Working Group II: Impacts, Adaptation and Vulnerability

Other reports in this collection Demography and Water Resources

Figure 10-7:
Water scarcity and people in Africa (Sharma et al., 1996).

Availability of water in sub-Saharan Africa (SSA) is highly variable. Only the humid tropical zones in central and west Africa have abundant water. Water availability varies considerably within countries as well, influenced by physical characteristics and seasonal patterns of rainfall. According to Sharma et al. (1996), eight countries were suffering from water stress or scarcity in 1990; this situation is getting worse as a consequence of rapid population growth, expanding urbanization, and increased economic development. By 2000, about 300 million Africans risk living in a water-scarce environment. Moreover, by 2025, the number of countries experiencing water stress will rise to 18—affecting 600 million people (World Bank, 1995). Figure 10-7 shows how countries will shift from water surplus to water scarcity as a result of population changes alone between 1990 and 2025, using a per capita water-scarcity limit of 1,000 m3 yr-1. Scarcity statistics also can be associated with challenges to international water resources: Many such basins face water stress or scarcity (Sharma et al., 1996). Long-term precipitation records from the Sahara give a clear indication of declining precipitation in that region (UNEP, 1997). These declines in precipitation register as reduced hydrological discharges in major river basins in the subhumid zones.

Given the climate scenarios discussed in this report, it is apparent that several countries will face water availability restrictions by the middle of the 21st century, if current consumption trends persist. Pottinger (1997) discusses some concerns about future water availability in South Africa. These examples show that the combination of demographic trends and climate change is likely to cause economically significant connstraints in some parts of Africa.

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