Modeling the impact of climate change on hydrological responses in the Lake Tana basin, Ethiopia

Quantifying the impact of climate change on the spatial and temporal hydrological processes is important for integrated water resource management. This study aimed to investigate the impacts of climate variability on streamflow and evapotranspiration in the Lake Tana basin, Ethiopia. Climate data was simulated using the Weather Research and Forecasting (WRF) model, with a 4km horizontal resolution. Dynamically downscaled climate data for the baseline (2005-2015) and future period (2045-2055) under two Representative Concentration Pathways (RCP4.5 and RCP8.5) were analyzed. The SWAT hydrological model was calibrated and validated using observed streamflow data. The SWAT model was used to estimate the baseline and future hydrology using the bias-corrected climate data. On average, the annual rainfall may increase by 7.9% and 21.2% under RCP4.5 and RCP8.5 scenarios, respectively. The average temperature may rise by 1.4 degrees C under RCP4.5 and 2.2 degrees C under RCP8.5. Climate change under RCP4.5 and RCP8.5 scenarios may cause streamflow increase by 7.2% and 33% and evapotranspiration increase by 11.2% and 15.2%, respectively. The findings provide valuable insights to implement appropriate water management strategies to mitigate and adapt to the negative impacts of climate change and variability on the Lake Tana basin and other regions which have similar agro-ecology.