Use of Water in Africa

1.3.3 Use of Water in Africa

Africa is home to about 13 percent of the world’s population, but has only about 9 percent of the world’s water resources (UNEP, 2002). Average annual per capita availability of water resources in Africa is lower than the world average and higher than that of only Asia (see Table 1.5). This low level of water availability in Africa is due to three basic factors (Vordzorgbe, 2003):

1. A significant decline in the average rainfall since the late 1960s. In recent times, most of the continent has experienced increased aridity as mean annual rainfall has reduced by 5 percent to 10 percent between 1931–1960 and 1968–1997. The decline in Sahelian rainfall has been the largest sustained decline recorded anywhere in the world since instrumental measurements began, while deviations from the trend have been larger than in other arid regions of the world.

2. Low runoff due to high evaporative losses. Total runoff as a percentage of precipitation is the lowest in the world, at about 20 percent, compared to 35 percent for South America and about 40 percent for Asia, Europe, and North America.

3. High variability of supply, due to highly variable rainfall. For example, precipitation ranges from almost zero over some desert areas in Namibia and parts of the Horn to very high levels in the western equatorial areas. The major outcome of these extremes of rainfall is a high frequency of floods and droughts on the continent. The high variability of rainfall and river flow also reduces runoff and exacerbates vulnerability to erosion and desertification. This extreme variability of climate and hydrological conditions imposes high costs on livelihoods and raises the risks of development interventions.

GlobalFreshwaterResourcesandTheirUse

Only about 4 percent of the nearly 4 million km 3 of renewable water available annually is used in Africa. Except for the northern Africa, the total amount of water withdrawn in all other subregions for use in agriculture, public water supply, and industry show that at both continental and subregional levels the withdrawals are rather low in relation to both rainfall and internal renewable resources. This may reflect a low level of development and use of water resources in the continent. However, variability in rainfall results in frequent bouts of water scarcity and, during these times, demand exceeds supply (UN Water/Africa, 2006).

In 2000, because of inadequate water storage, processing, and distribution systems, about 36 percent of the population did not have access to potable water, but the depriva- tion is higher in rural areas, where as much as 50 percent lacked access to safe water. Also, because of low investment in water supply and distribution infrastructure, increasing demand and weak water management policies, access to water is highly skewed in favor of urban consumers and some agricultural and industrial users (Vordzorgbe, 2003).

It is estimated that more than 75 percent of the African population uses groundwater as the main source of drinking water supply. This is particularly so in North African countries, such as Libya, Tunisia, and parts of Algeria and Morocco, as well as in southern African countries, including Botswana, Namibia, and Zimbabwe. However, groundwater accounts for only about 5 percent of the continent’s total renewable water resources and the groundwater withdrawal is mainly from the nonrenewable aquifer storage. In South Africa, for example, groundwater accounts for only 9 percent of the renewable water (UN Water/Africa, 2006).

Owing to the highly variable levels of rainfall in Africa, large numbers of people are dependent on groundwater as their primary source of freshwater for various uses (UNEP, 2002). For example, in Libya and Algeria 95 percent and more than 60 percent of all withdrawals, respectively, are from groundwater. Algeria, Egypt, Libya, Mauritius, Morocco, South Africa, and Tunisia are increasingly looking at the use of desalinated water to assist in meeting their withdrawal requirements (UNEP, 2002).

Water Use in Lake Chad Basin Water uses in eight countries of the Lake Chad Basin are typical of nonindustrialized, undeveloped, and developing countries in Africa and around the world. The majority of freshwater consumed in the region is used for agriculture followed by domestic use

(Fig. 1.11). In Africa, Nigeria is the sixth largest user of water by volume (4 billion m 3 /yr; Revenga and Cassar, 2002). In the Sudan sector of the basin (West Darfur), more than 50 percent of water is obtained from dug wells with bucket collection (The World Bank, 2003). Women have to travel great distances in order to gather water for drinking, cooking, and other everyday activities. Reservoirs formed by the Tiga and Challawa Gorge dams of the Kano City Water Supply (KCWS) supply the large Nigerian urban centre of Kano City for domestic and industrial purposes (GIWA, 2004).

Traditional agriculture in the basin is predominantly rain-fed. The rivers in the Chari- Logone and Komadugu-Yobe subsystems support flood farming and recessional farm- ing. Farmers in downstream areas therefore depend largely on river flow because rainfall is low and variable. The many large irrigation projects are located predominantly in the Komadugu-Yobe Basin.

According to GIWA (2004), there is little information concerning groundwater, but it is considered to be abundant, especially in the unconfined regional aquifers. However,

26 ChapterOne

l (liter/person

ithdrawa

w Water

Chad

CAR Cameroon Nigeria Niger Sudan Libya Algeria

Country

F IGURE 1.11 Freshwater withdrawal per person per day by economic sector in countries of the Chad Lake Basin, Africa. (From GIWA, 2004; source of data The World Bank, 2002.)

because of the recent declines in aquifer recharge due to prolonged droughts and reduc- tion in river flows, aquifers are currently vulnerable to overextraction exceeding their safe yield. Surface water scarcity during these droughts as well as adaptation strategy increased the extraction of groundwater for human, agricultural, and pastoral purposes (GIWA, 2004; Thieme et al., 2005). There has been an indiscriminate drilling of wells that has led to a decrease in groundwater reserves. Groundwater drawdowns of several tens of meters have been reported in the Maiduguri area of Nigeria due to overpumping. Isiorho et al. (2000) estimate that 10 to 25 percent of water in the region is used ineffi- ciently and attempts to improve the situation have achieved little. The droughts of the 1980s triggered the mass drilling of 537 wells between 1985 and 1989. This rapid devel- opment resulted in unsatisfactory logging of wells by several contractors who were not supervised. Most of these deep wells are uncapped and free-flowing. Normally, the local authorities cap artesian wells, but local people uncap them and allow the water to flow out and cool so that their animals can use it. This free flow of water is very inefficient and results in vast amounts of water being lost due to the high rates of evaporation in the region (Isiorho et al., 2000). Water points at Ala near Marte (Nigeria), monitored on a routine basis by the Lake Chad Basin Commission, have shown a sharp decline of about

4.5 m within a period of 1 year attributable to the general decline in the artesian pressure within the basin. Most desert species have also disappeared due to the declining water table (GIWA, 2004).