Hydrology and Earth System Sciences www.hydrol-earth-syst-sci.net 1027-5606 1607-7938 14 7 2010 10.5194/hess-14-1179-2010 http://www.hydrol-earth-syst-sci.net/14/1179/2010/ http://www.hydrol-earth-syst-sci.net/14/1179/2010/hess-14-1179-2010.html http://www.hydrol-earth-syst-sci.net/14/1179/2010/hess-14-1179-2010.pdf 1179 1194 2010-07-02 Effect of the spatial distribution of physical aquifer properties on modelled water table depth and stream discharge in a headwater catchment C. Gascuel-Odoux chantal.gascuel@rennes.inra.fr M. Weiler J. Molenat INRA, UMR1069, Soil Agro and hydroSystem, 35000 Rennes, France Agrocampus Ouest, UMR 1069, Sol Agro et hydroSystem, 35000 Rennes, France Institute of Hydrology, University of Freibourg, Freibourg, Germany Water table depth and its dynamics on hillslopes are often poorly predicted despite they control both water transit time within the catchment and solute fluxes at the catchment outlet. This paper analyses how relaxing the assumption of lateral homogeneity of physical properties can improve simulations of water table depth and dynamics. Four different spatial models relating hydraulic conductivity to topography have been tested: a simple linear relationship, a linear relationship with two different topographic indexes, two <i>Ks</i> domains with a transitional area. The Hill-Vi model has been modified to test these hypotheses. The studied catchment (Kervidy-Naizin, Western France) is underlain by schist crystalline bedrock. A shallow and perennial groundwater highly reactive to rainfall events mainly develops in the weathered saprolite layer. 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