rest of Britain. Brazil too, has a rich core based on the South East
and mega-cities of Rio de Janeiro and Sao Paulo, while other regions such as
Amazonia are significantly poorer. In both countries the core is a significant
magnet to migrants even though massive disparities in wealth occur in
those cores.
Cumulative causation
Cumulative causation is the process whereby economic activity leads to
prosperity and increases economic development. Cumulative causation tends
to concentrate in an area with an initial advantage, which drains investment
and skilled labour from the outlying (peripheral) areas; this is known as the
backwash effect.
A simpler form of cumulative causation is the multiplier effect-the
introduction of a new industry or the expansion of an existing industry in
an area encourages growth in other industrial sectors. In its simplest form,
the multiplier effect is how many times money spent circulates through a
country’s economy. Money invested in an industry helps to create jobs directly
in the industry but it also creates jobs indirectly elsewhere in the economy.
New industrial development, for example, requires construction workers
who themselves require housing and services such as schools and shops. An
increased demand for food will benefit local farmers who may increase their
spending on fertiliser. Workers employed directly in the new industry increase
the local supply of skilled labour, which attracts other companies who benefit
from sharing this labour pool. Other companies who supply components or use
the new industry’s products are attracted to the area to benefit from reduced
transport costs.
Spin-off effects of the multiplier effect include new inventions or innovations
that may lead to further industrial development and new linkages.
Economic transition
INTRODUCTION OF A
NEW INDUSTRY OR
figure
14.16 Cumulative causation
The management of regional development
Case Study
Morocco
Morocco is the most north-westerly country in Africa and is located in an area
known as the Maghreb-the ‘Arab West’. It has coastlines on both the Atlantic
Ocean and the Mediterranean Sea and most of the interior of the country is
mountainous and semi-arid. Morocco was a French protectorate from 1912-56
and prior to French rule was partly controlled by Spain.
Unlike many of its neighbours, Morocco has a liberal economy and,
since 1993, has privatised many key industries that used to be owned by
the government. It has become a leader in African affairs and is the sixth-largest
African economy by GDP (PPP) (2015). In 2005 Morocco was ranked the
fourth-best country to live in Africa by The Economist quality-of-life index
(66th in the world).
In the second half of the 1990s the Moroccan government introduced a
series of economic policies that included trade liberalisation and investment
promotion. The country has successfully realised strong economic growth and
poverty reduction. In 2005 the government started the National Initiative for
Human Development, a policy designed to address poverty and reduce social
and regional disparities. As a result of the political reforms undertaken since
2000, the effects of the Arab Spring in North Africa in 2011 were minimised and
did not cause a great deal of political turmoil to the country. Nevertheless, there
remain factors for social instability such as a high unemployment rate among
the urban young and lack of development in rural areas.
Economic transition
figure
14.18 The Sahara Desert (above) is a popular destination for adventure tourists and ecotourists.
Morocco’s exports consist of agricultural goods, especially oranges and
dates, clothing, phosphates and fertilisers and electrical wire. The service sector
accounts forjust over half of GDP. Industry, which is made up of mining,
construction and manufacturing, contributes 25 per cent of GDP. The industries
with the highest growth rates in recent years have been tourism, telecoms,
information technology and textiles.
Since 2000 Morocco has had a free trade agreement with the EU. The
abolition of tariffs on industrial goods has been beneficial for Moroccan
manufacturers as some 75 per cent of Morocco’s exports go to Europe. France
is Morocco’s largest trading partner for both imports and exports and France
controls more than 60 per cent of foreign direct investment in Morocco.
Morocco has emerged as a major low cost location for many European
manufacturers and the widespread use of French as a second language has
led French banking and call-centre firms to set up in Morocco as part of a
development initiative called Plan Emergence. The country now has about 200
call centres, including 30 of significant size that employ a total of over 18 000
people. Trading agreements exist with the USA, China and the Gulf States.
The current population of Morocco is around 34 million but this is expected
to rise to 42 million by 2050. The median age is increasing and although birth
and fertility rates are both decreasing, the working age population (15-64) will
increase between 2012 and 2050 (Figure 14.19). Net migration has been negative
since 1984. Over 50 per cent of Morocco's population still lives in rural areas. The
country also has a large pool of young people and its economy struggles to find
jobs for all of them.
Economic transition
2000
male
female
age group
100+
95-99
90-94
85-89
80-84
75-79
70-74
65-69
60-64
55-59
50-54
45-49
40-44
35-39
30-34
25-29
20-24
15-19
10-14
5-9
0-4
2000
1500
1000
500
0
0
1000
500
1500 2000
population (thousands)
2025
age group
male
female
100+
95-99
90-94
85-89
80-84
75-79
70-74
65-69
60-64
55-59
50-54
45-49
40-44
35-39
30-34
25-29
20-24
15-19
10-14
5-9
0-4
2000
1500 1000
500
0
upwards of US$2.2 billion. Its aims were:
•
•
•
•
to increase tourist numbers to 10 million by 2010 (including 7 million
international arrivals), to create 160 000 new hotel beds -130 000 at coastal
resorts and 30 000 in cultural destinations, thereby increasing Morocco’s
total number of hotel beds to 230 000
to increase the value of tourism revenue to around US$40 billion per year
to create 600 000 new jobs in the tourism sector
to increase tourism’s share of national GDP to 20 per cent by 2010, from
16 per cent in 2007.
0
1000
500
1500
2000
population (thousands)
2050
male
In 2012 Morocco’s largest city was Casablanca and this will remain the case
until 2030, when 16.2 per cent of the urban population could reside there. Since
independence (1956) many Moroccans have moved to Europe to look for work
and it is estimated that there are as many as 4 million Moroccans living in the
Ell; France (1.5 million), Spain, the Netherlands and Belgium are the main
destinations for these migrants.
In order to maximise Morocco’s potential, the High Commission for
Planning has embarked on a series of ambitious 10-year development plans
that will take the country up to 2030. The first of these plans, initiated in 1999
and named Vision 2010, aimed to boost the country’s GDP through increasing
tourism. Tourism is a powerful driver of economic growth and an important
tool for regional improvement and development. Tourism makes the most
of Morocco’s various territories, population groups and other assets in a
sustainable way. The multiplier effect of tourism impacts on all other sectors of
the economy and plays a significant role in the prosperity of the country as a
whole. Vision 2010 was a major development project and was expected to cost
age group
female
The centrepiece of Vision 2010 was Plan Azur-an ambitious plan to build
six new coastal resorts, five on the Atlantic Ocean and one on the Mediterranean
Sea. These were to be developed by private property development companies.
Morocco looked to emulate the success of Dubai by investing in tourism as
a model for development. As well as these large-scale resorts, investment in
urban cultural tourism was planned for more traditional cultural attractions
across Morocco, such as Marrakesh. Urban cultural tourism was to focus on
encouraging private sector investment in new and refurbished hotels and visitor
facilities to increase the quality of the tourism product and to compete with
European city-break destinations.
As part of Vision 2010 Morocco undertook a liberalisation of air travel,
including an Open Sky agreement with the EU signed in 2006. This has
encouraged low cost airlines from the EU, such as Ryanair and Easyjet, to
population (thousands)
figure
14.19 Morocco’s population 2000, 2025 and 2050
increase flights to Morocco.
In 2004 Royal Air Maroc founded its own low-cost airline, Atlas Blue, which
now flies between Menara International Airport in Marrakesh and many European
destinations. Mohammed V International Airport in Casablanca is currently
undergoing expansion to increase its capacity to 10 million passengers per year.
The world recession that started in 2008 hit Morocco hard; many developers of
the resorts were forced to abandon their plans and new hotels and other facilities
were left unfinished, with Moroccan developers unable to complete the building
programmes. However, the government is confident about the future of the
tourism industry in the kingdom. In 2011, 9.3 million tourists, around 83 per cent of
which were from Europe, visited Morocco as the world economy began to recover.
Vision 2010 has been a success. Morocco became the twenty-fifth most
visited country worldwide in 2010. Tourism is now Morocco’s top foreign
exchange earner, its second biggest contributor to GDP and the second biggest
creator of jobs in the country.
Undeterred by the events of the previous few years, Morocco embarked on
another ambitious plan in 2013 called Vision 2020. The aims of this plan include
a doubling of tourist numbers to 20 million by 2020, most of whom would
Economic transition
Plan Azur
i
2
3
4
5
6
Saidia: over 700 hectares, up to 17 000 hotel beds and
3000 villas, three golf courses and a marina. Developed
by Spanish property developer Martinsa-Fadesa.
Khemis Sahel: the development, called Port Lixus, is
being constructed by Belgian company Thomas and Piron
and French company Colbert-Oreo. Two golf courses, a
marina, 7500 hotel beds and villas are being constructed.
El Haouzia: a five-star hotel resort called Mazagan,
developed along 15 km of coastline, being built by the
Kerzner Group (based in the Bahamas), which also
developed The Palm, Dubai.
Mogador: 4 km from the World Heritage Site of
Essaouira, this golf resort with over 8000 hotel beds is
being developed by French company Accor.
Taghazout: Colony Capital (USA) is developing a seven­
hotel, two-golf-course beach resort along 5 km of
coastline.
Plage Blanche: A resort was planned to be built here,
where the Sahara meets the sea at Morocco’s wildest
beach, in the south of the country. An airport has been
built at nearby Tan Tan but so far no development has
taken place.
Portugal/
ATLANTIC
SPAIN
Tangi
Khemis Sahel (2
OCEAN
Rabat® Fez
Ceuta (Spain)
(Spain) (J
Saidia
Casablanca
El Haouzia®
Madeira
(Portugal)
Mogador^-
Marrakesh
AgadirC
Taghazout®
Canary Is
Blanche r"
Laayoune- WESTERN
°
ALGERIA
SAHARA
(Administered by Morocco)
MAURITANIA
figure
14.20 Plan Azur
originate in northern and western Europe. In addition, it is hoped that 470 000
jobs will be created directly over the period 2011-2020 along with around another 1
million jobs in ancillary industries. Tourism’s share of Morocco’s GDP is anticipated
to rise by 2 per cent, with tourist takings more than doubling to reach 140 billion
Dirham (around US$14 billion) by 2020.
It is hoped that all of this will be achieved thanks to a new Plan Azur. Much
of the new development will be sustainable, which is an opportunity for tourism
in Morocco to distinguish itself from its competitors. This would be done in the
following ways:
•
•
•
•
•
•
The Azur 2020 programme: providing an internationally competitive range
of seaside resorts for Morocco and strengthening Morocco’s seaside resorts
on both the Atlantic and Mediterranean shores by completing the Azur 2010
projects and developing new resorts in the south.
Sustainable development programme: developing ecotourism through
sustainable development products such as eco-lodges, desert resorts and
glamping.
High value-added programme: the creation of an infrastructure that can
host big international gatherings. Additionally, by setting up facilities
for wellbeing, exhibition and culture sectors to make Morocco a new
international destination for wellbeing and health.
Heritage programme: enhancing the range of cultural experiences on
offer by making the most of Morocco’s heritage by developing specific
accommodation, by the reconversion of historical monuments, the
construction of new museums, and the enhancement and valorisation of
traditional festivals.
Events, sports and leisure programme: developing a range of international­
class cultural and leisure events to enhance the attractiveness of tourist
destinations based on a full programme of events such as leisure cities,
theme parks and resorts.
Biladi programme: offering a product tailored to the needs of native
Moroccans. ‘Biladi’ means ‘my home’.
Economic transition
figure
14.21 Ait Ben Haddou - a traditional Berber settlement popular amongst tourists. It is also popular with filmmakers as a location.
It is hoped that sustainable tourism and a natural saturation point will be
achieved by maintaining capacity and arrivals for individual tourist sites. Some
areas of Morocco have been designated for increased growth, such as Tangier
and Casablanca, while others, such as Marrakesh and Essaouira, are to have
tourism development restricted to limit negative impacts on people and the
environment.
Ambitious 20-year development plans have been created for all walks of
Moroccan life including agriculture - a Green Morocco Plan will liberalise
farming from a semi-subsistence level to a commercial level by 2030. Energy
too, has a Vision 2030 - reliance on imported energy will be replaced by the
use of renewables including wind and solar power. Already, technological
leapfrogging has taken place and an extensive mobile phone network covers the
country-even in the Sahara Desert, where aerials and masts are powered by
abundant solar energy.
Overseas development agencies, such as the Japanese International
Cooperation Agency, have contributed to rural stability and balanced economic
development in Morocco by focusing on regional and social disparities and
sustainable economic growth. As a result of this development, from 1980-2010
Morocco achieved the best relative increase in HDI (61 per cent) across the
Maghreb. According to the Human Development Report (2014), Libya (55th),
Tunisia (90th) and Algeria (93rd) have High Human Development whereas Egypt
(noth) and Morocco (129th) fall into the medium group.
In terms of literacy and education achievements, for instance, nearly half of
the adult population was unable to read in 2010 and there was around 60 per
cent combined gross enrolment in primary, secondary and tertiary education.
For the other Maghreb countries adult literacy rates were much higher.
3
Economic transition
The rates of combined gross enrolment in primary, secondary and tertiary
education showed similar differences and these figures are hindering Morocco’s
development as a nation. When considering GDP per person in the Maghreb,
Morocco’s figure of US$7356 (2013) is significantly lower than that of its oil-rich
neighbour Algeria (US$13 788). According to the World Health Organization
(2013), life expectancy across the Maghreb varies as well, with the oil-rich states
of Libya (average age: 75) and Algeria (average age: 72) having higher levels than
Morocco (average age: 71).
NOW INVESTIGATE
1
Investigate other indices to measure Purchasing Power Parity and
the cost of living. Where are the most and least expensive countries
as far as the cost of living is concerned?
2
Investigate the Forbes 2000 list. How many companies from your
country are in the 2000 top TNCs? Find out more about a company
in the top 100 TNCs including how the company became so large,
what it produces and the countries it operates in.
3
Choose a MIC or LIC. What are the population indices such as
fertility, mortality and growth rates? How do they compare with
other indices such as the HDI and GNI per person?
4
Investigate the management of development for a MIC or LIC.
Does it have a development plan like Morocco? What sectors of
the economy is it investing in to aid its development? Have its
development plans resulted in a better Human Development Index
in recent years?
Economic transition 367
15
Geographical skills
UK population by age group
so
v>
-C
Q_
E
0
H Africa
under 15
15-44
45- 59
60-74
Bar graphs to Column graphs
Europe
k___ j Asia
Americas
over 74
Oceania
Divided bar graphs
Male
Female
E
I 40 50
60
Each full square represents
70 80 90 100 110 120
1% of the total population
Press-ups
Scatter graphs with line of best fit
Triangular graphs
Climate graphs
Hl
7*5
LI
Liechtenstein
Vaduz
Lithuania
Vilnius
Luxembourg
Luxembourg
Macedonia (FYROM)2
Skopje
Madagascar
Antananarivo
Malawi
Malaysia
JI
n
rc
4-»
Q
M
Age/sex structure diagrams
57 000 Aberystwyth
3 017 000
r,„
Temperature - max. (°C)
530 000
r
' '
2 107 000 Temperature - mln. (°C)
22 925 000 Rainfall - (mm)
Lilongwe
16 363 000
Kuala Lumpur/Putrajaya
29 717 000
Maldives
Male
Mali
Bamako
Malta
Valletta
Marshall Islands
Delap-Uliga-Djarrrt
Mauritania
Nouakchott
Mauritius
Port Louis
Mexico
Mexico City
Micronesia, Fed. States of
Palikir
Moldova
Chişiniu
Monaco
Monaco-Ville
Mongolia
Ulan Bator
P l.
>
345000 Acapulco
15 302 000 Temperature - max. (°C)
3 890 000 Rainfall - (mm)__________
Jan
Feb Mar Apr May Jun
Jul
Aug
7
7
9
11
15
17
18
18
2
2
3
5
7
10
12
12
97
72
60
56
65
76
99
93
Jan
Feb Mar Apr May Jun
M
Aug
31
31
31
32
32
33
32
33
22
22
22
23
25
25
25
25
6
1
0
1
36
281
256
252
Feb Mar Apr May Jun
Jul
Aug
1 244 000
122 332 000 ------ 7------------------------------104000 Algiers
Jan
3 487 000 Temperature - max. (°C)
38000 Temperature - min. (°C)
2 839 000
ah nnn ____
15
9
_ rmm\
112
'
___________
16
17
20
23
26
28
9
11
13
15
18
21
84
74
41
46
15
0
22
Diagrams without annotation
I
369
Geographical skills
The purpose of this chapter is to help with the process of conducting
fieldwork (recommended but not compulsory with the Cambridge
International A-Level), to show ways in which data can be represented (useful
for both fieldwork write-ups and exam questions that may be set in the
A-Level), and to begin thinking about the nature of different types of data
geographers collect and use.
Diagrams and graphs
Line graphs
Line graphs are used for showing the relationship between two variables,
such as temperature and altitude (Figure 15.1). Here are a few simple rules for
drawing line graphs.
1
figure
15.1 A line graph of temperature plotted against
altitude.
2
3
4
Usually one of the two variables causes the other to change (rather than
vice versa). For example, if you were plotting soil depth against slope angle,
it is obviously the angle of the slope that causes the soil depth to change,
rather than the other way round. In this case slope angle is called the
independent variable and goes on the horizontal or x-axis, while soil depth
is the dependent variable and goes on the vertical orjr-axis. One exception
to this rule is that altitude is usually plotted on the vertical axis, regardless of
whether it is the dependent or the independent variable. Thus in Figure 15.1
altitude is plotted on the_y-axis, although it is clearly independent of
temperature.
Axes should generally start at zero.
Always mark on the axes what the variables are.
Be aware of the fact that the scales you use on the axes will determine the
visual impression given by the graph.
Figure 15.2 shows the same set of figures plotted on two graphs with axes
of different scales. Note the difference in the way the two graphs look.
Bar graphs
In a bar graph, one axis has a numerical value, but the other shows categories.
Bars are drawn proportional in length to the value they represent (Figure 15.3).
Divided bar graphs (Figure 15.4) are useful when the variable being graphed
(such as population ethnicity) can be divided into parts (white, Asian etc.). Where
there is a clear pattern, the largest division of the bar should be on the bottom/
left-hand side and the smallest on the top/right.
Age/sex structure diagrams (Figure 15.5) are another form of bar graph.
The vertical axis shows age groups in five-year intervals. The horizontal axis
represents either the actual number or the percentage of people in each of
these age groups. The whole graph is divided into two, males on the left and
females on the right.
figure
15.2 Line graphs showing employment in the
London docklands.
370 Geographical skills
Logarithmic graphs
Logarithmic graphs are of two types: those where both axes are drawn
logarithmically (called log-log graphs) and those where only one axis (the
vertical axis) is logarithmic (semi-log graphs). Figure 15.6 (b) shows a semi­
log graph. The horizontal axis is quite normal. But on the vertical scale the
numbers are not spaced evenly: the interval between 20 and 30 is slightly less
than between 10 and 20 and the same as between 200 and 300 higher up the
scale. Numbers are regularly ‘bunched’, and each of these bunchings is called
a cycle. The top and bottom of each cycle must be 10 or some decimal or
multiple of io. In each successive cycle the values are io times greater than
those of the cycle below. Logarithmic graphs have two merits:
2014
2050
Japan
Germany
France
i
2
It is possible to represent a very great range of data on one piece of graph
paper. If you had to plot such values as i, 3,12 and 12 ooo, this would be
impossible on a normal graph, but possible on a logarithmic graph.
Equal rates of change are shown by lines of equal slope. Compare Figures 15.6
(a) and (b). Figure 15.6 (a) shows a normal line graph illustrating the output
from two factories over 20 years. Both factories doubled their output every
10 years (equal rates of change), but the slopes of their lines are different
because factory Y has higher absolute output levels. In Figure 15.6 (b) both
appear as a straight line. Logarithmic graphs are therefore used for plotting
rates of change.
UK
Canada
Poland
USA
Russia
China
Brazil
India
0 5 10 15 20 25 30 35 40 0 5 10 15 20 25 30 35 40
Percentage of population aged 65+
figure 15.3 Share of population aged 65 or over, 2014
and 2050
[3 White
I
I Asian
I
I Black or African American
Q American Indian and Alaska Native
IT! Native Hawaiian and other Pacific Islander
|
| Other
2010
2000
0%
figure
10%
20%
30%
40%
50%
60 %
70%
80%
90% 100%
15.4 Population of USA by ethnicity, 2000-2010
population (millions)
15.5 Age/sex structure diagram of the United
States, 2015
figure
figure
15.6 The same data plotted on (a) normal graph paper and (b) semi-log paper.
Scatter graphs
These are used to investigate the relationship between two variables
when you have data for many places. For example, Figure 15.7 shows
the relationship between population size and the number of services
offered in all the settlements of a region. This type of graph could
be used to see if there was any relationship between birth rate
and standard of living in 100 countries of the world, or between
precipitation and discharge in 20 rivers.
The pattern of the scatter describes the relationship. In Figure 15.7
there is a positive correlation (as one value goes up, the other goes
up) and there appear to be three main groups. Lines are drawn on
the graph that show the general trend of the dots. Three are drawn
on Figure 15.7. There should be an equal number of dots above and
below the line. These are called best-fit lines. If the points do not
form a clear trend, you should not draw a best-fit line.
Geographical skills
Dispersion graphs
House prices (USS)
A dispersion graph shows the range of a set of data and their tendency to group
or disperse. It may also be used for comparing two groups of data. For example,
Figure 15.8 shows prices for the same type of house in two areas of the same
town. Each house is shown as one dot.
Divided circles (pie graphs)
These are used for showing a quantity (such as the population of a country) that
can be divided into parts (for example, different ethnic groups). A circle is drawn
to represent the total quantity. It is divided into segments proportional in size to
the components (Figure 15.9).
Unless you are using a computer to draw the pie graph for you, the method
for dividing the circle is as follows:
2
Draw the circle, proportional in area to the total quantity to be represented
or not, as you wish.
Tabulate the values that will form the segments of the circle. Convert these
3
4
into a percentage of the whole.
Calculate the angle that corresponds to this percentage of 360 °.
Draw a vertical line from the centre of the circle to the top of the
1
figure
15.8 Dispersion graph showing house prices in two
parts of a town.
Arab states 6 %
World: 6 375 000 000
figure
15.9 Pie graph showing cell phone subscribers,
world, 2012
5
circumference.
