Transcript WATER SCARCITY MANAGEMENT

WATER SCARCITY
MANAGEMENT
by Özden BİLEN
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1. WHAT IS WATER SCARCITY ?
Some conceptual issues
• Scarcity : Excess of demand over usable water or available water in a given
region
• Water Availability : Annual average flow per head of population (Standard
Hydrological Index, SHI)
OR
The number of people dependent on given amount of
water (e.g. 1000 m3/caput = one million people reliant of one billion m3)
• Some problems defining and quantifying SHI :
Annual average (exploitable) flow
SHI(2)
(i) SHI(1) Annual average (total surface) flow or
population
population
e.g SHI(1) = 185 km3/67.3 million = 2700 m3/caput
SHI(2) = 95 km3/67.3 million = 1400 m3/caput
(ii) SHI does not include underground water
(iii) SHI masks extreme local variabilities
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(iv) Scarcity is partly a social and economic construct and it is difficult to
capture in a single quantitative index
• Water scarcity is influenced by social, institutional, policy factors, lifestyle,
water quality etc.
• Social & economic problems might feed back to water scarcity problems,
• A country having better social adaptive capacity may be better off than a
similar water scarce country as measured by SHI.
Ohlson suggests that an index for “Social Water Scarcity, SWS” could be
constructed through dividing SHI by the Human Development Index (HDI)
(according to the UNDP’s human development report ,1997, HDI changes in
between 0.176 - 0.960)
• SHI for water availability has some a.m. drawbacks. However, because of its virtue of
simplicity, it is being used as an “early warning indicator”. Yet a resource analysist
should be aware all these points for assessing and interpretation of water scarcity
issues.
• In order to make comparison among countries or regions using ‘SHI’, attempts have
been made to define a threshold under which a country may be considered in a
situation of water shortage. The limit of 1000 cubic meters per person is often quoted
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as representing a condition of severe water shortage
2. THE WORLD FRESH WATER SUPPLY/
WATER USES AND TRENDS
• SUPPLY
– Hydrological cycle
• Supply by rain on land
• Evaporation and transpiration
• Net effect of hydrological cycle
110 000 km3
- 70 000 km3
40 000 km3
( error margin of  %10 )
– Much of 40 000 km3 flows into the sea as floods, since flow rate is
too large to capture, it is held in soil and swamps, etc.
– Excluding flood flows, baseflow(stable-runoff) is about
9 000-14 000 km3.
– Uneven global distribution is striking. E.g. the Amazon River
accounts for 20% of global average and the Zaire River basin
accounts for 30% of Africa’s total runoff.
– TABLE 1 shows global water distribution by region and per capita
1 km3 = 1 billion(milyard) m3
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Table 1: Worldwide Net Renewable Water Distribution by Region and Per Capita
Net Annual Renewable Water
Population
Per Capita
Resources (billions of cubic meters)
(millions)
(cubic meters)
769
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36 619
Latin America
10 766
466
23 103
North America
5 379
287
18 742
Eastern Europe and
7 256
495
14 659
Africa
4 184
559
7 485
Western Europe
1 985
383
5 183
Asia
9 985
3 041
3 283
355
284
1 250
40 679
5 536
Oceania
Central Asia (ECA)
MENA
World Total
Sources: World Development Report, 1995; and World Bank estimates, 1995.
–In MENA countries ; Yemen 176 m3, West Bank & Gazza 105 m3, Jordan 213 m3, Israel 375 m3 per capita
–China’s situation is particularly important, since that country with approximately one-quarter of the World’s
population can claim only 8 % of its freshwater resources .
–In Africa, Kenya, Somalia, Rwanda, Etophia and some Sub-Saharan countries are water scarce. Other
countries with pronounced rainfall variability include Turkey, Pakistan, India (Western and Southern India),
parts of Mexico.
Global averages only tell us that this is a widely shared problem, there are
huge local and temporal variations.
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• Water Use / Trends
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– Figure 1 indicates that global annual abstractions of water out
of natural system of rivers and lakes was about 1360 km³/year
in 1950 and will be estimated as about 5000 km³/year in 2000
(Abernethy, 1996). In other words, global water abstractions
during the period 1950-2000 increased by more than threefold. In 1950 we were abstracting some 10-15 percent of the
abstractable total; now we take perhaps 35-50 %, and if
present rate of increase continue we can expect to reach the
ceiling (in terms of global averages) in some 30-50 years
from now.
