Estimating Sediment Loads using Bank Assessment of Non-point source Co - PDF document

Estimating Sediment Loads using Bank Ass
Estimating Sediment Loads using Bank Assessment of Non-point source Consequences of Sediment Watershed Assessment of River Stability and Sediment Supply (WARSSS): a technical quality scientists to use in evaluating streams and river impaired by excess sediment (images and forms available from EPhttp://water.epa.gov/scitech/dols/warsss/pla_box08.cfmabby.mcqueen@canaanvi.orgCanaan Valley Institute Bank Erosion Hazard Index(Very Low, Low, Moderate, High, Very High, Extreme)(NBS)Riffle (Very Low, Low, Moderate, High, Very High, Extreme)Predict annual streambank erosion rate (ft/yr) using BEHI and NBS RatingsModified from River Stability Field Guide (R

osgen, 2008) Erosion North Car
osgen, 2008) Erosion North Carolina Stream Bank (Erosion from ModerateNear Bank Stress Moderate BEHI Very High BEHI Extreme BEHI Very Low BEHIExpon. (Extreme BEHI) Expon. (Very High BEHI) Expon. (Moderate BEHI) Expon. (High BEHI)Channel Design Handbook" prepared by the ograms/extension/wqg/sr Vertical Distance(ft)D A E Bankful l Height Worksheet 20. BEHI variable worksheetCross Section:Date: Observers:Bank Height/Max Depth Bankfull (C)Bank SketchA/B = A B C Root Depth/Bank Height (E) Root Depth (ft) ted Root Density (G)Root Density(%) Bank Angle (H)(Degrees)Surface Protection (I)Protection

Horizontal Distance (ft)tudy Bank Heigh
Horizontal Distance (ft)tudy Bank Height Bank Erosion PotentialWorksheet 21. Summary of bank erosion hazard index (BEHI)Bank Erosion Hazard Rating GuideStream Reach Date CrewBank Height/Root Depth/ RootBank Angle SurfaceBankfull HtBank Height Density % (Degrees) Protection%VERY LOW LOW MODERATE VERY HIGHValue 1.0-1.1 1.0-0.9 100-80 0-20 100-80 Index 1.0-1.9 1.0-1.9 1.0-1.9 1.0-1.9 1.0-1.9 Choice V: I: V: I: V: Value 1.11-1.19 0.89-0.5 79-55 21-60 79-55 Index 2.0-3.9 2.0-3.9 2.0-3.9 2.0-3.9 2.0-3.9 Choice V: I: V: I: V: Value 1.2-1.5 0.49-0.3 54-30 61-80 54-30 Index 4.0-5.9 4.0-5.9 4.0-5.9 4.0-5.9 4.0-5.9 Choice V: I: V: I: V: Valu

e 1.6-2.0 0.29-0.15 29-15 81-90 29-
e 1.6-2.0 0.29-0.15 29-15 81-90 29-15 Index 6.0-7.9 6.0-7.9 6.0-7.9 6.0-7.9 6.0-7.9 Choice V: I: V: I: V: I: V: I: V: Value 2.1-2.8 0.14-0.05 14-5.0 91-119 14-10 Index 8.0-9.0 8.0-9.0 8.0-9.0 8.0-9.0 8.0-9.0 Choice I: V: Value �2.8  -1;ᢀ119 Index 10 10 10 10 10 Choice V: I: V: I: V: I: V: I: V: I: SUB-TOTAL (Sum one index from each column) Bank Material Description:Bank MaterialsBedrock (Bedrock banks have very low bank erosion potential) Boulders (Banks composed of boulders have low bank erosion potential) Cobble (Subtract 10 points. If sand/gravel matrix greater than 50% of bank material, then do not adjust) Gravel (A

