The impacts of climate change on hydrological processes of Gilgel Gibe catchment, southwest Ethiopia

minimum temperature will rise by an average of 1.70˚C and 2.79˚C for the intermediate term and far future, respectively. Under high emission scenarios RCP8.5, the maximum tempera- ture will rise by 1.83˚C and 3.55˚C, while the minimum temperature would rise by 2.04˚C and 4.35˚C, respectively, for the intermediate and far future (Table 5). Overall, the analysis showed that RCP8.5’s estimate is warmer than RCP4.5’s. [62] used five distinct GCMs which con- firmed the maximum temperature change in RCP8.5 in the Ilala watershed, Northern Ethio- pia. In addition to changing annually, the forecasted temperature changes were also anticipated to vary seasonally. Fig 12 illustrates that the seasonal changes are greater for the minimum temperature than the maximum temperature. Maximum temperature fluctuations are more pronounced during dry seasons (December, January, and February), while minimum temperature changes are more pronounced during wet seasons (June, July, and August) (Fig 13). The highest seasonal rise of maximum temperature is reported by RCP8.5 during 2071– 2099 while RCP 4.5 reported the lowest rise during 2041–2070. Similar to annual fluctuations, the high emission scenario is anticipated to cause a greater seasonal rise in temperature than the medium emission scenario. In addition, the far future scenario (2071–2099) is anticipated to have higher increases in maximum and minimum tem- peratures than the intermediate future scenario (2041–2070). Overall, the forecast of the maximum temperature and minimum temperature over both

future time horizons are consistent with other researchers’ ranges and falls within the IPCC’s range. Numerous research on climate change in Ethiopia have suggested that temperatures are likely to rise across the country’s various regions. However, the degree of change varies accord- ing on the downscaling methods and kinds of climate models. According to the Global Facility for Disaster Reduction and Recovery [63] analysis on the country profile for climate risk and adaptation, the mean annual temperature is expected to rise by 1.1 to 3.1 degrees Celsius by the 2060s and by 1.5 to 5.1 degrees Celsius by the 2090s. According to the analysis by [61], the entire upper Blue Nile basin’s average annual temperature will rise by 1.5˚C, 2.6˚C, and 4.5˚C between the years 2011 and 2040, 2041 and 2070, and 2071 and 2100, respectively. According to [64] study’s on the entire Nile Basin, which used an average of 11 GCMs, the yearly average temperature change between 1950 and 1999 and 2010 to 2039 will range from 0.91 to 1.9 Fig 12. Seasonal projected change in mean maximum temperature in Gilgel Gibe catchment for 2041–2070 and 2071–2099 under RCP4.5 and RCP8.5. https://doi.org/10.1371/journal.pone.0287314.g012 PLOS ONE The impacts of climate change on hydrological processes of gilgel gibe catchment PLOS ONE | https://doi.org/10.1371/journal.pone.0287314 June 28, 2023 18 / 28