Economic Model for Optimal Allocation of Water Resources with an Emphasis on Risk and Consistency Index in the Sistan Region: The Application of Interval Two-Stage Stochastic Programming Method

The issue of water resource management in the Sistan region has been complicated by water fluctuations of the Hirmand River in recent years and the competition of the drinking, agricultural, and environmental sectors on water use. The present study applies the economic model including interval two-stage stochastic programming (TSP) method under uncertainty conditions to study agricultural water allocation and the assessment of risk and consistency including stochastic simulation of the existing water, an optimization model of agricultural water, and the risk assessment of the water shortage under three scenarios of high, average, and low inflow levels in three regions of Zahak, Zabol, and Miankangi as the three main agricultural areas in Sistan for the time horizon of 2019-2020. The results show that there will be no water shortage for agricultural users in the Zahak region at the high and average inflow levels. But, this area will need 122 million m^3 more water at the low inflow level. Also, the water shortage in the Zabol area will be inadequate by 149.69 million m^3 at the average inflow level and by 185.65 million m^3 at the low inflow level. Also the results of the TSP model for Miankangi County indicate that no water will be allocated to this sector. The risk assessment of agricultural water shortage by the results of optimization will help decision-makers better understand the risk of water shortage under different scenarios. It is found that the Zabol region will have higher risk of agricultural water shortage than the Zahak region, so efficient risk management should be initiated from this region.