Effect of Pricing and Rationing Strategies of Irrigation Water on Cropping Pattern and Water Demand in Sistan Plain

Since agricultural sector is the largest consumer of water, it is crucial to introduce effective policies to manage water resources in this sector. In the present study, the economic analysis of allocation and pricing of irrigation water on cropping pattern and water demand management in Sistan plain was investigated by use of a positive mathematical programming model (PMP). In this regard, an economic modeling system including a state wide agricultural production model (SWAP) was used. The GAMS software version 24.1 was used to solve the proposed modeling system. The results showed that the use of pricing and allocation policies for irrigation water led to a decrease in the total area of designated cropping products and a reduction in the farm gross margins in Sistan plain. However, the aforementioned policies resulted in savings of 4.594 to 46.256 and 7.123 to 29.484 million cubic meters of water consumed in the region as a result of applying allocation and pricing, respectively. Decrease in total area of cultivation of selected crops under different scenarios of irrigation water quotas policy, especially higher economical crops such as watermelon, melon, and onion. Total gross yield of Sistani farmers would be reduced from 1425694 to 1292677 million Rials, reducing the gross profit by 2.17% to 9.33% in the region's agricultural pattern. Thus, applying the policy of water allocation could save about 30 million cubic meters of water available to farmers. Compared to pricing policy, the use of water allocation policy is recommended due to its superior effect on preserving water resources in the Sistan plain.