Modeling groundwater level fluctuations in Tehran aquifer: Results from a 3D unconfined aquifer model

Abstract

Heavy groundwater withdrawal results in aquifer compaction and increases the risk of land subsidence hazard with significant economic, environmental, and social consequences. Having an accurate model for hydraulic pressure loss and groundwater level changes is one of the crucial factors in proper modeling and evaluation of land subsidence hazard. This paper investigates dynamics of groundwater variations in Tehran aquifer. By analyzing a comprehensive geological and hydrological data such as alluvium depths, hydraulic conductivity, piezometric measurements, and pumping well information, we model the hydraulic heads and evaluate the hydraulic conductivity. For validation of the model, groundwater level changes resulting from the model are compared with piezometric measurements for the period 2006–2011. The comparison shows a good consistency between the predicted and observed hydraulic head values with the maximum absolute error of less than 7 m and RMS error of about 5 m, that is about 2% error, considering that the hydraulic head values are between 850 and 1250 m. This shows the capability and accuracy of the proposed model to simulate and predict the aquifer hydraulic head distribution and its changes. The model also indicates high hydraulic conductivity in the northern and central parts of Tehran Plain, which is attributed to the river sedimentation there.