Lecture 1
Lecturer: Eng Goodson Masheka
IWRM in context
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Traditional development practices
Challenges of IWRM, Management Principles in the
context of IWRM
Steps in establishing IWRM institutions
Introduction
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o
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Global water resource: 1,386 million Km3.
97%: saline sea/ocean water; and
3%: freshwater:
87% not accessible (Glaciers and inaccessible
groundwater);
13% accessible (0.4% of total)
(UN World Water Development Report, 2003)
Introduction
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The limited accessible freshwater, mainly found in lakes,
rivers, wetland and soil moisture, is however under pressure
as a result of natural factors and human activities.
The major global challenges
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Water resource challenges
Increasing food demand
Water supply and sanitation problems
Ecosystem challenges
Increase in competing needs and water
governance challenges
Water resource challenges
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1. Decreased availability
 Climate change is having a significant impact on
weather patterns, precipitation and the hydrological
cycle, affecting surface water availability, as well
as soil moisture and groundwater recharge
 The problem is further exacerbated by increased
and over-abstraction of the surface and
groundwater resources.
Water resource challenges cont’
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Trends of global water withdrawal
Sector
Annual water withdrawal
1950
In Km3
Agriculture
2000
In Km3
In %
In %
1100
79
2664
70
Industries
200
14
785
20
Municipalities
100
7
381
10
1400
100
3830
100
Total
(Source: FAO 2006a)
The problem of over-abstraction in surface water is mostly tied
to upstream diversions and reservoir constructions
Water resource challenges cont’
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2. Sedimentation
 Sediments occur in water bodies both naturally and as
a result of various human actions.
 When they occur excessively, they can dramatically
change our water resources.
 Sediments occur in water mainly as a direct response to
land-use changes and agricultural practices
 Sediment loads can occur naturally in poorly vegetated
terrains and most commonly in arid and semiarid
climates following high intensity rainfall
Water resource challenges cont’
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Principal sources of sedimentation
Source
Cause
Impact
Agriculture
Poor farming with excessive 
soil loss
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Forest land, grazing land, 
road construction
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Deforestation
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Overgrazing
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Poor rehabilitation efforts
Increased soil erosion
Sediment and pollutants
are added to streams
Irrigation
systems
maintenance
cost
increased
Increases runoff
Increased erosion
Water resource challenges cont’
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Impacts of sedimentation on aquatic systems and
water services
Sector
Impacts of sedimentation
Major
rivers
and Decreases water depth making navigation difficult or impossible
navigable waterways
Aquatic ecosystems
Affects the survival of aquatic habitats by
 decreasing light penetration
 delivering higher suspended solids concentrations
 releasing toxic agricultural and industrial chemicals
Water supply rivers,  increased pump/turbine wear and subsequent maintenance cost
lakes and reservoirs
 reduced water supply availability and suitability
 additional treatment for usability and subsequent increased cost
Hydropower/irrigation  reduced reservoir capacity and service life
dams
 reduced service delivery capacity
 increased pump/turbine wear and subsequent maintenance cost
 silted tunnels and canals and increased cost of dredging
Water resource challenges cont’
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3. Pollution
 Humans have long used air, land and water
resources as ‘sinks’ into which we dispose of the
wastes we generate.
 The disposal practices leave most wastes
inadequately treated, thereby causing pollution.
 This in turn affects precipitation, surface waters and
groundwater, as well as degrading ecosystems.
Water resource challenges cont’
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Impacts of pollution on precipitation (Acid rain)
Atmospheric contamination from industrial plants
and vehicle emissions leads to dry and wet
deposition.
This causes acidic conditions to develop in surface
water and groundwater sources and at the same
time leads to the destruction of ecosystems
Lowers the PH
Water resource challenges cont’
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Impacts of pollution on surface water
Surface water pollution risk is a widespread
problem particularly in developing nations.
There are generally two types of surface water
pollution, namely, point sources (PS) and non-point
sources (NPS).
Water resource challenges cont’
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Impacts of pollution on groundwater
The practices of urbanization, industrial development,
agricultural activities and mining enterprises have
caused groundwater contamination
The major global challengesIncreasing food demand
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According to the United Nations, as at 2003
population was 6.892 billion and with an average
annual growth rate of 1.2%, the population is
estimated to reach 8.108 billion in 2025
Currently, about 850 million people are
undernourished of which 815 million are in the
developing countries representing 17% of the
population of these countries.
Increasing food demand
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Region
World
Asia
Africa
Europe
Latin America
and Caribbean
USA
Oceania
Canada
2010 population
in 106
6,892
4,157
1,030
739
585
309.6
37
34.1
Rate of annual increase
2025 projected
in %
population
Average
Range
in 106
1.2
0.2 – 2.3
8,108
1.2
0.5 – 1.9
4,845
2.4
1.0 – 2.7
1,412
0.0
- 0.2 – 0.3
747
1.3
1.1 – 1.6
668
0.6
1.1
0.4
0.6
0.6 – 2.8
0.4
351.4
45
39.7
Water supply and sanitation problems
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Supply of clean water and sanitation services are
one of the major global concerns since they directly
affect human health.
Ecosystem challenges
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Biological diversity is in rapid decline in all the
world’s major biomes.
Rates of loss differ between regions and biomes,
loss of biodiversity is greatest among freshwater
dependent species-almost twice as fast as for
marine and terrestrial species
Ecosystem challenges
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
Global trend of living index of biodiversity
Source: MEA 2005
Increase in competing needs and water
governance challenges
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Increased competition
 While water quantity and quality continues to
worsen, water demand (competition) increases
between development sectors (agriculture, human
supply, industry, energy, ecosystem maintenance,
etc.) and users (upstream and downstream).
Increase in competing needs and water
governance challenges
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Governance crisis
 Sectoral approaches to water resources management have
dominated in the past and are still prevailing.
 This leads to fragmented and uncoordinated development
and management of the resource.
 Generally, water management is fragmented among
various users, institutions and physical aggregation levels,
with little regard for solving conflicts and competition.
Background to IWRM
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END OF THE PRESENTATION
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