dd 5-10 points depending percentage of b
dd 5-10 points depending percentage of bank material that is composed of sand) (Add 10 points) Silt Clay (+ 0: no adjustment)BANK MATERIAL ADJUSTMENTStratification Comments:StratificationAdd 5-10 points depending on position of unstable layers in relation to bankfull stage STRATIFICATION ADJUSTMENTVERY LOWMODERATEVERY HIGH5-9.5 10-19.5 20-29.5 30-39.5 40-45 46-50 Bank location description (circle one) GRAND TOTALStraight Reach Outside of Bend BEHI RATING Worksheet 22A. Various field methods of estimating Near-Bank Stress risk ratings for the calculation of erosion rate. Estimating Near-Bank Stress (NBS)Stream:Location:Date:Cre Methods for

Estimating Ne ar-Bank Stress(1) Trans
Estimating Ne ar-Bank Stress(1) Trans vers e bar or plit channel/central bar creating NBS/high velocity gradient: Level Reconnaisance.(2) Channel pattern (Rc/W): Level II - General Prediction.(3) Ratio of pool lope to average water urface s lope /S): Level II - General Prediction.(4) Ratio of pool lope to riffle lope (Sri f): Level II - General Prediction.(5) Ratio of near-bank maximum depth to bankfull mean depth (dnb bkf): Level III - Detailed Prediction.(6) Ratio of near-bank s hear tres s to bankfull s hear tres s (tnb bk ): Level III - Detailed Prediction.(7) Velocity profiles /Is ovels /Velocity gradient: Level I

V - Validation.Transverse and/or centra
V - Validation.Transverse and/or central bars - short and/or discontinuous. NBS = High/Very HighExtensive deposition (continuous, cross channel). NBS = ExtremeLevel I(1)Chute cutoffs, down-valley meander migration, converging flow (Figure X). NBS = ExtremeRadius ofCurvatureBankfullWidthRatio Rc (feet)bkf (feet)Rc/WNear-BankStress(2) Pool SlopeAveragSlopeRatio Near-BankStress(3)Dominant Near-BankStressPool SlopeRiffle SlopeRatio rifNear-BankStressLevel II(4) Near-BankMax DepthMean DepthRatio nb (feet)(feet)Near-BankStress(5) Near-BankMax DepthNear-BankSlopeNear-BankShearStressMean DepthAverageSlopeShearStressR

ationb (feet)nb (lb/ft(feet)(lb/ftNear
ationb (feet)nb (lb/ft(feet)(lb/ftNear-BankStressLevel III(6) Velocity Gradient (ft/s/ft)Near-BankStress Level IV(7) Conve rting Values to a Ne ar-Bank Stress RatingMethod NumberNear-Bank StressRa ting(3)(7)Ve ry �3.00.200.4.0.8.02.21 - 3.00.20 - 0.400.41 - 0.601.0 - 1.50.8 - 1.051.0 - 1.2ModeraeN/A2.01 - 2.20.41 - 0.600.61 - 0.801.51 - 1.81.06 - 1.141.21 - 1.6High1.81 - 2.00.61 - 0.800.81 - 1.01.81 - 2.51.15 - 1.191.61 - 2.0Ve ry High1.5 - 0.81 - 101.01 - 122.51 - 301.20 - 1.02.01 - 23Extre See Above1.51.01.23.01.62.3Overall Near-BankStress Rating Total Bank Length:Observers:Graph Used:(adjective)

*Near Bank Stress(adjective)Rate Bank (f
*Near Bank Stress(adjective)Rate Bank (ft)Height/yr) I. Sum erosion sub-totals for each BEHI/NBS combinationII. Divide total erosion (feet) by 27 feetIII. Multiply Total Erosion (yard) by 1.3 (conversion of to tons for average material type)(tons/year)Calculate erosion per unit length: divide total erosion (ton/year) by total lengthIV. of stream (ft) surveyed(tons/yr/ft)*Use numerical category spread to predict rates. ( i.e. 21 = Moderate but at start of category, where as 28 is on upper end of relation - use prediction values appropriate to numerical rating)