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