Determining Optimum Major Crops Cultivation Areas in Different Levels of Deficit Irrigation in Qazvin Irrigation and Drainage District

Designing and implementing suitable cropping patterns are necessary to control the limiting factors and optimal utilization of available water resources. In the present study, cropping pattern optimization in Qazvin irrigation and drainage district has conducted considering the five levels of irrigation including I1, I2, I3, I4, and I5 (representing water allocation of 100, 90, 80, 70, and 65 percents of the crop evapotranspiration) and three different levels of cultivated areas including S1, S2, and S3 (representing, current cultivated area, 10 percents increase and 10 percents decrease in the crop cultivated area compared to the current conditions). Crops cultivation areas and water allocation were optimized using a linear programming method and the objective function was to maximize the benefit. The results indicated that the model in condition S2 allocated the most cultivation area to strategic crops and in condition S3 allocated the most cultivation area to economic crops. The condition S3I1 had the highest income (315 million rials) among the all scenarios. Water allocation alternative named I2, increased the economic productivity by average 0.82 million rials per cubic meter of water at all the cultivation area alternatives while maintaining income. Therefore, it was possible to allocate less cultivation area and a lower amount of water while earning more income. Also,  water allocation alternatives named I4 and I5 were not recommended due to reduced income and yield. Model had a limited cultivation area of water-consuming crops such as tomato, sugar beet, and the alfalfa under water shortage condition.