Natural and man-made activities in the sub-basin have influenced the climate change and induced the hydrology of the watershed. Changes in climate could affect metrological parameters, and thus the available water resource and which directly lead to changes in irrigation water requirement in agriculture. Therefore, this study was conducted to assess the current and future crop water use of major crops grown under climate change scenarios in the Didesa sub basin. For this study, daily metrological data such as maximum temperature, minimum temperature, wind speed, sunshine hours, and humidity and precipitation data were used. Crop and cropping pattern data were used for the study area. Future climate data predicted for the periods 2025, 2055 and 2085 considering both the A2 and B2 scenarios using GCM HadCM3. Crop evapotranspiration (ETo) was calculated using mean monthly climate and rainfall data with help of the CROPWAT 8.0. The crop water requirement (CWR) was determined for each crop in the project area of the study area for the baseline period (2020) and downscaled climate data. Crop water use of tomato crops increased from 1.2% and 1.4 % for H3B2 and H3A2 scenarios, respectively at 2085s. Similarly, sugarcane water requirement increased from 1.5% to 1.8% for H3B2 and H3A2 scenarios, respectively at 2085s. This increasing crop water requirement results in the crop water stress during scenario periods. Therefore, to solve water shortages, alternative sources of water supply such as ground water and water harvesting technologies should be studied and integrated water management systems should be implemented. In addition, to improve the efficiency of irrigation water, different irrigation methods such as drip irrigation should be improved in areas that have implication for driving climate change resilience as early warning.