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Stream Stability Stream Stability AssessmentAssessment

& BEHI Surveys& BEHI Surveys

Joe RathbunJoe Rathbun

MDEQ MDEQ –– Water Resources DivisionWater Resources Division

rathbunj@michigan.govrathbunj@michigan.gov

517517--373373--88688868

StabilityStability

Stream can transport its Stream can transport its waterwater and and sedimentsediment inputs inputs without changing without changing channel channel dimensionsdimensions

Width, depth, slopeWidth, depth, slope

Complicating IssuesComplicating Issues

Stream bank & bed mobility is naturalStream bank & bed mobility is natural

Unnatural bank & bed mobility can Unnatural bank & bed mobility can

have multiple causeshave multiple causes

Causes can be local or largerCauses can be local or larger--scaledscaled

Local causes can be fixed with local Local causes can be fixed with local best management practices (BMPs)best management practices (BMPs)

LargeLarge--scale causes can only be fixed scale causes can only be fixed

with largewith large--scale BMPsscale BMPs

Local Causes Easy to IdentifyLocal Causes Easy to Identify

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LargeLarge--Scale Causes Harder to Scale Causes Harder to IdentifyIdentify Most common cause of Most common cause of

largelarge--scale channel scale channel degradation = degradation =

Hydrologic alterationHydrologic alteration and and increasing sediment loadsincreasing sediment loads

due to landuse changesdue to landuse changes

Causes of Hydrologic AlterationCauses of Hydrologic Alteration

Impervious surfaceImpervious surface

Soil compactionSoil compaction

Vegetation changeVegetation change

DamsDams

Tile drainageTile drainage

Water withdrawalWater withdrawal

Results of Hydrologic AlterationResults of Hydrologic Alteration

Changes in:Changes in:

Peak flows Peak flows

Stream “flashiness”Stream “flashiness”

Channel dimensionsChannel dimensions

–– WidthWidth

–– DepthDepth

–– SinuositySinuosity

–– SlopeSlope

Sources of Sources of Increased Sediment LoadsIncreased Sediment Loads

Upland erosionUpland erosion–– Agriculture, forestry, general developmentAgriculture, forestry, general development

Stream bank erosionStream bank erosion–– 10 to 90 % 10 to 90 % of total sediment loadof total sediment load

Dam failuresDam failures

Results of Increased Sediment Results of Increased Sediment LoadsLoads

Loss of macroinvertebrate & fish Loss of macroinvertebrate & fish

habitathabitat

Buried Buried rifflesriffles

Loss of Loss of poolspools

Channel filling (Channel filling (aggradationaggradation) = channel ) = channel wideningwidening

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Indicators of Channel ConditionIndicators of Channel Condition

QualitativeQualitative

–– ObservationalObservational

QuantitativeQuantitative

–– Observational = Observational = BBank ank EErosion rosion HHazard azard

IIndex (BEHI)ndex (BEHI)

–– MeasurementMeasurement--based = several optionsbased = several options

Positive Qualitative Indicators: Positive Qualitative Indicators: Herbaceous VegetationHerbaceous Vegetation

Positive Qualitative Indicators: Positive Qualitative Indicators: Aquatic MossAquatic Moss

Positive Qualitative Indicators: Positive Qualitative Indicators: Sensitive Fish or MusselsSensitive Fish or Mussels

Negative Qualitative Indicators: Negative Qualitative Indicators: Unvegetated MidUnvegetated Mid--Channel Bar, Channel Bar,

or Braided Channelor Braided Channel

Negative Qualitative Indicators: Negative Qualitative Indicators: Leaning Trees on Both SidesLeaning Trees on Both Sides

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Negative Qualitative Indicators: Negative Qualitative Indicators: Exposed InfrastructureExposed Infrastructure

Negative Qualitative Indicators: Negative Qualitative Indicators: Failed BMPsFailed BMPs

Negative Qualitative Indicators: Negative Qualitative Indicators: Headcuts (= Nickpoints)Headcuts (= Nickpoints)

Negative Qualitative Indicators: Negative Qualitative Indicators:

Exposed Tree Roots on Exposed Tree Roots on BothBoth SidesSides

Negative Qualitative Indicators: Negative Qualitative Indicators: Slumping Stream BanksSlumping Stream Banks

Negative Qualitative Indicators: Negative Qualitative Indicators: Downstream of a DamDownstream of a Dam

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“Stable” → → → → → → → → → → → → → → → → → → “Unstable”

Limitation to

qualitative

stability

indicators…

…the real world

is a continuum,

not a dichotomy

BBank ank EErosion rosion HHazard azard IIndexndex

““BEHI” BEHI” –– developed by Dr. Dave Rosgendeveloped by Dr. Dave Rosgen

Seven metrics:Seven metrics:

–– Plant root depthPlant root depth

–– Root densityRoot density

–– Bank angleBank angle

–– Surface protectionSurface protection

–– Bank compositionBank composition

–– Bank stratificationBank stratification

–– (Bank Ht./Bankfull Ht.)(Bank Ht./Bankfull Ht.)

BEHI ApplicabilityBEHI Applicability

Alluvial channels onlyAlluvial channels only –– those that form those that form

themselves through sediment transportthemselves through sediment transport

Alluvial Not alluvial

Also not alluvialAlso not alluvial

Root Depth = depth relative to Root Depth = depth relative to bank height, in %bank height, in %

~ 100 % ≤ 30 %

Values: < 5; 5-14; 15-29; 30-49; 50-89; 90-100

Scores: 10 8.5 7 5 3 1.5

Root Density = % of bank Root Density = % of bank surface covered by rootssurface covered by roots

~ 100 % ~ 40 %

Values: < 5; 5-14; 15-29; 30-49; 50-89; 90-100

Scores: 10 8.5 7 5 3 1.5

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Surface Protection = % of bank Surface Protection = % of bank covered by rocks, logs, etc.covered by rocks, logs, etc.

~ 30%

Top of bank

Values

< 10; 10-14;

15-29; 30-49; 50-89; 90-100

Bank AngleBank Angle

80°to 90°~ 10°

Values: 0-20; 21-60; 61-80; 81-90; 91-119; > 119

Scores: 1.5 3 5 7 8.5 10

Bank angle hardest to get right?Bank angle hardest to get right?Adjustment Factors: Bank materialsAdjustment Factors: Bank materials

Bedrock, boulders, & cobble = Bedrock, boulders, & cobble =

decreaseddecreased erosion riskerosion risk

Gravel & sand = Gravel & sand = increasedincreased erosion riskerosion risk

Bedrock = always “Very Low”Bedrock = always “Very Low”

Boulders = always “Low”Boulders = always “Low”

Cobble = subtract 10 pointsCobble = subtract 10 points

Gravel or mostly gravel = add 5 pointsGravel or mostly gravel = add 5 points

Sand or mostly sand = add 10 pointsSand or mostly sand = add 10 points

Silt or clay = no adjustmentSilt or clay = no adjustment

Adjustment Factors: Bank stratificationAdjustment Factors: Bank stratification

Sand layersSand layers within a bank of other within a bank of other

materials = materials = increasedincreased erosion riskerosion risk

–– No layers = no adjustmentNo layers = no adjustment

–– Single layer of erodible material = add 5 Single layer of erodible material = add 5 pointspoints

–– Multiple layers of erodible materials = add Multiple layers of erodible materials = add 10 points10 points

Rural Stream

Plant root depth ≈ 100 %

Root density ≈ 90 %

Bank angle ≈ 30º

Surface protection = 90 %

Materials = silt/loam

Stratification = none

BEHI = 9.5 = Low

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Urban Stream

Plant root depth ≈ 40 %

Root density ≈ 10 %

Bank angle ≈ 85º

Surface protection ≈ 10 %

Materials = sand = +10

Stratification = none

BEHI = 39 = Very High

Unstable Ag Stream

Plant root depth < 5 %

Root density < 5 %

Bank angle ≈ 90º

Surface protection < 10 %

Materials = silt/loam

Stratification = none

BEHI = 37 = Extreme(Upper Iowa River, MN)