Draw in segments, measuring the angles calculated in step 3. Start from the
vertical line and work in a clockwise direction. Draw the segments in order
6
of size (largest first etc.).
Different segments may be shaded differently and numbers or words
written in.
Triangular graphs
Triangular graphs, sometimes known as ternary diagrams, are graphs
with three axes instead of two, taking the form of an equilateral triangle
(Figure 15.10). The important features are:
1
2
3
Each axis is divided into 100, representing percentages.
From each axis lines are drawn at an angle of 60 ° to carry the values across
the graph (Figure 15.11).
The data used must be in the form of three components, each component
representing a percentage value, and the three percentage values must add
up to 100 per cent. You could plot, for example, the employment structure
of a town:
0
20
40
6 0 62
80
100
Tertiary %
figure
Employment
Primary
Secondary
Tertiary
Percentage
5
33
62
100
15.10 A triangular graph showing the employment
These figures have been plotted on Figure 15.10. Dotted lines show the way
in which the values are carried across the graph until they meet at one point.
The position of this point indicates the relative dominance of each of the three
components. If exactly one-third of workers were engaged in each of the three
employment types, the point would be in the middle of the triangle, marked
x on Figure 15.10. Care must be taken when plotting and interpreting such a
graph because it can be confusing at first.
Triangular graphs can be used for plotting any data that can be conveniently
divided into three portions, for example agricultural land use (arable, pastoral,
other) or age structure (Figure 15.12). Their main value arises when data for
several places (or one place at several different times) are plotted on one graph.
The relative position of the points then gives a quick visual impression of the
relative dominance of one component.
figure
15.11 A triangular graph showing the way values
are carried across the graph.
372 Geographical skills
Maps
Geographical Information Systems (GIS)
A Geographic Information System has a digital map as a base and layers of
other information over it (Figure 15.13) using computer databases. Selected types
of information currently held in Geographic Information Systems include:
•
•
•
•
•
•
Census data: information about population and housing characteristics.
Postcode/zipcode data: every group of 14 or so houses has its own unique
postcode, and some data about housing and other characteristics are being
linked to postcodes in the database.
Data collected by local government giving the location of such things as
road repairs, derelict land, or the homes of people needing the services of
social workers.
Data giving the location of drains, sewers, gas, water, telephone and
electricity lines.
Data collected by health authorities about illness and patterns of disease;
survey maps, in digital form.
figure
15.12 Age structure of Hatfield, UK
Data from remote sensing satellites, transmitted to Earth in digital form.
Every piece of information (such as the location of hospitals on a survey map)
is given a geographical coordinate when it is entered into the computer. Storing
GIS data on a computer in this way offers several advantages:
1
2
3
4
Data can be easily transferred from one computer to another. It is almost
always quicker to transmit data in this way than, for example, sending a
paper copy through the post.
Maps and overlays can be easily updated or even show real-time data. It is
time consuming to record the location of new telephone cables on existing
paper maps; it is far quicker to do this on a computer screen.
Data can be selectively mapped. Having input all the information from a
survey map, for example, it would be possible to print out just the location
of streams.
Data can be correlated quickly. It would be possible, for example, to compare
the location of the homes of children admitted to hospital with asthma with
the distribution of main roads, to see whether exhaust pollution could be a
factor in the prevalence of the condition. Analysis tools can also be used to
identify patterns and trends.
Geographic Information Systems have become common only in the last 10
years and are a result of three interrelated developments:
1
2
3
A huge increase in the amount of data being generated by governments,
local authorities, businesses and others. A good example of this is satellite
remote sensing data, which arrives in a constant stream day and night.
The development of computers powerful enough to handle the volume
of data, including software that enables the computer to draw maps computer-assisted cartography.
The increasing need for rapid availability of selected data. It is estimated
that 80 per cent of the data stored by local governments, for example, are
locational in some way, and are crucial for planning decisions of all kinds.
Global Positioning Systems (GPS)
Global Positioning Systems are used for navigating, especially in cars (Sat Nav)
but handheld GPS receivers can also be used for mapping. A GPS receiver
collects data from at least four satellites and this gives the map coordinates
of the receiver, normally to within 10 m. These can be recorded and used for
making a map of the area being studied - the data you collect at any place can
be given a precise map coordinate.
Geographical skills
Proportional symbols
These symbols are drawn proportional in size to the size of the variable
being represented. The symbol used can theoretically be almost anything:
proportional ‘people’ to show military strength, proportional ‘trains’ to show
the number of trains in an area, proportional ‘factories’ to represent industrial
output More common are proportional spheres and cubes, drawn three
dimensionally.
But the most usual and straightforward proportional symbols are
proportional bars (Figure 15.14), squares and circles (Figure 15.15).
Proportional bars
The method for drawing proportional bars or squares is:
1 Examine the data and decide on your scale. The length of the bar will be
proportional to the value it portrays. If the bars are too long, they get in each
other’s way, but if they are too short, the difference between one bar and
2
3
4
another becomes hard to see.
Draw your bars on a base map, one end of the bar located next to the
place to which it refers. Bars should be of uniform width, solid-looking
but not so wide that they overlap. They may be placed vertically or
horizontally.
Mark the scale on the map.
Bars may be divided.
Bars are easy to draw and simple to read, but they have two limitations:
1
Because bars are linear, it is hard to show data that have a great range: some
2
will be very big or very small.
Large bars are not always visually attached to the locality they are supposed
to symbolise. It is harder to get ideas of distribution from a bar map.
406
19 651 127
bdll.9%
'^Washington
1 015 165
<=>33%
Montana
3 930 065
1=12.3%
Oregon
38 332 521
1 612 136 >~^11.8%
Idaho
2 790 136
Lzd27.5% 2 900 872
Nevada
/
L=J13.4%
Utah
I
California
582 658
t==19.7%
Wyoming
5 268 367
tz)21%
Colorado
6 626 624
723 393
1=12.9%
5 420 380
North Dakota
844 877
*3.4%
South Dakota
linnesol
I—19.9%
Nebraska
3 850 568
38.4%
td 47.3%
New Mexico
—1 5.5%
Iowa
I
t===J9.6%
-.Oklahoma
26 448 193
17 000 000
Texas
Pennsylvania
6.3%
6 021 988
9.2%ndi’î
I—13.9% '
Missouri
=^*^76 \ 9 992
- 833 722\ —
Arkansas 7
I
<991207
2.9% J””4-1
. . Alabama
lississipf
Carolina
|8.9%
15.3%
South Carolina
Georgia
9.2 %f_
Louisiana
□ Non-Hispanic
□ Hispanic
20%
figure
15.14 Hispanic and non-Hispanic population in US states, 2013
Geographical skills
rir
Rhode Island
3 596 080
8 899 339
1=114.7%
Connecticut
□18.9%
New Jersey
West
060
Tennessee
\ 2 959 373
625 470
(State population)
118.4%
New York
Ohio
2 893 957
‘—«11.2%
Kansas
12 773
UJ4.7%'
6.3% Michigan
Wisconsin
11 570808.
3 090 416
2 085 287
I 130.3 %
Arizona
6 692 824
626 630 1
“1.7%
Vermont Maine
tdio.5%
459
Massachusetts
Florida
23.6 %-
925 749
. = 8.7%
Delaware
5 928 814
I=i9%
Maryland
Proportional circles
The area of the proportional circle is proportional to the values being mapped
(Figure 15.15). The procedure for drawing these is as follows:
1
2
3
4
Calculate the square root of the values. (This is necessary because we want
the area of the circle to be proportional to the values. If one value was, for
example, 2 and the other was 4, drawing one circle with a radius twice that
of the other would make it much more than twice the area.)
Multiply each square root by a constant: this gives you the radius of each
circle. The constant should be the value that will not make the largest circle
too large nor the smallest too small.
Draw the circles and mark the scale on the map.
The circles can be divided.
Choropleth maps
In choropleth or shading maps (Figure 15.16), areas are shaded according to a
prearranged key, each shading or colour type representing a range of values.
It is usually best to draw choropleth maps with a computer, scanning in the
boundaries of the areal units. The great advantage of computers, apart from
speed, is that they generally offer a wide range of shading types. You can
also experiment with different shades. The steps involved in the drawing of
choropleth maps are as follows:
1
2
Obtain a base map with boundaries of the areal units for which you have
data marked on. The smaller the areal units, the more accurate the map
will be.
Find the range of your data and devise a shading scale accordingly. For best
visual results, you should have no fewer than four shading types and no
more than eight, depending on the level of detail required. Your shading
should get darker as the value gets higher. It is nearly always best to use
Geographical skills
Arctic Circle
Literacy rate
95-100
84.3 - 94.9
78.6-84.2
60-78.5
40-59.9
0-39.9
no data
shades of one colour. If you are using a computer, it will suggest a suitable
range of tones for you. You can divide your data into groups of values or
figure 15.16 World literacy rates, 2013. The map shows
the percentage of the population over 15 years old which is
literate. The definition of‘literate’ may vary greatly.
classes in two ways:
•
•
3
Divide the range of values into equal-size classes such as 0-4.9; 5~9-9!
10-14.9; 15-19.9; 20 and over.
Rank the values you are expecting to map and divide the rank order into
the number of groups you want. Have an equal number of values in each
group. Base your shading division on the range of values represented.
Shade in the areal units and draw a key on the map.
The choropleth shading method is easy to do and gives a good visual
impression of change over space, as long as suitable shading is used. On the
other hand, it suffers from two limitations:
•
•
It gives a false impression of abrupt change at the boundaries of areal units.
This is an unavoidable problem when a technique of this type is used.
Variations within areal units are concealed, and for this reason small units are
better than large units. GIS software can cope with granularity: the changing
detail as one zooms into the map, which produces a more accurate map.
Flow-line maps
Flow-line maps (Figure 15.17) are used for portraying movements or flows, such
as traffic flows along roads or flows of migrants between countries. A line is
drawn along the road, or from the country of origin to country of destination,
proportional in width to the volume of the flow. The method for constructing a
flow-line map is as follows:
1
Draw a base map. Mark relevant details such as areal units or the course of
a road. If the map is to represent flows along a road network, mark in pencil
the points at which vehicles were counted and the quantity of traffic counted
at those points.
376 Geographical skills
figure
2
Examine the range of your data and decide upon a scale. If the data range is
not too great and the route density not too high, the scale can be a directly
proportional one, for example:
•
•
3
15.17 Brazil imports and exports, 2010
1 mm thickness: 100 cars per hour
2 mm thickness: 200 cars per hour, etc.
If the flow lines are too wide, they will tend to create blocks and obscure
the map. If this is the case, take the root of the value.
Draw the flow lines. These may go along the actual course of the
phenomenon being mapped, or direct from origin to destination, or by
some other more convenient route - as long as the ‘tail’ of the flow line
begins at the flow origin and the ‘nose’ of the line points towards the destination.
If the flow is a two-way movement, this can be shown by dividing a flow line
and shading it, one shading type representing flow in one direction, the other
representing the reverse flow.
Ray diagrams
Ray diagrams consist of straight lines (or ‘rays’) that show a movement or
connection between two places. On any one base map you can draw differentcoloured rays to show different kinds of movement or types of connection
between places. There are several types of ray diagram:
•
•
Desire lines: A desire-line diagram shows the movement of phenomena
from one place to another. Each line joins the places of origin and
destination of a particular movement (Figure 15.18).
Wind roses: A wind rose has rays focusing on the point from which
wind direction observations have been made (Figure 15.19). Each ray is
proportional in length to the number of days in the year that wind blows
from that direction.
Geographical skills 377
figure
15.18 Ray diagram joining homes of customers
in Yorkshire, England, to places where they go to buy
(a) bread; (b) hardware; (c) shoes.
S SW W NW Calm
Direction of wind
N NE
E
Number of days per year
26 37
39 32 30 57 60
figure
SE
53
51
15.19 A wind rose ray diagram showing wind direction in Liverpool, UK.
Isoline maps
Isolines are lines on a map that join points of equal value. We are all familiar
with isolines - contours on a relief map, isotherms of temperature and isobars
of pressure, for example. Isolines can only be used when the variable to be
plotted changes in a fairly gradual way across space and where plenty of data are
available (Figure 15.20). If the spatial distribution is disjointed and data are not
detailed enough, too much guesswork is involved in the drawing of the isolines.
The method for drawing an isoline map is simple:
1
2
3
Plot the data on a map as a series of points with accompanying values.
Decide on the interval you want between your isolines. If this is too small,
there will be many isolines and the map will look cluttered. If this is too
great, the map will become too generalised to be useful.
Draw in the isolines. You must stick to your chosen interval: all isolines
should have the same interval between them. There is a good deal of personal
judgement involved here. Knowledge such as ‘isobars tend to be circular
around low-pressure systems but straighter between the fronts’ is useful.
378 Geographical skills
4
The space between different-value isolines can be shaded or coloured. The
higher the value of the isolines, the darker the shading. This is the system
used for portraying relief in atlases, except that by convention greens are
used for low land, browns for high land, purple and white for very high
mountains. If you do shade or colour, include a key. If you do not shade
between isolines, mark on their numerical value.
Isolines are ideal for showing gradual change over space. They avoid the
‘unreal’ effect that boundary lines produce on choropleth maps.
figure
15.20 An isoline map of airline noise around Heathrow Airport, London.
The main limitations of isolines are that they are unsuitable for ‘patchy’
distributions, and a large amount of data is needed to draw an accurate isoline map.
Dot maps
In dot mapping dots of a fixed size are given a value representing a variable,
such as crop yield or numbers of people, cattle, shops etc. These dots are located
on a base map roughly where that phenomenon occurs (Figure 15.21). The main
steps involved in drawing a dot map are as follows:
1
2
3
4
5
6
Prepare your data. If the data you are using were gathered within districts,
obtain or draw a map showing the district boundaries. Remember: the
larger the areal units used, the less informative the map will be.
Find the total number of items to be shown on the map: the number of
people, cattle, etc.
Decide on the dot value. This should be high enough to avoid excessive
overcrowding of dots in areas with a high concentration of the phenomenon
being mapped, and low enough to prevent areas with low concentrations
of the phenomenon having no dots at all, so giving a false impression of
emptiness. It may not be possible to fulfil both these criteria so you may
have to choose a compromise value.
Decide on dot size. Dots should be drawn of uniform size. This size will
depend on the density of dots in the area of the map that has the highest
density. Ideally, dots should not be too large and should not merge.
Draw dots on the map to reflect as closely as possible the distribution of the
phenomenon being mapped.
You can use dots of different colours. For example, if you were mapping the
distribution of members of five different ethnic groups in a city, you could
use five different dot colours. The same dot value should be used for each.
15.21 A dot map showing the population of Brazil.
Each dot = 100 ooo people.
figure
Dot maps are useful for showing the distribution of phenomena where
values are known and a fairly accurate indication of their location is given. It is
the only technique that gives this accurate indication of distribution.
Geographical skills 379
Dot maps have two limitations:
i
Large numbers of dots are hard to count so that, while they are very good
at giving an impression of distribution, they are less valuable if you need
a precise idea of the values they represent.
2 If the dots are to be plotted within areas but you know nothing about
the distribution of the phenomena within these areas, other methods (such
as choropleth mapping) are better. In other words, you must have a large
amount of initial information before you begin to draw a dot map.
Satellite images and aerial photographs
Satellite images and aerial photographs can be used in field studies in two ways:
1
For showing elements of the landscape that are not found on survey
2
Chengdu, 1990
Chengdu,2000
maps, such as crop distributions, areas of bare soil left after harvest, water
pollution and private swimming pools.
Landscape change can be studied by comparing older and more recent
images.
A satellite does not record every detail of the surface, but looks at a block and
gives a generalised colour or wavelength reading forthat block; these blocks are
called pixels.
Satellites send images at a variety of different wavelengths, including visible
radiation (measuring the light reflected by different surfaces) and infrared (giving
an indication of the temperature difference between surfaces). The information is
sent in digital format- a sequence of numbers that are then decoded to give the
correct colour or tone of grey on the screen.
We cannot see infrared radiation with our eyes so infrared images have a
false colour placed on them by the computer. In order to interpret the image it
is necessary to find out how the false colours have been assigned.
You can use satellite images as the basis for individual studies, especially for
examining agricultural land use. Bare soil appears clearly, as do certain crop
types. Changes over seasons and over years can be measured. Other types of
study for which you might use satellite imagery are recreational impact projects,
water pollution studies, and soil-vegetation surveys.
Google Earth™, the free satellite imagery package, provides an excellent way
to present fieldwork data. Using Google Earth™, it is possible to attach maps,
photos, text and data to aerial photographs. Quikmaps.com shows you how to
do this. The Pro version of Google Earth™ is free of charge and allows access to
a range of supplementary images and layers.
Data types
•
Chengdu urban growth
15.22 Satellite images of Chengdu, China, showing
figure
•
rapid urban growth. In the last image, the yellow represents
the urban area in 1990 and the orange is the growth
between 1990 and 2000.
Quantitative research means collecting data that can be expressed in
numbers - such as the number of residents in a town or the temperatures
around a lake.
Qualitative research means collecting data that cannot be easily converted
into numbers, such as a study of people’s opinions. Examples of qualitative
research are:
1
2
Interviews, focus groups and oral histories.
Observations of people and places, recorded using field notes, video,
3
photographs and sketches.
Textual analysis of printed newspapers, books, magazines and
websites.
•
•
380 Geographical skills
Primary data is data collected first-hand, such as temperature
measurements you have taken.
Secondary data is data published by someone else, such as population
census data you have downloaded from a website.
Data are only reliable if they have been collected in a scientific way. Generally
it is not possible to measure the whole population of data (all the people, all the
rivers, all the shops) so it is necessary to sample. The sample needs to be large
enough to be representative of the whole population and needs to sample all sub­
sets. For example, research into shopping behaviour would need to sample some
young people, some middle-aged, some old, some men, some women, some
rich, some poor- because all these characteristics could influence behaviour. If a
sample is not large enough the data will not only fail to tell you anything useful
about the whole population but could suggest things that are simply untrue.
When collecting data you need to avoid bias (a false result). Bias in data can
arise for several reasons including:
i
The data from which the sample is taken is biased. For example, if you
2
select the addresses of 100 people from a telephone directory, this is biased
against people who do not have a landline.
The time the sample was taken. Conducting a street questionnaire during
the morning of a weekday is biased against working people and biased
towards those who do not work.
Here are a few sources of qualitative data:
Newspapers
Newspapers can be used as an information source for population and
settlement studies in a number of ways:
i
They provide information about the locations of local events and local
businesses (through advertisements), giving an indication of the sphere of
influence of the town concerned.
2
Most local newspapers have a large section devoted to advertisements
put in by house agents. By noting house prices and the types of property
advertised in different areas of a town, you can build up further information
about the local private housing sector.
All local newspapers provide coverage of the important planning decisions
reached by local authorities and analysis of the different views and interest
groups involved in controversial issues such as road building and office schemes.
3
Questionnaires
Questionnaires are a set of pre-planned questions, to which the answers are
written on a specially prepared form. They are the most widely used primary
data source in human geography and are important for two reasons:
i
2
They enable us to find out information about people’s opinions and
behaviour that is not available from any other source (such as why someone
moved house or how a decision was made to open a shop in a town).
They enable us to obtain information that is completely up to date.
The disadvantages of questionnaires are:
i
People do not like answering questions asked by a stranger.
2 Some people are particularly unlikely to be able to answer, such as parents
with young children on a shopping trip. Yet any survey that omits such
groups is biased.
3 It has been shown that people do not tell the truth in surveys and opinion
polls. They often give the answer they think you want to hear, or the answer
that they believe sounds good.
Two examples of questionnaires are given in Figure 15.23, one good and the
other bad. They illustrate some of the important points to remember when you
write questionnaires.
Geographical skills 381
A
Good Questionnaire
Introduction: 'Excuse me, I am doing a school geography project.
Could I ask you one or two quick questions about where you go
shopping?'
1
How often do you come shopping in this town centre?
More than once a week □ Weekly □ Occasionally □
2
How do you travel here?
WalkQ Car □ Bus □ Train/Tube □
Ot h e r__________________________________________________
3
Roughly where do you live?________________________________
4
Why do you come here rather than any other shopping centre?
Near to home □
Near to work □
More choice □
Pleasant environment □
Other__________________________________________ —----------
5
What sort of things do you normally buy here?
Groceries □ Clothes/shoes □ Everything □
Other__________________________________________________
6
Do you ever shop anywhere else, and if so where?
7
Why do you go shopping there?
8
What do you buy there?__________________________________ _
9
Sex: M □ F □ Age (estimate): under 20 □
20-30 □ 30-60 □ Over 60 □
'Thank you very much for your help.'
B
Bad Questionnaire
Introduction: 'Excuse me, but I wonder if I could ask you some
questions?'
1
Where do you live?_______________________________________ _
2
How do you get here?____________________________________
3
Do you come shopping here often?
4
Why do you come here?__________________________________
5
Do you buy high- or low-order goods here?
6
Is this a good shopping centre and if so, why?
7
Where else do you go shopping?
8
Do you shop there because it is cheaper or nearer to your
home?_________________________________ _ —-------------9
How old are you?________________________________________
'Right, that's it then.'
figure
382 Geographical skills
15.23 Good and bad questionnaires
i
2
3
4
5
6
7
8
9
Start by explaining the purpose of the questionnaire: most people are
suspicious of them and reluctant to answer. The more convincing your
explanation, the higher the response rate will be.
Plan the questionnaire so that the respondent is put at ease at the
beginning. Leave more difficult or probing questions to the end.
Keep the questionnaire short. Use tick boxes where possible.
Know why you are asking each question and be careful not to omit anything
you will need to know. It is impossible to go back later, find the same people
and fill in the gaps.
Do not ask questions that are too personal, such as questions about age or
income. It is normally possible to estimate age. You can form some estimate
about income by asking questions about occupation, housing tenure and car
ownership. People are usually reluctant to give their address, so ask for ‘the
area where you live’ or for their postcode.
Do not ask questions that ‘expect’ a certain answer, such as question 8 in the
bad questionnaire.
Always issue a few (pilot) questionnaires to see how people respond. You will
often want to make adjustments after this trial.
If you want to do statistical analysis on the results of your questionnaire,
you must ask questions in such a form that the results can be expressed
as numbers. This is one reason for giving people a limited choice in terms
of their answers: ‘Do you think this shopping centre is good, fair or not
very good?’ is a question that will enable you to express the answers as a
percentage response to each of three categories. If you simply ask, ‘What do
you think of this shopping centre?’you may not be able to do this.
