Water Resource Simulation in an Arid Watershed Considering an Allocation for Dust Stabilization and Different Scenarios of Water Supply and Demand

Water is the main demand of people settled in the arid areas of large watersheds.This demand is more necessary and critical in the areas with the potential of dustsources and fine sediments entering into the watershed in a long-time period. Sistanwatershed to the south-east of Iran is a region with the specific hydrologicalconditions. The 120-day winds blow continuously in the summer propagating largeamounts of dusts directly into the cities and rural areas. In this study, a demand isconsidered for the dust stabilization in the study area. A field surrounding thewatershed that directly affects the amount of dusts is selected. The amount of waterdemand that is needed for the stabilization and saturation of the soil is measured bythe soil sampling and experimental on-site works. A demand for dust stabilization isdefined and the water resources systems are simulated. Different scenarios of watersupply and demand are considered. Results show the unmet demands of the differentscenarios (Sc) in a 15-year period in the region. The highest amount of unmet waterdemand is calculated for the scenario No.10 that is the combined effects of reducingagricultural land use and increasing the agricultural efficiency and reducingevaporation from Chahnimeh reservoir and flow of discharge in accordance with theagreement between Iran and Afghanistan enforced in 2015. Different scenarios areevaluated in terms of dust stabilization priority and also agriculture using the analytichierarchy method. This shows the high score of Scenario No.9 that is the combinedeffect of reducing agricultural land use and the increasing the agricultural efficiencyand reducing the evaporation from Chahnimeh.