river bank erosion
DESCRIPTION
River Bank Erosion. Siskiwit River, Cornucopia, WI. How Do we Measure Bank Erosion?. The Big Questions…continued. Are there simple methods that can be used to estimate bank erosion rates in the field?. Answer…No. Lateral Movement of bank. Measured in feet/year. Resisting Force - PowerPoint PPT PresentationTRANSCRIPT
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Detroit District, Hydraulics & Hydrology OfficeUS Army Corpsof Engineers
River Bank Erosion
Siskiwit River, Cornucopia, WI
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Detroit District, Hydraulics & Hydrology OfficeUS Army Corpsof Engineers
How Do we Measure Bank Erosion?
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Detroit District, Hydraulics & Hydrology OfficeUS Army Corpsof Engineers
The Big Questions…continued
• Are there simple methods that can be used to estimate bank erosion rates in the field?
• Are there simple methods that can be used to estimate bank erosion rates in the field?
Answer…NoAnswer…No
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Detroit District, Hydraulics & Hydrology OfficeUS Army Corpsof Engineers
ErosivityyErodibilitErosionBank
Lateral Movement of
bank.
Measured in feet/year
Resisting Force
Intrinsic property of bank.
Function of:Soil
VegetationBank Angle
Etc.
Driving Force
Property of the hydraulics.
Function of:Near Bank
Shear Stress
Bank Erosion
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Detroit District, Hydraulics & Hydrology OfficeUS Army Corpsof Engineers
Bank Erodability
How do we determine how susceptible a bank is to erosion?
How do we determine how susceptible a bank is to erosion?
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Detroit District, Hydraulics & Hydrology OfficeUS Army Corpsof Engineers
ErosivityyErodibilitErosionBank
Predicting Bank Erosion
Bank Erosion
Hazard Index (BEHI)
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Detroit District, Hydraulics & Hydrology OfficeUS Army Corpsof Engineers
• Bank Height Ratio
• Root Depth Ratio
• Weighted Root Density
• Bank Angle
• Surface Protection
• Bank Material
• Stratification
• Bank Height Ratio
• Root Depth Ratio
• Weighted Root Density
• Bank Angle
• Surface Protection
• Bank Material
• Stratification
BEHI Variables
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Detroit District, Hydraulics & Hydrology OfficeUS Army Corpsof Engineers
Low Erosion Potential
Black River, Michigan (UP)
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Detroit District, Hydraulics & Hydrology OfficeUS Army Corpsof Engineers
Moderate Erosion Potential
Coldwater Creek, Union City, Michigan
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Detroit District, Hydraulics & Hydrology OfficeUS Army Corpsof Engineers
Very High / Extreme Erosion Potential
Ontonagon River, Michigan (UP)
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Detroit District, Hydraulics & Hydrology OfficeUS Army Corpsof Engineers
ErosivityyErodibilitErosionBank
Bank Erosion
Bank Erosion
Hazard Index (BEHI)
Near Bank Stress (NBS)
Index
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Detroit District, Hydraulics & Hydrology OfficeUS Army Corpsof Engineers
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
• 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
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Detroit District, Hydraulics & Hydrology OfficeUS Army Corpsof Engineers
NBS#2 – Ratio of Radius of Curvature (Rc) to Bankfull Width (Wbkf)
Rc/Wbkf Rating
> 3.00 Very Low
2.21 – 3.00 Low
2.01 – 2.20 Moderate
1.81 – 2.00 High
1.50 – 1.80 Very High
< 1.50 Extreme
Generally Rc Performed Using Aerial PhotographyGenerally Rc Performed Using Aerial Photography
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Detroit District, Hydraulics & Hydrology OfficeUS Army Corpsof Engineers
NBS#3 & #4 – Ratio of Pool Slope to Average Slope (Sp/S) or Riffle Slope (Sp/Srif)
Sp/Srif Rating
< 0.40 Very Low
0.41 – 0.60 Low
0.61 – 0.80 Moderate
0-81 – 1.00 High
1.01 – 1.20 Very High
> 1.20 Extreme
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Detroit District, Hydraulics & Hydrology OfficeUS Army Corpsof Engineers
dnb/dbkf Rating
< 1.00 Very Low
1.00 – 1.50 Low
1.51 – 1.80 Moderate
1.81 – 2.50 High
2.51 – 3.00 Very High
> 3.00 Extreme
NBS#5 – Pool Depth to
Average Depth
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Detroit District, Hydraulics & Hydrology OfficeUS Army Corpsof Engineers
Measuring Bank Erosion
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Detroit District, Hydraulics & Hydrology OfficeUS Army Corpsof Engineers
ErosivityyErodibilitErosionBank
Bank Erosion
Bank Pins & Bank Profiles
Bank Erosion
Hazard Index (BEHI)
Near Bank Stress (NBS)
Index
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Detroit District, Hydraulics & Hydrology OfficeUS Army Corpsof Engineers
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
Equipment
• Toe Pin (rebar)
• Toe Pin Cap
• Hammer
• Survey Rod (2) or
• Survey Rod & Pocket Rod
• Line Level
• Rod Level
• Field Forms
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Detroit District, Hydraulics & Hydrology OfficeUS Army Corpsof Engineers
Measuring Bank Profile
Source: Arkansas Department of Environmental Quality
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Detroit District, Hydraulics & Hydrology OfficeUS Army Corpsof Engineers
Comparison of Bank Profiles
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Detroit District, Hydraulics & Hydrology OfficeUS Army Corpsof Engineers
Bring it all
Together
Regional Curves
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Detroit District, Hydraulics & Hydrology OfficeUS Army Corpsof Engineers
Great Lakes Curves - Preliminary
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Detroit District, Hydraulics & Hydrology OfficeUS Army Corpsof Engineers
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
• Remotely-sensed data
• Radius of curvature
• Meander wavelength
• Beltwidth:valley width
• Valley slope
• Soils maps for resistance and infiltration
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Detroit District, Hydraulics & Hydrology OfficeUS Army Corpsof Engineers
Questions?
Contact: Dr. Jim Selegean, P.E., P.H.
U.S. Army Corps of Engineers, Detroit DistrictGreat Lakes Hydraulics and Hydrology Office
477 Michigan AveDetroit, MI 48226
313.226.6791