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.
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| Source: Bermudez 1999, Hailu 1998 |
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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
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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
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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
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