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Effects of watershed representation on runoff and sediment yield modeling

Lopes, V.L., Canfield, H.E.
Journal of the American Water Resources Association 2004 v.40 no.2 pp. 311
semiarid zones, rangelands, watershed hydrology, runoff, sediment yield, sediment transport, particle size distribution, hydrologic models, simulation models, water erosion, rain, infiltration (hydrology), slope, Arizona
This paper evaluates the effects of watershed geometric representation (i.e., plane and channel representation) on runoff and sediment yield simulations in a semiarid rangeland watershed. A process based, spatially distributed runoff erosion model (KINEROS2) was used to explore four spatial representations of a 4.4 ha experimental watershed. The most complex representation included all 96 channel elements identifiable in the field. The least complex representation contained only five channel elements. It was concluded that oversimplified watershed representations greatly influence runoff and sediment yield simulations by inducing excessive infiltration on hillslopes and distorting runoff patterns and sediment fluxes. Runoff and sediment yield decrease systematically with decreasing complexity in watershed representation. However, less complex representations had less impact on runoff and sediment-yield simulations for small rainfall events. This study concludes that the selection of the appropriate level of watershed representation can have important theoretical and practical implications on runoff and sediment yield modeling in semiarid environments.