Conjunctive use of Surface and Ground Water Resources in Arid Regions

Conjunctive use of surface and ground water resources is one of the aspects of integrated water resources management. In this paper, conjunctive use of water resources has been studied for arid regions in which the only source of surface water is the water transferred into the region. For this purpose, first, the region's groundwater has been simulated using the Modflow-Pmwin model. The results have then been used to develop an optimization model with a genetic algorithm and different alternatives have been investigated toward optimal use of water resources. Obtaining monthly patterns for water withdrawal based on controlling an aquifer's level is the main objective of the optimization model. Yazd's aquifer in central Iran has been selected as the case study. The results of the optimization model showed that supplying all the demands considering the present condition for the imported surface water (max 50 MCM annually), will cause a 2 meter fall in the aquifer's level in 5 years. An annual increase of 40 percent in the amount of imported surface water should be reached in order to meet all the demands with negligible drop in the aquifer's level.