HR: 09:45h
AN: H21B-07    [PDF]
TI: Improved Understanding of the 3D Hillslope Spatial Structure as a Prerequisite for Understanding the Hydrological Behaviour of Ungauged Basins.
AU: Bogaart, P W
EM: patrick.bogaart@wur.nl
AF: Hydrology and Quantitative Water Management group, Wageningen University, Nieuwe Kanaal 11, Wageningen, 6709 PA Netherlands
AU: * Troch, P A
EM: peter.troch@wur.nl
AF: Hydrology and Quantitative Water Management group, Wageningen University, Nieuwe Kanaal 11, Wageningen, 6709 PA Netherlands
AB: We study the first-order controls on hydrological behaviour of hillslopes and catchments. This hillslope response is driven by precipitation, but controlled by the geological, topographic, hydraulic, pedologic and ecological properties of the hillslope. In the common case of soil mantled landscapes, where water storage in perched groundwater tables is an important process and saturation excess overland flow dominates, a primary control on hillslope hydrology is formed by the geometry and properties of the soil layer. Improved dating techniques have enabled the formulation of geomorphological and pedological process laws that are supported by data. Using these laws, the prediction of the spatial structure of this soil layer becomes possible, enabling the a priori prediction of associated model parameters, based on assumptions regarding lithology, weathering, surface processes like erosion etc. In this paper we will give some examples of this approach. A simplified Landscape Evolution Model (LEM) is used to simulate the evolution of relief and regolith. From both the dynamic equilibrium and transient states of this LEM, parameters for the hillslope hydrological model can be collected. In our case, we apply the semi-distributed, physically based, `hillslope-storage Boussinesq model' [\emph{Troch et al.}, The hillslope-storage Boussinesq (hsB) model for subsurface flow and variable source areas along complex hillslopes: 1.\ Formulation and characteristic response, WRR, in press]. Model parameters for this hsB model include hillslope width and gradient, regolith depth, drainable porosity and saturated conductivity. We present some examples where the LEM is used to predict both surface and soil layer geometry. We show how the evolution of these parameters through geomorphological time results in trends in the characteristic (e.g.\ unit) hydrograph at the hillslope scale. This approach can be scaled up to the catchment or regional scale by investigating how model parameters differ for hillslopes draining to first, second etc. order channels. This relationship in combination with established scaling laws for channel network helps predicting the hydrographs on these larger scales. Examples of this scaling are also presented.
DE: 1800 HYDROLOGY
DE: 1824 Geomorphology (1625)
DE: 1860 Runoff and streamflow
DE: 1866 Soil moisture
DE: 1886 Weathering (1625)
SC: Hydrology [H]
MN: 2003 Fall Meeting