Water of good quality is a precious agricultural resource that requires careful management. Water management is a tool for reclaiming and improving agricultural lands, and it is essential for a balancing the needs of agriculture and the environment. The optimum combination of land and water resources is the key to sustaining the proper conditions for the survival of humans, animals and plants. In humid regions, flood protection and drainage of surplus water are important. In arid regions, irrigation without drainage can cause waterlogging and soil salinity.
Agriculture is the largest user of water in Africa, accounting for 88 per cent of total water use (WRI, UNEP, UNDP and WB 1998). However, with only 6 per cent of cropland under irrigation, there is considerable potential to increase food production through irrigation, and demand for water for irrigation will continue to grow. Some 40-60 per cent of the region's irrigation water is currently lost through seepage and evaporation. This contributes to serious environmental problems such as soil salinization and waterlogging, although water 'lost' in this way may end up in aquifers whence it can be pumped to irrigate nearby fields.