Management of Irrigation Water Allocation and Cropping Pattern with emphasis on Deficit Irrigation Strategy (Case study: Qazvin Irrigation Network)

Considering the limitation of water resources and their value in agriculture, the use of any strategy for consumption and optimal use of existing water is essential. One of these solutions is Deficit irrigation. The purpose of this study was to evaluate the effect of different percentages of reduction of water consumption in different growing stages as deficit irrigation scenarios on the Optimization of Water Use and dominant cropping pattern (Wheat, Barley, Sugar beet, Forage Corn, Maize corn and Alfalfa) in Qazvin plain irrigation network. In order to maximize farm income, the PMP method, along with the method of Maximum Entropy (ME) based on the reaction functions of the products yield comparing to water in the space of other constraints was used. The required information for this research was obtained by using two-stage cluster sampling method through completing 144 questionnaires in farm years of 2015-2016. Results showed that by applying deficit irrigation at best condition (first scenario), despite the 5.2% saving in water consumption, it is possible to increase farm income by 0.4%. On the other hand, depending on the severity of the crisis and the amount of the water scarcity, decision to determine the deficit irrigation strategy and the region's cultivation pattern would be different so that if more water conservation is desired, the results of the second and third scenarios are the best option for the optimal use of land resources and the minimum water consumption.