Influence du Bani sur la variabilité saisonnière et interannuelle de la crue du fleuve Niger dans le delta intérieur au Mali

Abstract

The inner delta of the Niger River is a Sahelian wetland, the extent of whose floodplain depends on the rainfall over the upper basins of Niger and its main tributary, the Bani River. The climate crisis that began in 1970 has very little influence the date of the flood peak on the upper reaches of the Niger and its main distributary the Diaka. Conversely, the influence is very strong on the Bani, at the confluence with the Niger at Mopti and in the downstream delta, with earlier dates of flood peak than before. This is due to the smaller extent of the flooded area during dry years. During wet years, the large amount of lateral overflows slows the spread of the flood, resulting in later dates of maximum flood peak. Furthermore, during wet years prior to 1970, these lateral overflows conferred on the upper delta a self-regulatory character by reducing floods at certain stations.