Development of an Integrated Free Surface and Groundwater Flow Model

An integrated novel, two-dimensional, numerical groundwater-surface flow model has been developed to simulate hydro-environmental interactions between wetland areas, the neighbouring coastal waters and the groundwater passages. For free surface flow modelling, an existing widely used two-dimensional, unsteady mathematical model, DIVAST (developed originally by Falconer 1976) has been refined. However, in order to simulate the flow and solute transport in porous media, a two-dimensional model, GWK (Ground Water Key), has been developed to include an aquifer influenced by tidal currents. The GWK model is based on the transient flow Boussinesq equation as the governing equation for groundwater flow, and the advection-diffusion equation is used as the governing equation for contaminant transport. A physical model has been constructed to provide experimental data of the groundwater transport between a wetland and the adjacent coastal waters. In the physical model the aim has been to study seepage behavior through the sand embankment by recording water levels on both sides of the sand, point velocity measurements, and the studies of a conservative dye tracer (a solute of 5g/l concentrations potassium permanganate) for constant water levels on one side of the embankment while running tidal cycle on the other side of the embankment. Comparison between the experimental data and the simulated physical model, involving integrated model, showed that the integrated model was capable of simulating groundwater and free surface water, with a high level of accuracy. An overview of the study is reported in this paper.

Keywords:

Free Surface/Groundwater Modelling , Wetland , Coastal water , Dye Tracer