Research Article ModellingtheImpactsoftheChangingClimateonStreamflowin Didesa Catchment, Abay Basin, Ethiopia Amsalu Gudeta Awetu 1 and Tadesse Tujuba Kenea 2 1 aculty of Water Resources and Irrigation Engineering, Water Technology Institute, Arba Minch University, P.O. Box 21, Arba Minch, Ethiopia 2 acultyofMeteorologyandHydrology,WaterTechnologyInstitute,ArbaMinchUniversity,P.O.Box21,ArbaMinch,Ethiopia Correspondence should be addressed to Tadesse Tujuba Kenea; tade2j@gmail.com Received 7 November 2022; Revised 28 June 2023; Accepted 4 July 2023; Published 12 July 2023 Academic Editor: Anzhen Qin Copyright © 2023 Amsalu Gudeta Awetu and Tadesse Tujuba Kenea. Tis is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Te Didesa catchment, which is the second largest subbasin of the Abay basin, signifcantly contributes to the Blue Nile’s outfow. Understanding the dynamics of water availability under the changing climate in such a basin assists in the proper planning of land use and other development activities. Tis study presents changes in climatic elements such as rainfall, temperature, and evapotranspiration using observation data and regional climate models (RCMs) under two representative concentration pathways (RCPs) for three future periods. We use a calibrated hydrological model to further assess climate change’s efects on streamfow. We select three RCMs and their ensemble’s mean by evaluating their performance with respect to observations. We apply the modifed Mann–Kendall test to detect trends in each dataset. Te result shows that annual mean maximum and minimum temperatures increase in the catchment for the 2021–2040, 2041–2070, and 2071–2100 periods as compared to baseline (1989–2018) under both RCP4.5 and RCP8.5 scenarios. Annual mean maximum temperature and potential evapotranspiration experienced a signifcant decreasing trend during the year from 1989 to 2018. Furthermore, there was an increasing trend in annual rainfall from 1989 to 2018, which could be related to the cooling of sea surface temperature over the equatorial Pacifc. We detect an increasing trend in temperature in both scenarios and all periods; however, no clear trend pattern is found in rainfall. Te result from hydrological model simulations reveals that the mean monthly streamfow slightly increases in the winter season while it decreases during the main rainy season. Further study of detailed weather systems, which afect the subbasin’s climate, is recommended. 1.Introduction About half of the global population is experiencing severe water scarcity due to climatic and nonclimatic factors for some part of the year. Te hydrological cycle is intensifed due to anthropogenic climate change, which is afecting the physical aspects of water security. Tis has exacerbated water•related vulnerabilities caused by other socioeconomic factors 1]. Te recent drying trends since the 1980s match the warming observed across the continent of Africa 2], including Ethiopia 3]. Te change in climate is a major challenge that afects the hydrological cycle. Besides, the Intergovernmental Panel on Climate Change (IPCC) assessment report shows that the global average temperature would rise with an increasing total carbon dioxide concentration. Furthermore, climate change induces changes in tributary fow characteristics and changes in rainfall patterns, afecting the interception process and changing the evapotranspiration process 4, 5]. Developing countries are likely among the most vul• nerable to the impacts of the changing climate due to the lack of economic development and institutional capacity 6]. Te impacts of climate change have the potential to weaken and even reverse the progress made in improving the socio• economic well•being of African countries 7]. Ethiopia and other developing nations will be more susceptible to the efects of climate change. A large part of the country is arid and semiarid, making it highly prone to Hindawi Advances in Meteorology Volume 2023, Article ID 2730839, 15 pages https://doi.org/10.1155/2023/2730839