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Abstraction of water from natural systems (000 km3/year)
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Estimates of the available abstractable
resources
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8
7
6
5
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– Currently 70% of the World’s cultivated land is watered
exclusively by rainfall and half of World’s food comes from
rainfed agriculture. However, Figure 1 does not include
agricultural uses under “rainfed” conditions.
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2
1
0
1940
1950
1960
1970
1980
1990
2000
2010
Source: Abernety (1996, quoted from Meybeck, Chapman and Helmer)
Figure 1: Annual global abstraction of water from the
natural system for human use
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http://www.unesco.org/science/waterday2000/water_use_in_the_world.htm
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5500
5000
4500
4000
(km 3/year)
3500
Agriculture
3000
Industry
Municipal Supply
2500
Reservoirs
2000
1500
1000
500
0
1950
1960
1970
1980
1990
2000
Source : I.A. Shiklomanov, 1990. Global Water Resources Nat. Resour., 26: 34-43
Note: Consumption by reservoirs is through evaporation
Figure 2 : World Water Consumption According to Use
– According to the Figure 2, agriculture’s share in overall global consumption was 85 percent in 1950 and dropped to
an estimated 68 percent in 2000 (as global averages). During the same period industrial consumption had grown to 25
percent, while consumption by cities increased from 2 percent to nearly 9 percent.
– The 21st century will be characterized by increased urbanization. By 2025, 60 % of the World population more than 5
billion people will be living in cities. Many countries will be unable to fund both economic growth and adequate
social and physical infrastructure for uncontrolled influx of people to the cities. Some 90 % of waste water generated
in the large urban centers is discharged without any treatment (Butt, 1997).
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– Table 2 says that the big users are not the developing countries
but the richer industrial countries of the temperate zones. On
Total water use Agricultural
Non-agric.
average, Africans only about a quarter of what North Americans
per person
water use per Water use per
use for agricultural purposes, and 3 % of which North Americans
person
person
use for other purposes. Even in Asia, where about 70 % of
m³/year
world’s irrigated land is, quite moderate amounts of water for
1692
829
863
agriculture is being used.
Table 2: Annual abstraction of waters in different regions of the world.
North and Central America
Former Soviet Union
1330
864
466
Oceania
907
308
599
Europe
726
240
486
Asia
526
452
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South America
476
281
195
Africa
244
215
29
World
660
455
205
Source: World Resources Institute, 1992
– Although water is abundant in Africa, poverty has a
tremendous impact on African water resources. Africa has
not developed irrigation to the same extent as other
developing areas, particularly in Asia. For example, India,
which has only about one-tenth the surface of Africa,
irrigates five times as much land (Kandiah, 1988).
Table 3: Sectoral Water withdrawals, by income group
Country
Income
Group
Low-income
Middle-income
High-income
Annual
Withdrawals
m3 per caput
386
453
1167
Withdrawals by sector
Agricultural
Ind.
Dom.
m3/ca
%
m3/ca
%
m3/ca
%
351
91
19
5
16
4
312
69
82
18
59
13
455
39
548
47
164
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Source: World Bank.1992 World Development Report 1992, based on WRI data.
– Table 3 suggests that as countries become richer, their
consumption of water for agriculture increase relatively
little, but non agriculture uses grow enormously.
– Water use patterns differ between industrialized and
developing countries. In the industrial countries, industrialuses account for about 50 %, while in developing countries
industries use no more than 20 %.
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SUFFICIENT WATER RESOURCES + LOW POPULATION DENSITY
WATER SCARCITY
?
In some cases, there is no relation between per capita water availability and
consumption
This analysis shows us that water can be scarce in different ways. There
are two major sources of scarcity with different implications:
• Water Scarcity due to Low Utilization
• Water Scarcity due to High Population Density and/or Aridity
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3. CAUSES OF WATER SCARCITY
• Growth in population
• Environmental degradation
– Modification in land use pattern
– Global climatic change
– Pollution of water resources
• Financial and institutional problems
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Growth in Population
• The United Nations publishes high, medium and low population
projections.
– Most people would agree that high projection can be ignored,
– According to medium projection : 7.8 billion in 2025 continue to grow
indefinitely,
– According to low projection : 7.3 billion in 2025 cease to grow around 2040 at
a level of 7.5 billion people
• Doubling time of World population is about four decades with compound
rate of 1.7% per year (USA 114 years, Egypt 31 years, India 37 years, Iran
24 years, Iraq 19 years, China 66 years, Mexico 32 years (Butts, 1997),
Turkey 44 years with compound rate of 1.6% per year)
• Classical Malthusian Discourse vs. Virtual Water Discourse
• Demographic Race between Countries
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Environmental Degradation
• Modification in Land Use Pattern
–
–
–
–
–
Land use pattern may reduce the amount of surface water
People are forced to use marginal lands
Forests are cleared so that land can be used as agricultural purposes
Reduction in dams’ storage capacity
Poverty feeds back to environmental problems
• Global Climatic Change
– Permanent increase of CO2
– Target values for greenhouse emissions reduction below 1990 levels by
2012 (the EU %8, the USA %7, Japan %6 etc.)
