Exact Solution of Groundwater Flow Response in a Confined Aquifer to Variation in River Level

In this paper a mathematical model is developed to investigate the effects of tidal river fluctuations on the groundwater head of confined aquifer. To simulate the interaction between groundwater flow of the confined aquifer near tidal river in unsteady flow, we used separation method. This model is for simulating groundwater level and it requires estimation of hydrogeological parameters of transmissivity and storage coefficient. Two things falling and rising water levels have been studied in this paper. To verify the analytical solution of the model used GMS software Modflow and the results of the survey conducted comparing the effectiveness of analytical and numerical model solved by separation of variables and methods proposed model for the hydraulic confined aquifer and river tidal showed. Compared with an analytical solution based on a sinusoidal assumption and a numerical solution generated by MODFLOW, this solution provided better performance in groundwater-level prediction in a confined aquifer According to the investigation done if the coefficient of transmissibility increases water level rises. Evaluations of analytical solutions show that the effect of changes in levels of transmission capability between 1 and 2 km from the border tidal was remarkable. And with increased transmission capability, head of the underground water level rises also away from the border reduced and it create wave whit lesser amplitude and need more time to create it.