Erosion Processes in Great Lakes Basin Forests
Nearly half of the land within the Great Lakes Basin is covered in forests. Sediment from forest is the greatest pollutant that may impact streams within the basin, and the lake water quality in the vicinity of estuaries. Sediment from forest watersheds can also increase the cost and frequency of dredging the many harbors on the perimeters of the Great Lakes.
Erosion rates from these forested areas are usually minimal unless they are disturbed by nature or management. Disturbances include occasional wildfire, timber harvest or other forest management activities including prescribed fire, roads and trails. In the absence of wildfire, roads and trails are likely to be the greatest source of sediment. Stream channels can also be a major source of sediment from forested watersheds. Through forest management and road network design, upland erosion can be minimized.
Predicting Surface Erosion in Forests
Forest Service Researchers, working collaboratively with Agricultural Research Service and university scientists, have developed a suite of erosion prediction tools to estimate sediment delivery from forest hillslopes and road networks. These tools include one for subwatersheds, several for forested hillslopes, and two for forest roads. The online sub watershed tool can aid in identifying erosion hotspots within forested sub watersheds, particularly following wildfire, or can aid in identifying areas to target treatments to reduce the risk of wildfire. The sub watershed interface can also be used to assist with a cumulative effects analysis to estimate sediment delivery from sub watersheds when only part of the sub watershed is disturbed. Guidelines for applying this tool to western forested watersheds are available.
The main difference in forested watersheds in the Great Lakes Basin compared to western watersheds is that soils seldom become water repellant following wildfire in the Great Lakes Basin, so modelers are advised to select low severity fire soils only, and describe the fire effects by amount of ground cover remaining after the fire. This approach will be described for hillslopes in an upcoming Great Lakes Basin webinar (see below). The online interface can also provide information about the length and steepness of hills within the watershed to use in the online forested hillslope interface (Disturbed WEPP).
The Disturbed WEPP interface is intended to be used to evaluate erosion on forested hillslopes that are either undisturbed, harvested, thinned, underburned, or have experienced a wildfire. A worksheet describing how to apply this interface to the Great Lakes Basin has been developed.
The WEPP Road interface allows forest watershed managers to compare sediment delivered from forest road segments for different road designs and management strategies. A worksheet is available to demonstrate how to apply this interface to a road segment in the Great Lakes Basin.
For both the WEPP Road interface and the Disturbed WEPP interface, batch processors are available to allow users to evaluate multiple treatments on the same road segment or hillslope, to consider multiple road segments or hillslopes, or both.
A webinar giving an overview of these technologies was held in December 2011. Handouts that accompanied the training presentation are available here:
- Forest Erosion Processes Handout
- Erosion Processes Worksheet
For further information on future webinars or workshops, contact Bill Elliot.
- U.S. Department of Agriculture – Forest Service, Rocky Mountain Research Station
- U.S. Department of Agriculture – Forest Service, San Dimas Technology and Development Center
- U.S. Department of Agriculture – Agricultural Research Service, National Soil Erosion Research Laboratory
- Washington State University Dept. of Biological Systems Engineering
- U.S. Army Corps of Engineers, Chicago District
- Great Lakes Commission
- Joint Fire Science Program
For More Information:
- Developed Tool
- Online forested hillslope and road erosion prediction interface
- Overview Presentations
- Related Papers
- Geospatial application of the water erosion prediction project (WEPP) model (Flanagan et al., 2013)
- Applying online WEPP to assess forest watershed hydrology (Dun et al., 2013)
David F. Bucaro, P.E.
Chief, Economic Formulation & Analysis Section
US Army Corps of Engineers – Chicago District
111 North Canal Street, Suite 600
Chicago, IL 60606-7206
Phone: (312) 846-5583