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– CO2 emission by region and per capita is shown in Figure 3 :
– Poor countries argue that they can not afford to put the brakes on their
own domestic industrialization
– Global warming may be irreversible
– Policy approaches for ‘adopting’ or ‘mitigating’ to global warming
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• Pollution of Water Resources
– Water scarcity is not only a problem of the amount of water availability
but increasingly as well a problem of water quality
– 1.2 billion people do not have access to safe drinking water and 2.9
billion lack to adequate sanitation facility
2000
3500
1800
3000
1600
2500
1200
1980
1990
1000
1997
800
600
Millions of People
Millions of People
1400
2000
1980
1990
1997
1500
1000
400
500
200
0
0
Africa
Latin American and
Carribean
Asia and the pacific
Total
Africa
Latin American and
Carribean
Asia and the pacific
Total
Source : World Water Vision (1999)
Source : World Water Vision (1999)
Figure 4 : Number of People without Safe Drinking Water
Figure 5 : Number of People without Adequate Sanita
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4. WATER SCARCITY MANAGEMENT
• To manage water scarcity, solutions could
be divided into two broad categories :
– Supply-side Measures
– Demand-side Measures
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Supply-side Measures
Table 4: Supply-oriented measures for water management:









Surface-water capture and storage.
Long-distance conveyance and inter-basin transfer.
Groundwater exploitation.
Catchment area (watershed) management.
Conjunctive use of surface water and groundwater.
Dual-quality water standards.
Desalination.
Other non-conventional solutions.
Pollution control.
– Renewable freshwater resources is to be utilized to the limits of sustainable yields by
dams, wells for groundwater exploitation, inter-basin water transfers, etc.
– 37 000 large dams were constructed in 20th Century, irrigated area increased from 74
million hectares in 1950 to 274 million hectares at the end of 20th century.
– In some water scarce regions, e.g. ME, seawater desalination, sewage reclamation seems
environmentally economic solutions.
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Table 6 : Alternatives in the Development of Water Resources
Alternatives
Estimated Cost
(US cents/m3)
Re-use of waste water in irrigation
30-60
Desalination of brackish water
45-70
Desalination of sea water
Prevention of illicit uses and leakage, introduction
100-150
5-50
of water saving devices in homes and enterprises
Source : World Bank Estimates (World Bank, 1995)
Only physical facilities failed to respond the needs of growing population.
And these measures should be complemented with Demand-side Measures
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Demand-side Measures
Table 5: Demand-management measures
1. Enabling conditions
Institutional and legal changes,
Utility reforms
Privatization
Macro-economic and sectoral policy.
2. Incentives
Marked-based
Active use of water tariffs
Pollution charges
Groundwater markets
Auctions
Water banking
Non-market
Restrictions
Quotas
Norms
Licences
Exhortations
Public awareness raising Information
3. Direct interventions and programmes
Canal lining.
Leak detection.
Water-efficient user appliances.
Industrial recycling; re-use.
Water efficiency.
– More efficient use of existing supplies.
– Dublin Principles of 1992 : Water has an economic
value in all its competing uses and should be
recognized as an economic good.
– Water pricing is an important element for sectoral
allocation of water.
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5. RECOMMENDATIONS
• Many countries confront the prospect of emerging water scarcity in the
long term and for some that spectre is already on them because of
decrease in the supply of water resource, increase in demand or
unequal resource distribution.
• It is therefore recommended to define and implement a comprehensive
and integrated framework for decision-making on water scarcity
management. Among the multitude of decisions to be taken, two
critical phases have been identified :
– Phase 1 : Water Resources and Demand Assessment
- Development of key indicators,
- Dynamic character of sectoral water demand,
- Forecasting complemented by backcasting.
– Phase 2 : Comprehensive Options Assessment
- Focus on the methodology to be developed so that one can study on
alternative choices in terms of prediction and management of increasingly
scarce water resources,
- Improving quality of decisions through Decision Support System,
- Water politics are shifting from projects to policies and institutional
development,
- As a key element, institutional capacity building,
- Assessing institutional capacity for implementation of selected options.
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