River Bank Erosion
description
Transcript of River Bank Erosion
Detroit District, Hydraulics & Hydrology OfficeUS Army Corpsof Engineers
River Bank Erosion
Siskiwit River, Cornucopia, WI
Detroit District, Hydraulics & Hydrology OfficeUS Army Corpsof Engineers
How Do we Measure Bank Erosion?
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
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
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?
Detroit District, Hydraulics & Hydrology OfficeUS Army Corpsof Engineers
ErosivityyErodibilitErosionBank
Predicting Bank Erosion
Bank Erosion
Hazard Index (BEHI)
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
Detroit District, Hydraulics & Hydrology OfficeUS Army Corpsof Engineers
Low Erosion Potential
Black River, Michigan (UP)
Detroit District, Hydraulics & Hydrology OfficeUS Army Corpsof Engineers
Moderate Erosion Potential
Coldwater Creek, Union City, Michigan
Detroit District, Hydraulics & Hydrology OfficeUS Army Corpsof Engineers
Very High / Extreme Erosion Potential
Ontonagon River, Michigan (UP)
Detroit District, Hydraulics & Hydrology OfficeUS Army Corpsof Engineers
ErosivityyErodibilitErosionBank
Bank Erosion
Bank Erosion
Hazard Index (BEHI)
Near Bank Stress (NBS)
Index
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
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
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
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
Detroit District, Hydraulics & Hydrology OfficeUS Army Corpsof Engineers
Measuring Bank Erosion
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
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
Detroit District, Hydraulics & Hydrology OfficeUS Army Corpsof Engineers
Measuring Bank Profile
Source: Arkansas Department of Environmental Quality
Detroit District, Hydraulics & Hydrology OfficeUS Army Corpsof Engineers
Comparison of Bank Profiles
Detroit District, Hydraulics & Hydrology OfficeUS Army Corpsof Engineers
Bring it all
Together
Regional Curves
Detroit District, Hydraulics & Hydrology OfficeUS Army Corpsof Engineers
Great Lakes Curves - Preliminary
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
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