HISTORICAL AND PROJECTED EXTREME PRECIPITATION INDICES CHARACTERIZATION IN THE NIGER RIVER BASIN (BENIN).
The climate changes of the last decades have made the Beninese basin of the Niger River a study area for several researchers in order to quantify, plan, and model water and related resources for a sustainable use. This research aims at characterizing historical (1976-2019) and projected (2021-2050) extreme precipitation indices in the Beninese Niger River basin. Five extreme precipitation indices namely: total rainfall on wet days (PRCPTOT), number of wet days (R1), maximum daily rainfall (RX1day), maximum rainfall in 5 consecutive days (RX5day), and total rainfall above the 95th percentile based on observed daily rainfall amounts and HIRHAM climate model outputs were calculated for each year and for each station. Kriging was used to characterize the spatial distribution of the obtained indices while the Mann-Kendall trend test was used to analyze their chronological evolution. The result is that the five indices show a latitudinal gradient that decreases with increasing latitude and increasing temporal trends over the historical period. Projecting these indices into the future (2021-2050) shows the same results with the difference that RX1day and RX5day show slight time series decreases. This situation is not without effect on the resources of the basin. The increase in these precipitation indices could lead to natural disasters such as floods, landslides, and soil erosion.
Keywords: extreme precipitation, index, climate projection, trend.
