Sustainable water use in agriculture faces several challenges due to future climate change, increasing population, and higher living standards. Adapting to possible future changes in climate and sustaining the use of water are some of the challenges that face future agricultural water management. In this research, the sustainability of irrigation water use was assessed by performance criteria that consider the effects of climate change and adaption management on irrigation. The model, built using the Water Evaluation and Planning (WEAP) system, is calibrated using the stream flow and the requirement of water for irrigation. The model was used to examine two future climate projections (A2 and B2), for time periods until 2099, and for four scenarios: (1) an increase in the irrigated area, (2) an increase in crop intensity, (3) a change in the crop pattern, and (4) a combination of increased irrigation area and increased crop intensity. Results show water supply is projected to increase by about 85 and 60% (relative to the historical period) in A2 and B2 climate scenarios, respectively, by the end of the century. The requirement for irrigation water will decrease in the future, relative to the historical period. The sustainability index will also decrease in the future, relative to the historical period. Relative to the baseline scenario, increasing the irrigated area is more sustainable than increasing the crop intensity or combining increased crop intensity with increased area under irrigation. Increasing the irrigated area is more amenable to adaption to possible future climate changes.