Quarterly Journal of Engineering Geology and Hydrogeology

Abstract

Currently, one of the solutions to improve the decline in the water table of aquifers due to their uncontrolled extraction is artificial recharge schemes, especially in arid and semi-arid regions. The present study applies a Nonuniform Rational B-Spline functions (NURBS) based Isogeometric method to investigate the effects of injection well on rising of water table, unconfined aquifer hydrodynamic parameters, plus injection rate on it. Also, the best injection rate was determined by linking the IGA simulation model to the PSO optimization model. Initially, the Isogeometric Analysis (IGA) method was implemented to simulate water table over an unconfined aquifer by two extraction wells with discharges of 1142.85 and 1428.57 m3/day for 210 days and was compared with Modflow model. The model was tuned and run by constructing an injection well with 8214.28 m3/day injection rate for 1500 days. The IGA simulation results with ME=-0.0096, MAE=0.0111, and RMSE=0.0146 indicated the accuracy of the model in water table simulation compared with the Modflow model with ME=-0.0188, MAE=0.023, and RMSE=0.0284. The findings revealed that use of an injection well has a positive impact on increasing the water table with a rise of 1.24 m in the observation well. Investigating the effect of the parameters on the water table changes indicated that the injection rate directly affects changes in the water table. The water table rises by more than 43% with a 50% increase in the injection rate. Also comparing the effect of the injection rate parameter on the water table, the transmissivity and specific yield effects were not substantial. The results of IGA-PSO showed the best value of injection rate is 2000 m3/day, whereby the aquifer water table rises by an average of 37.12 cm.