Hard or Soft engineering?
Floodwalls
Washlands
1. Use P. 110. Describe each picture and explain whether it is soft
or hard engineering. Which type?
2. Write a definition of Hard engineering, link it to a different example
from P.110 (or use the glossary handout).
3. Write a definition of Soft engineering, link it to a different example
from P.110 (or use the glossary handout).
Learning Objectives:
1)To compare the advantages and
disadvantages of river defence techniques
2)To consolidate our knowledge of river
landscapes, river processes and river flooding
• Hard engineering is a method of river flood
management which involves major
construction work
Soft engineering is a method of river
flood management which works or
attempts to work with natural river
processes. It does not tend to involve
major construction work e.g.
Floodplain zoning
HARD ENGINEERING
• These are structures built by engineers, with the help of
geographers and hydrologists.
• They are expensive and often not an option in LICs.
• They often have a negative impact on the environment
and can even cause more flooding further down the
river’s course.
Complete question 2 P.79 from Tomorrow’s Geography
or use the table below to help you.
Hard
engineering
Flood banks
(embankments)
Channelisaton
(straightening and
deepening)
Dams and
reservoirs
Flood walls
Storage areas
Barriers
Description
Advantages
Disadvantages
Flood banks
Advantages
1) Can be used as
a path for
pedestrians beside
the river.
2) Concrete
embankments
are effective at
stopping
bank erosion.
3) Earth
embankments
provide habitat for
plants and animals
These are raised banks along the river, so it can
hold more water
Disadvantages
1) The banks are
often not built
high enough
2) Concrete
embankments
are ugly and
spoil the view.
Los Angeles channelisation - straightening and deepening of the river)
Advantages
1) Effectively
protects immediate
area because water
is moved away
quickly.
2) Long lasting
The river channel may be widened and
deepened allowing it to carry more water.
A river channel may be straightened so
that water can travel faster along the
course
Disadvantages
1) Altering the
river channel may
lead to greater risk
of flooding
downstream, as
the water is carried
there faster.
2) Unnatural and
visually intrusive.
Dams and
reservoirs
Dams are often built
1) Water is usually stored
1) Building a dam is
along the course of a
in a reservoir behind the
very expensive.
river in order to control
dam. This water can then
2) Sediment is often
the amount of discharge. be used to generate
trapped behind the
Water is held back by the hydroelectric power or
wall of the dam,
dam and is released in a
leading to erosion
controlled way.
for recreation purposes.
further downstream.
3) Settlements and
agricultural land may
be lost when the river
valley is flooded to
form a reservoir.
Construction of a flood relief
channel
Flood relief
The channel course
1) Makes the people who
1) They require a
channels
of the river can be
live close to the main
large amount of
altered, diverting
river safer as the flood
land which might
floodwaters away
water is diverted into
be difficult to
from settlements.
the relief channel.
purchase
particularly if it is
2) Can be used for water
sports.
productive farmland.
2) Extremely
expensive.
Flood wall on the River
Moskva, in Moscow
Flood walls
A vertical barrier usually
made from prefabricated
concrete.
1) Can be used in areas
where space is limited.
2) Easily and quickly
erected
in pre-constructed sections.
1) They have to be
assembled very well
so that water doesn't
get through joints.
A large depression close
Storage areas to the river that will fill
1) Natural looking
with water if the river
2) Does the damage the
overflows and therefore environment.
protecting the
surrounding
land.
1) Need a large
area
of land that is not
being used.
2) Only come into
use when the river
has flooded.
Barriers, such as the Thames
Barrier.
• The barrier is raised when a high tide or
flood is forecast.
Complete question 2 P.79 from Tomorrow’s Geography
or use the table below to help you.
Hard
engineering
Flood banks
(embankments)
Channelisaton
(straightening and
deepening)
Dams and
reservoirs
Flood walls
Storage areas
Barriers
Description
Advantages
Disadvantages
The Three Gorges Dam
U: the social, economic and environmental issues
from building this dam
The Three Gorges Dam in
China
• Use the resource sheet to complete a fact file on this
example of a hard engineering scheme.
• Include:
• Its main features,
• Why it was built?
• The impact : social, economic, environmental.
• Do you think it should have been built? Do the benefits
outweigh the costs?