Do not include questions about information you can obtain from another
source.
When you deliver a questionnaire:
i
Decide how you are going to administer the questionnaire:
•
•
•
2
3
Standing in the street and catching passers-by.
Going from house to house knocking on people’s doors. This has the
advantage that you are able to select the streets and houses you want.
Post the questionnaire into specific houses and pick them up later or
enclose a stamped addressed envelope. This method is quicker but
more expensive and will not always achieve a very high response rate.
A response rate of 30 per cent is typical for such a method. The other
disadvantage with this method is that it does not allow the respondent
to ask for clarification of a question. If you use a postal questionnaire,
you must have a carefully written covering letter explaining the purpose
of the questionnaire.
Decide to whom you want to administer the questionnaire. To ensure that
all relevant sections of the community are represented, you may want to
make sure that a proportion of the questionnaires are answered by men,
a proportion by women, a proportion by younger people, a proportion by
older, some by higher-income people, some by lower-income individuals
and so on. To find out what these proportions should be (for example, what
proportion of the local population are of retirement age), you need to obtain
census data.
Plan carefully when and where you are going to conduct the
questionnaire. If, for example, you are hoping to interview people about
their shopping habits, you must decide whether you wish to do a houseto-house survey or stop people in a shopping street. You must decide
which days of the week to do the questionnaire and which times of day.
Working people will not be around during the normal working day, so
any questionnaire you undertake at this time is biased against them. The
important point is to think these things through and to explain them
when you write up your study.
Geographical skills 383
Choose times and places that are safe. It is best to work in pairs for what
can sometimes be a rather unpleasant task. Some places will not permit
4
you to conduct questionnaires on the premises. This is true of most covered
shopping centres.
Decide how many questionnaires you are going to administer. If you have
too few, you will not be able to draw any overall conclusions from the results.
Interviews, focus groups and oral histories
With a questionnaire the questions are fully planned beforehand, but often this
is not the most appropriate means of finding out information from people: we
need a much more open-ended approach.
Interviews
Most studies about the decision-making process, such as the reasons why a firm
located where it did, or the thinking behind a local authority town plan, should
involve an interview with the person who made the decisions or someone who
can represent his or her views. Usually this will involve writing to the firm or
local authority requesting an interview. Explain who you are and the purpose of
the interview, indicate which days would be possible for you and how long the
interview will take, and make clear what use will be made of the results.
Interviews should be approached in the same way as questionnaires- you
go with a list of questions and paper to write the answers down (or a recording
device - although some people dislike being recorded). The only difference is
that you should listen carefully to the answers and be prepared to probe a bit. If
you have arranged an interview with someone in advance, it is normal to write
and thank them afterwards.
Focus groups
Focus groups are groups of people who are gathered together to discuss
attitudes towards an issue. Political parties use focus groups to discover what
the electorate think about issues. Focus groups should consist of a sensibly
selected sample of representative people (a representative selection of different
age groups, males and females, different ethnic groups, different levels of
income), up to 12 people at a time (too many participants and the meeting
becomes harder to handle) and the discussion can be recorded or filmed. The
researcher leads the focus group through the discussion using a series of
open-ended questions - questions that allow a variety of responses.
Oral histories
Oral histories are accounts that people give of‘what life used to be like’. They
are often recorded and are similar to questionnaires except that they tend to be
much more open-ended. The reason for this is that, although there will always
be a set of specific questions you want to ask, there may be other important
aspects of a person’s life that had not occurred to you. This is why it can be
profitable to start with a very open-ended question such as: ‘What was life like
when you were a teenager?’
Oral histories of this sort are especially useful in studies of demography
where we need to know about the influences of such things as age of marriage,
number of children born to each parent, diet and health. Do not be afraid to use
interviews and oral histories to find out about people’s feelings - geography is
not only concerned with facts.
384 Geographical skills
3
antecedent conditions the conditions that exist before a
3D jobs are dirty, difficult or dangerous-these jobs are
aquifers formations of porous rock that store underground
unpopular
water; aquifers are vital to facilitate irrigation for farming and
for supplies of drinking water
A
arcuate delta a fan-shaped delta (the most common shape of
precipitation (rainfall) event
delta) where the river mouth splits many times on the way to
the sea, for example the Niger Delta
absolute humidity is the total mass of water vapour in a
given volume of air, regardless of the temperature
area of assimilation parts of a city’s central business district
abrasion in erosion, the impact of particles hitting rock and
(CBD) where offices are converted to residential use or houses
are turned into offices
soil
area of discard parts of the central business district
acculturation when one culture becomes similar to another
through contact
(CBD) where old buildings that can no longer be used are
demolished
acid rain rain that contains a high concentration of
aridisols soils that are usually saline or alkaline, with little
pollutants, notably sulfur and nitrogen oxides; these pollutants
are produced from factories and power stations burning fossil
fuels, and car exhausts and once in the atmosphere the sulfur
and nitrogen oxides combine with moisture to give sulphuric
and nitric acids, which fall as corrosive rain
organic matter and little moisture; aridisols are typically found
in deserts
arroyo(s) a name for a wadi used in south-western USA; a
wadi is a dry watercourse in an arid region
acidification when liquids become acidic; rocks and minerals
asthenosphere the upper layer of the Earth’s mantle, below
can be dissolved by water that contains acids-where acids are
more concentrated, for example acid rain, the weathering is
more extreme
the lithosphere, which is estimated to be between 85 and
advection fog forms when warm air passes over a cold
surface, for example warm air from the sea passing over the
land in winter
several hundred kilometres in depth; the rock here is not as
rigid as the surface rock
aspect in geology, the direction a slope faces as defined by
compass bearing
atmospheric counter-radiation when the terrestrial
agro-technology the technology used in agriculture to
increase the volume of food produced
air masses winds that blow regularly and have uniform
characteristics over a horizontal distance of thousands of
kilometres; air masses are categorised according to their
temperature and humidity
radiation that is absorbed by water vapour, CO2 and other
gases in the atmosphere heats up and is returned as counter­
radiation to the ground
attrition when boulders and large stones carried by a river or
by the ocean bash into each other and break up into smaller
pieces
akle dunes long sinuous ridges formed when there is plenty
of sand (they are similar to barchanoid ridges); akle dunes are
common in the western Sahara
B
albedo the proportion of solar radiation reflected from areas
bajada a series of merging alluvial fans along a mountain
of the Earth’s surface
front
alluvial fan a triangle-shaped deposit of gravel, sand and silt
balance of trade the difference between a country’s imports
built up by streams, created where the water moving through
the mountains or hills abruptly decreases in velocity
and exports
Glossary 385
barchans crescent-shaped sand dunes formed in desert
biodiversity the diversity of plant and animal life in a
regions where the wind direction is very constant; wind
blowing round the edges of the dunes cause the crescent
shape, while the dunes may advance in a downward direction
particular habitat, geographic region or in the world as a whole
biomass the total mass of living organisms, both plant and
as particles are blown over the crests
animal, in a given area
base flow the water flowing in a stream that is fed only by
bird’s foot delta a delta where the river splits offinto ‘fingers’
groundwater; during dry periods it is only the base flow that
passes through the stream channel
that jut out into the sea, like a bird’s foot, for example the
Mississippi Delta, USA
base level the lowest point to which a river can flow; sea level
birth rate the total number of live births in a year (for every
is usually the base level for large rivers but a large river is often
the base level for its tributary streams
1000 people)
batholiths large areas (100 sq km or more) of igneous rock
smaller blocks of rock
that have been formed underneath the surface of the Earth by
magma intruding and solidifying; they are between 10 and 15
km deep
floodplain
block disintegration large blocks of rock that break into
bluff the slightly raised line that marks the edge of a
bedload particles that are transported by water along a
bottomset beds sediment made up of fine silt and clay
riverbed
deposited in a delta by a river; the finest sediment is carried
the furthest by the river
Benioff zone a downwards sloping contact zone situated
beneath a destructive plate boundary where oceanic plates
or ocean-continental plates converge- when they collide
earthquakes occur; also called a Wadati-Benioff zone after
break-of bulk unloading a portion or all of a shipment at a
the seismologists Kiyoo Wadati (1902-95, of Japan) and Hugo
Benioff (1899-1968, of the USA) who independently discovered
buttes relatively small outliers of mesas
particular location
the zones
berm another word for a raised barrier composed of shingle
c
and sand created by wave action
calide the hard protective limestone skeleton of a coral polyp;
Bhopal disaster (2-3 December 1984) took place in India
this forms the structure of a coral reef
at a pesticide factory owned by American company Union
Carbide; a gas leak exposed the local population to toxic gas
and chemicals, killing an estimated 3000 people and injuring
half a million
capacity in rivers, the load that can be theoretically carried
given the velocity of the river flow
capillary migration water at the surface evaporates and this
bid rent theory states that the price and demand for property
and land changes as its distance from the central business
district (CBD) increases, for example retailers will pay more to
locate their business as close as possible to the CBD because a
central location will help their business to be more profitable
Bill and Melinda Gates Foundation founded in 2000, this
is the biggest private foundation in the world and it engages
in poverty reduction, expanding education opportunities for
the most disadvantaged people in the world, and enhancing
healthcare provision; Bill Gates (b. 1955) was the co-founder of
draws up more water from depths that can exceed 3 m; when
this water evaporates at the surface it leaves salts
capital intensive in agriculture, the use of mechanical goods
like machinery, tools, vehicles and factories to produce large
amounts of agricultural goods, with minimal human labour
carbonation the process where carbon dioxide, often from
rainwater, produces carbonic acid, which dissolves rock
Microsoft and it is the success of this business that funds the
carrying capacity the maximum number of species that the
resources (for example, water, food) in an environment in a
Foundation
given area can sustain
bioconstruction the colonisation of mudflats by vegetation
that can withstand high salinity and water submergence; the
vegetation forms a mat that creates friction between the waves
and the salt marsh, which makes the waves slow down and
cavitation a type of hydraulic action where collapsing air
deposit more material on the salt marsh
by the government of India in 1952; some of the Institute’s
objectives include finding ways to stabilise shifting sand
dunes, limit deforestation and renew degraded forests
Glossary
bubbles create small shock waves, known as cavitation
Central Arid Zone Research Institute (CAZRI) set up
chain migration when people migrate to a particular place
because they have family connections there, friends as social
networks or because people of the same nationality already
live there
condensation nuclei the name given to the particle of salt,
soot or dust needed for raindrops to form around in order to
achieve droplets
channel flow the name given to water moving through a
condense the process by which cooling vapour turns into
liquid, for example clouds are formed by the condensation of
defined channel, for example a stream or river
water vapour in the atmosphere
channel storage water contained within a river channel or
stream
conservative migration when people migrate in order to
preserve a certain standard of living
chelation a bio-chemical weathering process; organisms
continental climate places that have seasons because they
produce chelates that can decompose minerals and rocks by
removing metallic cations
have annual variations in temperature; this tends to occur in
the middle of countries, where the land is unaffected by the
maritime climate
circular migration where a migrant repeats a circular
journey between their home and host areas, usually in search
of employment
coastal squeeze the name for what happens to a coastal area
that is ‘squeezed’ between a man-made land-based boundary,
such as a sea wall, and an ocean that is storm-prone or rising
in level; the squeezed coastal environment is trapped and
begins to deteriorate
continentality the climates of places far from the sea, such as
Central Asia
convection currents heat from the Earth’s core (which,
at 6000 °C, is very hot) is carried up to the mantle through
convection currents; the currents move around, destroying the
crust in some places and creating new crust in other places
convectional with reference to precipitation, the name given
Coastal Zone Management managing coastal areas so
to rain formed by hot ground heating the air above it, making
that human activities, economic needs and environmental
priorities are balanced
this air less dense, causing it to rise; as the air cools to below
the dew point the water vapour condenses and falls as water
droplets
cold currents an ocean current that carries water from the
poles towards the equator, taking cold polar water into warmer
seas
competence the maximum size of material that a river is
capable of transporting
command economy government, rather than market,
control of the production of goods and services; in agriculture
this means that the state decides what crops should be grown
and how much they will cost the consumer
convergent in plate tectonics, plates that move towards each
other. Where two continental plates move together and collide,
large mountain ranges are formed, for example the Andes
(South America). Where a continental plate converges with an
oceanic plate volcanoes are common and a subduction zone
is formed.
coral bleaching when the symbiotic relationship between the
including livestock, with the use of modern technology
coral and the zooanthellae (the algae that provides the coral
with food, energy and colour) breaks down, the coral loses
its colour; this happens when the temperature of the water
increases (by no more than 1 or 2 °C, which can take place
more easily in shallow water)
commodification to give something a price
core-periphery concept developed in 1963 by John
commercial farming farming crops for sale and profit,
European Union to support and subsidise certain crops and
methods of animal husbandry
Friedmann (b. 1926); the concept looks at development and
states that core cities, regions or countries develop faster
than periphery areas because they have physical or human
advantages
concentric zone model also known as the Burgess model,
Coriolis Force a force exerted by the Earth’s rotation that
is an early (1925) theoretical model to explain social structures,
particularly social groupings in cities and their location in
relation to the central business district, which lies at the centre
of the model, with the most affluent groups of people living in
the best locations
causes moving objects to move to the right in the Northern
hemisphere and to the left in the Southern hemisphere; it is
responsible for the direction of movement in various weather
condensation level the height at which a body of air reaches
corrasion when sand and stones carried by a river rub against
the riverbank and riverbed and knock off other particles; also
known as abrasion
Common Agricultural Policy (CAP) the policy of the
the dew point
events such as hurricanes and anticyclones; the Coriolis Force
is not present on the equator
Glossary 387
corrosion when acids in a river dissolve the rocks that make
desertification land degradation in arid, semi-arid and sub-
up the bank and riverbed, for example the dissolving of
limestone by water; see also solution
humid areas resulting from various factors including climatic
variations and human activities
counter-stream in migration, migration that moves in the
opposite direction to a migrant stream
dew when water on the Earth’s surface condenses due to
counterurbanisation the movement of people from urban
dew point the temperature at which the atmosphere, being
areas to rural areas
cooled, becomes saturated with water vapour; this vapour is
then deposited as drops of dew
atmospheric cooling it forms droplets of water known as dew
cultural clashes when differences between cultures lead
people to misunderstand or resent each other, sometimes
leading to verbal or violent encounters
dissolved load the process by which small dissolved
sediments and minerals are transported within a river; also
known as solution
cuspate delta a delta where material from the river is evenly
spread on either side of the
river meets the sea the land
forms a shape like the head
for example the Ebro Delta,
channel; this means that as the
around the mouth of the river
of an arrow jutting into the sea,
Spain
distal the end furthest away from the attached end or the
centre
diurnal range the difference between the highest and the
lowest temperature in a 24-hour period
cutoff another name for an oxbow lake
divergent in plate tectonics, plates that move away from each
D
death rate the total number of deaths in a year (for every
other, both on land and as sea floor spreading. These become
rift valleys on land, for example the East African Rift.
divided bar graphs a graph in the form of either horizontal
or vertical bars, which illustrate the size of values
1000 people)
Doha Amendment an amendment to the Kyoto Protocol,
debris avalanche a sudden landslide of hot or cold material
from the side of an unstable steep-sided mountain
adopted on 8 December 2012 in Doha, Qatar, which commits
signatory nations to reduce greenhouse gas emissions by 2020
deflation loose particles picked up by the wind and carried
dragging theory another name for slab-pull mechanism
away, causing erosion
deflation hollows hollows in rock left by deflation
duricrusts formed by the evaporation of groundwater-this
gives a hard mineral crust near the soil’s surface; usually found
in semi-arid areas
deflocculation the dispersal of particles that had been stuck
together
dune slacks the area in the dip between sand dunes
deglomerating the process of breaking a large mass up into
dust devil a small whirlwind or air vortex over land, visible as
smaller parts
a column of dust and debris
deindustrialisation the process of decline and removal of
heavy industry from a country or region
dynamic equilibrium a lack of change in a system as inputs
demography the statistical study of human populations
using information about areas such as births, deaths, disease
and outputs remain in balance. If changes do occur, feedbacks
allow for correction. In sediment/littoral cells, the result of the
inputs, processes and outputs that operate within the cell
and income
dendritic the name given to a drainage pattern that looks like
E
a tree, with water converging from several directions before it
joins a main channel
dependent variable the variable (usually labelled as7) that is
being measured and whose value depends on that of another
dependency ratio the ratio of dependents (people younger
than 15 or older than 64) to the working age population (those
aged 15-64). Usually shown as the proportion of dependents
per 100 working age population.
388 Glossary
economies of scale the economic advantage gained by
producing larger quantities of goods - this is because the
fixed cost of each item produced is reduced if the cost of
production is spread over a larger number of goods; economy
of scale also increases operational efficiency, further reducing
fixed costs
ecotourism tourism that is concerned with the support and
conservation of natural environments, local economy and local
Ester Boserup (1910-99) a Danish agricultural economist;
her most influential work was The Conditions of Agricultural
society
Growth: The Economics of Agrarian Change under Population
Pressure (1965) in which she challenged Malthus’s view on
population (that agricultural methods determine population),
believing that population determines agricultural methods
edge city a mostly American term for a relatively large area
of businesses, shopping and entertainment situated on the
outskirts of a city in what was previously a residential area
effective precipitation the percentage of rainfall that
erg in geography, a broad large area of sand, also known as a
sand sea
becomes available to plants and crops
eustatic fall a drop in sea level related to changes in the
emerging market an economy that is moving from a low
income per person to a middle income per person; emerging
markets are home to 80 per cent of the world population and
represent 20 per cent of the world economy
embryo dunes the youngest sand dunes that sit nearest the
shoreline at the front of the dunes on a beach
volume of seawater in the oceans or because of a change in
the shape of an ocean basin, which affects how much water the
ocean can hold; eustatic change occurs during and after an ice
age
eustatic rise a rise in sea level related to changes in the
volume of seawater in the oceans
emigrants people who leave a country
event modifications actions that limit the ability of a flood
emigration the act of leaving one’s country to go and live
permanently in another country
to cause damage and impact on people’s lives, for example
hazard avoidance by land use zoning, hazard-resistant
building design, engineering flood defences
endorheic relating to interior drainage basins
evaporation (EVP) the change of state from water droplets
(liquid) to water vapour (gas) caused by heating; evaporation
energy mix the energy consumption of a household, region
or country; energy mix includes both renewable (for example
wind power, wave power, solar power) and non-renewable (for
particularly takes place over large bodies of water and rates of
evaporation vary depending on factors such as wind speed,
temperature and humidity
example, oil and natural gas) energy sources
enhanced greenhouse effect the warming of the Earth’s
atmosphere caused by an excess of carbon dioxide, which
acts like a blanket preventing the natural escape of heat; this
situation has been developing over the last 150 years because
of (a) the burning of fossil fuels, which release vast amounts
of carbon dioxide into the atmosphere, and (b) deforestation,
which results in fewer trees being available to take up carbon
dioxide
entrenched meanders well developed symmetrical
meanders that form in a river when the river’s base level falls,
allowing the river to quickly vertically erode, leaving little time
for lateral erosion; also known as incised meanders
evapotranspiration (EVT) loss of water into the atmosphere
from plants (transpiration) and water surfaces (evaporation)
excavation the removal of material such as rocks and soil
to obtain access to underlying layers of the Earth’s surface;
excavation can be necessary for activities such as mineral
extraction or to study the geology of an area
exfoliation a form of weathering whereby the outer layers of
rock or boulder shear off due to the alternate expansion and
contraction produced by diurnal heating and cooling; such a
process is especially active in desert regions
exogenous something that originates externally
ephemerals plants that live for a very short time
epidemiological transition the name given to a sudden
increase in population due to improvements in medicine;
this spike in population growth is often followed by a drop in
fertility rates (people have fewer children as they become more
affluent), leading to a re-levelling of population growth
falling limb on a hydrograph, the part of the graph that
shows the river discharge decreasing and water levels moving
back towards base level
Equatorial low pressure belt the area of low pressure
fertility rate the number of children that would be born alive
(rising air) found at or near the equator
to a woman if she were to live to the end of her childbearing
years
fetch the name given to the potential distance a wave can
travel; in the south-west of England the maximum fetch is
from the south-west and is 5000 miles
Glossary 389,
financial capital the funds available to a business for
frontal fog forms when warm air meets cold air at a front
investment
Frontier Five a group name for Bangladesh, Nigeria, Peru,
fixed capital the money a business invests in items that are
fixed such as machinery and buildings
Vietnam and Oman; economists have predicted that these
countries are poised to experience significant economic
growth
fixed costs costs that remain the same regardless of how
many items of a product are manufactured, for example rent is
a fixed cost
fixed dunes sand dunes that are grey in appearance,
frontier market developing countries with slower economies
and less established stock markets are referred to as ‘frontier’
markets; frontier markets include countries such as Nigeria,
Argentina and Qatar
immobile, and support the most plant life of any found on
dunes as a result of their richer soil
fulls another name for sand ridges on a beach
flash floods sudden flooding in low-lying areas; this can
be a result of severe rain brought by thunderstorms, tropical
storms or hurricanes, or due to the failure of a man-made
structure such as a dam
G
gender analysis in migration, examines the different roles
flocculation the process of saltwater and freshwater mixing,
which causes tiny clay particles to stick together into larger
masses; these masses are too heavy to stay suspended in water
so they sink to the seabed
of men and women in migration and how sex discrimination
affects migration
geostationary satellites satellites that travel in a circular
orbit around the Earth over the equator at an altitude of
fog when the air becomes saturated with water droplets,
resulting in the reduction of visibility near the surface of
the Earth (to less than i km); there are different types of fog
and they are classified according to the process that causes
the air to cool to saturation point, for example radiation fog,
around 35 800 km; they travel once around Earth every day so
they appear to be stationary
geothermal energy heat from the Earth or stored in the
Earth, for example pools fed by hot springs
advection fog, frontal fog and hill fog
global shift the movement of manufacturing from HICs
fold mountains mountains that have been formed by large-
scale and complex folding; studies of typical fold mountains,
for example the Himalayas, Andes, Alps and Rockies, indicate
that folding has taken place deep inside the Earth’s crust and
upper mantle as well as in the upper layers of the crust
to MICs and LICs by TNCs seeking cheaper labour and less
regulated business environments
global warming a gradual increase in the overall temperature
of the earth’s atmosphere, generally attributed to the
enhanced greenhouse effect
footloose industries an industry that is free to choose any
location
gradient the measure of steepness of a slope; also the
forced [migration] when people are made to leave a country,
measure of change in a property such as population density or
land values
for example because of war or a natural disaster
granular disintegration when rock breaks into fine particles
foreset beds in a river, deposits of medium-sized particles
of sediment that are carried less far than the finest sediment
(bottomset beds) but further than the coarsest material
(topset beds)
free [migration] when people migrate in order to improve
their circumstances and life chances
Gravitational model was developed by Stouffer and explains
why migrants settle for a location that is not their intended
location; the number of migrants moving from one town
to another is related to the opportunities available at the
final destination but inversely proportional to the number of
opportunities that present themselves (intervene) along the
way, before they get to their intended destination
friable something with a crumbly texture that can easily be
broken into small pieces, for example soil
green belt land surrounding urban areas that is protected so
that it cannot be built on
front a boundary between two air masses
greenfield undeveloped land in urban or rural locations used
frontal with regard to precipitation, the name given to rain
that is the result of warm air meeting cold air; the lighter
warm air is forced up over the cold air and the line where the
warm air and cold air meet is called a front
390 Glossary
for farming, grazing or left to lie fallow
Green Revolution in agriculture, the series of technological
and research advances that took place from the 1940s onwards
that increased the efficiency of farms; the application of
chemical fertilisers, herbicides and pesticides increased
yields and the creation of new disease-resistant crops led to
increased productivity
groundwater flow the part of the streamflow that has
infiltrated the ground, entered the phreatic zone, and has
been discharged into the stream channel through springs or
seepage
groundwater recharge the restocking of groundwater with
surface water
hotspots volcanic areas fed by underlying magma; often
found near tectonic plate boundaries, for example Japan.
