Africa has abundant freshwater resources in large rivers and lakes such as the Congo, Nile and Zambezi river basins, and in Lake Victoria, the second largest freshwater lake in the world. However, there are great disparities in water availability and use within and between African countries because the water resources are so unevenly distributed. Other contributing factors are the inadequate assessment and underdevelopment of water resources, the lack of technical and institutional infrastructure as well as the lack of investment in water resource development.
Most freshwater comes from seasonal rains, which vary with climatic zone.
The greatest rainfall occurs along the equator, especially the area from the Niger delta to the Congo River basin. The Sahara desert has virtually no rain. In Western and Central Africa, rainfall is exceptionally variable and unpredictable. While the Sahelian countries have limited supplies of freshwater, most countries in the humid tropical zone have abundant water. The availability of water varies considerably even within countries and the situation is further complicated by frequent droughts as well as inappropriate water management programmes.