Figure 2e.1: Annual renewable water availability per capita (1995)
Source: Shiklomanov 1999
Freshwater availability is one of the most critical factors in development, particularly in Africa. Some 71 per cent of the earth's surface is water. However, less than 3 per cent is freshwater, and most of that is either in the form of ice and snow in the polar regions, or in underground aquifers.
Africa's share of global freshwater resources is about 9 per cent, or 4 050 km3/yr (Shiklomanov 1999, UNDP, UNEP, World Bank and WRI 2000). These freshwater resources are distributed unevenly across Africa, with western Africa and central Africa having significantly greater precipitation than northern Africa, the Horn of Africa and southern Africa. The wettest country, the Democratic Republic of Congo (DRC), has nearly 25 per cent of average annual internal renewable water resources in Africa, with 935 km3/yr. By contrast, the driest country, Mauritania, has just 0.4 km3/yr, or 0.01 per cent of Africa's total (UNDP and others 2000). Average water availability per person in Africa is 5 720 m3/capita/year compared to a global average of 7 600 m3/capita/year, but there are large disparities between sub-regions, as shown in Figure 2e.1
Problems with freshwater availability in Africa are further complicated by highly variable levels of rainfall. As a result, large numbers of people are dependent on groundwater as their primary source of freshwater. In Algeria, for example, more than 60 per cent of all withdrawals are from groundwater and, in Libya, 95 per cent of all withdrawals are from groundwater (UNDP and others 2000). Some countries, including Algeria, Egypt, Libya, Mauritius0, Morocco, South Africa and Tunisia, make use of desalinated water to assist in meeting their withdrawal requirements (UNDP and others 2000, GOM/ERM 1998).
Figure 2e.2: Countries expected to experience water stress or scarcity in 2025
Source: UNEP 1999a
Most African countries also experience extremes of rainfall (periodic flooding or drought). There is some evidence that both droughts and floods have increased in frequency and severity over the past 30 years (OFDA 2000). In particular, the Sahelian zone has experienced a continued decline in rainfall compared to pre-1960s averages, and Lake Chad has shrunk to 5 per cent of its size 35 years ago (NASA Global Earth Observing System 2001). Severe droughts were experienced in 1973 and 1984, when almost all African countries suffered reduced rainfall, and several million people in the Horn of Africa and the Sahelian zone, and in southern Africa, were affected.
The freshwater lakes of Africa have a total volume of 30 567 km3, covering a surface area of 165 581 km2. Not only are they important in water flow regulation, flooding control and water storage, but they are also important for meeting human needs. Lake Tanganyika alone could supply water to 400 million people through the annual extraction of less than 1 per cent of its volume (Khroda 1996). With the exception of Lake Tana in Ethiopia, all African lakes are shared across international borders, which makes international cooperation a necessary condition for equitable use and development of lake resources. Wetlands cover about 1 per cent of Africa's total surface area, and are found in almost every country (WCMC 1992). The largest wetlands include: the Zaire swamps; the Sudd in the upper Nile River; the Lake Victoria basin; the Chad basin; the Okavango delta; the Bangweulu swamps; and the floodplains and deltas of the Niger and Zambezi rivers.
Africa has the highest rate of population growth in the world, and is also one of the regions that is most vulnerable to climate change. The Intergovernmental Panel on Climate Change (IPCC) predicts that average runoff and water availability will decline in the countries of northern and southern Africa, impacting on freshwater ecosystems, and advancing desertification in the Sahelian zone and in northern Africa (IPCC 2001). In addition, increased frequency of flooding and drought will also stress freshwater systems and pressurize water supply networks. As a result, 25 African countries are expected to experience water scarcity or water stress over the next 20-30 years, as shown in Figure 2e.2 (UNEP 1999a).
All the above factors combine to create enormous challenges for water storage, supply and distribution, as well as for water treatment (purification and wastewater treatment). Despite considerable efforts to develop water storage and infrastructure, particularly in the past 30 years, large numbers of people remain without access to water for domestic use, and many farmers do not have access to water for irrigation. By contrast, some industrial, agricultural and domestic users have access to subsidized water supplies, and have no incentive to use water carefully, or to reuse or recycle water. Access to water resources is thus a priority issue for the countries of Africa, together with rising concerns over water quality, due to excessive water withdrawal and declining availability, and pollution from a variety of sources.
|Box 2e.1 Africa's Water Vision|
|Source:World Water Council 2000|