Grondwater budget calculation of Iranshahr plain by using numerical model and manuall methods

Category Hydrogeology
Group GSI.IR
Location 23th symposium on geosciences
Holding Date 05 May 2008

      Iranshahr plain with average elevation of 600 meter above the mean see level is one of fertile plain in Sistan and Baluchestan Provice. However, in the recent years, declines of groundwater level reported for some parts of the plain. So it seems that the water budget studies are needed for this aquifer. At beginning, Thessen polygon and unit hydrograph of the aquifer are prepared by using data of 20 observation well for years December 1999 to December 2000. Then volume change of the aquifer is calculated by using of water budget equation manually. Finally, a comparison was made between the result of manually calculated water budget and the result of PMWIN numerical model. This conceptual model of the aquifer is designed based on the available data. The model is automatically calibrated for steady state condition, and hydraulic conductivity and drain hydraulic conductance optimized and then it is 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 is performed for years 2000-2001. Results indicate that annual discharge is more than the annual recharge rate. The results show that the aquifer storage reduction is 19.47 million cubic meters and it is compare with the decreasing unit hydrograph of the aquifer and water budget that calculated manually