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Stream Assessment Techniques

Stream Assessment Techniques. March 2013. What is Stream Restoration?. “Reestablishment of the structure and function of ecosystems” as closely as possible to pre-disturbance conditions – (NRC, 1992). Stable Stream. Unstable Stream. Goals of Stream Restoration Projects.

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Stream Assessment Techniques

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  1. Stream Assessment Techniques March 2013

  2. What is Stream Restoration? “Reestablishment of the structure and function of ecosystems” as closely as possible to pre-disturbance conditions – (NRC, 1992)

  3. Stable Stream

  4. Unstable Stream

  5. Goals of Stream Restoration Projects Enhance functions of natural systems • Physical • Chemical • Biological • Societal

  6. Areas of Consideration • Flow • Magnitude, timing, frequency, duration • Sediment • Flux, particle shape, size distribution, timing • Chemical and thermal • Geomorphology • Stream types, channel slope, bed and bank materials • Landscape • Geology, vegetation, land use

  7. Pools and Riffles

  8. Controlling Factors in Stream Stability • Width • Depth • Slope • Velocity • Discharge • Size of sediment • Concentration of sediment • Roughness of channel

  9. Discharge Calculation Q = VA

  10. Sketch Map

  11. Dimension: Cross Sections

  12. Dimension: Cross Section

  13. Bankfull Indicators • Top of streambank • Break in slope • Top of point bar • Presence of fines

  14. Top of bank Bankfull Left Bank Right Bank Thalweg Riffle Dimensions

  15. Riffle Dimensions Wbkf Bankfull Abkf Dbkf W/D = Wbkf / Dbkf R = A / WP = Abkf / WPbkf

  16. Entrenchment Ratio Wfpa Wbkf Bankfull Dmax 2 x Dmax ER = Wfpa / Wbkf

  17. Channel Pattern

  18. 6.5 m 5 m Sinuosity of Channel Length of Channel 6.5m Sinuousity = = = 1.3 Length of Valley 5.0m

  19. Longitudinal Profile

  20. Bed Material

  21. Resistance • Roughness is a factor in determining depth and velocity of flow • Decrease in velocity results in increase in depth given constant discharge • Important factors • Particle sizes • Vegetation • Other obstructions

  22. Physical Characteristics • Sediment • Fines can impact fish and macroinverebrate habits • Water temperature • Impacts dissolved oxygen • Governs biological processes in some species

  23. Chemical Constituents • pH • Dissolved oxygen • Nutrients • Toxic organic chemicals • Metals • Salinity

  24. Stream Assessment Techniques • Reach Wide Pebble Count • Velocity Measurement • Temperature Measurement • Color/Appearance Observation • Surveying • Riffle Cross-section • Pool Cross-section • Longitudinal section • Plant/Animal Identification*

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