Numerical modeling of groundwater flow in Ali Abad Plain of Qom to predict fluctuations of the water table and hydraulic conductivity

In the present study, numerical modeling was performed on groundwater of Ali Abad Plain using the GMS (MODFLOW 2005) in 120 time steps within the time frame of 2006 to 2016. For this purpose, the hydraulic level of the area was simulated using the comprehensive geological and hydrological data of the study area. Next, hydraulic conductivity was simulated as the last step of the modeling. To validate the prepared model, water table fluctuations predicted by the model were compared with the piezometric measurements. Also, it was observed that in 13 out of 26 observation wells, the difference between the observed and predicted mean hydraulic level is less than 0.5 m, with the maximum difference being 2.94 m. Considering the range of water table fluctuations in the study area, this difference indicates a 2.5% modeling error, which is negligible. Comparing the hydrograph of the observed and predicted groundwater level indicate an acceptable consistency of the results and thus the efficiency of the model in simulating the long-term average variations of groundwater level in the study area. Furthermore, hydraulic conductive estimates of the model in the final step of the simulation indicate the high values of this parameter in the confluence of two main rivers in the study area, which is attributed to sedimentation in the study area. Overall, the results show the capability of the proposed model for simulating the hydraulic levels distribution and hydraulic parameters, as well as predicting the behavior of the aquifer in the study area.