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Freshwater: Africa

Africa's renewable water resources average 4 050 km3/year, providing in the year 2000 an average of about 5 000 m3 per capita/year - significantly less than the world average of 7 000 m3 per capita/year and less than one-quarter of the South American average of 23 000 m3 per capita/year (Shiklomanov 1999 and United Nations Population Division 2001).

Rainfall variability in the Lake Chad basin

Over the past 30 years, the surface area of Lake Chad has varied considerably - from 25 000 to 2 000 km2 - due to rainfall variability over the past 30 years. The lake supports globally important wildlife, particularly migratory birds. The economic activities of about 20 million people are based on the lake's resources. A new GEFfunded project in the Lake Chad Basin aims to decrease environmental degradation by improving cooperation between interested and affected parties, with the benefits from projectrelated activities accruing to the local communities.

Source: Coe and Foley 2001

Lake Chad in 1973 and 1997; red colour denotes vegetation on the lake bed

Source: NASA 2001

However, the distribution of both surface water and groundwater is uneven. For example, the Democratic Republic of Congo is the wettest country, with average annual internal renewable water resources of 935 km3 compared to the region's driest country Mauritania, where the annual average is 0.4 km3 (UNDP, UNEP, World Bank and WRI 2000). The spatial distribution of water resources in the region does not coincide with the highest population densities, resulting in many areas (particularly urban centres) being water stressed or dependent on external sources of water.

At least 13 countries suffered water stress or scarcity (less than 1 700 m3 per capita/year and less than 1 000 m3 per capita/year respectively) in 1990 and the number is projected to double by 2025 (PAI 1995). This presents a major challenge to water planners in terms of supply and distribution.

Groundwater is a major source of water in the region, contributing 15 per cent of Africa's resources (Lake and Souré 1997). The major aquifers are found in the northern Sahara, Nubia, Sahel and Chad basins as well as the Kgalagadi (Kalahari). Groundwater is used for domestic and agricultural consumption in many areas, particularly the more arid sub-regions where surface water resources are limited. However, areas heavily dependent on groundwater reserves are also at risk of water shortages, as water is extracted far more rapidly than it is recharged.