Résumé :
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The hydrology and water quality in landscapes with hydromorphic soils depends on the space and time extension of wetland areas and on water pathways within the landscape at different scales. To study the control of nitrate fluxes by these areas, investigations were carried out on a detailed study site - the Coet Dan catchment (1200 ha) in Brittany, France - involving various disciplines: pedology, soil physics, hydrology, geochemistry and agronomy. An attempt of functional modelling at different hierarchical levels from the horizon level (i-1) to the region level (i + 3) of soil distribution, extension of saturated areas, horizons physical characteristics, water transfer in a multilayer soil profile and nitrate fluxes was carried out. The soil system, which can be described as a spatial arrangement of a limited number of horizon types with genetic relationships, is tightly controlled by topography. Predictive models of hydromorphic soil distribution using different topographic indexes and DEM were established. Regarding to their hydrodynamic properties, horizons of the soil system have been classified into 'building blocks', which allows to define physically based parameters for a two-dimensional multilayer water transfer model.
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