Niger River - Geography

Geography

The Niger River is a relatively "clear" river, carrying only a tenth as much sediment as the Nile because the Niger's headlands are located in ancient rocks that provide little silt. Like the Nile, the Niger floods yearly; this begins in September, peaks in November, and finishes by May.

An unusual feature of the river is the Inner Niger Delta, which forms where its gradient suddenly decreases. The result is a region of braided streams, marshes, and lakes the size of Belgium; the seasonal floods make the Delta extremely productive for both fishing and agriculture.

The river 'loses' nearly two-thirds of its potential flow in the Inner Delta between Ségou and Timbuktu due to seepage and evaporation. All the water from the Bani River, which flows into the Delta at Mopti, does not compensate for the 'losses'. The average 'loss' is estimated at 31 km3/year, but varies considerably between years. The river is then joined by various tributaries, but also loses more water due to evaporation. The quantity of water entering Nigeria measured in Yola was estimated at 25 km3/year before the 1980s and at 13.5 km3/year during the 1980s. The most important tributary of the Niger in Nigeria is the Benue River which merges with the river at Lokoja in Nigeria. The total volume of tributaries in Nigeria is six times higher than the inflow into Nigeria, with a flow near the mouth of the river standing at 177.0 km3/year before the 1980s and 147.3 km3/year during the 1980s.