Niger River Basin
The Niger River basin, located in western Africa, covers 7.5% of the continent and spreads over ten countries, including Guinea, Côte d'Ivoire, Burkina Faso, Algeria, Benin, Niger, Chad, Cameroon and Nigeria.
Algeria and Chad together cover about 9% of the total Niger River basin, but there are almost no renewable water resources in these areas.
The area of the Niger River basin in Guinea is only 4% of the total area of the basin, but the sources of the Niger River are located in this country. The quantity of water entering Mali from Guinea (40 km 3 /yr) is greater than the quantity of water entering Nigeria from Niger (36 km 3 /yr), about 1800 hen further downstream. This is due among other reasons to the enormous reduction in runoff in the inner delta in Mali through seepage and evaporation combined with almost no runoff from the whole of the left bank in Mali and Niger.
The most important areas of the Niger basin are located in Mali, Niger and Nigeria (25 % in each of these three countries). Mali and Niger are almost entirely dependent on the Niger River for their water resources. In the case of Niger nearly 90% of its total water resources originates outside its borders (the Niger River and other tributaries from Burkina Faso and Benin).
Rivers and discharges
The Niger River, with a total length of about 4100 km, is the third-longest river in Africa, after the Nile and the Congo/Zaire Rivers, and the longest and largest river in West Africa.
The countries with the largest water requirements are Mali, Niger and Nigeria. Water problems may arise in the Niger basin if the whole potential is developed. The effect of water abstraction upstream of the inner delta on the quantities that disappear within this delta has not been studied. Probably, as is the case with the Sudd swamps in the Nile basin, the lower the quantity of water entering the swamp area the lower the quantity of water disappearing in absolute as well as relative terms.
In Nigeria, the most downstream country, of the 177 km 3 /year flowing to the sea, only 36 km 3 /year enter from Niger and 25 km 3 /year from Cameroon. The rest is produced internally. More than 1 million ha of its potential of nearly 1.7 million ha is located in the tributary Benue basin.
In all cases, important storage works for the development of irrigation are necessary throughout the whole basin. Probable navigation and hydropower problems may arise if more water is abstracted for agricultural purposes.