Hoyt’s sector theory was proposed by the land economist
Homer Hoyt (1895-1984) in 1939 and it is a development of
the concentric zone model; Hoyt placed a CBD at the centre
of his model and he observed that as differences in function
occurred in the growing city variations tended to endure, for
example low income housing tended to occur in the least
favoured locations while high income housing sought out
more favourable locations
Human Development Index (HDI) published by the
H
United Nations Development Programme (UNDP) is a
measurement of a country’s achievements in three areas
- longevity, knowledge and standard of living: longevity is
measured by life expectancy at birth; knowledge is measured
by a combination of the adult literacy rate and the combined
gross primary, secondary and tertiary school enrolment ratio;
standard of living is measured by Gross Domestic Product
(GDP) per person
haffs long shallow lagoons; they are separated from the open
HWM the spring tide high water mark
groundwater storage water stored in the pores and spaces
of underlying bedrock
sea by a narrow sandbar
hydration the ability of something to absorb water
halophytes plants that can live in saline areas, for example
salt marshes
hydraulic action the erosive force of water alone, as distinct
Harbin explosion on 13 November 2005 there was an
from corrasion; a river or the sea will erode partially by the
sheer force of moving water and this is termed hydraulic
action
explosion ata petrochemical plant in Jilin Province, China,
which caused 100 tonnes of toxins to enter the Songhua River;
six people were killed in the explosion and 10 000 people were
evacuated from the city of Harbin due to the threat posed by
the contaminated water of the Songhua
hydraulic fracturing a process that extracts oil and gas from
shale rock by drilling deep into the earth and then forcing a
high-pressure mixture of water, sand and chemicals into the
rock to bring the gas or oil stored there to the surface
heat transfer the transfer of heat from one place or object to
another
hydrolysis is a reaction involving the breaking of a bond in a
heave the name given to a type of mass movement of
molecule using water. The reaction mainly occurs between a
hydrogen ion in water molecules and often changes the pH of
a solution.
downhill weathered rock material; this movement is
characterised by a slow expansion and subsequent movement
of debris to the surface perpendicular to the slope; heave
raises the slope profile in a series of ridges or mounds
hygroscopic nuclei the name given to the microscopic
particles of salt, soot or dust onto which water vapour can
condense to form rain
helicoidal flow a corkscrew-like river flow associated with the
formation of sediment bars and slip-off slopes; this flow is
mainly found as water travels around river bends
hyper capital-intensive a business that needs large
quantities of money to produce a service or a product, for
example car manufacturing, some types of agriculture
High Income Countries (HICs) countries that have a high
income according to the World Bank’s World Development
Indicators; there are 80 HIC countries with a Gross National
Income (GNI) per person of more than US$12 735 (2014 figure)
hill fog forms when air is forced to rise up a slope and cools
igneous rocks rocks formed when magma cools and
solidifies
holistic an approach that views the whole as being more
important than a focus on just a few individual parts
immigrants people arriving in a new country
honeycomb weathering another name for pitting
immigration the movement of people into a country or
region from other countries or regions
Glossary
impelled [migration] when people believe that they are under
intervening obstacles things that happen to stop migrants
physical or human threat and they respond by leaving an area
in an effort to ensure their safety, for example people fleeing
from religious persecution
from getting to their original destination, for example not
being able to afford to migrate or being too far away from the
migrant’s preferred destination
impermeable something that cannot be penetrated by water
Inverse Distance Law the volume of migrants decreases
with the distance from the origin
in-migration to move around one’s own country to settle in a
new location
irrigation artificially diverting water to fields to grow crops
incised meanders another name for entrenched meanders
island arc a line of volcanoes situated on islands that sit
independent variable a variable (usually labelled as x) that is
above an oceanic-oceanic subducting plate and form the
shape of an arc, for example the Ryukyu Islands, Japan
manipulated or changed
Index of Multiple Deprivation (IMD) is calculated by
K
combining a number of‘domains’ relating to employment,
income, education and skills, health, crime, barriers to housing
and services, and living environment; each domain is given a
score, each score is weighted, then added together to produce
the overall level of multiple deprivation
knowledge economy an economy based on the use of
industrial inertia when an industry does not relocate,
for example a factory, even though the original reasons for
Kuznets curve in environmental economics, proposes that as
a country develops economically levels of pollution decrease
choosing the site, such as a cheap supply of energy to power
the factory, are no longer applicable; often it is cheaper for the
industry to adapt to the changed circumstances than it is to
build a new plant in a new location
innovative migration when people migrate in order to
improve their standard of living
information, for example intellectual products and services, to
create wealth
Kyoto Protocol an international treaty (signed 1997,
came into force 2005) that extended the United Nations
Framework Convention on Climate Change (UNFCCC 1992)
and committed signatory nations to reduce greenhouse gas
emissions by 2012; the Protocol was updated in 2001 and was
amended in 2012 (the Doha Amendment)
infant mortality rate the number of deaths of children
under one year of age per 1000 live births
L
inter-annual variability the difference in precipitation from
one year to the next
lag time the amount of time between peak rainfall and peak
river discharge
interception water that is caught and stored by vegetation;
see interception loss, throughfall, leaf drip, and stemflow
lahar a type of destructive mudflow or debris flow which
contains a mix of volcanic rock fragments and water flowing
interception loss water that is retained by plants
rapidly downhill on the slopes of a volcano
Intergovernmental Panel on Climate Change (IPCC) a
laminar flow a flow of river that is a smooth horizontal
scientific intergovernmental body set up by the United Nations
in 1988; the IPCC produces reports to support the UNFCCC,
the main international treaty on climate change
motion; this pattern of flow is unusual because natural river
environments are characterised by complex conditions such as
gradients
international migration people moving from one country
to another; this happens for many reasons, for example for
landslide hazard analysis the analysis of all types of
increased employment opportunities or to escape conflict
landslides using computer mapping and Geographic
Information Systems; analysis of this type can provide
information to help prevent future landslides
Intertropical Convergence Zone (ITCZ)an area of low
atmospheric pressure and ascending air found near or at
the equator; global winds converge here and rise thanks to
convection from thermal heating
internal migration people relocating within a country, for
example for education or employment
Glossary
land use the function of an area of land. For example, the
land use in rural areas could be farming or forestry; and urban
land use could be housing or industry
latent heat the energy released when a material changes
state, for example ice melting or water boiling; latent heat
measures the change in internal energy that appears to be
hidden from a thermometer (the temperature reading does
not change)
lateral planation rivers swing from side to side eroding the
mesas flat-topped isolated hills in arid regions; mesas have
a protective cap of hard rock underlain by softer, more readily
eroded sedimentary rock
mass [migration] when large numbers of people, sometimes
whole communities, move as one to a new location. Can also
surface, causing lateral planation
apply to mass tourism, when large numbers of people go to
the same resort at the same time of year
Laws of Migration proposed by the German-English
metamorphic rocks rocks that have been changed by
cartographer Ernst Georg Ravenstein (1834-1913) in 1889, these
laws were a result of Ravenstein’s research into migration
patterns within the UK; these laws provide the foundation for
modern migration theory
intense heat or pressure, often accompanied by an increase in
hardness and resistance to erosion, for example shale can be
metamorphosed by pressure into slate and limestone can be
metamorphosed into marble
leaf drip water that travels through the plant canopy by
mid-latitude depressions weather systems that result from
running down and off leaves and twigs
frontal rain in mid-latitudes (warm air coming up from the
tropics meets cold air from the poles)
life expectancy the number of years a newborn infant would
live if prevailing patterns of mortality at the time of its birth
were to stay the same throughout its life
line haul costs the cost to a business of moving goods from
one place to another; costs that must be taken into account
include wages and fuel
lithosphere the hard and rigid outer surface-the crust and
Middle Income Countries (MICs) countries that have
a middle income according to the World Bank’s World
Development Indicators; there are currently 86 MICs,
accounting for just under half of the world’s population, and
they have a wide range of incomes - the highest MIC has an
income 10 times that of the lowest MIC
top of the mantle - of the solid Earth
migrant stream a pattern of migration established by a
group of people with common characteristics, for example
littoral cells another name for sediment cells
the same ethnic group or people from the same geographical
origin
long-wave radiation the infrared energy radiating from the
mountain building the building of mountains on continents
Earth to space
due to the interaction of tectonic plates, principally subduction
loss-sharing adjustments mechanisms designed to help
mudflow the name given to a type of mass movement of
cope with flooding, for example insurance against flooding,
grants to rebuild after flood damage, sharing of equipment
and technical assistance
downhill weathered rock material; this movement distorts and
shapes to the land over which it travels like a viscous liquid
and the rate of flow is influenced by gravity
Low Income Countries (LICs) countries that have a low
multiple nuclei theory (1945) this theory of urban structure
income according to the World Bank’s World Development
Indicators
challenged the idea that a city developed around a single
central nucleus (usually the CBD), rather than a number of
separate nuclei - these nuclei might be suburban village
centre/s or town centres that become enveloped as the town
spreads outwards
lunette the name of a small sand dune formed in the lee of a
deflation hollow
LWM the spring tide low water mark
N
M
maritime climate places where the land is affected by the
close proximity of an ocean, which lowers the temperature of
the area during the summer and keeps it warmer in winter
National Parks areas of scenic countryside protected by
law from uncontrolled development in order to conserve the
natural beauty of the landscape and to enable the public to
visit and enjoy the countryside for leisure and recreation
natural increase in a population is a rate calculated by
Marxist theory derived from the work of Karl Marx (1818-83),
with reference to the study of migration, argues that migration
is one of the results of capitalism
subtracting the death rate from the birth rate
nebkha the name given to a small sand dune in the shelter of
the lee of a bush
negative externalities costs that third parties have to bear
overland flow the movement of precipitation from high
when a product is made or consumed, for example building
a new road causes pollution that people other than the road
users have to experience
ground to lower ground over the surface
nehrungs sand spits that can be many kilometres in length
Newly Industrialised Countries (NICs) countries that
oxbow lake a crescent-shaped lake originating in a meander
that was abandoned when erosion breached the neck between
bends, allowing the stream to flow straight on, bypassing
the meander: the ends of the meander rapidly silt up and it
becomes separated from the river; also known as a cutoff
are developing their economies through rapid expansion of
secondary industries
oxidation the breakdown of rock by oxygen and water when
Next Eleven (N-n) Bangladesh, Egypt, Indonesia, Iran,
the rock is exposed to air. Iron-rich rocks will often obtain a
rusty-coloured weathered surface
Mexico, Nigeria, Pakistan, Turkey, the Philippines, South Korea
and Vietnam; countries that have good a chance of becoming,
along with the BRICS (Brazil, Russia, India, China and South
Africa), the world’s largest economies in the twenty-first
P
century
pastoral nomadism farmers who travel (usually on foot or
nomadic systems in agriculture, where farmers move to
different locations in search of the best climatic conditions for
by animal) to different locations in search of grazing land and
water for livestock
farming crops and grazing animals
peak flow the maximum river discharge for any given event
measured in cubic metres per second m3s x (cumecs)
o
pedimentation the name given to the parallel retreat over
time of a hillslope
ocean conveyor belt another name for thermohaline
circulation; this process begins in the polar regions with the
formation of ice-the surrounding water gets saltier because
the creation of the ice leaves salt behind, which increases the
seawater’s density, making it sink; surface water is then pulled
in to replace the sinking water, which in turns becomes colder
and saltier and also sinks, thereby initiating the currents deep
in the ocean that power the ocean conveyor belt
peeling another name for exfoliation
people trafficking the trade in people; people who are
trafficked are sold into sexual exploitation or forced labour
-this may or many not involve individuals being moved
across international borders - and the trade is dominated by
transnational criminal gangs
oceanic trenches deep-sea trenches that form long narrow
permeable something that can be penetrated by water
depressions in the surface of the seafloor along a tectonic
plate boundary; at between 6000-11 000 m, these are the
deepest parts of the ocean and often run parallel to island arcs
phreatic zone the part of an aquifer found just beneath the
water table (the uppermost layer) that is saturated with water;
open system a system that transfers energy and matter
across its boundaries to the surrounding area, for example a
drainage basin
the size of the zone can vary according to the season and the
weather conditions
phreatophytes plants that have root systems that delve deep
into the ground to draw water from the water table
Organisation for Economic Co-operation and
Development (OECD) founded in 1961, headquartered in
Paris, with 34 member countries, the OECD works to promote
policies that aim to improve the economic and social wellbeing
piedmont zone the zone at the foot of a mountain covered
in loose stones, rock, dust and sand and featuring playas, salt
lakes and inselbergs
of people all ever the world
orogenesis another name for mountain building; from the
Greek ‘oros’ for ‘mountain’ and ‘genesis’ for ‘creation’
pitting a type of salt weathering that creates cavities in a
rock surface that make the surface look aerated; also called
honeycomb weathering because it looks like honeycomb
candy
orographic the name given to precipitation (rain) that is the
result of air being forced upwards by a mountain - as the air
planar landslides happen when weathered rock becomes
cools to below the dew point water vapour condenses into
detached from the main body of rock along a plane or joint;
landslides of this type often feature a clean and straight break
water droplets
out-migration to leave an area and settle in a new location
within one’s own country
94 Glossary
playa the name given to a salt lake that has dried out
Pleistocene pluvials landlocked basins (called pluvials) that
date from the Pleistocene geological epoch, which ended
n 700 years ago; ‘Pleistocene’ was the name given to this
epoch by Charles Lyell (1797-1875) in 1839, which he created by
combining the Greek words for ‘most’ and ‘new’
Q
qualitative research primary exploratory research that looks
at trends, opinions and people’s thoughts on a particular
subject
pluvial a period marked by intense rainfall
quantitative research data that expresses an issue or
point bars another name for slip-off slopes
problem in numbers
polar high pressure system the area of high pressure
(descending air) found at or near the poles
R
positive externalities in economics, when the manufacture
or consumption of a product benefits a third party, for
example a company that invests in research and development
may produce technology that other businesses then adopt and
derive benefit from
radial the name given to a drainage pattern where water
drains away from a central high point, such as a hill or a
mountain, into separate channels
radiation fog forms when the ground has cooled due to
country than leaving
radiation from the ground, usually at night in an anticyclone
(high pressure-clear skies with little wind)
post-industrial cities cities that have gone through the
rain shadow the relatively dry area on the leeward side of
process of deindustrialisation, for example Detroit, USA
high ground in the path of rain-bearing winds
practical salinity units (psu) the measure of salt
concentration in seawater; the highest concentrations of
salinity are usually found in the centre of the ocean
recession another name for falling limb
positive net migration balance more people entering a
precipitation (ppt) water deposited on the Earth’s surface in
various forms, for example rain, snow, sleet, hail and dew
regolith the layer of loose broken rock, soil and other
materials that covers solid rock; from ‘rhegos’, the Greek word
for ‘blanket’ and ‘lithos’, the Greek word for ‘rock’
relative humidity (RH) the amount of water vapour in the
reason, for example the results of an experiment
air expressed as a percentage of the amount that would be
present if the air was saturated
primitive [migration] the migration of nomadic peoples due
to seasonal or climatic factors, for example nomadic shifting
cultivators in Africa
rectangular drainage the name given to a drainage pattern
where a river or stream follows geological weaknesses and
gaps in block-like bedrock
Principles of Migration by Everett Lee (1966) examines
repeat migration another name for circular migration
primary data data that is collected first-hand for a specific
internal ‘push’factors, which are negative aspects of the place
someone lives in, and ‘pull’ factors, which are positive aspects
of a different geographical location that ‘pulls’ people
towards it
Rev. Thomas Malthus (1799-1834) an English cleric active
in the study of poulation and political economy; his most
influential work was An Essay on the Principle of Population
(1798)
process industries industries that process raw materials into
other products
pro-poor tourism tourism that provides net benefits for
poor people thanks to the support of their local economy
proximal another name for updrift
resource curse theory where countries with valuable natural
resources do not prosper economically because they fail to
invest in other areas of the economy
rias submerged river valleys caused by a rise in sea level or
subsidence of the land relative to the sea
pseudo bedding planes as the ‘pseudo’ in the name
rising limb on a hydrograph, the part of the graph that
suggests, these are structures in igneous rock that look like
bedding planes (dividing lines between layers, called beds,
of sedimentary rock) but are not bedding planes; caused by
expansion of the rock on pressure release due to erosion of
the surface rock
initially rises, indicating the increasing level of water
as determined by the combined rate of surface runoff,
throughflow, and groundwater flow following a precipitation
event
Glossary
river discharge the amount of mobile volume of water
seismometers instruments that measure movement in the
moving in a river
ground created by events such as earthquakes and volcanic
eruptions
river regime the annual variations in a river’s flow over the
period of a year; this will be influenced by many factors, for
example rainfall and temperature
semi-fixed dune sand dunes that are less bare, less mobile
and more fertile than embryo dunes but not as fixed or fertile
as a fixed dune, or grey dune
rockfalls sudden movements of rock from cliff faces caused
by gravity, chemical erosion, coastal action, earth movements,
weathering or freeze-thaw action
sensible heat this is the heat that we can feel; it can be
rotational slides a type of landslide that occurs on a curved
sensible heat transfer when air or water moves from one
failed surface, causing the upper surface to tilt back; also
known as slumping
place to another, taking its temperature with it
measured by a thermometer (unlike latent heat)
sharecropping a type of land use where a tenant farmer
cultivates land owned by someone else; a percentage of the
crops grown on the land is then given to the landowner as
rent for the land
s
sabkhas a translation of the Arabic word ‘sabaka’ for ‘salt flat’,
shifting cultivation a type of land use characterised by
these are coastal salt flats subject to occasional flooding by the
sea
farming one area of land until it is no longer fertile, then
moving to a new area of land. Also known as swidden.
