Numerical simulation of groundwater flow and aquifer-system compaction using simulation and InSAR technique: Saveh basin, Iran

In this research, a multidisciplinary approach has been presented to evaluate land subsidence due to heavy groundwater withdrawal. Land subsidence in aquifers with complex stratigraphy was predicted using the Terzaghi’s 1D instantaneous compaction principle and was incorporated into a 3D groundwater flow model (MODFLOW). The integrated model was then calibrated for Saveh aquifer located in Iran to simulate observed hydraulic heads and compaction. In order to control the model results, interferometric synthetic aperture radar (InSAR), a generated 3D geological model, monitoring wells, and available literature were used to predict land subsidence in Saveh aquifer and apply the results in the developed model. The results showed that the InSAR, extensometers, and numerical simulations closely agree in predicting the land subsidence. The simulation results show that the regional subsidence began in the mid-1990s and that the area has experienced up to 70 cm of subsidence, where heavy pumping and thick clay layers are found. The calibrated model indicates that if the pumping rate remains at the current level, the subsidence will reach as high as 170 cm over the next 5 years. The results show that the proposed approach which integrates various sources of data is useful in estimating land subsidence, especially in areas where field measurements are scarce and satellite radar images are available.