Crop pattern planning and irrigation water allocation compatible with climate change using a coupled network flow programming-heuristic optimization model

Sustainable agricultural production has encountered difficulties such as water scarcity, improper use of available water resources and climate change in arid countries like Iran. Simulation-optimization approaches are helpful tools for crop pattern planning and irrigation water allocation to ensure maximum net benefit is gained from the system. In this paper, optimum cultivation area and allocation of irrigation water in conditions compatible with climate change are obtained for the Borkhar plain in Iran. To achieve this, the network flow programming-based MODSIM, as a water allocation simulation model, is coupled with the grey wolf optimization (GWO) algorithm to obtain the optimum irrigation amounts and cultivation areas in the plain under two conditions: status quo, and with climate change-affected streamflows. The Hadley Centre coupled Model version 3 (HadCM3) and the second-generation Canadian Earth System Model (CanESM2) are used to generate the climatic parameters in the study area. The Identification of unit Hydrographs and Component flows from Rainfall, Evapotranspiration and Streamflow (IHACRES) rainfall-runoff model is applied to calculate the coefficients of variation for the Zayandehroud River streamflows, as the surface water resource for irrigation of the plain. Results indicate that the agricultural net benefit gained from the plain will decrease by 1.5% in the A2 emissions scenario, and by 3.5%, 8% and 17.5% in the three representative concentration pathway (RCP) scenarios in the optimum states obtained by the GWO-MODSIM model. Moreover, the cultivation areas are decreased in the climate change scenarios. Therefore, appropriate management policies should be adopted for adaptation to the likely future situation.