Niger River Basin Freshwater in Average Year

Within the Niger river the highest runoff is recorded during the rainy season which lasts from June to October. Runoff is important for maintaining channel flow particularly as a number of hydroelectric dams are placed on the Niger River and its tributaries ( The Niger River is the largest in West Africa and the inner delta formed by the river is an important network of channels and swamps which can spread over 30,000 km2 in the flood season. Flow decreases due to swampy and sandy soil that encourages seepage (recharging ground water). Evaporation is high especially where the basin touches the lower reaches of the Sahel, or sub-desert region. An inner delta forms just ahead of the middle section where, during the rainy period, the northern reaches remain low in runoff. It is estimated that water entering the inland delta takes 3 months to exit and is important in sustaining inland habitats.

Freshwater Legend (mm/month)

Bargraph referencing the colours on the evaporation maps.

Other Niger Maps

Niger Freshwater Maps