Should water supply for megacities depend on outside resources? A Monte-Carlo system dynamics simulation for Shiraz, Iran

Abstract

In recent years, the need for sustainable urban water management is more crucial than before due to rapid urbanization and limited water resources. However, as a main question, should the city look to outside water resources or the resources inside the city? The present study developed a system dynamics model to evaluate different water supply scenarios for the Shiraz City, Iran at the horizon 2025. Based on the results, by construction of Tange-Sorkh dam and transfer line from Droudzan dam (as outside resources), the water shortage will be decreased just by 2%. In the case of inside resources, using treated wastewater for the landscape by rates of 30, 60 and 100%, the water shortage will be reduced by 6, 12 and 20%, respectively. Moreover, the results showed that an increase in the irrigation efficiency by 10 and 20%, the shortage will be decreased by 14 and 25%, respectively. Therefore, to eliminate the water shortage it is necessary to concentrate more on inside the city resources, in the next decade. Furthermore using the Monte Carlo approach in the system dynamics simulation presented that the shortage is more sensitive to the irrigation efficiency than the treated wastewater rate and the dam capacity.