OPTIMAL CULTIVATION RULES IN MULTI-CROP IRRIGATION AREAS

A linear programming model is developed for annual cultivation rules of multi-crop irrigation areas in a reservoir-irrigation system. The objective is to maximize the annual benefit of the system by assigning annual irrigation areas as well as monthly irrigation schedules over the planning horizon. The annual irrigation areas are considered to be a linear function of both total volume of storage at the end of the last operating year and the average inflow rate of the current year. The methodology is applied to a previously analyzed problem, without considering operational rules. Results are compared with those of a linearized modeling of the problem and the advantages of the proposed approach are discussed. Furthermore, results indicate that although there is a 40% decrease in the value of the objective function when using cultivation rules, the model is nonetheless a helpful tool for planners and/or stakeholders to decide at the beginning of each year how much and which type of product should be cultivated. This has been verified by applying the extracted rules with a generated five-year inflow time series. Results show the robustness of the rules facing the uncertainty of model parameters. Copyright (C) 2008 John Wiley & Sons, Ltd.