AFRICA ENVIRONMENT OUTLOOK
Past, present and future perspectives

EASTERN AFRICA

Eastern Africa experiences high variability in rainfall over time and space, including frequent episodes of flooding or drought. There is also competition for access to water resources between user groups and between countries. Some of the countries are not only dependent on freshwater for domestic, agricultural and industrial consumption, but also for hydropower generation. Hence, freshwater availability and access is a priority issue for the sub-region. Concerns have been raised in recent years about declining water quality and, in particular, about the infestation of Lake Victoria with water hyacinth (Eichornia crassipes).

AVAILABILITY OF FRESHWATER IN EASTERN AFRICA

Eastern Africa, on the whole, is fairly well endowed with freshwater, with total average renewable freshwater resources amounting to 187 km3/yr (UNDP and others 2000). Uganda has the largest share of this, with 39 km3/yr (1 791 m3/capita/yr), whilst Eritrea has the least, with 2.8 km3/yr (data on per capita resources are not available) (UNDP and others 2000). The amount and distribution of rainfall varies across Eastern Africa, with annual averages ranging from 147 mm for Djibouti to more than 1 000 mm for Uganda, Rwanda and Burundi (FAOSTAT 2000). Intra-annual variations are also high, ranging from: 50-300 mm for Djibouti; 250-700 mm for Somalia; 750-2000 mm for Uganda; and 100-2 400 mm for Ethiopia (FAOSTAT 2000). These intra-annual variations determine, to some extent, water availability. For example, more than 75 per cent of Ethiopia's rainfall occurs in intense downpours over a period of 3-4 months, whilst conditions are relatively dry for the rest of the year (Ministry of Water Resources 1998). The intensity of these rains and the lack of vegetative cover cause most rainfall to be lost as run-off or evaporation, with only a small percentage available to recharge underground aquifers. Surface water, therefore, dominates freshwater resources in easter Africa (the groundwater resources of Ethiopia and Eritrea, for example, are just 2.6 km3 of the total resources for these countries) (FAOSTAT 1996). Surface water resources are also important in power generation (see Box 2e.4).

Box 2e.4 Hydropower development in Eastern Africa
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T. de Salis/Still Pictures

The world's largest storage dam is the Owen Falls Dam on the River Nile in Uganda. The 162-megawatt (MW) capacity hydroelectric station at the dam supplies most of Uganda's electricity requirements, and exports 30 MW each year to Kenya. In 1999, however, increased domestic demand in Uganda resulted in a drop in supply to Kenya. Kenya's own hydropower stations supply 78 per cent of the country's electricity (670 MW in 1999). Ethiopia's hydropower potential has been estimated at 15 000-30 000 MW, although less than 2 per cent of this had been exploited by 1993, and 90 per cent of all energy consumed is derived from biomass.With such dependency on hydroelectric power, the eastern African countries are vulnerable to power shortages during times of low rainfall, as experienced during 1999 and 2000 by Kenya and Ethiopia. This, in turn, adversely impacts on the economy, as a result of losses in industrial productivity, commercial activities, and transport and communication networks. The government of Kenya is subsequently promoting the development of diesel and geothermal power plants.

Source: Bermudez 1999, Hailu 1998

Annual freshwater withdrawals are a small percentage of the total available, ranging from less than 3 per cent of the total resources available in Burundi to 12 per cent in Rwanda

The drier countries in the Horn of Africa (Ethiopia, Eritrea and Somalia) frequently experience drought, and have been devastated by drought-induced famine on several occasions over the past 30 years. The largest freshwater source in eastern Africa is Lake Victoria, the second largest lake in the world. Lake Victoria provides freshwater to the populations of Uganda, Kenya and Tanzania directly and, through the Nile River, to Sudan and Egypt. It is also the life and livelihood support of millions of people living around the lake, providing: fish; irrigation water; tourism and recreation; communications; and transport. Other major freshwater lakes in eastern Africa include: Lake Tanganyika in Tanzania; Lake Edward, Lake George, Lake Kyoga and Lake Albert in Uganda; Lake Turkana in Kenya; and eleven freshwater lakes in Ethiopia.

Annual freshwater withdrawals are a small percentage of the total available, ranging from less than 3 per cent of the total resources available in Burundi to 12 per cent in Rwanda (UNDP 2000). However, variability in rainfall results in frequent bouts of water scarcity and, during these times, demand exceeds supply. Human settlement patterns also influence, and are influenced by, freshwater availability. For example, in Kenya only 33 per cent of the land area has adequate and dependable water, but this area is home to 70 per cent of the population.

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Figure 2e.7: Water use by sector in Eastern Africa, 1900-2025

Source: Shiklomanov 1999

With Eastern Africa's population growing rapidly, demand for freshwater is already becoming a problem. Figure 2e.7 shows the current and expected sectoral water use for eastern Africa. Demand for freshwater in the domestic sector is also rising because of increasing per capita water usage. In 1980, per capita urban water usage in Uganda was 90 litres/day; and this was expected to almost double by the year 2000 (NEMA 1999).Eastern Africa is home to a sizeable population of pastoralists. One of the main environmental problems associated with pastoralism is overstocking of animals, leading to depletion of drinking water sources and degradation of vegetation. Currently, Uganda's livestock freshwater demand is reported to be 81 million m3/yr, and is projected to increase to 233 million m3/yr by 2010 (NEMA 1999). Compounded by increasing demand from the domestic sector, this will present huge challenges to water resources management and water supply services. In addition, more land is being brought under cultivation in many countries, as part of strategies to increase food production and security. Ethiopia's potentially irrigable land area is 3.7 million ha, of which only 160,000 ha have been developed (Ministry of Water Resources 1998). Ethiopia is considering expanding irrigation activities into the Shebelle and Genale river valleys, with some of the irrigation plans also calling for diversion of streams. This could have adverse effects on downstream water users, and could potentially disrupt hydrological systems and aquatic ecosystem health.

IPCC predicts that rainfall will decrease in the already arid areas of the Horn of Africa, and that drought and desertification will become more widespread (IPCC 2001). As a result of the increasing scarcity of surface freshwater, groundwater aquifers are being mined. Wetlands areas are also being used to obtain water for humans and livestock, and as additional cultivation and grazing land. This alters hydrological cycles, leaving the surrounding area more prone to flooding.

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View of the southern end of Lake Turkana in Kenya

acknowledgement