The Optimal Allocation of Water-Land-Crop System Based on Fuzzy Linear Programming Models
基于模糊线性规划模型的水-土-作物系统优化配置研究

In order to further plan and develop the agriculture of Pudong irrigated areas in Shaanxi province, this paper has applied the linear programming and fuzzy optimization models into the planning and management of available land-water-crop system. In this study, the linear programming and fuzzy optimization models were used to optimize the economic return, crop production and labour utilization, and to search the related cropping patterns and intensities with specified land, water, fertilizer and labour availability, as well as constraints of water use patterns. The optimal allocation of agricultural systems is a complex large scale system, which involves land resources, water resources and crops grown, and at the same time is subjected to the effects of many uncertainty factors, so using an allocation model solely is difficult to coordinate and aggregate all of the system characteristics. Based on the situation of the study area, the land-water-crop system planning of Pudong irrigated area has been carried out with the fuzzy optimization of three independent linear-programming-based objective functions and one multi-criteria decision function. The land and water resources have been optimally allocated by three linear programming models in order to achieve the maximum value of the objective function. Then we have decided to keep all the three objectives of the linear programming models at the same priority level to obtain the compromised solution in a fuzzy environment that incorporates the imprecision in fuzzy goals and fuzzy constraints. These non-structural models can facilitate the conjunctive use of available surface water and groundwater resources. Besides, a comparative evaluation along with the benefit-cost ratios of the existing and proposed farming systems has been presented. The results show that the LPP model has the least deviation from the optimized values of production and benefit as compared to the other models, followed by the LPNR model and models like LPP, LPNR and FOP are best suited for the study area, depending upon the objectives of the decision makers and the farmers. The linear-programming-based management models have the capability for optimal land-water-crop system planning in case of single criteria decision systems, while the fuzzy-rule-based management models can be used to deal with multiple criteria management decision systems, providing a powerful reference for the establishment of scientific optimal allocation of the agricultural system of land-water-crop. The method that applies the multi-objective fuzzy linear-programming-based management models into the optimal allocation of land-water-crop systems is feasible, and the reasonable distribution of land and water resources, has improved crop production and net benefits.