saltation in water, the transport of sediment by water along a
Shoreline Management Plans (SMPs) plans that assess the
riverbed; in wind erosion, particles bouncing along the surface
of the ground, dislodging other particles as they impact
risks to a coastline and then set out details of policies that can
manage these risks, for example erosion
Saskia Sassen (b. 1947)3 Dutch-American sociologist working
short-wave radiation the visible light and ultraviolet energy
in the fields of globalisation and human migration; Sassen
introduced the term ‘global city’ in her seminal work The
radiating from the Sun to Earth
Global City: New York, London, Tokyo (1991)
slab-pull mechanism the motion of a part of a tectonic
scarp the steep side of an inselberg
seasonal lag the delay between the hottest or coldest month
of the year (when the Sun is directly overhead or is lowest in
the sky) and the point at which it is experienced on Earth; the
delay is caused by the sea taking a long time to either heat up
or cool down
plate by subduction; this happens when the oldest edge of
a tectonic plate, furthest from the molten magma, becomes
cooler and more solid and sinks into the mantle; also known
as dragging theory
slide the name given to a type of mass movement of
downhill weathered rock material; this movement takes place
in a cohesive unit with minimal internal dislocation and
deformation
saturated when something holds as much water or moisture
as it is possible for it to absorb, it is saturated
slip-off slope in a river, a sloping bar located on the inside
secondary data data collected by someone else, for example
bank of a meander; created by the accumulation of sediment
on the inside of the meander bend, where discharge is at a
minimum and friction and deposition are at their greatest
the results of a survey
sediment cells there are 11 large sediment cells in England
and Wales and their areas are dependent on the shape of the
coastline; erosion, transportation and deposition take place
within sediment cells and they are closed systems, which
means that no sediment is transferred between cells
slope overloading when a slope becomes overloaded with
material such as mud, earth and rubbish, which increases the
pressure on the slope, causing it to fail
slope stability analysis the analysis of the safety of a slope,
for example a hillside, a railway embankment or a landfill site
sedimentary rocks rocks formed by the consolidation
of sediment derived from pre-existing rocks, for example
sandstone, chalk and limestone
seif dunes sand dunes that run in straightish ridges parallel
to the wind; they are caused by either of two main wind
directions or by helical-roll vortices
Glossary
smog an air pollutant which is a combination of fog and
smoke (from soot particulates released into the air by burning
coal or from other forms of pollution such as emissions from
cars) typically found in urban areas
soil creep a slow movement of soil that takes place on
very gentle slopes due to the way soil particles expand at
right angles in wet conditions and contract vertically in dry
conditions; the soil moves downslope at a very slow rate,
perhaps only i cm a year
subduction zone where the oceanic crust of a tectonic plate
is forced under the continental crust and sinks into the mantle
as the plates converge. Occurs where two oceanic plates
converge
sublimation the transition of a substance directly from a
solution in transport in river systems, the process by which
small dissolved sediments and minerals are transported within
a river; in erosion, another name for corrosion
solid to a gas without passing through the intermediate liquid
phase
specific heat capacity a measure of the thermal energy
(descending air) found 30° north and south of the equator
contained in an object or substance - this is not the same as
the temperature of an object or substance, which is a measure
of how hot it is; water has a high specific heat capacity so it is
good for storing heat energy, which is why central heating that
uses pipes filled with hot water works so well
current; it moves in a westerly direction at a height of between
10 and 15 km and follows the boundaries between hot and cold
air
spits low narrow banks of sand and shingle built out into an
estuary by the process of longshore drift
are pushed along the surface of the desert, causing erosion
standardisation to set a standard and then make everything
surface storage any part of a system where water lies above
meet that standard; this can apply to objects, for example,
nails manufactured to a certain length and width, and to many
aspects of culture, for example a word consistently spelled one
way within a language
ground on the Earth’s surface
star dunes sand dunes in the shape of a star
suspension in wind and water erosion, where the lightest
sand particles, dust and dirt (less than 0.1 mm in size) are
carried along by strong winds or water
sub-tropical high pressure belt the area of high pressure
stemflow water that runs down the trunk and branches of a
sub-tropical jet stream a high-speed (400 km/hr) narrow air
surface creep in wind erosion in deserts, where sand grains
suspended load in a river or stream, the portion of the
stream load carried suspended in the flowing water
tree into the ground
Sustainable Resource Management (SRM) management
step migration a series of migrations from a person’s place
of origin where each stage of migration is a shorter journey
than one long-distance migration; step migrations gradually
move towards the migrant’s initial goal destination or
sometimes migrants remain at a location on the way to their
original destination
of an environment that takes into account issues such as waste
disposal and the protection of natural resources
stone pavements the landscape formed when rainwater
causes chemical weathering of limestone, enlarging the
natural bedding planes and joints to form blocks
and are not significantly affected by local winds
swales long, narrow and shallow troughs between ridges on
beaches; swales run parallel to the coastline
swell the name given to waves that are generated by the wind
storm flow the additional discharge experienced by a river as
a result of a precipitation event
technology transfer initiatives the sharing of technical
structural engineering the design, construction and
implementation of man-made structures that aid the stability
of the landscape, for example the construction of retaining
walls on unstable slopes
knowledge and skills, particularly from HICs to MICs and LICs
temperate low pressure belt the area of low pressure
(rising air) found at or near the temperate (mild temperature)
zone
structuration theory is a social theory of migration
proposed by Anthony Giddens (b. 1938), a sociologist, that
looks at individual motives for migration and at the structural
and cultural factors and rules within which migrants have to
terminal costs another name for fixed costs
operate
rocks being added to land
terrestrial deposition the process of sediments, soil and
succulent when referring to plants, with thick fleshy leaves
terrestrial radiation short-wave radiation energy coming
or stems adapted to storing water in arid climates or soil
conditions
from the Sun heats the ground and is then reradiated as
infrared long-wave radiation
Glossary
thalweg in a stream channel, the line of deepest water-the
unit labour costs the amount of money a firm needs to pay
path of least resistance where water flows the fastest
its staff to make one unit of one thing; a low unit labour cost
means that it costs less to produce one unit of a product
thermohaline circulation seawater currents that reflect
variations in temperature and salt content
throughfall water that travels through the plant canopy by
running down and off leaves, twigs and stems
throughflow the name given to the process of water
United Nations Environment Programme (UNEP) an
agency of the United Nations, founded in 1972, concerned
with issues to do with the atmosphere, ecosystems, the
green economy and environmental governance; it promotes
environmental science and works with governments to
develop and implement environmental policy
flowing through the soil substrata; rates of throughflow vary
depending on the soil type
United Nations Framework Convention on Climate
Change (UNFCCC) is an international climate change
tombolo a spit which extends to join an island to the
treaty dating from 1992 that aims to stabilise greenhouse gas
concentrations in Earth’s atmosphere by bringing pressure on
the 165 signatory nations to reduce emissions
mainland
topset beds coarse material carried by a river into a delta; the
coarsest material is carried the shortest distance
traction the transport of large items such as stones and
boulders along a riverbed by the strong flow of moving water
unroofed upper layers of rock erode and allow lower layers of
rock to relax and crack - these lower layers are referred to as
unroofed
unsaturated something with remaining capacity to hold
trade blocs groups of countries that agree to trade with each
water
other and to exclude countries that they do not have trade
agreements with
updrift an area where coastal material, such as sand, is
deposited on a beach further along a coastline
trade winds surface winds in the tropics that blow from the
sub-tropical high pressure zone to the equator (ITCZ): trade
winds in the Northern hemisphere move from the northwest
to the southwest and are called the Northeast Trades; trade
winds in the Southern hemisphere flow from the southeast to
the northwest and are called the Southeast Trades
transform in plate tectonics, plates that move past each other
side by side, often causing earthquakes; the San Andreas fault
(USA) is a transform boundary
transpiration the loss of water from somata and pores of
vegetation into the atmosphere
trellised the name of a drainage pattern where streams follow
slopes downhill and converge along areas of eroded rock
triangular graphs these diagrams take the form of an
V
vegetation storage moisture stored by vegetation directly
through the root system
volcanoes fissures in the Earth’s crust through which magma
reaches the Earth’s surface: there are four main types of
volcano; acid lava cone - a very steep-sided cone composed
entirely of acidic, viscous lava which flows slowly and congeals
very quickly; composite volcano - a single cone comprising
alternate layers of ash (or other pyroclasts) and lava; fissure
volcano - a volcano that erupts along a linear fissure in the
crust, rather than from a single point; and shield volcano - a
volcano composed of very basic, non-viscous lava that flows
quickly and congeals slowly, producing a gently sloping cone
equilateral triangle and have three axes instead of two.
Sometimes known as ternary diagrams
turbulent flow a river flow characterised by a series of
erratic horizontal and vertical spiral flows, known as eddies,
influenced by factors such as the velocity of the water and the
friction it encounters; turbulent flow is the dominant method
w
warm currents an ocean current that carries water from the
equator polewards, taking warm water into colder seas
of flow in a river environment
water balance the balance between the input of precipitation
(rainfall) and losses due to evaporation and transpiration by
plants
u
watershed the boundary, often a ridge of high ground,
urban heat island the name given to the phenomenon of
urban areas being warmer than the rural areas that surround
them
Glossary
between two river basins
waves of oscillation inside the wave water molecules travel
in a circular to elliptical orbit and do not move with the wave
form; these are mainly deep sea waves
waves of translation inside the wave water molecules move
forward with the wave form then form on the shoreline, where
the waves break
wind-shadow dune the name given to a sand dune that
forms in the lee of a hill
World Health Organization (WHO) founded in 1946, this
is an agency of the United Nations tasked with improving
global public health; WHO played a central role in ridding the
world of smallpox and is currently focussed on tackling HIV/
AIDs, Ebola, malaria and tuberculosis
X
xerophytes plants that do not need a lot of water
Y
yardangs long, roughly parallel ridges of rock in arid and
semi-arid regions; the ridges are undercut by wind erosion
and the corridors between them are swept clear of sand by
the wind; the ridges are orientated in the direction of the
prevailing wind
yazoo tributary a tributary that runs parallel to a river
within the same valley (floodplain) for some distance before
eventually joining it; named for the Yazoo River, which runs
parallel to the Mississippi River (USA) for 280 km before
joining it
yellow dunes are found after embryo dunes appear on a
beach, yellow dunes develop behind them; their average depth
is 5 m and they are mostly sand, so are yellow in appearance
z
zeugen pedestal rocks in arid regions; wind erosion is
concentrated near the ground, where corrasion by wind-borne
sand is most active-this leads to undercutting and a pedestal
profile emerges
Glossary 399
Index
3
3D jobs 128
A
Aberfan 82
abortion 106, 107
abrasion 243
acculturation 329
accumulation 186-7,193
acid conditions 83-4,195
acid rain 70, 83-4
acidification 53, 70,199, 200
adaptation 251-2
ADF see African Development Fund
Advance Turbine Systems (ATS)
286-7
advection fog 52
aerial photographs 380
affluence 358
see also wealth
afforestation 30, 35
Africa
land competition 142-3
urbanization 139,142
African Development Fund (ADF) 319,
321
African Rift Valley 74
aftershocks 211
age structure 90, 91, 98-9
age/sex structure diagrams 95, 370
agglomeration, industrial 275
AGRA see Alliance for a Green
Revolution in Africa
Agricultural Revolution 97,100, 137
agriculture 105, 258-68, 279
arable farming 263
capital intensive farming 260
case study 263-4
commercial farming 261
and desertification 253,254, 266
and environmental degradation 297-8,
304-6
and environmental protection 302
extensive farming 262
factors affecting agricultural land use
258-61
and FairTrade 316
and global warming 54
and globalisation 297
and the 'Green Revolution’ 266-8
and groundwater withdrawal 31
400 Index
hyper-capital intensive systems
264-5
industrialisation 297
intensive farming 262, 264-5, 297
and international debt 318
and irrigation 31-2
and land tenure and land rights 261
livestock farming 263-4
and mechanisation 265, 298
mixed farming 263,264
pastoral systems 263-4
policies 134
and profit 261
and salinisation 265
slash-and-burn method 101,173
and soil erosion 265
subsistence farming 261, 342
and trade 313, 317
and water supplies 31, 260
agro-technology 260
agrochemicals 267, 298
aid
bilateral 322
development 322
food 102,105
humanitarian 322
impact 323
international 318-24
multilateral 323
Overseas Development Assistance
322, 323
relief (short-term) 322
tied 322, 323
air, saturated/unsaturated 48
air masses 48
air pollution 102,145-6,155, 252, 299
albedo 15, 57
algae 197,198, 200
Alliance for a Green Revolution in Africa
(AGRA) 268
alluvial fans 248
alluvium 19, 28, 245
Alonso 148
altitude 46
AMO see Atlantic Multidecadal
Oscillation
Amudar’ya River 32
anaerobes 197
Andes 65
animals 176, 252, 263-4
Anna Creek Station farm 263-4
Antarctic sea ice 38
antecedent conditions 18,19
anti-natalist policies 92
aquifers 13,104
Arabia 238-9
arable farming 263
Aral Sea 11, 32
Arctic 290-1
Arctic Ocean 8
Arctic sea ice 39
areas of assimilation 151
areas of discard 151
Areas of Outstanding National Beauty
123,133
Argentina 360
arid environments 160, 232-55
causes of aridity 235
defining aridity 234
difference from semi-arid areas 238
and high wind energy 238
landforms 242-50
and precipitation 236-7,238
and salinisation 253,265
soils 250-3
sustainable management 254—5
temperatures 237-8
vegetation 250-2
Aridity Index 232-3
Armero 217
arroyos 245
aspect 74-5
asthenosphere 63, 209
asylum seekers 125
Atacama desert 39,240
Atlantic Multidecadal Oscillation (AMO)
252
Atlantic Ocean 8
atmosphere 10, 38-59
diurnal energy budgets 40-1
human impacton 52-8
weather processes and phenomena
48-52
atmospheric counter-radiation 40
atmospheric disturbances
hazards resulting from 219-25
prediction, monitoring and risk
perception 224-5
atmospheric moisture 48
ATS see Advance Turbine Systems
attrition 23,190,191
Australia
cloud seeding 30
deserts 241
livestock rearing 263-4
migration 118
salinisation 265
savanna 175-7
urban trends 143-4
automotive industry 356
avalanches 79
B
‘baby booms’ 91, 94, 95, 97
backwash 182
bajadas 249
balance of trade 311
‘banana wars’ 315
Bangladesh
flooding 18, 34
manufacturing industry 278-81
bar graphs
age/sex structure 370
divided 370
barchans 244
barrier islands 191,192-3
bars 190,191, 192
bartering 310
base flow 14
base levels 11
batholiths 164
Beachell, Henry 103
beaches 185, 190-1
backshore zones 191
barrier islands 192-3
beach nourishment 202
beach reprofiling 202
drainage 202
foreshore zones 191
offshore zones 191
sand dunes 195
bed-lowering 36
bedload 21,185
Benioff zone (Wadati-Benioff zone) 66
berm 190,191
best-fit lines 371
Bhopal disaster 296
bias 381
bid rent theory 148-9
Bill and Melinda Gates Foundation 154
bioconstruction 196
biodiversity 166-7,173-5, 200, 294,
298-9, 327-8
biofuels 104, 289
biomass 169-70, 250, 251
bioreclamation 270
biosphere (living world) 10
bioturbation 30
birth rate 88-98,100-1, 107
blizzards 38
blockfields 68
bluffs 28
body waves 211
Bogota, Colombia 155
‘boom and bust’ 317
Borlaug, Norman 102-3, 267
bornhardts 164-5
Boscastle flood 2004 34
Boserup, Ester 100-1
bottomset beds 28
Boxing Day tsunami 2004 212
brackish water environments 197
braiding 28
Brandt Line 350, 354
Brandt Report 350
Brazil 103, 358
break-of-bulk points 272
breakers 181-2
plunging 181,182
spilling 181, 182
surging 181-2
breakwaters 202
Bretton Woods agreement 321
BRIC countries 358
Brunei 95
bunchings 370
Burgess 147
Burj Khalifa, Dubai 83
Burkina Faso 268-70
Butler Model 331-3
buttes 249
Byerlee 117
c
calicles 197
California 260, 273
call centres 354
Cambodia 302
cancer 267
canopy 167
canyons 245
CAP see Common Agricultural Policy
capillary migration 242
capital
financial 273
fixed 273
and industrial location 273
mobility 273
capital intensive farming 260
car ownership 141,152
carbon dioxide (CO2)
emissions 52-3, 282-3, 291
in seawater 199, 200
carbonation 70
carbonic acid 70, 199
carnivores 170
carrying capacity 100,102, 329-30
Caspian Sea 11
castle kopjes (tors) 164,165
catchment hydrology 18
cattle 263-4
caves 188
cavitation 23
CAZRI see Central Arid Zone Research
Institute
CBD see central business district;
Convention on Biological Diversity
Central Arid Zone Research Institute
(CAZRI) 254
Central Asian deserts 241
central business district (CBD) 147,149,
150, 151-2
cereal grains 256, 267
see also wheat
CFCs see chlorofluorocarbons
chain of production 340
primary stage 340
secondary stage 340
tertiary stage 340
Chances Peak, Montserrat 166-7
change 256-81
agricultural 258-70
manufacturing industry 278-81
plotting rates of 371
channel flow 14
channel modification 35
channel storage 13
channelisation 36
chelation 70
Chernobyl 295
Chesil Beach, Dorset 193
Chevron Texaco 174—5
Chicago 55-8,147
child labour 279
children
dependency ratio 94
‘insurance’ 91, 96, 97
Chile earthquake 2010 212
China 358
age/sex diagram 95
cloud seeding 30
energy requirements 291-5
one-child policy 106-7
pollution 145, 299
population 89-90, 95, 106-7
trade 351
urbanization 139
china clay see kaolin
chlorofluorocarbons (CFCs) 53
cholera 96, 98, 223
choropleth maps 375-6
cities
edge 141
first 137
global 146-7
and the Industrial Revolution 137-8
megacities 131,146-7
post-industrial 151
Index 401
world 130-1,146-7
CIVETS 358
Clark-Fisher Model 343
clay cliffs 190
clays 19, 69, 74,184, 250
cliffs
drainage 202
falls 184,190
profiling 187-90, 202
river 26
structure 187,188
toe protection 202
climate
and agriculture 259-60
continental 46
and industrial location 272-3, 273
maritime 46
and slope processes 75
tropical monsoon 156,158, 159, 162
tropical rainforest 156,158,161-2,
166-75
tropical savanna 156,158-9,162-3,
166-72, 175-7
urban heat islands 55-8
and weathering 71, 75
climate change
and coral reefs 199
and food production 104
and glacial retreat 218
and human impact 29
local 298, 299
monitoring 53
policies 53-4
and storms 18
see also global warming
climate-related disease 344
climatic climax 166
climatic evidence 63, 250
climatic hazards 219-25, 344
cloud seeding 30
clouds 30, 46, 51
Club of Rome, The (think tank) 100
coal 63, 82,102, 272, 284, 292, 294, 312
consumption trends 288
coastal defences 201
coastal environments 178-205
case studies 185, 186-7, 203-5
characteristics and formation of coastal
landforms 187-97
coastal processes 180-8
coral reefs 197-200
measuring coastlines 179
sustainable management 201-5
tide dominated 182
wave dominated 182
wind dominated 182
coastal erosion 184, 185-90,193
coastal platforms 190
coastal squeeze 185
Coastal Zone Management 201
Index
coffee, FairTrade 317
cold currents 46
colonialism 313,318-19, 361
Columbia River sediment cell 186-7
command economies 260, 275
commodification 329
commodities 317, 342
Common Agricultural Policy (CAP) 261,
315
communication problems 274
communication technology 352
Community Future’s Programme
(Canada) 135
commuting 145
competition, for land 142-3
concentric zone model 147
condensation 40, 48, 51, 52, 237
condensation level 48
condensation nuclei 51, 52, 58
consumers
primary/secondary 170
tertiary 170
consumption 358
container shipping 351
continental climates 46
continental crust 64, 208, 210
continental shelves 13
continentality 235
convection currents 209
Convention on Biological Diversity
(CBD) 199
coordination problems 274
coral polyps 197
coral reefs 197-200, 204
atoll 198
barrier 197,198
coral bleaching 198-9
fringing 198
global coral health reports 199-200
global limiting factors 197
and human impact 198-9
local limiting factors 198
origins 198
patch 198
sustainable management 200
and tourism 328
types 198
core 63, 64
core-periphery concept 119,122,148,
360-1
Coriolis Force (rotation of the Earth) 46,
62,182, 220-1, 238
corrasion 23
correlations 371
corrosion 23
cost-benefit model 117
costs
fixed/terminal 272
labour 273
line haul 272
transport 272
unit 273
Council for the Protection of Rural
England (CPRE) 135
counterurbanisation 119,122-4,141-2
cow pea 269
crime 329
crocodile 176
crop rotation 264-5
crops
genetically modified (GM) 103
herb 264-5
indigenous 270
maize 264
potato 264
crust 63, 65, 208-10
continental 64, 208, 210
Cud Lie Mnong Fairtrade Agriculture
Cooperative 317
cultivation, shifting/swidden 261
cultural clashes 329
cultural globalisation 353
cultural loss 295
culverts 37
cumulative causation 361
currency 320-1
currents, ocean 46,199, 200, 235
cuspate forelands 193
customary tenure 142
cutoffs (oxbow lakes) 27
D
Daly’s Glacial Control theory 198
dams 31, 32, 294-5,318
Darfield earthquake, New Zealand 211
Darfur 302-7
Darwin, Charles 198
Darwin, Australia 162
data types 380-4
primary data 380
secondary data 380
daytime energy budgets 40
death, and migration 114—15
death rate 88-90, 95-9,106
and age structure 90
and economic development 90
and gender 90
and medical services 90, 97, 98
and nutrition 90
and urbanisation 90
and wars 90
debris avalanches 79
debt
international 318-24
odious 320
sovereign 318
debt cancellation 320, 321
debt crisis 321
debt relief 321
debt restructuring 319
decentralisation 134
decomposers 167,170
deepwater drilling 287
Deepwater Horizon oil spill 291
deflation 243
deflation hollows 243, 246
deforestation 80, 174
and desertification 253
and environmental degradation
297-8
and erosion 265
and flooding 20
and global warming 53
and hydrology 30
and slope stability 230
and tourism 327
deglomeration 275
deindustrialisation 151, 290, 296, 353,
358
deltas 28-9
arcuate 29
bird’s foot 29
cuspate 29
demographic transition 96-9
demography 96
Department for International
Development (DFID) 154
dependency ratio 94
dependency theory 361
deposition 24-6, 28, 243, 294
depositional coastlines 190-3,196
drift-aligned 190
swash-aligned 190
depositional features, localised 191-3
desertification 251, 252-4, 266, 298
deserts 235-55
landforms 242-50
soils 250-3
the world’s main 238-41
desire lines 377
developed markets 279
development
sustainable 322, 365
see also economic development;
