11

Stream Assessment Stream Assessment TechniquesTechniques

March 2013March 2013

22

What is Stream Restoration?What is Stream Restoration?

““Reestablishment of the Reestablishment of the structurestructure and and functionfunction of ecosystems” of ecosystems” as closely as as closely as possiblepossible to pre-disturbance to pre-disturbance conditions – (NRC, 1992)conditions – (NRC, 1992)

33

Stable StreamStable Stream

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Unstable StreamUnstable Stream

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Goals of Stream Restoration Goals of Stream Restoration ProjectsProjects

Enhance Enhance functionsfunctions of natural systems of natural systems

• Physical Physical

• ChemicalChemical

• BiologicalBiological

• SocietalSocietal

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Areas of ConsiderationAreas of Consideration

• FlowFlow– Magnitude, timing, frequency, durationMagnitude, timing, frequency, duration

• SedimentSediment– Flux, particle shape, size distribution, timingFlux, particle shape, size distribution, timing

• Chemical and thermal Chemical and thermal • GeomorphologyGeomorphology

– Stream types, channel slope, bed and bank Stream types, channel slope, bed and bank materialsmaterials

• LandscapeLandscape– Geology, vegetation, land useGeology, vegetation, land use

77

88

Pools and RifflesPools and Riffles

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Controlling Factors in Stream Controlling Factors in Stream StabilityStability

1.1. WidthWidth

2.2. DepthDepth

3.3. SlopeSlope

4.4. VelocityVelocity

5.5. DischargeDischarge

6.6. Size of sedimentSize of sediment

7.7. Concentration of sedimentConcentration of sediment

8.8. Roughness of channelRoughness of channel

1010

Discharge CalculationDischarge Calculation

Q = VA

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Sketch MapSketch Map

1212

Dimension: Cross SectionsDimension: Cross Sections

1313

Dimension: Cross SectionDimension: Cross Section

1414

Bankfull IndicatorsBankfull Indicators

• Top of streambankTop of streambank

• Break in slopeBreak in slope

• Top of point barTop of point bar

• Presence of finesPresence of fines

1515

1616

Bankfull

Top of bank

Left Bank Right Bank

Thalweg

Riffle DimensionsRiffle Dimensions

1717

Riffle DimensionsRiffle Dimensions

Bankfull

Wbkf

Dbkf

Abkf

W/D = Wbkf / DbkfR = A / WP = Abkf / WPbkf

1818

Entrenchment RatioEntrenchment Ratio

Bankfull

Wbkf

Dmax

ER = Wfpa / Wbkf

Wfpa

2 x Dmax

1919

Channel PatternChannel Pattern

2020

Sinuosity of ChannelSinuosity of Channel

6.5 m

5 m

Sinuousity = Length of ChannelLength of Valley

6.5m5.0m= = 1.3

2121

Longitudinal ProfileLongitudinal Profile

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Bed MaterialBed Material

2323

ResistanceResistance

• Roughness is a factor in determining Roughness is a factor in determining depth and velocity of flowdepth and velocity of flow– Decrease in velocity results in increase Decrease in velocity results in increase

in depth given constant dischargein depth given constant discharge

• Important factorsImportant factors– Particle sizesParticle sizes– VegetationVegetation– Other obstructionsOther obstructions

2424

Physical CharacteristicsPhysical Characteristics

• SedimentSediment– Fines can impact fish and Fines can impact fish and

macroinverebrate habitsmacroinverebrate habits

• Water temperatureWater temperature– Impacts dissolved oxygenImpacts dissolved oxygen– Governs biological processes in some Governs biological processes in some

speciesspecies

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Chemical ConstituentsChemical Constituents

• pHpH

• Dissolved oxygenDissolved oxygen

• NutrientsNutrients

• Toxic organic chemicalsToxic organic chemicals

• MetalsMetals

• SalinitySalinity

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Stream Assessment Stream Assessment TechniquesTechniques• Reach Wide Pebble CountReach Wide Pebble Count• Velocity MeasurementVelocity Measurement• Temperature MeasurementTemperature Measurement• Color/Appearance ObservationColor/Appearance Observation• SurveyingSurveying

– Riffle Cross-sectionRiffle Cross-section– Pool Cross-sectionPool Cross-section– Longitudinal sectionLongitudinal section

• Plant/Animal Identification*Plant/Animal Identification*