Optimum Multi Crop Pattern Planning By Integration of SWAT Simulation Model and the Harmony Search Optimization Algorithm

Crop planning and water resources allocation to the agricultural demands in arid and semi-arid regions such as Iran are a serious challenge. One of the procedures to meet this challenge is to devise approaches for determining the optimal crop patterns based on the limited water resources. In this study, a simulation-optimization approach was applied in which SWAT (Soil and Water Assessment Tool) has been applied for simulating the complex climate-soil-plant relationships. The Harmony Search (HS) algorithm has been coupled with SWAT to find the optimal irrigation plan and crop pattern in two scenarios in the Azadegan plain in the Karkheh basin southeast of Iran. In the first scenario, the crops pattern was the variable of the model while in the second one it was predefined as the existing situation in the pain. The objective function of the coupled model was to maximize the net profit subject to the total available land and water constraints. Results obtained by the developed model show that the net profit gained in the plain has a potential of increasing up to 213% in the first and 25% in the second scenario while the water consumption decreased 28% and 48% respectively comparing to the present situation of the plain. Accordingly, the performance of the HS-SWAT model indicates its capability for solving the optimum crop pattern and irrigation planning problems.