Ensemble modeling of the hydrological impacts of climate change: a case study of the Baro River Sub-basin, Ethiopia

Given the Baro River basin's high climatic variability and frequent flooding, climate change is expected to exacerbate the existing issues in the region. Three best-performing climate models from Coupled Model Intercomparison Project phase 6 (CMIP6) were used to examine the potential impact of climate change on the hydrology of the Baro River Basin. The ensemble of the climate models were bias-corrected for the climate change analysis and a calibrated and validated Soil and Water Assessment Tool (SWAT) model was used to examine the impact of the climate changes under two shared socioeconomic pathways (SSP2-4.5 and SSP5-8.5) in the future (2031-2060). The climate change scenarios projected an increase in precipitation and temperature under all scenarios. Consequently, annual increase in surface runoff, water yield, and potential evapotranspiration (PET) was reported by 30.33% (44.67%), 6% (18.1%,), and 4.49% (6.63%) and decline in groundwater by 13.17% (2.64%) under shared socioeconomic pathway, SSP2-4.5 (SSP5-8.5), respectively. The rise in temperature and PET could be responsible for the decline in groundwater, while the projected increase in precipitation is expected to enhance surface runoff, perhaps leading to flooding. This requires an improved water management policy that involves all sectors and takes into account the equity for different users.