Northern Africa is one of the most arid areas of the world, with rainfalls that vary widely in terms of both temporal and geographical distribution. Northern African countries are also the most urbanized in Africa and are heavily dependent on fossil fuels for energy. The major issues of concern in the sub-region are therefore climate variability, climate change, and air quality in urban centres.
Figure 2a.5: Predicted inundation of the Nile Delta
Sources: adapted from Otto Simonette, UNEP/GRID Geneva; Prof. G. Sestini, Florence; Remote Sensing Center,Cairo; DIERCKE Weltwirtschaftsatlas
Northern Africa experiences highly variable rainfall and recurrent droughts. The sub-region receives only 7 per cent of Africa's total precipitation and this is not evenly distributed. Egypt, for example, receives just 18 mm/yr of rain (FAO 1995), Algeria, Morocco and Tunisia experienced 6-7 years of drought between 1980 and 1993, and Morocco has experienced a drought in one year out of every three over the last century (Swearingen & Bencherifa 1996).
Flash floods-short-lived but very rapid rises in the level of water courses or filling of dry beds-are a typical feature of several African countries. Often following a brief downpour, flash floods rapidly erode soils, particularly where natural vegetation cover has been cleared from slopes (Swearingen & Bencherifa 1996). In Egypt, flash floods are often accompanied by mudflows which can be more disastrous than the floods themselves (Nemec 1991). Prior to the building of the Aswan High Dam, Egypt was also subject to frequent floods during the rainy season in the Ethiopian plateau (August through October) and to water shortages in years with below normal rainfall.
Swearingen and Bencherifa (1996) have suggested that the hazard of drought in Northern Africa has increased mainly as a result of expansion of cereal cultivation to drought-prone rangeland and reduction of fallow systems. This process was fostered during the colonial period by large-scale land expropriation and by displacement of peasants to marginal lands. It was also influenced by incentive-raising policies for cereal production, mechanization of agriculture, and by increased demand for food associated with rapid population growth.
Drought has major socio-economic significance in Northern Africa because rain-fed
cereal cultivation is predominant. In 1997, for example, Algeria's cereal harvest
decreased sharply as a result of severe drought. In Morocco, agricultural output
recorded losses in 1992, 1995 and 1997. Drought also aggravates the effects
of overgrazing, increasing degradation of natural vegetation and soils. The
Nile River and Delta were much affected by the drought in the 1980s which resulted
in loss of output from agriculture and fisheries and a drop in water level in
Lake Nasser which exacerbated the country's existing irrigation problems (Abdel-Rahman,
Gad & Younes 1994). In the Sudano- Sahelian area, hundreds of thousands of people
were affected by famine, infectious diseases, and displacement (OFDA 1987).