The northern Africa sub-region is dominated by arid conditions and extensive deserts, with the exception of parts of southern Sudan and an intermittent narrow strip along the Mediterranean shoreline, where the climate is more humid. The major issue of concern is, therefore, freshwater availability for domestic, agricultural and industrial consumption. Although most people have access to water resources, as a result of high levels of infrastructure development, demand management and integrated water resources management are priorities for improving adequacy and equity in supply. Water quality is an emerging issue, particularly with regard to salinization from poor irrigation methods, and pollution from industrial and domestic wastewater disposal.
Figure 2e.5: Map of the sandstone aquifer in the Nubian Basin
The average total annual precipitation in northern Africa is estimated at 1 503 km3/yr, equivalent to 7 per cent of the total precipitation for Africa (FAO 1995). Distribution of this precipitation varies dramatically, with almost 75 per cent falling in Sudan (the average is 436 mm/yr, but it ranges from 20 mm/yr in the north to more than 1 600 mm/yr in the south) and just 3 per cent in Egypt (about 18 mm/yr) (FAO 1995). Only 5.6 per cent of the precipitation is available for renewing stream flows and for recharging shallow groundwater aquifers. The rest is mainly lost by evaporation, transpiration and seepage. Per capita water availability ranges from 26 m3/yr in Egypt to 1 058 m3/yr in Morocco (UNDP and others 2000).
Further disparity is evident when the countries of northern Africa are compared to those in sub-Saharan Africa. The total internal renewable water resources for northern Africa represent 2.5 per cent of the African total, but northern Africa's withdrawals represent 46 per cent of the total African withdrawals. This disparity partially reflects the harsh climatic conditions, and partially indicates an enhanced level of water resources development. It is the effectiveness of such management schemes, and heavy dependence on transboundary supplies, that has facilitated the growth of the sub-region's population and economies.
Renewable groundwater resources are in the form of shallow alluvial aquifers, recharged from the main rivers (for example, the alluvial aquifer beneath the Nile delta in Egypt) or from precipitation (along the north African Mediterranean coast). In the Sahara desert, the major water resources are the combined NSA and the Continental Intercalaire non-renewable aquifer, which extend from Egypt to Mauritania. Current annual rates of groundwater withdrawal in the sub-region are 407 per cent of the recharge rate in Egypt, and 560 per cent in Libya (UNDP and others 2000). Exploitation of groundwater resources over the past ten years has led to a reduction in water pressure levels at the oasis of the western desert. Overextraction from the delta shallow aquifer has led to increased water salinization and a rapid inland advance of the saltwater interface.
The NSA is a huge fossil water resource, located in the eastern Sahara desert in northeastern Africa (see Figure 2e.5). It is shared among four countries-Chad, Egypt, Libya and Sudan-and contains an estimated 150 000 km3 of groundwater (CEDARE 2000). The total current extraction from the NSA is estimated at 1 500 million m3/yr. The Centre for Environment and Development for the Arab Region and Europe (CEDARE) is developing a regional strategy for the sustainable utilization of the aquifer, to be adopted by the four sharing countries. This strategy will consider sustainability of the resource, as well as the development dimension in each country, based on current and future needs.
Global warming and regional climatic change impose an additional possible threat to the already scarce freshwater resources in northern Africa. The Nile basin has a low run-off efficiency index and a high dryness index, rendering it highly susceptible to climate change (IPCC 1998). Run-off is likely to decrease with global warming, even if rainfall increases, because evaporation rates are so high. Scenarios for the future range from a 30 per cent increase in river flow to a 78 per cent decrease in river flow (IPCC 1998), presenting even greater challenges for international cooperation in water resources management. Northern Africa is already frequently affected by cycles of droughts and flooding and, with climate change, these are expected to increase. In the dry lands, which dominate most of the sub-region, population growth will push people onto marginal land, which is highly vulnerable to desertification, thus exacerbating the impacts of climate change.