Evaluating watershed hydrological responses to climate changes at Hangar Watershed, Ethiopia

The aim of this study is to model the responses of Hangar Watershed hydrology to future climate changes under two representative concentration pathway (RCP) scenarios. Future changes in precipitation and temperature were produced using the output of dynamically downscaled data of a regional climate model (RCM) 0.44 degrees resolution under RCP 4.5 and 8.5 scenarios for 2025-2055 and 2056-2086. The future projection of the RCM model of precipitation and temperatures showed an increasing trend relative to the base period (1987-2017). At 2025-2055 average annual precipitation increments of +15.7 and +19.8% were expected for RCP 4.5 and RCP 8.5 respectively. For 2056-2086 of RCP 4.5 and 8.5, a similar trend was also shown as average annual precipitation may increase by +20.1 and +23.4% respectively. The changes of climate parameters were used as input into the SWAT hydrological model to simulate the future runoff at Hangar Watershed. The increment in precipitation projection resulted in a positive magnitude impact on average runoff flow. The average annual change in runoff at 2025-2055 of both RCP 4.5 and 8.5 may increase by +24.5 and +23.6% respectively. In 2056-2086, a change in average annual runoff of +73.2 and +73.2% for RCP 4.5 and 8.5 may be expected, respectively.