• Use the Wider World and the two handouts to help you
produce a case study on the negative and positive
issues of this dam.
SOFT ENGINEERING
• These do not involve expensive structures,
but instead uses the natural features of the
drainage basin to control flooding.
• It involves planning the land use in the
drainage basin.
• Forecasting and warning systems are
also important
Floodplain
zoning
Local authorities and the
national government
introduce policies to
control urban development
close to or on the flood
plain.
1) A very cheap way of
reducing the risk of damage
to property.
2) It is sustainable because
it reduces the impact of
flooding and building
damage is limited.
3) Also because the floodplain has not been built on,
surface runoff is less likely
to cause flooding.
1) There can be
resistance to
restricting developments
in areas where there is a
shortage of housing.
2) Enforcing planning
regulations and controls
may be harder in LICs.
Washlands
The river is allowed to flood
naturally into wasteland
areas, to prevent flooding
in other areas, for example,
near settlements.
1) Very cost effective as
nothing is built.
2) Provides potential
wetland sites for birds and
plants.
3) The deposited silt may
enrich the soil, turning
the area into agricultural
land.
1) Large areas of land are
taken over and cannot be
built on.
2) Productive land can be
turned into marshland.
Warning
systems
A network of sirens which
give people early warning
of possible flooding. The
Environment Agency uses
TV, radio, email, fax, text
and phone messages to
keep people informed.
1) A very cheap system.
1) The sirens could be
2) Electronic communication vandalized, so they are
is a very effective way of
tested annually.
informing people.
2) There might not be
3) Because the people have enough time for residents
warning of floods they can to prepare.
move valuable belongings
to safer places.
Afforestation or
Flood
abatement
Trees are planted in the
1) This is a relatively low
1) It is often conifers that
catchment area of the river
cost option.
are planted which can
to intercept the rainfall and
2) It improves the qulaity of
make the soil acidic.
slow down the flow of water
the environment.
2) Dense tree plantations
to the river.
3) Soil erosion is avoided as
spoil the natural look of
trees prevent rapid runoff
the landscape.
after heavy rainfall.
3) It increases fire risks
4) Very sustainable.
because of leaisure
activities in the forest.
Flood proofing
• This is where buildings are either designed
or altered to make them less at risk of
flooding.
• Do you recognise
• this place?
ACTIVITY:
1. Use the photo of Skipton, you have been given,
to annotate with evidence of flood management.
Try to identify evidence of the different types of
hard and soft engineering.
2. Draw 2 spider diagrams, one for soft and one for
hard engineering schemes and include their
advantages and disadvantages.
The Environment Agency manage floods in
England and Wales.
Your task:
•
You work for the Cumbrian Flood Action Group.
•
•
You have a brief to report to the Environment Agency and the Cumbrian County Council your
views on the flood.
Go back to the previous page where you have already:
•
1. Stuck the OS map of the area in to the centre of a double page,
•
2. Around the edge of the map included details on why it happened, it’s impacts (social, economic
and environmental) and the responses to the event.( Put these in neat boxes with headings)
•
NOW:
•
3. On the same map label your ideas on which hard and soft engineering techniques should be
used to protect Cockermouth against a future flood event of this magnitude.
Outline the benefits and problems of each around your base map.
You must also state your reasons for the choices you made (weighing up the balance between
social, economic and environmental benefits). Be prepared to present this to the rest of the class!
•
•
•
•
•
Resources available to you:
You have been given a resources pack to help you produce your report, as well as a base map of
the area to detail your ideas for your flood alleviation plan.
Use your notes on methods of flood protection looked at in this lessons.
What decisions have the
Environment Agency made?
Open the sealed envelope to find out!
Cumbrian Floods of 2009
What are the proposals for flood alleviation?
Flood defence works begin!
Innovative developments in Cockermouth.
Plenary:
Name and describe each method of flood management.
a.
c.
b.
Relief channels
Washlands
Floodwalls
d.
Flood warnings
e.
g.
f.
Channelisation
Floodplain zoning
Afforestation
HARD
Engineering
Floodwalls
Channelisation
Flood relief channels
SOFT
Engineering
Flood warnings
Floodplain zoning
Washlands
Afforestation
Flood
relief
channels
Floodplain
Flood
Channelisation
Washlands
Afforestation
Floodwalls
warnings
zoning