national development; regional
development
dew 12, 52, 237
dew point 48
DFID see Department for International
Development
Diani Beach, Kenya 203
discharge relationships (within drainage
basin systems) 15-20
and antecedent conditions 19
and catchment hydrology 18
discharge variations 15
and drainage basin morphology 18
and drainage density 19
and infiltration rate 18
and land use 19
and parent material 19
and precipitation types 18
and relief 18-19
and rick types 19
and river discharge 15-16
and soil type, structure and density
19
and storm hydrographs 16-18
and storm surges 20
and tides 20
and urbanisation 19
and vegetation 20
diseases
climate-related 344
degenerative 90
infectious 90, 96, 97, 98
water-borne 222, 223, 296
diseconomies of scale 275
disintegration (rock)
block 69, 242
granular 69, 242
dispersion graphs 372
displaced persons 304-7
dissolved load 23
distal end 191
diurnal energy budgets 40-1
diurnal range 40-1
divided circles (pie graphs) 372
Doha Amendment 54
‘doldrums, the’ 159
Dominican Republic 328
dot maps 379-80
downdrift 183
dragging theory 64
drainage basin systems 8,10-15
dendritic 11
discharge relationships within 15-20
drainage patterns 11
endorheic 8,11, 242
and flooding 34
inputs 12
morphology and discharge 18
as open systems 11
outputs 14-15
radial 11
rectangular 11
storage 12-13
transfers 14
trellised 11
drainage density 19
drainage patterns 11
drilling, deepwater 287
drought 251, 252-3, 264, 268, 270
dumping 82
dunes 190
Dungeness, Kent 193
duricrusts 251
dust 32, 58
dust devils 238
dynamic equilibrium 186
E
Earth
formation 62
structure of the 63-4
earthflows 77
earthquake zones, sustainable
management 225, 227
earthquakes 65, 66, 208-12, 214, 216
hazard mapping 214-15
human impact 214
monitoring 214-15
prediction 214-15
and Three Gorges Dam 294-5
Earth’s axis, tilt 45, 54
East Timor 204-5
economic activity
and agricultural land use 260
globalisation 351-8
economic development
and birth rates 91
and death rates 90
disparity in 358-67
and fertility 91
and pollution 296
and populations 90, 91, 98
and regional development
management 362-7
and urbanisation 138,147
economic transition 338-67
case studies 362-7
globalisation of economic activity
351-8
national development 340-50
regional development 358-62
economic wellbeing, global inequality
in 344
economies 278
command 260, 275
knowledge 340
rural 133
transitional 357
economies of scale 260, 262, 275
administrative 274
external 274
financial 274
internal 274
purchasing 274
risk bearing 274
technical 274
ecosystems
coral reefs 197-200
humid tropical rainforest 166-75
humid tropical savanna 166-72,175-7
and tourism 327-8, 337
ecotourism 205, 333-7
Index 403
Ecuador 334-7
edge cities 141
education 91-2, 97, 347, 366-7
Ehrlich, Paul R. 100
elderly people 94, 97
electricity 139, 291-2
see also hydroelectric power
elites 318
emergent layer 167
emerging markets 279, 357
emigrants 110
emigration 110
mass 98
employment
categories/sectors 340
changing structures 343
formal sector 276-7
informal sector 276-7, 342
primary sector 340, 341, 342, 343
quaternary sector 340, 341, 343
secondary/ sector 340, 342, 343
structural variations in 341-2
tertiary sector 340, 341, 342, 343
in urban Africa 139
see also underemployment;
unemployment
endoreic dra nage basins 8,11, 242
energy
balance between sources 286-7
consumption trends 287-90
daytime energy budgets 40
diurnal energy budgets 40-1
environmental impact of energy
production, transport and use 290-1
global energy budgets 41
and industrial location 272
management of energy supply 291-5
national factors affecting demand for
284-6
night-time energy budgets 40
non-renewable resources 284-6
see also sustainable/renewable energy
supplies
energy flows 169-70
energy generation 33
energy mix 284, 291
engineering
hard 35, 84, 85, 201-2
soft 35, 84-5, 201-2
England
demographic transition 96-8
migration 122^f
settlement dynamics 135
entrepreneurship 277, 335-6
environment
and energy production, transport and
use 287, 290-1
and fossil fuels 290-1
Environment Agency 34, 35
Catchment Abstraction Management
>13 Index
Strategy 31
environmental degradation 295-302
and bioreclamation of degraded
lands 270
constraints on combating 300
management 302-7
measures of 301
needs 301
outcomes 301
and pollution 295-6
protection of environments at risk
301-2
rural 297-8
and tourism 326-8
urban 298-9
and water quality 296-7
environmental deterioration 102
environmental management 282-307
and energy supplies 284-95
and environmental degradation
295-307
environments at risk, protection 301-2
ephemeral plants 251
epidemiological transition 90
epiphytes 167
EPZs see export processing zones
equal rights 280
equator 45
Equatorial low pressure belt 42
equifinality 249
ergs 244
erosion
coastal 184,185-90, 193
desert 243, 244-5,248,255
peat 84
and pressure release weathering 69
river 21, 23-6, 294
soil 251
wind 243
estuaries, deep 27
etchplanation 165
ethnic minorities 153
European Economic Community 313
European Union (EU) 312, 313, 315,
363
evaporation
and arid environments 236, 248
and drainage basin systems 12,
14-15
energy requirements 40
influences on 14—15, 31
evapotranspiration 12, 15,172
event modifications 34-5
excavation 81, 83
exfoliation 69,163, 164, 242
exploitation 173-4, 285-7, 355, 361
export processing zones (EPZs) 276
exports 308-12, 313, 363
visible and invisible 310-11
extensive farming 262
extraction 81
Eyjafjallajokull 214
F
FairTrade 316-17
Fairtrade Foundation 316, 317
falls 215
family life cycle 153
famine 102
FAO see Food and Agriculture
Organization
farmland 100,101,104, 124
farms 259-60
see also agriculture
favelas (slums) 81,150
FDI see foreign direct investment
feldspar 72, 81,163,164
‘Fengcong’ 165
‘Fenglin’ 165
Ferrel Cell 42, 235
fertiliser 103, 298
microdosing 268-70
fertility rate 89, 91-3, 105,136
fetch 181
Fiji 121-2
filtering 145
financial crises 319
flexible working practices 141, 145
flocculation 28, 185,196
flood hazard mapping 37
flood protection 34-7
flood storage areas 36
flooding 18,216-17, 294
amelioration 34-7
case study 35-7
causes of 34, 36
coastal 222, 223,230
and deforestation 20
flash floods 236, 244
prediction 34
prevention 34-7
recurrence intervals 34
risk of 16
river 35, 222
and storm surges 183, 222
and urbanisation 30
floodplains 19, 21, 28, 34
see also river terraces
flow 76, 77-8,215
flow-line maps 376-7
fluvial geomorphology 10-37
drainage basin systems 8, 10-20
and human impact 29-37
river channel processes and
landforms 20-9
focus groups 384
fog 38, 40, 52, 236
advection fog 52
frontal fog 52
hill fog 52
radiation fog 52
fold mountains 67
Food and Agriculture Organization
(FAO) 102,103
food aid 102,105
food insecurity 268
food production 99-100,102-5,
258-68
case study 105
emerging producers 103
high income importers 104
limits to 104
low income importers 104
self-sufficiency 103
and technology 102-3,104
traditional producers 103
food shortages 100
footloose industries 272
Ford, Henry 271
foreign direct investment (FDI) 312-13,
353,355,357,360
backward 353
in Bangladesh 278
conglomerate 353
forward 353
greenfield entry 353
horizontal 353
and Newly Industrialised Countries
341-2
takeover entry 353
vertical 353
forelands 191
foreset beds 28
fossil fuels 284, 285, 291^1
burning of 52-3, 54—5,102, 290-1
consumption trends 287-90
environmental impact of 290-1
and fertiliser 103
mining 81, 82
see also coal; gas; oil
fossils 62, 250
‘fracking’ (hydraulic fracturing) 287
framing 53
France
agriculture 259
river discharge 15
free trade 311-12, 315, 363
freeze-thaw (frost shattering) weathering
68, 76, 242
friction 210
frontal fog 52
Frontier Five 278-9
frontier markets 279
fronts 48
fuel
nuclear 284
renewable 104
see also fossil fuels
fulls 191
G
G8 Gleneagles Summit 321
gabions 202
Galapagos Islands 334-7
Gansu Wind Farm Project 293
gas 284, 312
consumption trends 288
deepwater drilling 287
undiscovered 291
GATT see General Agreement on Tariffs
and Trade
GDP see Gross Domestic Product
gender
and death rate 90
and migration 118
General Agreement on Tariffs and Trade
(GATT) 313, 315
general principal theories of
geographical mobility 115-18
genetically modified (GM) crops 103
Geographical Information System (GIS)
84, 373
geographical skills 368-84
aerial photographs 380
data types 380-4
diagrams 370-2
graphs 370-2
maps 373-80
satellite images 380
geology
and plate tectonics 62
and slope processes 74
and weathering 72-3
see also lithosphere; rocks
geos 188
geostationary satellites 224
geotextiles 202
geothermal energy 214
Gersmehl diagram 169
ghettoes 147
Gini coefficient 358
GIS see Geographical Information
System
glaciers 63,198
glacial retreat 218
Global Assessment of Human-induced
Soil Degradation (GLASOD) 266
global energy budget 41
global interdependence 308-37
international tourism 324-37
trade flows and trade patterns
310-24
Global Positioning System (GPS)
373
global shifts 313, 341, 358
global temperature 45-8
‘global village’ 138
global warming 52^4, 290
globalisation
and agriculture 297
cultural 353
definition 351
and the division of labour 354
of economic activity 351-8
and employment 343
and immigration 352
political 353
and trade 351
and transportation 352
and urbanisation 138-9
Glossopteris (fern) 62
GM (genetically modified) crops 103
GNI see Gross National Income
GNP see Gross National Product
Goldman Sachs 358
golf courses 327
Gondwanaland 62
Google Earth™ 380
governance, good 323
government policy 275
goz (sandstone hills) 302
GPS see Global Positioning System
gradients, river 20
granite 72, 81,163,164
graphs 370-2
bar graphs 370
dispersion graphs 372
line graphs 370, 371
logarithmic graphs 370-1
pie graphs (divided circles) 372
scatter graphs 371
triangular graphs 372
grasses 169, 254
Gravitational model (intervening
opportunity model) 116
Great Barrier Reef 197,198
Great Leap Forward 95
Greater Noida 143
green belt 134
‘Green Revolution’ 102-3, 266-8, 268,
297
greenfield entry 353
greenfield sites 133, 142,151, 273
greenhouse effect 52-4
greenhouse gases 52-4,199, 294
Gross Domestic Product (GDP) 325, 338,
344, 358, 363, 365, 367
Gross National Income (GNI) 323, 328,
335, 344-6, 354-5
Gross National Product (GNP) 344
groundwater 104
flow 14
and human activity 31, 33, 307
recharge 13
storage 13
withdrawal 31, 33
Index 405
groynes 187, 202
Grupo Punta cana resort, Dominican
Republic 328
Gunwarf Keys, Portsmouth 151
gypsum 70
H
Hadley Cells 42,158,160, 219, 235
haffs 192
hail 51-2
halophytes 195, 251
‘hanging coffins’ 295
Harbin explosion 296
Harbourne River 35-7
Harbury cutting, UK 216
Harris 149
Hawaiian hotspot 208-9
Hawaiian Islands 211
hazardous environments 206-31
case studies 227-31
defining hazards 208
hazards resulting from atmospheric
disturbances 219-25, 344
hazards resulting from mass
movement 206-7, 215-19
hazards resulting from tectonic
processes 208-15
primary hazards 211, 213-14, 221-2,
223
secondary hazards 211-12, 213, 214,
222,223
sustainable management 225-31
HDI see Human Development Index
headland erosion 188
health 96
see also medicine
heat transfer 41
heatwaves 38
heave 76
Heavily Indebted Poor Countries
(HIPCs) 319, 321
HEP see hydroelectric power
herb crops 264-5
Hess, Harry 63
High Income Countries (HICs)
agriculture 260, 262, 263
aid 322
cereal consumption 256
deindustrialisation 358
division of labour 354
employment structures 341
energy consumption 290
global warming 54
international debt 318, 319
Iabour273
migration 119,122, 124
settlement dynamics 132,141, 151
tourism 326, 328, 330,333,334
trade flows and trade patterns 310,
311,315
high pressure 42,160,161
and aridity 235, 237-9, 241
high water mark (HWM) 190,191
high-tech industry 133
high-yielding varieties (HYVs) 102-3,
104, 267-8
Highly Skilled Migrant Programme 128
hill fog 52
Hilmarton 135
Himalayan mountain range 65, 67, 68,
208, 241
HIPCs see Heavily Indebted Poor
Countries
HIV/AIDS 136
Hjulstrom’s Curve 24
holistic approach 201
honeycomb weathering 68
hotspots 64, 211
housing 147-53
filtering 145
residential segregation 153
residential zones 147
Hoyt’s sector theory 149
HPI see Human Poverty Index
HR see hydraulic radius
HSBC 358
Human Development Index (HDI) 86-7,
136, 268, 347-9, 350, 366
human factors, and industrial location
271
human impact
on the atmosphere 52-8
on coral reefs 198-9
on desertification 253
on earthquakes 209
on flooding 34-7
on groundwater supplies 31, 33
on hydrology 29-37
on land use change 30
on mass movement 217
on plagioclimax 166
on precipitation 30
on slope processes 79-85
on the weather 52-8
human lives
and atmospheric disturbances 221-2,
223-4
and mass movement hazards
216-18, 230-1
and relocation 295
and tectonic hazards 214, 227-30
and tourism 329
Human Poverty Index (HPI) 349-50
humidity 48
absolute 48
in arid environments 236
relative 48,162
of tropical climates 161,162
of urban heat islands 58
humus 250
hunter-gatherers 137
Hurricane Katrina 183,193, 222, 225
Hurricane Sandy 223-4
hurricanes 223-5
distribution 219
formation 220-1
hazards caused by 221-2
prediction 224-5
HWM see high water mark
hydration 70, 242
hydraulic action 23
hydraulic fracturing ('fracking’) 287
hydraulic radius (HR) 22
hydroelectric power (HEP)
Chinese use 293, 294-5
consumption trends 288-9
limitations 285, 286
hydrographs 19
base flow/groundwater flow 18
falling limb/recession 18
lag time 18
peak flow 18
rising limb 18
storm 16-18
storm flow 18
hydrological cycle 10, 29, 170
hydrology 10-37
catchment hydrology 18
drainage basin systems 8,10-20
and human impact 29-37
river channel processes and
landforms 20-9
hydrolysis 69-70,72, 163,164
hydro power 33
hygiene 96
hygroscopic nuclei 30
hyper-capital intensive systems 264-5
HYV see high-yielding varieties
IAEA see International Atomic Energy
Agency
ice 18, 38
ice sheets 52, 63
Ice Valley, Andes 31
ICT (Information, Communication and
Technology) 280, 343
IDPs see Internally Displaced Persons
igneous rocks 19, 72, 164
11 ASA see International Institute for
Applied Systems Analysis
ILO see International Labour
Organization
IMF see International Monetary Fund
immigrants 110,147
immigration 91, 97,110, 352
imperialism 361
impermeable rock 14,19
impermeable surfaces 83, 236, 245, 250,
255
imports 308-13
and free trade 312
and mercantilism 311
and protectionism 313
visible and invisible 310-11
income, disposable 326
India 358
agriculture 267
deserts 238-9
monsoon 160-1
Partition 278
sustainable management of arid
environments 254
urban renewal 143
Indian Ocean 8
indigenous crops 270
Indonesia 145
industrial development 298-9
industrial estates 276
industrial growth 358
industrial inertia 272
industrial location 271-3
Industrial Revolution 52, 53, 97,100,
137-8, 150, 272
industrial usage 33
industrialisation 285, 296, 357
see also deindustrialisation
industry
high-tech 133
see also manufacturing industry
inequality 344, 358-674
infant mortality rate 89, 96
infanticide 107
infiltration 18, 30
infiltration capacity 18
infiltration rate 18
inflation 319
Information, Communication and
Technology (ICT) industry 280, 343
information technology 141,145
infrared radiation 380
infrastructure, inadequate 298-9, 357
inner city areas 122-3
inselbergs 164,165, 249, 250
insurance 34
intensive farming 262, 264-5, 297
inter-cropping 254
interception 12, 20, 30
interception loss 12
interest rates 319
Intergovernmental Panel on Climate
Change (IPCC) 53, 54
interlocking spurs 25
Internally Displaced Persons (IDPs)
304-7
international aid 318-24
International Atomic Energy Agency
(IAEA) 285
international debt 318-24
International Institute for Applied
Systems Analysis (IIASA) 100
International Labour Organization (ILO)
276-7
International Monetary Fund (IMF) 174,
278,319, 321,361
origins 321
International Organization for
Migration (IOM) 114, 352
international tourism 324-37
international trade 310-24
International Union for Conservation of
Nature (IUCN) 301
Intertropical Convergence Zone (ITCZ)
42,158,159-61,219,235,237
intervening obstacles 116
intervening opportunity model see
Gravitational model
interviews 384
inventory credit 270
Inverse Distance Law 116
investment see foreign direct
investment
IOM see International Organization for
Migration
Ipad Mini Index 344
IPCC see Intergovernmental Panel on
Climate Change
irrigation 31-2,104,105, 253, 260, 265
low pressure drip 269
Isles Dernieres, Mississippi deltas 193
isoline maps 378-9
Italy 218-19
ITCZ see Intertropical Convergence
Zone
IUCN see International Union for
Conservation of Nature
J
Jakarta 145
Japan 65, 95, 227
jarrah tree 176
JEM see Justice and Equality Movement
jetties 186
Jiabao, Wen 293
jo-jo tanks 31
jobs, 3D 128
Justice and Equality Movement (JEM)
304
K
kangaroo paw 176
kaolin (china clay) 70, 81,163
karst 165
cockpit 165
cone 165
tower 165
Kazakhstan 32
Kedarnath, India 216
Keynes,John Maynard 321
Kiunga-Aiambak road project 174
knowledge economy 340
Köppen climate classification 156,158
Kutubu Petroleum Development Project
174-5
Kuznets curve 296
Kyoto Protocol 53-4, 285
L
labour
child 279
exploitation 355
and industrial location 273
New International Division of Labour
353-4
quality 273
unit labour costs 273
lagoons (sounds) 191
lahars (mudflows) 77-8, 82, 211-12,
214,217
land
competition for 142-3
and industrial location 272-3
overuse 80-1
land clearance 80-1,177
land degradation 80
bioreclamation of degraded lands
270
constraints on combating 300
rural 297-8
and tourism 32708
urban 298-9
land rights 261
land tenure 261
land use 19, 30
landforms
arid/semi-arid environments 242-50
coastal 187-97
river 20-9
and slope processes 76
tropical environments 162-5
landlocked countries 344
landslides 211-12, 216-19, 230-1
landslide hazard analysis 84
Langmeads Farms, West Sussex 264-5
latent heat 40
lateral planation 248
laterites 163
Latin America, city models 150
latitude 45
latosols 171-2
Index 407
Laurasia 62
lava 209,210,212-13,214
Laws of Migration 115
leaf drip 12
leakage 330
Lee 116-17
lending, mismanaged 320-1
Lesotho 142-3
lettuce 264
levees 28
LICs see Low Income Countries
life expectancy 89-90, 94,106, 347-9,
367
lifestyles 326
lightning 38
limestone 72,165
line graphs 370, 371
Linfen 145
liquefaction 211-12
lithology 74, 185,187-8
lithosphere (geological world) 10, 63-4
littoral cells (sediment cells) 185-7
livestock farming 263-4
load
deposition 28
dissolved 23
suspended 21, 23, 185
location 256-81
locational advantage 312
logarithmic graphs 370-1
bunchings 370
cycles 370-1
log-log graphs 370
semi-log graphs 370
logging 174,175, 298
Loma Prieta earthquake 211
long-wave radiation 40, 52
longshore drift 183,186-7, 191,193
Lorenz curve 358
Los Angeles 140-1
loss-sharing adjustments 34
Love and Rayleigh waves 211
Low Income Countries (LICs)
agriculture 261, 263, 297-8
birth rate 91
cereal consumption 256
debt 318-19, 321
development 344, 350
division of labour 354
earthquakes 225
employment structures 342, 343
energy consumption 287, 289
environmental degradation 297-8
global warming 54
industrial growth 358
inequality 344
labour 273
mangroves 197
migration 119,125
non-governmental organisations 324
>1-1 Index
pollution 296, 300
populations 91, 97-8
settlement dynamics 132,138,139,
146,150,151
tourism 328,329,330
trade 315
trade flows and trade patterns 310,
312,315,316
urbanisation 138,139,146, 299
volcanoes 214
low pressure 42,161
low water mark (LWM) 190
lunettes 244
Lystrosaurus 62
M
Mabogunje 117
macronutrients 169
macrotidal coasts 193
magma 64, 65, 209,210,215
Maisin people 173—4
maize crop 264
Majorca 332-3
malaria 98
Malawi 136-7,153-4
Malawi City Development Strategy and
Slum Upgrading Programme (CDS/
SUP) 153
Malaysia 230-1
Mali 268-70
Malthus, Rev. Thomas 99-100,102
mangroves 197, 203
Mann 149
mantle 63, 64, 66, 209, 211
manufactured produce 310, 313
manufacturing industry 150-1, 271-7,
341-3, 358, 363
and agglomeration 275
case studies 278-81
change management in 278-81
and diseconomies of scale 274
and economies of scale 274
and export processing zones 276
and flexible industry 271
and Fordist industry 271
and formal/informal sectors Tltr-J
global shifts in 313
and government policy 275
and industrial estates 276
and industrial location 271-3
and linkages 275-6
and pollution 296
maps 373-80
choropleth maps 375-6
dot maps 379-80
flow-line maps 376-7
Geographical Information Systems
373
Global Positioning Systems 373
isoline maps 378-9
proportional symbols 374-5
ray diagrams 377
maritime climates 46
market gardening 264-5
markets 272
Marrah Mountains 302
marriage 92
marsh creation 202
marsupials 176
Marxist theory 117-18
Maseru 142-3
mass movement 76-9
definition 215
flow 76, 77-8
hazards resulting from 206-7,
215-19
heave 76
monitoring 218-19
prediction hazard mapping for
218-19
rapid movements 78-9
risk perception 218-19
slide 76
slow movements 76-8
sudden movements 79
sustainable management 230-1
Mattel 355
MDRI see Multilateral Debt Relief
Initiative
meanders 25-8
entrenched 28
form 25,26-7
incised 28
over time 27
mechanisation 265, 298, 341
media 326
medical services 90, 97, 98
medicine, see also health
Mediterranean, migration routes
114-15
megacities 131, 146-7
Melbourne Docklands 143-4
meltwater 34
mercantilism 311
mergers and acquisitions 353
mesas 249
mesocyclones 221
mesotidal coasts 193
Met Office 34
metamorphic rocks 19, 72
methane 53
Mexico City 146
Miami, Florida 162
micro-regions 135
microdosing 268-70
micronutrients 169
microtidal coasts 193
Mid-Atlantic Ridge 65
mid-latitude depressions 49
Middle Income Countries (MICs)
agriculture 262
cereal consumption 256
cities 146, 150
deindustrialisation 358
division of labour 354
energy consumption 287, 289
floodplains 34
global warming 54
industry 280
inequality 358
tourism 326
urbanisation 299
migrant counter-stream 110,119
migrant populations 108
migrant stream 110
migrants 91,124
contributions of 128
working 94
migration 108-29
barriers/obstacles to 118
case studies 111-12,114-15,121-2
causes of 112,113,119-20
chain 110
circular 110
as component of population change
110-18
conservative 113
definition 110
forced 113,125
free 113,114
and the general principal theories of
geographical mobility 115-18
Gravitational model 116
impelled 113
in-migration 110
innovative 113
internal 110,118,119-24
international 110, 116,118,124-9
intra-urban 122
mass 113,114
negative net migration balance 110
out-migration 110,112,117
permitting factors 112
positive net migration balance 110
primitive 113
pull factors 112,116-17
push factors 112,116-17
repeat 110
retirement 134,142
rural-urban 117-18, 119,121-2,143
step 110,122
types of 110,113-14
urban-rural migration 119,133-4,
141-2
urban-urban migration 119,122
voluntary 113, 124
Millennium Development Goals 297,
319, 322
Millennium Villages Project (MVP)
136-7
millet 269
Mimosa pigra (mimosa) 176-7
mining 33,81-2, 318, 342
MINTS 358
mixed farming 263, 264
mobile phone services 139
Mohorovifid Discontinuity (Moho) 64
Mojave Desert 254-5
monsoon 42, 160-1
dry season 160
rainfall 18
wet season 160
Montserrat 228-30
Morgan Stanley Capital Investment
(MSCI), Emerging Markets Index 357
Morocco 362-7
mortality 90
motivation 274
mountain building 67, 68
Mtandire 153-4
mudflats 196
mudflat recharge 202
mudflows (lahars) 77-8, 82, 211-12,
214,217
Multilateral Debt Relief Initiative (MDRI)
319
multiple nuclei theory 149
multiplier effect 330, 361, 364
Murray 198
MVP see Millennium Villages Project
Mwandama 136-7
N
Namib 239
National Centre for Atmospheric
Research (NCAR) 30
national development 340-50
chain of production 340
changing employment structures
343
development gap 350
employment categories/sectors 340
employment structure variations
341-2
and global inequality 344
measurement 344-50
stages of development 350
National Energy Council (NEC) 293
National Food and Security Strategy
(NFSS)105
National Hurricane Centre (NHC) 224
National Parks 123,133, 301-2, 334,
335
National Severe Storms Laboratory
(NSSL)225
Native American Indians 255
natural disasters
classification 206-7
see also hazardous environments
Nazca plate 65
NCAR see National Centre for
Atmospheric Research
nebkhas 244
NEC see National Energy Council
negative externalities 274
nehrungs 192
neo-Malthusians 100
Neolithic revolution 137
NERICA see New Rice for Africa
‘nesses’ 193
Net Primary Productivity 167
Nevada Desert 33
Nevado del Ruiz, Colombia 77-8,
217-18
New Delhi 143
New International Division of Labour
(NIDL) 353—4
New Orleans 183, 222, 225
New Rice for Africa (NERICA) 268
Newly Industrialised Countries (NICs)
312,313
characteristics 357
