Effect of climate change on water availability in Bilate catchment, Southern Ethiopia

This study aims to evaluate the effect of climate change on water availability in the Bilate catchment, Southern Ethiopia. The bias-corrected outputs of five climate models and their ensemble mean were used for the baseline (1976–2005), the 2050s, and 2080s under Representative Concentration Pathways (RCP) for both RCP4.5 and RCP8.5 scenarios. A semi-distributed physically-based Hydrologic Engineering Center of Hydrologic Modeling System (HEC-HMS) was used to perform rainfall-runoff simulation after sensitivity analysis, calibration, and validation. The forecasted temperatures of the watershed will increase in the future. The forecasting from all the climate models indicated that rainfall of the watershed will increase by 34% in the 2050s and 21% in 2080s under RCP4.5 and RCP8.5 respectively. The discharge projection for almost all climate models shows an increment up to 27% whereas it will decline up to 30% under RCP 4.5 and RCP8.5 respectively in the 2050s. In the 2080s, nearly all climate models will show an increment up to 25% in discharge whereas it will decrease up to 32% under RCP4.5 and RCP8.5 respectively. This research paves the way to reduce the impacts of changing climate for sustainable water resources management.