3D flow and transport groundwater modelling including river interactions

Abstract

In the framework of the SALMON project (Sea Air Land Modelling Operational Network) supported by the IBM International Foundation at the University of Liege (Belgium), three existing models (ocean, river and groundwater) are to be connected adequately in order to form one single model. This model should be able to describe all water and contaminant fluxes in a whole system at regional scale including marine, river, groundwater and atmospheric inputs. In practice, the connection of the different models is done through a specific interface, called ' Junction'. In the SUFT3D groundwater model, the interactions with the river are based on the Fourier boundary conditions. In the presence of 'wet docks', supplementary equations based on flow and solute mass balance have to be added in the 3D groundwater model in order to compute the appropriate water and solute mass fluxes which are exchanged with the 'wet dock' in connection with the 1 D river model. As each model has its own time and space discretizations, the junction must organize the data exchanges, including various time and space interpolations schemes The particular role of the junction between the groundwater and the river models is tested on an actual site located in the river Meuse valley (Belgium) where two production wells are stressing the groundwater-river interactions in the alluvial aquifer. The test results show the impact of these interactions on the computed groundwater quantity and quality. Transactions on Ecology and the Environment vol 17, © 1998 WIT Press, www.witpress.com, ISSN 1743-3541 570 Computer Methods in Water Resources XII