GPS-assisted road surveys and GIS-based road erosion modeling using the WEPP model

Brooks, E.S.; Boll, J.; Elliot, W.J. 2003. GPS-assisted road surveys and GIS-based road erosion modeling using the WEPP model. Paper No. PNW-03-109. Presented at PNW ASAE and Salmon "The Fight for Survival." The 2003 Pacific Northwest Region Meeting sponsored by ASAE. Quality Inn and Suites Conference Center, Clarkston, WA. September 25-27, 2003. Paper no. PNW2003-9. St. Joseph, MI: American Society of Agricultural Engineers.

Keywords: sediment yield, runoff, low-volume roads, watershed modeling, TMDL, road

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Abstract: Roads have been identified as a major source of sediment loading to streams in most forested watersheds. The Watershed Erosion Prediction Project (WEPP) model, as developed by the USDA-Forest Service, simulates the detachment and delivery of sediment through a road, fill, and buffer system. Time and budget constraints typically prevent a comprehensive sediment loading analysis using the WEPP model throughout a large watershed. We describe a step-by-step approach to allow use of the WEPP model to simulate erosion throughout a large road network. Road attributes are acquired from detailed global positioning system-assisted road surveys and mapped in a geographic information system (GIS). After data manipulation in GIS and Excel, the required input files for the WEPP model are developed. The approach was applied to 1017 km of road, divided into 6955 road segments, throughout a 3040 km² watershed, ranging in elevation from 377 m to 2706 m. The approach can be applied to insloped, outsloped, and crowned road designs, multiple climate regimes, and unique physical attributes for each road segment. Analysis of the WEPP results within a GIS provides a spatially explicit tool for the management and evaluation of sediment production throughout large road networks.

Moscow FSL publication no. 2003k