division of labour 354
employment structures 341-2
factors in the emergence and growth
of 357
industrial growth 358
newspapers 381
Next Eleven 278
NFSS see National Food and Security
Strategy
NGOs see non-governmental
organisations
NHC see National Hurricane Centre
Niagara falls 25
NICs see Newly Industrialised
Countries
NIDL see New International Division of
Labour
Niger 268
Nigeria 298, 299
night-time energy budgets 40
nitrogen oxide 83
nitrous oxides 53
nocturnal animals 252
nomads 253, 262
non-governmental organisations
(NGOs) 323-4
North Pole 45
Northeast Greenland National Park
301-2
NSSL see National Severe Storms
Laboratory
nuclear disasters 295
nuclear power 284, 285, 287, 288
nutrient cycling 169-70, 251
Index 409
nutrient leaching 169-70,172
nutrition 90
see also undernourishment
Nyiragongo 214
o
ocean acidification 199, 200
ocean conveyor belt 41
ocean currents 46, 199, 200, 235
ocean trenches 66
ODA see Overseas Development
Assistance
OECD countries 134, 359
oil 105,284,312
consumption trends 288
deepwater drilling 287
spills 291
undiscovered 290-1
oil crisis 1973-4 319, 320-1
O’Neill,Jim 358
OPEC see Organization of Petroleum
Exporting Countries
open systems 11
oral histories 384
organic action 71
Organization for Economic Cooperation
and Development (OECD) 134, 359
Organization of Petroleum Exporting
Countries (OPEC) 319
orogenesis 68
outsourcing 341, 354
overgrazing 253, 265, 266, 304
overland flow 14
overpopulation 101-2, 297-8
Overseas Development Assistance (ODA)
322, 323
oxbow lakes (cutoffs) 27
oxidation 69, 242
ozone 53
P
P (Primary) waves 211
Pacific Ocean 8
Pakistan 238-9, 278
paleomagnetism 63
palm oil 174
Palmer Dam 36
Pangaea 62
Papua New Guinea 173-5
parent material 19
Park 147
particulate matter, airborne 299
Partition 278
pastoral nomadism 263
pastoral systems 263-4
Patagonian desert 240
Index
peat
burning 53
erosion 84
pediments 248, 249
pedimentation 248
peeling 69
Peltier, Louis C. 71
people trafficking 124,125
percolation 14,191
permeable rock 13,19
Peru 31, 240, 349
pesticides 267, 298
Peterson, William 113
petroleum 292-3
Philippines 65
photography, aerial 380
photosynthesis 170,198, 251
phreatic zones 14
phreatophytes 251
physical factors
and agricultural land use 259
and industrial location 271
pie graphs (divided circles) 372
Piedmont zones 249
PIGS countries 329
pioneer species 166-7,195,197
pitting 68
pixels 380
plagioclimax 166
planar landslides 78
plate boundaries 64—5
collisional 65
conservative/transform 65, 210-11
constructive 65
destructive 65,210
and hazardous environments 208
ocean plate 65
plate movement 64-5, 209-10
plate tectonics 62-73
convergent plates 64, 209, 210
divergent plates 64, 209, 210
evidence for 62-3
hazards resulting from 208-15,
227-30
and orogenesis 68
plate boundaries 64-5, 208,
210-11
plate movement 64-5,209-10
sea floor spreading 63, 66
and the structure of the Earth 63-4
subduction zones 64, 66-7
and the sustainable management of
hazards 227-30
playas 246-8
Pleistocene 248, 250
plunge pools 25
pluvials (wet periods) 248, 250
point bars (slip-off slopes) 22, 26
Polar Front 42
polar high pressure system 42
policies 275
anti-natalist 92
pro-natalist 92
regional 134
rural 134-5
political globalisation 353
political influences
and agricultural land use 260-1
and birth rate and fertility 92
and the elderly 94
pollution
air 102, 145-6,155,252,299
and environmental degradation
295-6
and mangroves 197
and tourism 327
and urbanisation 299
polytunnels 265
pools 25,26,35, 37
plunge pools 25
population 86-107
age/sex structure diagrams 95, 370
ageing 128
and birth rate 88, 89-95
case studies 89-90
and death rate 88, 89-90
demographic transition 96-9
and the dependency ratio 94
and desertification 253
and development 363-4
and fertility rate 89, 91-3
and food supply 99-100,102-5
growth 253,299, 304,357
and infant mortality rate 89
and infrastructure 299
and land degradation 304
and life expectancy 89-90, 94,106
managing natural increase 106-7
migrant populations 108-18
natural increase 88-95, 96, 97,101,
106-7
old 94
optimum 102
population-resource relationships
99-105
urban 137-9, 143,146-7
world population growth 88-9
young 94, 357
positive externalities 274
post-industrial cities 151
post-industrial societies see High
Income Countries
potato crop 264
poverty 105,136,153-4
absolute 322
and agriculture 317
and desertification 253
and industry 280
and the informal sector 277
measurement 349-50
and the Millennium Development
Goals 322
reduction strategies 321
and tourism 328
and urbanisation 138,139
Poverty Reduction Strategy Paper (PRSP)
321,328
PPP see Purchasing Power Parity
PPT see pro-poor tourism
practical salinity units (psu) 197
pre-industrial phase 343
precipitation (ppt) 48-9
antecedent conditions 18,19
and arid environments 236-7
convectional 48-9
and drainage basin systems 12,15,
18
effective 236
and flooding 34
frontal 48-9
human impact on 30
inter-annual variability 236
orographic 48-9
and overland flow 14
and river discharge 15
and savanna soils 172
types of 18
and urban heat islands 58
and weathering 71
see also rainfall; snow
pressure
high 42,160,161, 235, 237-9, 241
low 42,161
seasonal variation 41-2
pressure cells, seasonal 42
pressure release weathering 69
pressure surges 223
primary data 380
primary produce 310, 313
Principles of Migration 116
Pripyat 295
pro-natalist policies 92
pro-poor tourism (PPT) 205
process industries 272
producers, primary/secondary 170
production 256-81
agricultural systems and food
production 258-70
chain of 340
manufacturing and related service
industries 271-81
productivity 273
profit 261
property
impact of atmospheric disturbances
on 223-4
impact of mass movement hazards
on 216-18
impact of tectonic hazards on 214
proportional bars 374
proportional circles 375
proportional symbols 374-5
protectionism 312, 313, 315, 323
proximal end 191
PRSP see Poverty Reduction Strategy
Paper
pseudo bedding planes 69
psu see practical salinity units
Punjab 267
Purchasing Power Parity (PPP) 344-6
pyroclastic flows 213-14, 217-18
pyrophytic 169
<2
qat (narcotic) 105
qualitative research 380, 381-4
‘quantitative easing’ 320
quantitative research 380
quarrying 81
quartz 72,164
questionnaires 381-4
Quirkmaps.com 380
R
radiation 40-1
atmospheric counter-radiation 40
of the Earth’s core 64
infrared 380
long-wave 40, 52
net radiation balance at the Earth’s
surface 40
short-wave 40
solar 40, 52
terrestrial 40
radiation fog 52
rain shadows 49, 235, 241
rainfall
acid rain 70
antecedent conditions 18
and clouds 51
convectional 48-9
desert 236
and discharge 16
and flooding 34
frontal 48-9
global figures 38, 39, 234
intensity 236
monsoonal 18
orographic 48-9
processes of 30
and slope processes 75
and tropical savanna 162
and tropical storms 221
Rajashtan, India 254
rapids 25
Ravenstein, Ernst Georg 115
raw materials 272, 340, 361
ray diagrams 377
desire lines 377
wind roses 377
RDPE see Rural Development
Programme for England
recession, global 364
Refugee Convention 125
refugees 125
regional development 358-67
core-periphery 360-1
cumulative causation 361
dependency theory 361
management 362-7
within country disparities 358-61
regional policy 134
regolith 74, 76
rejuvenation T1
relief 18-19
religion 91
relocation 295
renewable energy supplies see
sustainable/renewable energy
supplies
reservoirs 31
residential segregation 153
residential zones 147
resource curse theory 286, 344
resources
exploitation 285-7
lack of 344
limited nature 99-100
see also Sustainable Resource
Management
retaining walls 85
retirement migration 134,142
reurbanisation 142
revetments 202
rias (deep estuaries) 27
rice
high-yielding varieties 103, 267-8
IR8 267
New Rice for Africa (N ERICA) 268
riffles 26, 35, 37
rights, equal 280
Rio de Janeiro 81, 217
rip rap 202
river cliffs 26
river deltas 28-9
river discharge 15-16
river flow 21
helicoidal 22, 26
laminar 21
thalweg 22
turbulent 21-2
river regime 15
river terraces 28
rivers
in arid areas 244-5, 248
base level 27
Index
braiding 28
capacity 23, 24, 28
channel processes and landforms
20-9
competence 23, 24, 28
deposition 24, 25-6, 28
effect on fluvial features 28
endoreic 244
ephemeral 244, 245
and erosion 21, 23, 24, 25-6
exogenous 239, 244
flooding 35, 222
floodplains 28
gradients 20
gravitational potential 21
and Hjulstrom’s Curve 24
hydraulic radius 22
and levees 28
load 21,23,28
long profiles 20-1
lower course 21
management 35
meanders 25-8
middle course 21
and pools 25
rapids 25
rejuvenation 27
and sea level change 27
and transport 23, 24
upper course 21
velocity 22, 24
and waterfalls 25
Rochinha, Rio de Janeiro 217
Rock Cycle 60
rock falls 79
'rock litter’ 68
rock pinning 202
rocks 60-85
disintegration 69, 242
human impact on 79-85
igneous 19, 72,164
lithology 74
and plate tectonics 62-73
sedimentary 19, 72,165
slope processes 74-85
structure 74
types 19
water-eroded 244-5
wind-sculpted rocks 243
see also weathering
root density 75
rotational slides 79
runoff
and deserts 245, 255
and drainage basin systems 12
and urbanisation 30
Rural Development Programme for
England (RDPE) 135
rural economies 133
rural environments, degradation 297-8
Index
rural policies 134-5
Rural Policy programme (Finland) 135
rural settlements
birth rates 91
changes in 132-7
contemporary issues 132-4
gentrification 134
temperatures 56
rural-urban migration 117-18, 119,
121-2,143
Russia 358
s
S (Secondary) waves 211
sabkhas 242, 248
Sahara 238-9, 252
Sahel zone 239, 252, 270
salinisation 253, 265,298
salinity 41,197
salt 250,251,253
salt crystallisation (salt weathering) 68,
242
salt lakes 246-8
salt marshes 196
saltation 21, 23, 243
saltwater intrusion 33
Sami population 301
sampling 381
San Andreas Fault 65
sand bypassing 202
sand dredging 203
sand dunes 195, 250
akle dunes 244
desert dunes 244
dune slacks 195
embryo dunes 195
fixed dunes 195
regeneration 202
seif dunes 244
semi-fixed dunes 195
star dunes 244
succession 195
types 244
wind-shadow dunes 244
sandbars 193
sanitation 153-4
Sassen, Saskia 147
satellite images 380
saturated air 48
scarps 249
scarps recession 249
scatter graphs 371
scavengers 170
schools 137
scree 68
sea
acidification 53
and global temperatures 46
sea floor spreading 63, 66
sea ice (Arctic), melting 290-1
sea level change 27
and barrier islands 193
and coral reefs 198
eustatic falls 27
eustatic rises 27
sea walls 185, 202
seasonal lags 46
seasonal pressure cells 42
seasonal variations
and arid temperatures 237-8
and pressure 41-2
and rainfall 236
and wind belts 41-2
Second World War 90, 118,123,151,
260,265,312, 351,361
secondary data 380
sediment
and coral reefs 198
and desert runoff 245
remodelling coastal 191,193
size 191
transport 23,185,186, 190, 294
sediment cells (littoral cells) 185-7
sedimentary rocks 19, 72,165
segregation, residential 153
‘seismic isolation’ technologies 227
seismic waves 211
seismometers 211
self-sufficiency 103
semi-arid environments 232-55
causes of aridity 235
difference from arid areas 238
and high wind energy 238
landforms 242-50
and precipitation 236-7, 238
and salinisation 253, 265
soils 250-3
sustainable management 254-5
temperatures 237-8
vegetation 250-2
sensible heat 40
sensible heat transfer 40
service sector 271-7, 363
settlement dynamics 130-55
case studies 135-7,140-1,143-4,
153-5
changes in rural settlements 132-7
changing structure of urban
settlements 147-53
urban settlement management
153-5
urban trends 137—47
sewers/sewage 96,153-4, 327
sex ratios 91
sex/age structure diagrams 95, 370
shading maps see choropleth maps
shale gas 287
sharecropping 261
shear stress 215-16
sheet flow 245
shifting/swidden cultivation 261
shipping, container 351
Shiva, Vandana 267
Shoreline Management Plans (SMPs)
201
short-wave radiation 40, 52
shuijiao 31
sial 64
Sichuan Basin, China 39
Siesmo-Electromagnetic Satellites
214-15
Singapore 92,161-2
Single European Market 313
SLA see Sudan Liberation Army
slab-pull mechanism (dragging theory)
64
slash-and-burn agriculture 101,173
slaves 125
slides 76,78-9,215
slip-off slopes (point bars) 22, 26
slope overloading 82
slope processes 74-85, 215-16, 230
and agriculture 259
and aspect 74-5
and climate 75
human impact on 79-85
and landforms 76
and mass movements 76-9
and rock geology 74
and rock lithography 74
and rock structure 74
and soil 74-5
and vegetation 75
and weather 75
slope retreat 249
slope stability analysis 84
slums 81,138,139,150,153-4, 217
smog 52
SMPs see Shoreline Management Plans
snow 18, 38, 51
Snow,John 96
snow-melt 18
social development/wellbeing,
disparities in 344, 358-67
social factors, and birth rate and fertility
91-2
socio-economic factors, and
international migration 128
socio/cultural factors, and agricultural
land use 261
soil
arid environment 250-3
clay 19, 69, 74, 184, 250
degradation 32,177
density 19
desert (aridosoils) 250-2
erosion 172,174,251, 265
exhaustion 268, 270
ferralitic 171
fertility 169-70, 259, 268, 279
formation 170-2
friable 265
profiles 170-2
rainforest 169-72
sandy 19
saturation 14
savanna 170,172
and slope processes 74—5
structure 19
and throughflow 14
types 14,19,170-2, 259, 265
soil creep 76-7
solar power 55, 255, 286, 293, 366
limitations 285
solar radiation 40, 52
solifluction 75, 77
solution (erosion process) 23
sorghum 269
Soufriere Hills volcano 228-30
South American deserts 240
South American plate 65
South Pole 45
Southern African deserts 239
sovereign debt 318
Soviet Union 32
specific heat capacity 46, 56
spits 190,191-2
spurs, interlocking 25
SRM see Sustainable Resource
Management
stable bay creation 202
stacks 188
standard of living 347, 349-50
standardisation 329
Stark 117
statutory tenure 142
steel industry 312
stemflow 12
sterilization 106,107
stone pavements 250
storm beaches 191
storm drains 37
storm hydrographs 16-18
storm surges 20,182-3, 221-2
storms 38, 39
and coastal erosion 185
and coral reefs 198,199
and flooding 34
see also hurricanes; tornadoes;
tropical cyclones; typhoons
Stouffer 116
Strakhov’s diagram 71
stream flow 245
structural adjustment programmes 321
structural engineering 84-5
structuration theory 118
sub-aerial processes 184
sub-climax 166
sub-tropical anticyclones 160
sub-tropical high pressure belts 42
sub-tropical jet stream 160
subduction zones 64, 66-7,187, 210
sublimation 48
subsidence 33,198
subsistence farming 261, 342
suburbanisation 140-1,145
succession 166
succulents 251
Sudan Liberation Army (SLA) 304
sulfur dioxide 83
Sun
daytime energy budgets 40
formation 62
and latitude 45
sunlight 39,170,197
supercells 221
surface creep 243
surface storage 13
suspended load 21, 23,185
suspension 243
sustainable development 365
Sustainable Development Goals 322
sustainable management
arid environments 254-5
coastal environments 201-5
coral reefs 200
hazardous environments 225-31
tropical environments 173-7
Sustainable Resource Management
(SRM) 305
sustainable tourism 333, 366
sustainable/renewable energy supplies
55,255,284-91,293,366
consumption trends 287-90
geothermal energy 214
solar power 55, 255, 285, 286, 293,
366
see also wind power
swales 191
swash 182,183,191
swells 181
swidden (slash and burn) gardens 173
‘switched-on’/’switched-off’ places
360
symbiosis 197,198-9, 200
takeover entry 353
TALC (Tourism Area Life Cycle) Model
331-3
talus 68
TAP seeTrans-Alaska Pipeline
tariffs 313, 315, 363
technology
agro-technology 260
and food production 102-3,104
Index
information technology 141, 145,
280, 343, 352
'seismic isolation’ 227
travel/transport technology 326, 333
and working structures 343
technology transfer initiatives 266-7
tectonic uplift 165
telephone services 139
temperate low pressure belt 42
temperature 39
and arid environments 237-8
and coral reefs 197,199, 200
diurnal range 40-1, 237, 242
diurnal variation 237
global 45-8
and rural areas 56
and tropical climates 158, 161-3
and urban heat islands 55-7
and weathering 71
terawatt-hours (TWh) 287
ternary diagrams see triangular
graphs
terrestrial deposition 191
terrestrial radiation 40
terrorism 326
textile industry 279, 280-1
thalweg 22
Thar Desert 254
thaw 18
thermal expansion (insolation)
weathering 69
thermal fracture 242
thermohaline circulation (ocean
conveyor belt) 41
Three Gorges Dam, China 294-5
throughfall 12
th roughflow 14
thunderstorms 221
Tibetan plateau 65
tidal cycles 182
tidal power, limitations 285
tidal range 182,193
tides 20,182
timber 174,175, 298
TNCs see Transnational Corporations
tobacco plantations 137
Todaro 117
Tohoku earthquake and tsunami 2011
212,215,227
tombolos 190,191,193
topset beds 28
tornadoes 39, 223-5
distribution 219-20
formation 221
hazards caused by 221-2
prediction 225
tors (castle kopjes) 164,165
tourism 254-5, 324-37, 364—6
and carrying capacity 329-30
case studies 332-3, 334-7
Index
coastal 203,204-5
economic impacts 328-9
and the environment 326-8
growth in 324-6
international 324-37
leakage 330
and the multiplier effect 330
negative impacts 326-30, 335-7
social and cultural impacts 329
sustainable 333, 366
trends 333
Tourism Area Life Cycle (TALC) Model
331-3
towns 147
Toyota 356
traction 21, 23, 243
trade
free 311-12, 315, 363
international 310-24, 351
trade agreements 312, 313
trade barriers 312
trade blocs 312, 313
trade deficits 311
trade flows and trade patterns 310-24
‘banana wars’ 315
factors affecting global trade
312-13
FairTrade 316-17
Fairtrade Foundation 316,317
global inequalities in 311-12
and imports and exports 310-11
and international aid 318-24
and international debt 318-24
and the World Trade Organization
314-16
trade sanctions 314
trade surplus 311
trade winds 42, 235
trams 146
Trans-Alaska Pipeline (TAP) 290
transitional economies 357
Transnational Corporations (TNCs) 139,
260,273,351
and the ‘banana wars’ 315
and division of labour 354
and employment structures 343
and environmental degradation
297-8
and exploitation 355
and exports 311
factors affecting the growth and
structure of 354-5
and foreign direct investment
312-13,353
global spatial organisation and
operation 356
and Newly Industrialised Countries
341-2, 357
and outsourcing 354
transpiration 15, 251
transport 147
cars 145,146, 155
costs 272
and globalisation 352
and industrial location 272
infrastructure 155
public 145,146,155
technology 326, 333
transportation
coastal 185,186, 190
by rivers 23, 24
Treaty of Rome (1957) 260-1
trees
deciduous 20
jarrah tree 176
tropical rainforest 167-9
see also afforestation; deforestation
triangular graphs 372
trophic levels 170
Tropic of Cancer 156,158
Tropic of Capricorn 156,158
tropical climates 158-62
tropical cyclones 223-5
distribution 219
formation 220-1
hazards caused by 221-2
prediction 224-5
tropical environmental zone 156
tropical environments 156-77
case studies 173-7
ecosystems 166-75
landforms 162-5
sustainable management 173-7
tropical climates 158-62
tropical monsoon climate 156,158,159,
162
tropical rainforest climate 156,158,
161-2
ecosystems 166-75
tropical savanna climate 156,158,159,
162
ecosystems 166-72,175-7
landforms 163
tsunamis 211-12, 227
Turkey 112
TWh see terawatt-hours
Tyger Valley Shopping Centre, Cape
Town 151
Typhoon Vamei 162
typhoons 223-5
distribution 219
formation 220-1
hazards caused by 221-2
prediction 224-5
Tysons Corner 140-1
u
Ullman 149
underemployment 277
undernourishment 102,105
underpopulation 102
understorey 167-9
unemployment 277
United Kingdom
agriculture 264-5
international trade 313
migration 128
see also England
United Nations (UN) 53,102-3,110,
146, 298-9, 304-5,319,322
United Nations Environment
Programme (UNEP) 199, 327
United Nations Framework Convention
on Climate Change (UNFCCC) 53
United States
age/sex structure diagrams 95
‘banana wars’ 315
deserts 239, 254-5
food production 103,104
storms 224
suburbanisation 140-1
United States Geological Survey (USGS)
218, 290-1
unroofed layers 69
unsaturated air 48
updrift 191
urban activities 149, 150-2
urban climates 55-8
urban environmental degradation 298-9
urban heat islands 55-8
Urban Household Sanitation
Improvement Project 154
urban renewal 143
urban settlements
changing structures 147-53
management 153-5
urban sprawl 154
urban trends 137-47
urban-rural migration 119,133-4,
141-2
urban-urban migration 119, 122
urbanisation 137-47,153, 298-9
and the death rate 90
and discharge relationships in
drainage basin systems 19
and earthquakes 225
and fertility rate 91
and hydrology 30
and impermeable surfaces 83
and land degradation 298-9
and mangroves 197
and mass movement 217
and slope stability 81, 83
USGS see United States Geological
Survey
water
and agriculture 260
demand and supply of 296-7
V
V-shaped valleys 25
value-added 365
variables 370
dependent 370
independent 370
vegetation
of arid environments 250-2, 254
and coastal stabilisation programmes
202
and discharge relationships in
drainage basin systems 20
interception 12
pioneer species 166-7,195, 197
of sand dunes 195
and slope processes 75
storage 13
of tropical rainforests 167-9
of tropical savannas 169
xerophytes 169,195, 251
see also afforestation; deforestation
Vegetation Management Act (Australia)
177
VEI see Volcanic Explosivity Index
Vietnam 317
virtual water 297
viticulture 259
volcanic eruptions 209, 212
Hawaiian (effusive) 212-13, 214
and mass movements 217-18
Plinian 212-13
Volcanic Explosivity Index (VEI) 212
volcanoes 65, 77-8
and debris avalanches 79
hazard mapping 214-15
hazards presented by 208-10,
212-13
human impact 214
monitoring 214-15
opportunities provided by 214
prediction 214-15
sustainable hazard management
228-30
and tropical rainforest ecosystems
166-7
w
Wadati-Benioff zone 66
wadis 245, 302
Walsh 121
Wamberal Beach, New South Wales,
Australia 185
war 90
‘warrantage’ scheme 270
washlands 35
waste disposal 299, 327
finite nature 104
liquid 40
plants’ need for 251
quality 29, 296-7
quantity 29
storage 13, 31
and tourism 327
virtual 297
see also groundwater
water abstraction 31
water balance 234, 252
water leakage 83-4
water scarcity 296-7, 307, 327
water stress 296
water vapour 30, 40, 48, 51-2, 237
water-borne diseases 222, 223, 296
waterfalls 25
watershed 10
wave abrasion/corrasion 185
wave attrition 185
wave deposition 185
wave quarrying 185
wave refraction 183,188,191
wave transportation 185
wave-cut platforms 190
waves 181-2
breakers 181-2
constructive 182,183,190, 191
and coral reefs 198
destructive 182,183,191
and erosion 185
Love and Rayleigh 211
of oscillation 181
of translation 181-2
wealth 358-61
see also affluence
weather 38-59
and climate change 29
and diurnal energy budgets 40-1
human impacton 52-8
processes and phenomena
48-52
and slope processes 75
weathering 68-73, 75-6, 78, 216
in arid/semi-arid environments
242, 248, 249, 250
biological 70-1
chemical 69-71, 75, 81,162-5, 242,
249, 250
and coastal erosion 184
controls of 71-3
freeze-thaw (frost shattering) 68, 76,
242
honeycomb 68
isolation 242
mechanical 68-9, 70, 71, 162-3
pressure release 69
Index
salt crystallisation (salt weathering)
68, 242
thermal expansion (insolation) 69
thermal fracture 242
Wegener, Alfred 62
wetland areas 36
wheat 264
high-yielding varieties 102,103
WHO see World Health Organization
Wilderness Areas 301
wildfire 175-7
wind 42
dry monsoon 161
dry trade 235
erosion 243
and global temperatures 48
hazardous 223
high wind energy 238
and storm surges 182
‘the doldrums’ 159
of tornadoes 223
trade 42,235
of tropical storms 223
and urban heat islands 57, 58
and wave refraction 183
wind-sculpted rocks 243
wind belts 41-2
Index
wind farms 55
wind power 55, 255, 285, 286-7, 289,
293
wind roses 377
wine-making 259
WMO see World Meteorological
Organization
women
equal rights 280
working 279-80
wood
burning 53
see also logging; timber
World Bank 32,128,142,174, 277-8,
319, 321,323,330,361
origins 321
world cities 130-1,146-7
World Health Organization (WHO) 154,
367
World Heritage Sites 134, 334, 337
World Meteorological Organization
(WMO) 199
world population growth 88-9
World Trade Organization (WTO) 134,
312,314-16,315,329-30,351
World Wide Fund for Nature 175
X
xerophytes 169,195, 251
Y
Yangtze River 294
yardangs 243
yazoo tributary 27
yellow dunes 195
Yemen 105
Yuma, Arizona 39
z
zeugens 243
Zimbabwe 95
Zipf 116
zones in transition 147
zooanthellae 197,199
Acknowledgements
The publishers would like to thank the
following for permission to reproduce
images. Every effort has been made to
trace copyright holders and to obtain
their permission for the use of copyright
materials. The publishers will gladly
receive any information enabling them
to rectify any error or omission at the
first opportunity.
