Quantification of the hydrological consequences of climate change in a typical West African catchment using flow duration curves

Abstract The quantification of the consequences of climate change (CC) on the hydrology of the West Africa region was performed using a validated Hydrologiska Byrans Vattenbalansavdelning hydrological model and regional climate models which was driven by different general circulation models (GCMs) from the Coordinated Regional Downscaling Experiment (CORDEX) and the Regional Climate Division of the Institute of Meteorology and Climate Research at Karlsruhe Institute of Technology (IMK-IFU). The quantile mapping and linear-scaling bias adjustment methods were used to correct the inherent errors in the climate simulations. Flow duration curves (FDCs) and generic annual discharge cycles were used in determining the impacts of the change on hydrology (river flow) in the Black Volta catchment within the subregion. It was found out that, in the first segment of the FDCs representing high flows, there was a slight increase in the future flow characterizing a higher watershed water yield from high rainfall events in the future. The 10–40% exceedance probabilities of flow representing wet conditions; 40–60% relating to mid-range flows; 60–90% representing dry period conditions; and low flows (90–100%) all show a decrease in the future flows for four out of the five GCM driving models. Most worrying is the reduction in flows for the 90–100% exceedance probabilities in the future relating to the sustainability of streamflow in the long term. It was concluded that CC could negatively impact and decrease the hydrology of the subregion in the future with most of the rivers in the catchment running dry in most months of the annual discharge cycle.