Impacts of climate change on water balance components of Guder Catchment, Upper Abbay Basin, Ethiopia: SWAT model

Climate change would cause changes in hydrological cycles and water availability. The quantification of hydrological components is critical for assessing and managing water resources. The SUFI-2 algorithm of the Soil and Water Assessment Tool (SWAT) model is used to calibrate and validate the hydrological modeling of the Guder Catchment. Model calibration from (1986 to 1997) and validation from (1998 to 2001) was performed for the monthly flow at the Guder measuring station. After being validated by monthly flow data observed by Guder hydrological station, the model is used to assess the water yield of each hydrological component by simulating the whole watershed hydrological process. Results show that the calibrated SWAT model performs ideal under both the calibration and validation periods. The minimum water depth in the shallow aquifer required for return flow to occur, The effective hydraulic conductivity of the channel and the curve number for moisture condition II CN2.mgt were sensitive flow characteristics. The average yearly precipitation in the Guder watershed will fall in the future under both RCP scenarios. Under observed climate data, the contributions of precipitation to Streamflow, evapotranspiration, and groundwater percolation to shallow aquifers were 88%, 9% and 65%, respectively. The Guder Catchment will have the highest rain loss, up to 14.4%, in the 2080s under RCP 8.5. Between 2057 and 2086, the mean annual maximum air temperature within RCP 8.5 might increase by 4.4 °C, and the yearly average temperature could rise in the 2030s. The expected monthly temperature in both RCP scenarios increases in all months. Under RCP 8.5 and RCP 4.5 in the 2080s, the biggest temperature rise may occur in January, with 6.60 °C and 3.70 °C, respectively. The findings provided a reliable forecast on the climate of Guder Catchment and water balance components in the foreseeable future. It could also be a baseline to determine other effects caused by land cover change and climate change. Local government agencies might also organize projects to address community water challenges.