HR: 0800h
AN: H31F-1356    [Abstracts]
TI: Soil-type based prediction of contributing areas for diffuse losses of agrochemicals
AU: * Stamm, C
EM: christian.stamm@eawag.ch
AF: Swiss Federal Institute of Aquatic Science and Technology, Ueberlandstr. 133, Duebendorf, 8600 Switzerland
AU: Lazzarotto, P
EM: Patrick.Lazzarotto@fal.admin.ch
AF: Swiss Federal Research Station for Agroecology and Agriculture, Reckenholzstr. 191, Zurich, 8046 Switzerland
AU: Prasuhn, V
EM: Volker.Prasuhn@fal.admin.ch
AF: Swiss Federal Research Station for Agroecology and Agriculture, Reckenholzstr. 191, Zurich, 8046 Switzerland
AU: Fluehler, H
EM: fluehler@env.ethz.ch
AF: Swiss Federal Institute of Technology, Soil Physics Universitaetsr. 16, Zurich, 8092 Switzerland
AB: The lack of adequate spatial data often limits the prediction of contributing areas for diffuse losses of agrochemicals using distributed hydrological models. This data problem is often amplified by the use of highly parameterized simulation tools. In order to overcome the problem of over-parameterization we present a parsimonious rainfall-runoff model that was adapted to the spatial soil data available in the study region. The approach is based on the hydrologic responses of two soil types and includes effects of topography. It requires 10 parameters that were obtained by simultaneously fitting the model to discharge from four neighboring catchments in the area of Lake Sempach in the Swiss Plateau. They differ significantly with respect to soil composition and hydrological behavior. The higher the percentage of poorly drained soils in a catchment, the more responsive is the discharge behavior. Monte Carlo simulations resulted in 8100 accepted parameter sets yielding satisfactory calibrations during the simultaneous fitting procedure. Under the soil and climate conditions prevailing in the study area saturation-induced flow processes (overland flow, preferential flow to tile drains) dominate the transport of agrochemicals like Phosphorus to surface waters. Conceptually, these processes were represented in the model by a single fast flow component. It originated from all areas of a given soil type with a topographic index above a saturation-dependent critical value. Hence, the model allowed for predictions of soil-type specific delineation of contributing areas that obey the spatial distribution of soil types in different catchments and are consistent with the respective overall hydrological responses.
DE: 1804 Catchment
DE: 1847 Modeling
DE: 1865 Soils (0486)
SC: Hydrology [H]
MN: Fall Meeting 2005