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Scale-dependent parameterization of groundwater–surface water interactions in a regional hydrogeological model

Tijdschriftbijdrage - Tijdschriftartikel

In regional hydrogeological models groundwater–surface water interaction is generally represented with aCauchy boundary condition, in which a conductance parameter governs the exchangeflux rate. In some models,the conductance is controlled by the streambed properties, since it has generally a lower hydraulic conductivitythan the aquifer. However, depending on the specific system and the spatial discretization of the hydrogeologicalmodel, aquifer conductance can be a limiting factor for groundwater–surface water interactions. The presentstudy introduces a new expression to represent the aquifer conductance as a function of aquifer properties,surface water network density and model discretization. This expression is based on the Dupuit-Forcheimertheory, the Ernst equation and vertical 2D numerical experiments at thefield scale. The main assumptions usedto derive our formulation are the presence of a no-flow boundary at the bottom of the hydrogeological model andthe homogeneity of the aquifer. The expression is evaluated using simulations with 3D hydrogeological modelsat different spatial resolutions and compared against previously published parameterization approaches. Theresults show that the new expression outperforms the other approaches by capturing accurately both the grid-size and the surface water network density dependency of the conductance, which is caused by pressure headlosses due toflow within the aquifer grid cell to the surface water, without any additional numerical calculation.Moreover, the proposed expression can be implemented directly in hydrogeological models thereby improvingcurrent approaches to represent groundwater–surface water interactions in regional hydrogeological models
Tijdschrift: Journal of Hydrology
ISSN: 0022-1694
Volume: 576
Pagina's: 494 - 507
Aantal pagina's: 14
Jaar van publicatie:2019