Keywords: groundwater–surface water interaction, horizontal unconfined aquifers, nonlinear modelling, numerical modelling, groundwater, surface water, drainage water, water management
Analysis of groundwater–surface water interaction in horizontal unconfined aquifer bounded by a stream and groundwater divide using a non–linear numerical model
In this study, a non–linear numerical model was developed to analyse the interaction between the drainage water moving from an unconfined aquifer and a surface water body. This interaction can occur during or after a rainfall event, which can cause the groundwater table to change. At first, a laboratory–scale aquifer model with stream and groundwater divide boundaries was established to examine horizontal unconfined aquifer condition. Both steady–state and transient experiments were performed by setting the water table at a steady–state using a constant recharge rate, and then allowing the aquifer to drain. The transient water table data showed highly non–linear variations. Then the experimental data were recreated using a non–linear numerical model, which used non–linear one dimensional Boussinesq equation and Picard iteration for solving non–linear term of the Boussinesq equation. The numerical model was able to predict the observed groundwater table data. The proposed numerical model is a useful and cost effective tool for managing groundwater–surface water management problems.