Stream assessment techniques
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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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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

Enhance functions of natural systems

  • Physical

  • Chemical

  • Biological

  • Societal


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


Pools and Riffles


Controlling Factors in Stream Stability

  • Width

  • Depth

  • Slope

  • Velocity

  • Discharge

  • Size of sediment

  • Concentration of sediment

  • Roughness of channel


Discharge Calculation

Q = VA


Sketch Map


Dimension: Cross Sections


Dimension: Cross Section


Bankfull Indicators

  • Top of streambank

  • Break in slope

  • Top of point bar

  • Presence of fines


Top of bank

Bankfull

Left Bank

Right Bank

Thalweg

Riffle Dimensions


Riffle Dimensions

Wbkf

Bankfull

Abkf

Dbkf

W/D = Wbkf / Dbkf

R = A / WP = Abkf / WPbkf


Entrenchment Ratio

Wfpa

Wbkf

Bankfull

Dmax

2 x Dmax

ER = Wfpa / Wbkf


Channel Pattern


6.5 m

5 m

Sinuosity of Channel

Length of Channel

6.5m

Sinuousity =

=

=

1.3

Length of Valley

5.0m


Longitudinal Profile


Bed Material


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


Physical Characteristics

  • Sediment

    • Fines can impact fish and macroinverebrate habits

  • Water temperature

    • Impacts dissolved oxygen

    • Governs biological processes in some species


Chemical Constituents

  • pH

  • Dissolved oxygen

  • Nutrients

  • Toxic organic chemicals

  • Metals

  • Salinity


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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