HR: 17:30h
AN: H54C-06    [Abstracts]
TI: Parameterization of Natural Depressions in Distributed Hydrologic Models: Implications for Scaling up Predictions of Sediment and Nutrient Yields in Ungauged Agricultural Watersheds
AU: * Chien, H
EM: hchien@buffalo.edu
AF: Department of Geography State University of New York at Buffalo, 105 Wilkeson Quad, Buffalo, NY 14261 United States
AU: Mackay, S
EM: dsmackay@buffalo.edu
AF: Department of Geography State University of New York at Buffalo, 105 Wilkeson Quad, Buffalo, NY 14261 United States
AU: Cabot, P E
EM: pecabot@wisc.edu
AF: Department of Biological Systems Engineering University of Wisconsin-Madison, 1450 Linden Drive 430 Agriculture Hall, Madison, WI 53706 United States
AU: Karthikeyan, K
EM: kkarthikeyan@wisc.edu
AF: Department of Biological Systems Engineering University of Wisconsin-Madison, 1450 Linden Drive 430 Agriculture Hall, Madison, WI 53706 United States
AB: Digital Elevation Models (DEMs) are widely used in distributed hydrologic modeling. In general, interior depressions within catchments are viewed as errors in the DEM, even though they are hydrologically significant features. Natural depressions in catchments are capable of trapping surface runoff and associated sediment, but they are difficult to identify and represent, especially in ungauged basins. We examined the errors associated with the removal of such depressions on predictions from hydrologic models, Soil and Water Assessment Tool (SWAT) and Agricultural Policy/Environmental eXtender (APEX). Automated water and sediment samplers were installed in the outlets of three natural depressions in a small catchment in the North Fork of Pheasant Branch watershed in Dane County, Wisconsin, to collect surface runoff and sediment yields for the period 2003-2004. The data showed that when daily precipitation is over 26 mm, surface runoff with suspended sediment overtops the depressions. SWAT and APEX were calibrated to this data to examine the influence of nested depressions on sediment yields. The hypothesis addressed in this study is: sediment transport parameters can be used as proxies for the functioning of surface depression and to obtain the correct sediment response. The alternative is to explicitly prescribe depressions as reservoirs with more geometric details of depressions if the hypothesis failed. Initial model results showed that the adjustment of sediment transport parameters mimics the response of the depressions and significantly reduces sediment yields. Implications of a simple proxy of sediment deposition for scaling to larger, ungauged basins will be discussed.
DE: 1839 Hydrologic scaling
DE: 1846 Model calibration (3333)
DE: 1862 Sediment transport (4558)
DE: 1879 Watershed
SC: Hydrology [H]
MN: Fall Meeting 2005