OICC Press Anthropogenic Pollution 2588-4646 10 1 2026 06 30 Scenario-Based Conjunctive Management of Surface Water, Groundwater and Reclaimed Wastewater to Improve Groundwater Conditions in the Hashtgerd Aquifer, Iran 10.57647/AP.2026.1001.10 EN Davod Najafian Ghoje Biglo Department of Water Engineering and Sciences, SR.C., Islamic Azad University, Tehran, Iran Mahdi Sarai Tabrizi Department of Water Engineering and Sciences, SR.C., Islamic Azad University, Tehran, Iran Ali Saremi Department of Water Engineering and Sciences, SR.C., Islamic Azad University, Tehran, Iran Amir Khosrojerdi Department of Water Engineering and Sciences, SR.C., Islamic Azad University, Tehran, Iran Journal Article 2026 06 30 This study aimed to optimize the integrated exploitation of water resources to reduce the drop in the level of the Hashtgerd aquifer, Iran, based on an integrated management. Firstly, hydroclimatology and groundwater balances were estimated, revealing that the 25-year drop in the aquifer level is 20.32 m. By modeling scenarios of population increase with a five-year growth rate of 3.4% and the construction of two wastewater treatment plants, along with optimizing the supply of demand through integrating the use of resources in the WEAP model, it was determined that in a five-year perspective, discharge from the aquifer to supply the water needs of drinking and industry will increase by 5.70 and 6.58 million cubic meters (MCM), respectively. By treating 11.32 MCM of industrial wastewater for industrial use along with treating 40% of urban wastewater and 57.37 MCM of agricultural wastewater for agricultural use, discharge from the aquifer showed a reduction. The model determined that agricultural needs exhibited the greatest effect on the aquifer level drop. The results showed that implementing the optimized scenario not only prevents the aquifer level drop in the five-year perspective, but also the aquifer balance will increase up to +2.1 MCM.