مدل سازي نوسانات سطح آب زيرزميني در محدوده ي مركزي طرح متروي اصفهان

Modeling of Groundwater Fluctuations in the Central Area of Isfahan Metro Project

In this paper, the hydrogeological characteristics of Isfahan unconfined aquifer have been studied. The effect of metro tunnelling operations on groundwater regime also has been investigated. Since, due to recharge from Zayandehroud river, the water level in Isfahan aquifer is high and tunnelling operations can rise this water level more, so the probable effects of groundwater fluctuations had to be investigated. In this study, the data due to water level in piezometers during 4.5-year period (1376 - 1380) and pumping test results, along with characteristics of aquifer and topography of the area have been collected. All the above mentioned data were processed in GIS(Idrisi 2), WINSURFER(7.1), AUTOCAD2002, and the obtained data was fed into 3D PMwin (5.1) in order to model the aquifer behavior. Calibration of the model shows 95% accuracy when comparing the calculated water level from the model with observed water levels in piezometers. In this study, the hydrodynamic parameters obtained from few pumping tests have been adjusted using steady state modeling and then obtained results were used in unsteady state modeling in order to calculate the effect of metro tunnelling operations on groundwater level. Studies show that in case of twins tunnelling (with 6 meter diameter for each tunnel), like the another case (means single tunneling with 9 meter diameter), there is no significant effect on groundwater level. Moreover, model indicates that construction of water passage between two unpermeable wall around the metro tunnel (near Zayandehroud river), results in considerable reduction in groundwater fluctuations.