Pacific Southwest Research Station

Assessing the sources and transport of fine sediment in response to management practices in the Tahoe basin using the WEPP Model

The WEPP model is a process-based model that simulates soil detachment, deposition, transport and delivery through hillslope, channel, and structural impoundment units within a watershed. This project will refine the toolset for the Tahoe basin and train local implementers to use these new tools. The model's predictions will be evaluated using monitoring data from the Heavenly Valley Ski Resort and other sites where management practices have been applied in the basin.

Final Report [pdf]

Lead Researchers: William Elliot, USDA–FS Rocky Mountain Research Station; Erin S. Brooks, University of Idaho; Jan Boll, University of Idaho; Joan Wu, Washington State University

Goals

1. Develop a tool to evaluate how management practices generate fine (< 20 microns) sediment at the hillslope and watershed scales.
2. Assess model predictive capabilities using existing data sets having unique micro-climates, soil properties and management practices (e.g. impacts of prescribed burns and mechanical forest harvesting techniques, management of vegetative surface cover, road erosion, soil compaction, re-vegetation of disturbed soils, and residential/ski resort development). WEPP Model output.
3. Refine model of sediment transport in the basin.

Sites: Upper Truckee River, Logan House Creek, General Creek, Blackwood Creek

Timeframe: October 2007 through June 2010 (2.5 years)

Products:

• Tahoe basin-specific database for the WEPP technology
• Improvements to the stream channel routing algorithms in WEPP
• Assessment of the accuracy of the models
• Technology transfer workshops in which workshop participants will model a test catchment within the Lake Tahoe basin

Figure: Example of a WEPP watershed windows interface with delineated hillslopes and channels over an aerial photo with elevation contours (courtesy USFS-RMRS)