Impact of statistical bias correction on the projected climate change signals of the regional climate model REMO over the Senegal River Basin

Abstract

We assess the impact of a statistical bias correction method based on histogram equalization functions on the projected climate change signals of regional climate model (RCM) simulations over the Senegal River Basin in West Africa. Focus is given to projected changes in precipitation, temperature, and potential water balance (P-PET) following the RCP4.5 and RCP8.5 emission scenario pathways by the end of the 21st century (2071-2100) compared to the 1971-2000 reference period. We found that applying the bias correction substantially improved the simulations of present day climate for both temporal and spatial variations of the analysed climate parameters when compared to gridded observations data sets and station data. For the future, the non-corrected RCM projections show a general decrease of precipitation by the end of 21st century for both scenarios over the majority of the basin, except the Guinean highlands where a slight increase is found. The reduction in mean precipitation is accompanied by a projected increase in the annual number of dry days, most pronounced in the northern basin. Furthermore, a general temperature increase is projected over the entire basin for both scenarios, but more pronounced under the RCP8.5 scenario. In addition, the deficit in the water balance (P-PET) above 12°N is projected to increase in the future. Applying the bias correction to the RCM projections leads to a general dampening of the projected change signals, strongest in the case of heavy precipitation events. However, for all analysed parameters the general directions of change as well as the predominant large-scale change patterns are conserved after applying the bias correction. © 2015 Royal Meteorological Society

Modelling blue and green water availability under climate change in the Beninese Basin of the Niger River Basin, West Africa

“…Mbaye et al () working in western Sahel over the Senegal River Basin showed that precipitation would decrease by the end of the century for most parts of the study area with the exception of the southern part (Guinean Highlands). Potential water yield (the difference between precipitation and potential evapotranspiration) would decrease as well.…”

“…Hence, more research is needed to better understand, with less uncertainty, the direction and magnitude of climate change impacts over West Africa. In that sense, multimodel assessment approach is thus expected to capture the uncertainties in the modelling of climate change impacts (Mbaye et al, ; Oyerinde et al, ; Yira et al, ). The objectives of this study are therefore, for the Beninese part of the Niger River Basin, to statistically downscale the outputs of RCMs and assess future climate trends; quantify the impact of climate change on future blue water (BW) and green water (GW) availability; and quantify the uncertainty associated with the evaluation of BW and GW. …”

“…For Oyerinde et al (2016), climate change in the future will be beneficial for hydropower production caused by an increase in precipitation and streamflow despite an increase in potential evapotranspiration for more than 70% of the Niger River Basin (2.2 million km 2 ), the largest river basin in West Africa. Mbaye et al (2015) working in western Sahel over the Senegal River Basin showed that precipitation would decrease by the end of the century for most parts of the study area with the exception of the southern part (Guinean Highlands). Potential water yield (the difference between precipitation and potential evapotranspiration) would decrease as well.…”

Future Climate Change Impacts on Streamflows of Two Main West Africa River Basins: Senegal and Gambia

“…However, Bodian et al [16] used a model at monthly step to predict streamflow which is not adapted for flood and base-flow modeling. Recently, Mbaye et al [17] used the regional climate model REMO as input for the Max Planck Institute for Meteorology-Hydrology Model (MPI-HM) and found general decrease of river discharge, runoff, evapotranspiration, soil moisture under the two Representative Concentration Pathways (RCP4.5 and RCP8.5) by the end of the century in the Upper Senegal Basin (West Africa) at Bakel station. Mbaye et al [17] did not take into account the effect of Manantali dam in the river and used only one climate model which can bias the results.…”

“…Recently, Mbaye et al [17] used the regional climate model REMO as input for the Max Planck Institute for Meteorology-Hydrology Model (MPI-HM) and found general decrease of river discharge, runoff, evapotranspiration, soil moisture under the two Representative Concentration Pathways (RCP4.5 and RCP8.5) by the end of the century in the Upper Senegal Basin (West Africa) at Bakel station. Mbaye et al [17] did not take into account the effect of Manantali dam in the river and used only one climate model which can bias the results. In the Gambia River Basin, only the study of Ardoin-Bardin et al [18] was interested to the impact of climate on river basin water resources at Gouloumbou station by using four GCM (CSIRO-Mk2, ECHAM4, HadCM3 and NCAR-PC) under the AR3 (A2) scenario and the GR2M hydrological model.…”