History and Projection of Hydrological Droughts in the Benin Basin of the Niger River (Benin)

In the context of a changing climate, the Beninese Niger River basin has been the focus of several research studies for the quantification, planning, and modeling of water and related resources for sustainable use. This research aims to characterize the historical (1976-2019) and projected (2021- 2050) hydrological drought of the Beninese Niger River basin. The study used daily observations of rainfall, maximum and minimum temperatures, runoff rates and simulations of HIRHAM and REMO RCMs from fifteen (15) rainfall stations installed around the basin. It uses standardized streamflow indices (SDI) at 12-month and 36-month time steps. The results show that the calculated SDI indices show, on average, for all the model scenarios used, chronological trends of increase. These increases are not significant (are of the order of 0.00001 per year). The analysis of the SDI indices shows that, on average, the hydrological droughts in the Beninese basin of the Niger River will increase at 36 months and decrease at 12 months of the SDI. In fact, these small variations of hydrological droughts will be accompanied by the increase of their duration and the decrease of their magnitudes. The droughts detected in the Benin basin of the Niger River during the historical period will continue until 2050 in the same range but with more extended drought lengths. It should be noted that most of the changes observed in the calculated and analyzed indices are not significant.