Experimental and Numerical Analysis of Groundwater-Surfacewater Interaction in Horizontal and Sloping Unconfined Aquifers.

Abstract

We investigated the interaction between the water moving from an unconfined aquifer and a surfacewater body. This interaction can occur during or after a rainfall event, which can cause the groundwater table to change. We developed a laboratory-scale aquifer model, which is bounded by a stream and a water divide. The model simulates both horizontal and sloping aquifer conditions. We conducted both steady-state and transient experiments. First, we set the water table at a steady state using a constant recharge rate and then the aquifer was allowed to drain. The experimental data were recreated using a numerical model, which simulated the observed water table variations. The transient water table data indicated highly non-linear changes. It was found that under similar recharge conditions, water table in the horizontal unconfined aquifer is higher than that in the sloping unconfined aquifer (2.03 degree slope). Also, the horizontal unconfined aquifer required more time to drain. The numerical model was able to predict the observed groundwater table data. The proposed numerical model is a useful tool for managing groundwater-surfacewater management problems.