Development of Adaptive Strategies for Irrigation Water Demand Management under Climate Change

The HadCM3 climate model is applied with greenhouse gas emission scenario A2 to predict climatic variables in the Aidoghmoush Basin (East Azerbaijan, Iran) over the period 2026-2039. The impacts of the predicted climate variables on reservoir inflow and irrigation water use are calculated with the IHACRES model and the Food and Agricultural Organization's (FAO) evapotranspiration method, respectively. The presented results show that reservoir inflow and irrigation water use in the prediction period relative to the baseline period (1987-2000) would be decreased by 0.7% and increased by 6%, respectively. Therefore, the Aidoghmoush Basin is likely to face increasing water shortage under a changing climate. As a result, irrigation water use should be reduced by applying the following three adaptive strategies to climate change: delaying the planting date, applying irrigation deficit stress, and increasing the irrigation efficiency. Simulations are performed to evaluate the yield of the agricultural crops arising from the application of the three adaptive strategies. Optimal reservoir operating rules are calculated considering the adaptive strategies and the dual objectives of minimizing vulnerability and maximizing reliability of water supply by means of multiobjective genetic programming (MO-GP). The strategy of applying water stress would improve the vulnerability and reliability of the irrigation water supply. The strategy of increasing the irrigation efficiency would maintain crop yields in the study area under climatic change.