The Effect of Water Extraction from Iranshahr Aquifer on Bampour River Base Flow

Iranshahr aquifer is one of balanced aquifer in Sistan and Balouchestan province. Discharging of Iranshahr aquifer by permanent Bampour river supported this point. Nevertheless, in the recent drought there is a sign of decreasing of base flow in this river. So it seems that the hydrogeological and managerial studies are needed for this aquifer. In this research a ground water model was developed to study the effect of water level decline on the base flow of Bampour river. Firstly, hydrogeological evaluation of Iranshahr aquifer was studied using the result of the pumping test, geological logs and profile, geoelectrical studies and field observation. Data from November 1999 is selected for designing the model in the steady state condition. Then, conceptual model of the aquifer and provision any input files to the model, is constructed for stable conditions to optimization of k parameter and conductance factor of bottom sanitation and edges of flow by using available data for processing Modflow Windows (PM WIN) software. In the next step, the model was calibrated and hydraulic conductivity and drain hydraulic conductance optimized. The model is then calibrated to a transient condition. A transient calibration or a transient verification test is necessary to calibrate values of the specific yields and recharge parameters. Calibration in the transient state for years 1999-2000 accomplished and model verification was performed for years 2000-2001. Verification results indicate that calibrated model is capable for managerial practices. Output results of the model, during this two years indicate that annual discharge is more than the annual recharge, which correspond with the decreasing unit hydrograph of the aquifer and any wells in the model environs.