Effects of Water Pricing Policy and Water Quota on Water Resources Sustainability in Golestan Province

Sustainability of water resources has the most important role in the sustainability of agricultural systems. In this study,  positive mathematical programming was applied in 2018-19 to evaluate the sustainability of water resources and to determine the cropping pattern in Golestan province based on water demand management policies, i.e. water price increase by 50% and 100%, and reducing water quota by 10% and 20%. First, according to water price increases and water quota policy scenarios, the cropping pattern was evaluated in this area. Then, by using the sustainability indicators such as gross margin (GM), water consumption, economic efficiency, and labor efficiency the sustainability of water resources was calculated. Based on water price increases by 50% and 100%, water consumption and GM decrease by, respectively, (2.72% and 5.44%) and (5.06% and 9.99%). Also, based on water quota policy of 10% and 20% reduction, water consumption and GM decrease by, respectively, (8.9% and 11.56%) and (0.54% and 1.75%). In addition, GM per unit of water in agricultural sector decreases by 2.41% and 4.81% in response to to water price increase by 50% and 100%, respectively, and in case of 10% and 20% reductiion in water quota policy, it increases by, respectively, 9.17% and 11.09%. Water price increase by 50% and 100% and water quota reduction by 10% and 20%, increase water labor efficiency by, respectively, (0.78% and 1.6%) and (2.6% and 5.8%). Based on the result, if the government is going to increase water sustainability by using demand management policies, the water quota policy is more efficient. Also, the government should support farmers by direct payments to compensate for their lost profits.It is also recommended that irrigation methods with high efficiency be employed.