Assessment of Climate Change Impact on Water Resources in the Senegal River Basin at Bakel


In this study we assess the impact of climate change on water resources by using uncorrected and bias corrected datafrom the regional climate model REMO simulations over the Senegal River  Basin (SRB).  Both  simulations were used asinput of the Max Planck Institute for Meteorology-Hydrological Model (MPI-HM) over the Upper Senegal Basin (USB). Applying the  bias correction simulations of present  day climate(1971-2000) substantially improved for both temporal and spatial variations of the analyzed climate parameters (precipitation, temperature) when compared to interpolated gridded observations and station data.Additionally, the bias corrected input give better repres entation of the mean river flow, the low flows(10thpercentile) andthe high flows (90th percentile) at the outlet of the USB. For the future, the regional  climate model projections for precipitation show a general decrease by the end of 21st century (2071-2100) for both narios (Representative Concentration  Pathways RCP4.5  and  RCP8.5)  and  datasets  in  the  majority  of  the  basin, except the  Guinean  highlands  where a slight  increase  is  found.  In  case  of  the  potential changes of the maximum consecutive number of dry days and wet days, the northern basin is likely to face the most pronounced increase of dry days and decrease of wet days, although a slight  increase  of  heavy  rainfall  is  found  with  similar  spatial  patterns in both data. Higher decadal variability of the maximum 5-day precipitation with the uncorrected data in RCP8.5 is projected, while uncorrected and bias corrected data depict similar temporal variability for extremely wet days. Furthermore, a general temperature increase is projected over the entire basin  for both scenarios, but more pronounced under the RCP8.5 scenario. Warm night’s percent is found to be higher than warm day’s percent. As for the potential changes of the basin’s hydrology, a general decrease of river discharge, runoff, actual evapotranspiration, soil  moisture  is  found  under  RCP4.5  and  RCP8.5  in  all  simulations.  The  decrease  is higher under RCP8.5 with uncorrected data in the northern basin. However, there are some localized increases  of  runoff in some parts of the basin (e.g.Guinean  Highlands). Furthermore, the available water resources are projected to substantially decrease by more than -50% in the majority of the basin for all data, except the southern basin in Guinea where no change is projected. The impact of the bias correction on the projected climate change signal, affects mainly the magnitude of the signal rather than its direction of change although some modifications may occur in particular months and localities.