Images not listed here were created by the
team at Collins and are therefore © Collins
Bartholomew Ltd 2016
Cover: Dead Sea sinkholes: Photostock-lsrael/
Science Photo Library
1.1: Dr. Morley Read/Shutterstock
1.3: Sirilipix/Shutterstock
1.7a $b: Fiveless/Wikipedia/CC BY-SA 3.0
1.12: cdrin/Shutterstock
1.13: Smileus/Shutterstock
1.14: patjo/Shutterstock
1.15: Dmitry Naumov/Shutterstock
1.18: Tango22/Wikipedia/CC BY 3.0
1.20: Deymos.HR/Shutterstock
1.21: The Niagara Parks Commission
1.22: Graham R Prentice/Shutterstock
1.25: Mike Charles/Shutterstock
1.26: Kunal Mehta/Shutterstock
1.27: Elaine Burt/CC BY 2.0
1.28: Walter Siegmund/Wikipedia/CC BY-SA
3.0
1.29: NASA
1.30: NASA
1.31: Florin Stana/Shutterstock
1.32: ShaunWilkinson/Shutterstock
1.33: NASA
1.34: goriilaimages/Shutterstock
1.36: MODIS/NASA
1.37: Daniel Prudek/Shutterstock
1.39: Tim Padfield 2012/CC BY
1.40: Andy Schindler
1.41: Contains Environment Agency
information © Environment Agency
and database right
Case study Harbertonford: The British Dam
Society, http:Wwww.britishdams.
org/2004conf/papers/bradley.PDF,
WT BRADLEY, M E JONES $AC
MORISON
2.4 : Science Photo Library
2.5 b8<c: Sailorr/Shutterstock
2.10 base image: Bananaboy/Shutterstock
2.19: Maksym Darakchi/Shutterstock
2.20: Fir0002/Flagstaffotos/Wikipedia/GNU
1.2
2.21: A.Fitzsimmons/ESO/Wikipedia/CC BY
4.0
2.27: Songquan Deng/Shutterstock
2.28 base images: J PL Designs, KID_A,
zeber, Potapov Alexander, Evellean/all
Shutterstock
2.30: TonyTheTiger/Wikipedia/CC BY-SA 3.0
3.2: Nobu Tamura/Wikipedia/CC BY-SA 3.0
table 3.1c: Booyabazooka/Wikipedia/public
domain
table 3.1d: USGS/Wikipedia/public domain
table 3.1e: USGS/Wikipedia/public domain
3.8: Oggmus/Wikipedia/CC BY-SA 3.0
3.9: shrimpol967/Wikipedia/CC BY-SA 2.0
3.10: ASC Photography/Shutterstock
3.11: Wilson44691/Wikipedia/public domain
3.12: Martin Fowler/Shutterstock
3.13: Phil MacD Photography/Shutterstock
3.14: Andrew Mayovskyy/Shutterstock
3.17 base image: TheBlackRhino/Shutterstock
3.24: Jeffrey Marso, USGS geologist/
Wiki pedia/public domain
3.26: Olaf Speier/Shutterstock
3.27: Kedsirin.J/Shutterstock
3.29: Rich Carey/Shutterstock
3.32: Jeff collins/CC BY-SA 2.0
3.33: Wikipedia/CC BY-SA 3.0
3.35: robbinsbox/Shutterstock
3.36: Phil.Tinkler/Shutterstock
4.15: Wikipedia/CC BY 4.0
4.20: Micheline Pelletier/Sygma/Corbis
4.23: Dmitry Chulov/Shutterstock
4.24: TonyV3U2/Shutterstock
5.1: Borisl5/Shutterstock
5.2: Daily Herald Archive/Getty
5.3: IL Palöt
5.11: Frontpage/Shutterstock
5.12: Humane Borders, Inc
5.13: Atlaslin/Wikipedia/CC BY-SA 3.0
5.14: Yu Zhang/Shutterstock
5.17: kathmanduphotog/Shutterstock
5.18: Alex Pix/Shutterstock
5.19: Dynamic Graphics/Thinkstock
5.20: IL Palöt
5.21: IL Palot
5.22: IL Palot
5.23: Jackie Gillham
5.25: r.martens/Shutterstock
5.26: TonyV3112/Shutterstock
5.27 base image: Epsicons/Shutterstock
6.1
components: Epsicons. KID_A/both
Shutterstock
6.2: IL Palot
6.4: IL Palot
6.8: YolLusZaml802/Shutterstock
6.11: BenjPHolm/Wikipedia/ I, the copyright
holder of this work, release this work
into the public domain. This applies
worldwide.
6.13: David Hughes/Shutterstock
6.14: IL Palot
6.15: Him2586/Wikipedia/CC BY-SA 3.0
6.16: Kiranverma2/Wikipedia/public domain
6.17: deb22/Shutterstock
6.18a : Bart Everett/Shutterstock
6.18b : Scott Leigh/Getty
6.19: Frontpage/Shutterstock
6.21: Videowokart/Shutterstock
6.22: Gillian Entress/Shutterstock
6.23: Christian Mueller/Shutterstock
6.28: lazyllama/Shutterstock
6.29: Slava Gerj/Shutterstock
6.30: T photography/Shutterstock
6.31: Gunwharf Quays Management Limited
6.36: Agencja Fotograficzna Caro / Alamy
6.37: F. A. Alba/Shutterstock
6.38: Matthew Otsuka/Alamy
6.39: Jeremy Pembrey/Alamy
7.2:
Wikipedia/NASA
7.3
7.4
7.6:
7.7:
7.8:
7.9:
7.12:
7.13:
7.15:
7.16:
7.18
7.19:
7.20:
7.21
7.22:
7.27:
7.30:
7.31:
7.32:
7.33:
7.34:
7.35:
7.36:
component: Mats Haldin/Wikipedia/
CC-BY
component: Saravask/Wikipedia/CC
BY-SA 3.0
Dr. Marli Miller, Visuals Unlimited/
Science Photo Library
Daniel Mayer/Wikipedia/CC BY-SA 3.0
Vaikoovery/Wikipedia/CC BY 3.0
Marco Schmidt/Wikipedia/CC BY-SA 2.5
D. Gordon E. Robertson/Wikipedia/CC
BY-SA 3.0
Gfonsecabr/Wikipedia/CC BY-SA 3.0
P199/Wikipedia/CC BY-SA 3.0
Mr. Tickle/Wikipedia/CC BY-SA 3.0
base image: Rcolel7/Wikipedia/CC-BYSA 4.0
Felipe Menegaz/Wikipedia/CC BY-SA
2.0
Thomas Schoch/Wikipedia/CC BY-SA
base image: Kozoriz Yuriy/Shutterstock
Christopher T Cooper/Wikipedia/CC
BY 3.0
Sandra A. Dunlap/Shutterstock
Alba Casals Mitja/Shutterstock
Vladislav T Jirousek/Shutterstock
John Gerrard Keulemans/Wikipedia/
public domain
metriognome/Shutterstock
PeterVrabel/Shutterstock
ken browning/Shutterstock
Le Do/Shutterstock
IL Palot
NOAA
AudreyJackson/Geograph.org/CC BY-SA
2.0
8.8: Navy photo by Gary Nichols/Wikimedia/
public domain
8.10: IL Palöt
8.12: IL Palot
8.13: IL Palot
8.14: IL Palot
8.15a : Peter Harrison/Getty
8.16: IL Palot
8.18: USGS
8.20: IL Palot
8.21: IL Palot
8.22: IL Palot
8.23: IL Palot
8.24: IL Palot
8.25: IL Palot
8.27: IL Palöt
8.28: IL Palot
8.31: Alistair Rennie/Shutterstock
8.32: Carter, D., Bray, M.J. $ Hooke, J. (2004)
‘SCOPAC Sediment Transport Study',
Report to SCOPAC
8.33: Judi Darley, Chichester Harbour
Conservancy
8.34: reproduced with the permission of
David Carter, based on an original
map in Searle (1975)The TidalThreat.
8.35: NASA
8.36: USGS
8.39: CreativeNature R.Zwerver/Shutterstock
8.42: IL Palöt
8.43: IL Palöt
8.44: IL Palöt
8.47: USGS
8.48: Ethan Daniels/Shutterstock
8.49: Chris Mellor/Getty
8.53: Nigel Pavitt/JAI/Corbis
8.55: David Mckee/Shutterstock
8.1:
8.6:
8.7:
9.5:
9.6:
9.8:
9.9:
9.10:
9.12:
9.13:
9.14:
9.18:
9.19:
9.21:
9.22:
9.27:
9.28:
9.29:
9.30:
9.31:
9.32:
9.33:
9.34:
9.35:
9.36:
9.38:
Ikluft/Wikipedia/CC BY-SA 4.0
NOAA
USGS
KPG_Payless/Shutterstock
Photovolcanica.com/Shutterstock
phaechin/Shutterstock
audioscience/Shutterstock
Cardaf/Shutterstock
Chensiyuan/Wikipedia/CC BY-SA 4.0
NASA
KPG_Payless/Shutterstock
Magnus Manske/Wikipedia/CC BY-SA
3.0
Minerva studio/Shutterstock
Leonard Zhukovsky/Shutterstock
NASA
NOAA
Edward Haylan/Shutterstock
arindambanerjee/Shutterstock
Pioneron/Shutterstock
Aurora Photos/Alamy
public domain
Stefan Krasowski/Flickr.com/CC BY 2.0
Decha Thapanya/Shutterstock
10.5: Everett Historical/Shutterstock
10.6: n. yanchuk/Shutterstock
10.7: Nina B/Shutterstock
10.11: Tomas Sykora/Shutterstock
10.15: Fedorov Oleksiy/Shutterstock
10.17: summer.wu/Shutterstock
10.19: Denis Burdin/Shutterstock
10.22: Neil Rhodes/Wikipedia/public domain
10.24: sumikophoto/Shutterstock
10.26: Michael Muraz/Shutterstock
10.27: Chris Howey/Shutterstock
10.28: Francesco R lacomino/Shutterstock
10.30: TanArt/Shutterstock
10.31: kawhia/Shutterstock
10.32: Homercles/Shutterstock
10.33: heckeöl/Shutterstock
10.34: Paul B. Moore/Shutterstock
10.35: Jo-anne Hounsom/Shutterstock
10.36: Morphart Creation/Shutterstock
10.37: Stephane Bidouze/Shutterstock
10.38: Blacknote/Shutterstock
10.39: USDA/public domain
10.41: Matyas Rehak/Shutterstock
10.43: S.Borisov/Shutterstock
11.5:
11.6:
11.8:
11.9:
11.10:
11.11:
11.13:
11.15:
11.16:
11.17:
11.18:
11.19:
11.20:
11.21:
11.22:
11.23:
11.24:
11.26:
11.28:
11.29:
11.33:
11.34:
11.36:
Dee Yorke-Hasted
Hung Chung Chih/Shutterstock
Sherjaca/Shutterstock
Kochneva Tetyana/Shutterstock
PlanetObserver/Science Photo Library
sunsinger/Shutterstock
Aurora Photos/Alamy
Eitan Simanor/Alamy
David Cavagnaro/Getty
KYTan/Shutterstock
RioTinto
IL Palot
IL Palot
IL Palot
IL Palot
IL Palot
IL Palot
lain McGillivray/Shutterstock
Cartoonresource/Shutterstock
Thomas Saupe/Getty
IL Palot
projectlphotography/Shutterstock
Jaber Al Nahian/Flickr.com/CC BY-SA
2.0
11.37: zakir hossain chowdhury zakir/Alamy
12.1:
12.2:
12.4:
12.5:
12.6:
VLADJ55/Shutterstock
Panacea Doll/Shutterstock
Robert Lucian Crusitu/Shutterstock
a katz/Shutterstock
jaddingt/Shutterstock
Acknowledgements
12.9: Heather Lucia Snow/Shutterstock
12.10: Cheryl Casey/Shutterstock
12.11 base image: Mrfebruary/Wikipedia/CC
BY-SA 3.0
12.12 base image: Theanphibian/Wikipedia/
CC BY-SA 3.0
12.13: Sadik Gulec/Shutterstock
12.14: Vmenkov/Wikipedia/CC BY-SA 3.0
12.15: NASA
12.17: Nowozin/Wikipedia/CC BY-SA 3.0
12.18: Manuel Abinuman Jr/Shutterstock
12.19: Sergey Kamshylin/Shutterstock
12.21 data: WaterStat/Water Footprint
Network, Enschede, Netherlands
12.21 base images: Tribalium, forest_strider,
karawan, Wiktoria Pawlak, RedKoala,
VKA, darsi/all Shutterstock
12.22: USDA
12.23: Dirk Ercken/Shutterstock
12.24: lvan_Sabo/Shutterstock
12.26: De Visu/Shutterstock
12.27: Pejo/Shutterstock
12.29: HammyO7/Wikipedia/CC BY-SA 3.0
12.30: USAID
12.31: USAID
12.32 data: tearfund
12.32 base images: Leremy, KoQ Creative,
tulpahn, HuHu/all Shutterstock
12.33: Photodiem/Shutterstock
13.6: Gregory James Van Raalte/Shutterstock
13.9: Scott Dexter/Flickr.com/CC BY-SA 2.0
13.10: Robert Morris
13.11 base images: Leremy/Shutterstock
13.12 base images: Leremy, VoodooDot/both
Shutterstock
13.16: ReptOnlx/Wikipedia/CC BY-SA 3.0
13.18: Rafael Ortega Diaz/Wikipedia/CC
BY-SA 3.0
13.19: Shahid Khan/Shutterstock
13.20: Michael Zacharz/Wikipedia/CC BY-SA
2.5
13.23: Marc Figueras/Wikipedia/CC BY-SA 3.0
13.24: David Adam Kess/Wikipedia/CC BY-SA
3.0
14.1 base images: Leremy, Annlris,
VoodooDot, bioraven, RedKoala,
Anthonycz/all Shutterstock
14.6: Citizen59/Wikipedia/CC BY 3.0
14.10: Gerard Koudenburg/Shutterstock
14.11: Raihan S.R. Bakhsh/Wikipedia/CC
BY-SA 2.0
14.12: Buckers/Wikipedia/public domain
14.18: Robert Morris
14.21: Robert Morris
15 infographic: Mike Flippo, Miks Mihails
Ignats, Click49, Luciano Mortula,
holboxjust Keep Drawing,
Konstantnin/all Shutterstock, and one
image NASA/USGS
15.22: Annemarie Schneider, Boston
University and NASA Landsat Science
Team
Text references:
Chapter 1: Sauquet, E.; L. Gottschalk; and
I. Krasovskaia (2008). ‘Estimating mean
monthly runoff at ungauged locations: an
application to France’. Hydrology Research,
Vol. 39, No. 5-6, pp. 403-423. IWA
Publishing.
Chapter 3: Osman, N. (2006). ‘Parameters to
predict slope stability- Soil water and root
profiles’. Ecological Engineering, Vol. 28, No.
1, pp. 90-95. Elsevier Journals.
Chapter 5: Dustmann, C. and T. Frattini
(2013). ‘The Fiscal Effects of Immigration
to the UK’. University College London
Discussion Paper, UK.
Chapter 6: Sassen, S. (1991) The Global City:
New York, London, Tokyo. Princeton University
Press, USA.
Key concepts
Key concepts
The key concepts on which this syllabus is built are set out below.
These key concepts can help teachers think about how to approach
each syllabus topic in order to encourage learners to make links
between topics and develop a deep overall understanding of the
subject.
i. Space:
the implications of spatial distributions and patterns of a range
of physical and human geographical phenomena.
2.
Scale:
the significance of spatial scale in interpreting environments,
features and places from local to global, and time scale in
interpreting change from the geological past to future scenarios.
3. Place:
the importance of physical and human characteristics which create
distinctive places with different opportunities and challenges.
4. Environment:
how the interactions between people and their environment create
the need for environmental management and sustainability.
5. Interdependence:
how the complex nature of interacting physical systems, human
systems and processes create links and interdependencies.
6. Diversity:
the significance of the similarities and differences between places,
environments and people.
7. Change:
the importance of change and the dynamic nature of places,
environments and systems.
Teachers are expected to embed the key concepts through the study
of the topics, both in general and specifically through examples and
case studies.
Key concepts 419
Notes
Notes