Physical and Numerical Modelling of Groundwater and Surface-Water Interactions with a Conservative Tracer.

This paper outlines recent and on-going physical and numerical modelling work carried out at Cardiff University, the novel approaches used, some of the initial results obtained, the problems encountered and the envisaged solutions.

A laboratory flume has been adapted to simulate the interaction between surface water and groundwater. At the same time an integrated surface-water/groundwater model has been developed from an existing hydrodynamic two dimensional surface water model (DIVAST). The flume uses 60ppi open-cell foam as ‘river-bank’ material to allow flow and solute transport through the aquifer. The computer model extends the surface-water model horizontally into the groundwater by discretising the equations of flow for porous media in the same way as the surface water equations. The interactions between the two domains can then be modelled together, in the same numerical model.

The laboratory setup is described, together with problems encountered. Initial results from the laboratory are compared with the computer model in general terms, although there are significant hurdles to overcome in the physical modelling before it can be used to refine the numerical model.