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scarcity?
Water Scarcity“Water is life”
Prof Kader Asmal, Chairman, World Commission on Dams
“Whiskey is for drinking, water is for fightin’ over”Mark Twain, commenting on water conflicts in the
American Midwest
“We have one common goal: to provide water security in the 21st Century”Ministerial Declaration of The Hague, World Water
Forum, April 2002
What is Scarcity?
Water shortage, water scarcity, and water stress are three terms used in the discussion of how to meet human water needs
What is Scarcity?
Assuming a minimum need for renewable water per person of 1,000 cubic meters:20 countries, mostly in the Middle East and North Africa
(MENA), are at or below this level now
At 2,000 cubic meters per person:water is potentially a serious constraint, especially in
drought years, and about 40 countries fall in this range, according to the FAO.
While these may be reasonable benchmarks for water shortage, the issue really is one of supply and demand, and so scarcity is a relative term
What is Scarcity?
From a water planning perspective, it is argued that– shortage is absolute– scarcity is relative– stress is a sign of approaching scarcity or
shortage
For example, Tunisia and Kenya both have water availability less than 1000 m3 per capita, but demand is less than supply
What is Scarcity?
Regardless of definition, in most areas:– demand is increasing faster than supply– so scarcity is increasing
Measures of Scarcity
Stress Level
Description People competing for a million m3 of water
Water availability per capita (1000s m3)
1 Water surplus < 200 >5
2 Water management
problems
200 - 600 1.67 – 5.0
3 Water stress 600 - 1000 1.0 - 1.67
4 Absolute scarcity 1000 - 2000 0.5 – 1.67
5 Beyond water barrier
> 2000 <0.5
Source: Falkenmark, 1989
Measures of Scarcity
Source: UNEP, 2002
Measures of Scarcity
Source: UN/WMO, 1997
Stress Level Description Demand/Supply
1 Low < 0.1 or 10%
2 Moderate 0.1 to 0.2
3 Medium-high 0.2 to 0.4
4 High > 0.4 or 40%
Causes of Scarcity(assuming climate is constant)
• Agriculture• Domestic water use• Industrial water use• Pollution• Climate change
Causes of Scarcity
Source: Gleick et al., 2001
Pollution
Source: Gleick et al., 2001
Pollution
Percent population without access to adequate sanitation services
Source: Gleick et al., 2001
Morbidity and Mortality from Water-related diseases
Source: Gleick et al., 2001
Morbidity and Mortality from Water-related diseases
Source: Gleick et al., 2001
Types of Scarcity
• First order scarcity– a physical shortage of water
• Second order scarcity– an institutional inability to satisfy demand
or deliver clean water
• None of the maps shown take account of second order scarcity
Drop in Groundwater Level
Impacts of groundwater over-pumping
• Increased costs• Decreased water quality• Loss of farmland• Subsidence
Subsidence
Subsidence
1952
1985