Evaluation of the Potential Effects of Hydrological Drought on Agricultural Situation, Farmers’ Revenue and Water Consumptions in Tehran Province

Hydrological drought is a phenomenon that occurs due to the reduction of surface water and groundwater resources supply. Because of the dependence of the agricultural sector to soil moisture storage, it primarily affects this sector. Therefore, the analysis of the effects of this phenomenon is important for the better management and planning of water resources available in the agricultural sector. Theeffects of hydrological drought arising from reducing the supply of water resources on agricultural situation, water consumptions and farmers' gross profit in Tehran province were evaluated. For this purpose from Multi Period Positive Mathematical Programming and statistical information related to period 2013-2018 wereused. The results showed that the current cropping pattern in Tehran province is not optimal and with occurrence of hydrological drought, farmers’ tend decreases for the water-full crops such as watermelon, tomato and sunflower. In addition, the results showed that in the hydrological drought conditions, about 9.13 percent of agricultural water demand in Tehran province will not provided. This will change the pattern of cultivation inthe region. Reduction in the farmers' gross margin amunt 7.28 percent and increase in the economic value of irrigation water amunt 38.2 percent compared to the base period are other consequences the occurrence of hydrological drought in Tehran province. Overall, the results indicate that with the occurrence of drought, the cropping pattern toward products with lower water requirements and higher profits, but for tomato and corn products (despite the high water requirement) due to integrated farming in region reducing acreage is less visible.