Evaluation of impact of climate change on the watershed hydrology, case of Wabe Watershed, Omo Gibe River basin, Ethiopia

Abstract

Investigating the impact of climate change on watershed hydrology is vital in order to undertake proper mitigation meas ures and to develop a sustainable climate change adaptation strategy. The objective of this study was the evaluation of the impact of climate change on watershed hydrology, a case study on Wabe watershed, Omo Gibe River basin, Ethiopia. The observed hydro-meteorological data for the baseline period of 1990–2019 was collected from the Ethiopian Ministry of Water, Irrigation and Energy (MoWIE) and the Ethiopian Meteorological Agency (EMA). Three regional climate models (RCMs), i.e., RACMO22T, RCA4, and CCLM4-8-17 derived by one MOHC-HadGEM2-ES Global Climate Model (GCM) were downloaded from CORDEX-Africa. The climate projection of the three RCMs and their ensemble for near-future term (2024–2053) and mid-future term (2054–2083) under RCP4.5 and RCP8.5 climate change scenarios was conducted based on the 1990–2019 baseline data. The climate projection showed that the monthly rainfall will increase by 44.3% in the near future term under RCP4.5 and by 34.8% and 49% under RCP4.5 and RCP8.5, respectively, in the mid-future term by the CCLM4-8-17 model while a maximum decline of − 45.3% and − 27.1% in rainfall amount was detected by RCA4 in the near- and mid-future terms, respectively, under RCP4.5. The mean monthly maximum temperature rises by 2.55 °C to 3.1 °C while the mean monthly minimum temperature increases by 1.54 °C to 1.89 °C in both time horizons, respectively, under RCP4.5 and RCP8.5. The SWAT model outcome indicated that the stream fow will decline by − 10.67% and − 17.94% under RCP4.5 and RCP8.5, respectively