Project Number: 6408-13000-023-06
Project Type: Reimbursable

Start Date: Oct 01, 2009
End Date: Mar 31, 2013

Objective:
The primary objectives of the proposed work are to determine rates and loadings of sediment from streambank erosion along main stem and selected tributaries of a large agricultural watershed draining to Lake Champlain.

Approach:
The scope of the project is the main stem and four tributaries (Hereford Brook, Trout River, Tyler Branch and Black Creek) of the Missisquoi River, VT. Tests of the geotechnical and hydraulic erosion resistance of bank materials will be conducted at each site that is selected for detailed investigation. Surveys of bank geometry and vegetation characteristics (species, age and density) will also be conducted at the sites. These data will be used to determine appropriate input parameters for each bank layer at the selected sites for bank-stability modeling. The major controlling processes responsible for bank erosion will be modeled iteratively using the Bank-Stability and Toe-Erosion Model (BSTEM) developed by the ARS, National Sedimentation Laboratory that has been successfully used previously for these purposes in the Mid South and other regions. Simulations for existing bank conditions along the main stem and tributaries will be conducted for each site over a range of annual hydrographs representing the 99th, 95th, 90th, 75th, 50th, and 25th percentile flow year. Discharge data from U.S. Geological Survey (USGS) gauging stations will be converted to flow depths for each significant storm event for input into the toe-erosion sub-model. Combined toe-erosion and mass failure will then be simulated for each event at each site in an iterative fashion. Results will then be extrapolated to the remainder of the channel lengths based on field and aerial reconnaissance of the extent of streambank failures.