Stable Ag Drain

Plant root depth ≈ 100 %

Root density ≈ 100 %

Bank angle ≈ 60º

Surface protection ≈ 100 %

Materials = silt/loam

Stratification = none

BEHI = 7.5 = Low

Unstable Ag Drain

Plant root depth ≈ 10 %

Root density ≈ 15 %

Bank angle ≈ 80º

Surface protection ≈ 5 %

Materials = sand = +10

Stratification = none

BEHI = 40.5 = Extreme

Stabilized Bank

Plant root depth ≈ 10 %

Root density ≈ 20 %

Bank angle ≈ 80º

Surface protection ≈ 30 %

Materials = silt/loam

Stratification = none

BEHI = 27 = High

Urban stream, in park

Plant root depth ≈ 90 %

Root density ≈ 60 %

Bank angle ≈ 90º

Surface protection ≈ 0 %

Materials = silt/loam

Stratification = none

BEHI = 21.5 = High

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BEHI Application BEHI Application ––Local Problem = Local BMPLocal Problem = Local BMP

Low

Moderate

Extreme

Project site

BEHI Application BEHI Application ––

Widespread Problem = LargeWidespread Problem = Large--scale BMPsscale BMPs

Low

Moderate

Extreme

Project site

BEHIBEHI

ProsPros

Quantitative, & a continuum Quantitative, & a continuum

Minimal training requiredMinimal training required

Low level of effort; 1 day = Low level of effort; 1 day = multiple stationsmultiple stations

ConsCons

InterInter--person variation person variation

No estimate of No estimate of erosion rateerosion rate or or sediment loadingssediment loadings

OnOn--going Study to Calibrate going Study to Calibrate BEHIBEHI

BEHI + bank pin or toe pin BEHI + bank pin or toe pin

measurementsmeasurements

Quantify Quantify bank erosion ratesbank erosion rates and and

calculate sediment loadingscalculate sediment loadings for for different BEHI categoriesdifferent BEHI categories

Army Corps, DEQ, DNRArmy Corps, DEQ, DNR

Throughout Great Lakes statesThroughout Great Lakes states

Calibrating BEHI Calibrating BEHI –– Toe PinsToe Pins Calibrating BEHI Calibrating BEHI –– Toe PinsToe Pins

Eleventh St.

0

0.5

1

1.5

2

2.5

3

3.5

0 1 2 3 4

Feet

Feet

7/20/2010

7/13/2011

1.Square feet of soil lost x bank length = cubic feet of soil lost

2.Cubic feet x soil density = mass of soil lost

BEHI = 10

= Low

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Another option: Another option: crosscross--channel transectschannel transects

86

87

88

89

90

91

92

93

94

95

96

0 20 40 60 80 100 120 140Station (ft)

Ele

vati

on

(ft

)

2010

2011

RichardsRichards--Baker Baker Stream Flashiness IndexStream Flashiness Index

““FlashyFlashy” stream = frequent, ” stream = frequent, rapid, shortrapid, short--term changes in term changes in

streamflowstreamflow

Due to impervious surfaces, Due to impervious surfaces, tile drainage, etc.tile drainage, etc.

Stream Flashiness IndexStream Flashiness Index

Calculate using USGS gage station Calculate using USGS gage station

datadata

Time

Dis

ch

arg

e (

m3/s

ec)

High Flashiness Index Low Flashiness Index

04135700 SOUTH BRANCH AU SABLE RIVER NEAR

LUZERNE, MI

0

0.01

0.02

0.03

0.04

0.05

0.06

1960 1970 1980 1990 2000 2010

Water Year

Ind

ex

Stable flashiness

04136500 AU SABLE RIVER AT MIO, MI

0

0.02

0.04

0.06

0.08

0.1

0.12

1950 1960 1970 1980 1990 2000 2010

Water Year

Ind

ex

Decreasing flashiness

10

04135500 AU SABLE RIVER AT GRAYLING, MI

0

0.01

0.02

0.03

0.04

0.05

0.06

0.07

0.08

0.09

0.1

1940 1950 1960 1970 1980 1990Water Year

Ind

ex

Complex flashiness

Flashiness Index Results Flashiness Index Results –– 308 sites308 sites

Thanks! Questions?Thanks! Questions?