Optimization of Cultivated Area Based on Reservoir Volume and Available Water Scarcity Conditions (Case Study: Arasbaran Dam Downstream)

Suitable planning for the use of limited water resources can increase the production of agricultural crops effectively. In this research, optimal cultivation areas were determined based on reservoir volume and available water scarcity conditions in Arasbaran plain. At first, the net benefit from cultivation in the period (2002-2011) obtained using the Stewart model and the region economic values. Optimal water allocation program was run using the linear programming for each time period of year for maximizing the net benefit objective function considering the restrictions. Optimization performed for five scenarios of available irrigation water (NIV) and for each of them, optimal annual cultivated areas for the proposed plants were obtained. By optimizing the annual cultivated areas, a constant optimal form was also obtained for the region. The results showed that the net benefit changes per unit volume of water, decreased with the increase of available water in both cases as a second degree curve and in all NIVs the benefit of the variable cultivated area was 7% higher. Also, the total net benefit of the annual optimal cultivated area for available water of 8 million cubic meters was 8% more than the fixed cultivated area, and for 10 to 16 million cubic meters, this value increases linearly from 11% to 18%, that shows the relative superiority of the variable optimal cultivated area without considering the management benefits of the fixed mode such as design, irrigation and mechanization.