Application of Positive Mathematical Programming Model to Analysis the Effect Policy of Changes in Price and Quantity of Agriculture Water on Cropping Pattern of Crops of Neka County

In this study, in order to save and improve agricultural water consumption in Neka county, the farmers' response to the policy of price change and the amount of available water in agriculture was studied. In this regard, the Positive Mathematical Programming (PMP) method was used to simulate the farmers' responses in Neka county. Data gathering was done by Simple random sampling method during the 2011-2012 crop year. The scenarios included increase in water prices per cubic meter of 4, 6 and 8 times, and 20, 30 and 50 percent reduction in the amount of available water and as a complementary policy, increase of 4, 6 and 8 times the price of water, with decrease of 50, 30, 20% of available water which was considered. The results showed that with the policy of raising the price of water up to 4 times and the policy of reducing the amount of water up to 20%, there is not Considerable change compared to the primary data. with regard to the policy of rising water prices, the shift in the pattern of cropping of irrigated products into rainfed products and the level of crops are allocated to products that require a lower water requirement and higher production value. In fact, this policy doesn’t reduce water consumption significantly. Also, in the policy of reducing the amount of available water, There have been no changes from cropping pattern of irrigated crops to rainfed crops, but Water consumption decrease significantly. In conclusion, water demand is elastic to its price.