Bernd Diekkrüger, Gero Steup, and Aymar Y. Bossa
Hydrology and Earth System Science Discussion


This study evaluates climate change impacts on water resources using an ensemble of six Regional Climate Models (RCMs)-Global Climate Models (GCMs) in the Dano catchment (Burkina Faso). The applied climate datasets were performed in the framework of the COordinated Regional climate Downscaling Experiment (CORDEX-Africa) project. After evaluation of the historical runs of the climate models ensemble, a statistical bias correction (Empirical Quantile Mapping) was applied to daily precipitation. Temperature and bias corrected precipitation data from the ensemble of RCMs-GCMs was then used as input for the Water flow and balance Simulation Model (WaSiM) to simulate water balance components. The mean hydrological and climate variables for two periods (1971–2000 and 2021–2050) were compared to assess the potential impact of climate change on water resources up to the middle of the twenty-first century under two greenhouse gas concentration scenarios, the Representative Concentration Pathways (RCPs) 4.5 and 8.5. The results indicate: (i) a clear signal of temperature increase of about 0.1 to 2.6 °C for all members of the RCMs-GCMs ensemble; (ii) high uncertainty about how the catchment precipitation will evolve over the period 2021–2050; (iii) individual climate models results lead to opposite discharge change signals; (iv) the RCMs-GCMs ensemble average suggests a +7 % increase in annual discharge under RCP4.5 and a −2 % decrease under RCP8.5; (v) the applied bias correction method only affected the magnitude of climate change signal. Therefore, potential increase and decrease of future discharge has to be considered in climate change adaptation strategies in the catchment. The results further underline on the one hand the need for a larger ensemble of projections to properly estimate the impacts of climate change on water resources in the catchment and on the other hand the high uncertainty associated with climate projections for the West African region. An ecohydrological analysis provides further insight into the behavior of the catchment.