Modelling hydrological processes under climate change scenarios in the Jemma sub-basin of upper Blue Nile Basin, Ethiopia

Abstract

This study examines the response of hydrological processes to different climate change scenarios in the Jemma sub-basin of the Blue Nile Basin. Future near-term (2021–2050) and long-term (2071–2100) climate scenarios were developed from six statistically bias corrected Regional Climate Models (RCMs) under two Representative Concentration Pathways (RCPs) scenarios: RCP4.5 and RCP8.5. The outputs of climate models were used as input to a calibrated and validated Soil and Water Assessment Tool (SWAT) model to assess the impact of climate change on the hydrology of the sub-basin. For a robust hydrologic representation, the SWAT model was calibrated and validated at three River gauging stations and provided an acceptable result. The climate scenarios developed from bias corrected RCMs projected an increase in temperature in all models and a decrease in rainfall in the ensemble mean of the models in the near-term and long-term climate scenarios. Climate change may cause a consistent decrease in surface runoff and total water yield and an increase in evapotranspiration under all climate scenarios. This study recommends water management structures which can conserve water for agriculture and other ecosystem services in the Jemma sub-basin and in other similar areas in Ethiopia.