Predicting Groundwater Table Fluctuations under Different Management Scenarios by MODFLOW Model

Due to recent droughts and excessive extraction of groundwater resources, water table of Qom aquifer has had sharp drop resulted in intrusion of saline water into the groundwater and land subsidence. In order to prevent the crisis, operation management of water resources should be a principle in country planning. Simulation models are suitable tools for management and qualitative and quantitative conservation of groundwater resources. In this study, a two-year period data (September 2003- September 2005) were used for evaluating MODFLOW model to simulate the aquifer water table. The model showed the most sensitivity to specific yield, hydraulic conductivity, recharge and discharge, respectively. The correlation coefficient and root mean square error in the calibration stage varied from 0.24 to 0.99 and 0.01 to 0.14 m, respectively. The correlation coefficients and root mean square error in the verification step change between 0.52 to 0.97 and 0.002 to 1.14, respectively. To assess the aquifer response to various stresses, six management scenarios (continued current extraction of groundwater and recharge to groundwater resources, decrease by 10, 20 and 30% and reducing step by step of groundwater extraction, continued current extraction of groundwater and artificial recharge of groundwater using urban wastewater) were defined up to 2020. Based on the model results, the best scenario for restoring and balancing the groundwater is artificial recharge scenario using wastewater up to 2020.