A GIS-based MCDM approach to achieve optimal cropping pattern (theory and application in a semi-arid region)

Water and soil are two important inputs in the production of agricultural products in order to ensure food security on the global scale. Considering the critical situation of water in the arid and semi-arid regions of the world, improving the physical and economic water productivity is one of the most effective measures to deal with water shortage and increase agricultural production. The purpose of this research was to present a combined MCDM-GIS framework to investigate the factors affecting the increase in physical and economic agricultural water productivity in order to achieve an optimal cropping pattern. 21 sub-criteria were selected from six criteria including water resources, soil, technical, social, economic, and agricultural. Seven options were selected, including the basic crops of Wheat, Barley, Alfalfa, Forage Corn, Beans, Potato and Orchards. The Delphi method, CVR index, DEMATEL model, and AHP-TOPSIS hybrid model were used to determine criteria and sub-criteria, examine their validity, correlate sub-criteria with each other, and determine the weight of effective sub-criteria, respectively. In the following, classification and data layers for each sub-criterion were prepared, and by applying weighting coefficients and overlapping layers, a map of susceptible areas for each crop was presented. Finally, seven cropping patterns were proposed with priority allocation to each of the seven crops and were compared in terms of physical and economic water productivity. In order to evaluate the proposed hybrid MCDM-GIS framework, Arak County in central Iran with arid and semi-arid climate was considered as a case study. The results of the DEMATEL method showed that the most significant factor in the technical criterion was related to the sub-criterion of using a modern irrigation system with a value of 7.3215, in the water resources criterion related to the type of water source with a value of 4.992, in the soil criterion related to soil texture with a value of 6.9286, in the social criterion related to land ownership status with a value of 6.1285, in the economic criterion related to costs with a value of 10, and in the agricultural criterion related to crop water requirements with a value of 7.3365. According to the results of the combined AHP-TOPSIS model, the water resources criterion in the Barley, Forage Corn, Wheat, and Alfalfa crops, had the highest weight with values ​​of 0.328, 0.26, 0.221, and 0.205, respectively; The soil criterion in the Bean and Potato crops, had the highest weight with values ​​of 0.258 and 0.22, respectively; And the agricultural criterion in Orchards crops, had the highest weight with a value of 0.257. Finally, the fourth cropping patterns (with priority allocation of Orchards with an economic productivity of 65,835 IRR/m3) and the fifth (with priority allocation of Forage Corn with a physical productivity of 4.07 kg/m3) were proposed as superior cropping patterns.