Impact of 1.5 and 2.0 °C global warming on the hydrology of the Faleme river basin

Abstract

Study region: Faleme river basin, Senegal, Mali, and Guinea. Study focus: This study proposes an assessment of the impact of climate change on the hydrology of the Faleme basin, located in West Africa. The applied methodology consists in calibrating and validating the hydrological model GR4J before simulating the future evolution of flows in this catchment under of 1.5 and 2 °C global warming. Observed rainfall, potential evapotranspiration (PET), and river flows were used for calibration and validation of the GR4J model. Furthermore, output of three regional climate models (DMI-HIRHAM, SHIM-RCA, and BCCR-WRF) were used as input to the GR4J hydrological model to simulate future flows. New hydrological insights: The results show good correspondence between the simulated flows and those observed during calibration and validation, with Nash–Sutcliffe efficiencies (NSE) greater than 70 %. Projections show a general increase in mean annual temperature and PET; two models, DMI-HIRHAM and BCCR-WRF, project a decrease in mean annual rainfall, while a third, SMHI-RCA, projects a slight increase. For future flows, a downward trend in annual and monthly average flows is expected in the Faleme basin with input from the DMI-HIRHAM, BCCR-WRF models and the overall mean. However, the GR4J forced by the SMHI-RCA model output projects increased flows. Thus, we make recommendations to mitigate the likely impacts of climate change on socio-economic activities that use water resources.

Keywords

• Faleme basin
• GR4J model
• Climate change