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River Bank Erosion

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River Bank Erosion

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  1. River Bank Erosion Siskiwit River, Cornucopia, WI

  2. How Do we Measure Bank Erosion?

  3. The Big Questions…continued • Are there simple methods that can be used to estimate bank erosion rates in the field? Answer…No

  4. Lateral Movement of bank. Measured in feet/year Resisting Force Intrinsic property of bank. Function of: Soil Vegetation Bank Angle Etc. Driving Force Property of the hydraulics. Function of: Near Bank Shear Stress Bank Erosion

  5. Bank Erodability How do we determine how susceptible a bank is to erosion?

  6. Predicting Bank Erosion Bank Erosion Hazard Index (BEHI)

  7. BEHI Variables • Bank Height Ratio • Root Depth Ratio • Weighted Root Density • Bank Angle • Surface Protection • Bank Material • Stratification

  8. Black River, Michigan (UP) Low Erosion Potential

  9. Moderate Erosion Potential Coldwater Creek, Union City, Michigan

  10. Very High / Extreme Erosion Potential Ontonagon River, Michigan (UP)

  11. Bank Erosion Near Bank Stress (NBS) Index Bank Erosion Hazard Index (BEHI)

  12. NBS#1 - Channel Patterns • Transverse and/or central bars – short and/or discontinous • NBS = High or Very High • Extensive deposition • NBS = Extreme • Chute cutoffs, down-valley meander migration, converging flow • NBS = Extreme

  13. NBS#2 – Ratio of Radius of Curvature (Rc) to Bankfull Width (Wbkf) Generally Rc Performed Using Aerial Photography

  14. NBS#3 & #4 – Ratio of Pool Slope to Average Slope (Sp/S) or Riffle Slope (Sp/Srif)

  15. NBS#5 – Pool Depth to Average Depth

  16. Measuring Bank Erosion

  17. Bank Erosion Bank Pins & Bank Profiles Bank Erosion Hazard Index (BEHI) Near Bank Stress (NBS) Index

  18. Bank Profile Measurement Equipment • Toe Pin (rebar) • Toe Pin Cap • Hammer • Survey Rod (2) or • Survey Rod & Pocket Rod • Line Level • Rod Level • Field Forms

  19. Measuring Bank Profile Source: Arkansas Department of Environmental Quality

  20. Comparison of Bank Profiles

  21. Bring it all Together Regional Curves

  22. Great Lakes Curves - Preliminary

  23. Is there a better correlation for predicting bank erosion? • Remotely-sensed data • Radius of curvature • Meander wavelength • Beltwidth:valley width • Valley slope • Soils maps for resistance and infiltration

  24. Questions? Contact: Dr. Jim Selegean, P.E., P.H. U.S. Army Corps of Engineers, Detroit District Great Lakes Hydraulics and Hydrology Office 477 Michigan Ave Detroit, MI 48226 313.226.6791 james.p.selegean@usace.army.mil