Groundwater recharge evaluation due to climate change using WetSpass-M distributed hydrological model in Bilate river basin of Ethiopia

Abstract

Sporadic change in climate is altering the hydrologic processes affecting the groundwater recharge (GWR) systems across the planet. Distributed groundwater recharge (DGWR) is studied in the Bilate river basin of Ethiopia to predict the current and future for long-term groundwater utilization, planning and management. Precipitation and temperature were acquired from the Coordinated Regional Climate Downscaling Experiment (CORDEX) Africa platform using RCP4.5 and RCP8.5 scenarios for the periods 1986–2015, 2041–2070, and 2071–2100. WetSpass-M distributed hydrological model was used to analyze the seasonal and annual GWR under varying amplitude and dispersion. Particularly in the spring and summer, due to increase in temperature and scanty rainfall GWR is severely affected. Average minimum and maximum temperatures are anticipated to rise by 0.11 °C–0.61 °C and 0.75°C–2.15 °C respectively during mid-RCP4.5 and long-term RCP8.5 scenarios. For the baseline period, RCP4.5, and RCP8.5 for both mid-term and long-term periods, the maximum annual GWR was predicted to be 442.5 mm/yr, 371.6 mm/yr, 347.6 mm/yr, 319.6 mm/yr, and 327.41 mm/yr, respectively. The maximum annual GWR is decreased by 83.3 mm–138.7 mm in the RCP4.5 scenario during the years 2041–2071, but in the RCP8.5 scenario during the years 207–2100, the maximum annual GWR is decreased by 26.1 mm–72.3 mm, while the mean annual GWR is decreased by 26.1 mm–72.3 mm. There have been numerous studies about how climate change (CC) may affect GWR, but this study focuses specifically on forecasting precipitation and temperature to determine GWR in the basin. The results could be crucial for suitable water management use by interpreting the direct and indirect effects of climate change on recharge systems.