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United States Department of Agriculture

Agricultural Research Service

Title: Watershed Model Channel Hydrology and Erosion Processes, Chapter 13

Authors
item Ascough, James
item Baffaut, Claire
item Nearing, Mark
item Flanagan, Dennis

Submitted to: Water Erosion Prediction Project Documentation
Publication Type: Book / Chapter
Publication Acceptance Date: September 15, 1995
Publication Date: N/A

Technical Abstract: The Water Erosion Prediction Project (WEPP) watershed model is a process- based, continuous simulation model built as an extension of the WEPP hillslope model (Flanagan and Nearing, 1995). The model was developed to predict erosion effects from agricultural management practices and to accommodate spatial and temporal variability in topography, soil properties, and land use conditions within small agricultural watersheds. The model contains three primary components: hillslope, channel, and impoundment. The hillslope component calculates rainfall excess by a Green-Ampt Mein-Larson (GAML) infiltration equation; peak runoff rate by kinematic wave overland flow routing or simplified regression equations; interrill erosion as a process of soil detachment by raindrop impact and sediment delivery to rill flow areas; and rill erosion as a function of sediment detachment, sediment transport capacity, and the existing sediment load in the flow. The following hillslope hydrologic and erosion output is stored in a pass file and then read in and used by the channel and impoundment components: 1) storm duration; 2) overland flow time of concentration; 3) Rational equation dimensionless alpha; 4) runoff depth; 5) runoff volume; 6) peak runoff; 7) total sediment detachment at the end of the hillslope; 8) total sediment deposition at the end of the hillslope; 9) sediment concentration by particle size class at the end of the hillslope; and 10) dimensionless fraction of each particle size in the eroded sediment.

Last Modified: 11/27/2014
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