Climate change and the response of streamflow of watersheds under the high emission scenario in Lake Tana sub-basin, upper Blue Nile basin, Ethiopia

Abstract

Study region: Lake Tana sub-basin, Upper Blue Nile basin, Ethiopia. Study focuses: This study evaluated the degree to which climate is changing in the region, and its impact on stream flow of watersheds simulated by Soil Water Assessment Tool (SWAT) under the Representative Concentration Pathway (RCP8.5) emission scenario using six climate models including CanESM2, EC-EARTH, CNRM-CM5, HadGEM2- ES, NORESM1-M, and CSIRO-Mk3–6–0 by comparing the last thirty years of the past century (1971–2000) and the same years of this century (2071–2100). Bias correction for maximum temperature, minimum temperature, and rainfall data obtained from all climate models have been done using CMhyd software. The SWAT model is calibrated and validated using eleven sensitive hydrological parameters. New hydrological insights: The result revealed that the change in maximum temperature ranges from 2.93 °C (November) and 5.17 °C (March), and the change in minimum temperature also ranges from 3.08 °C to 4.79 °C on a monthly basis. Rainfall is expected to increase up to 29.75% (November) and decrease up to 9.26% (March) in different seasons. Due to the change in climate, a flow is predicted to increase up to 27.82%, 27.47%, 26.47%, and 24.97% in Ribb, Gilgel Abay, Gumara, and Megech watersheds, respectively, and it is also decreasing in winter and spring seasons. On average, the streamflow is expected to increase by 5.89%, 5.63%, 4.92%, and 4.87% in Ribb, Gumara, Megech, and Gilgel Abay watersheds, respectively.

Keywords

• Climate change
• Stream flow
• SWAT
• Lake Tana sub-basin
• Upper Blue Nile basin