Latest Innovations in Stream Restoration

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Latest Innovations in Stream Restoration
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Fluvial Geomorphology

• Branch of science concerned with influence
• of rivers and streams on the formation of
• the earths surface

Governing Processes

• Erosion
• Sediment Transport
• Sediment Deposition

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Bankfull Discharge

• Controls Channel Form
• Corresponds to the Discharge at Which Channel
  Maintenance is Most Effective
• Recurrence Interval on Order of 1.0 to 1.6 Years
• Higher Recurrence Interval in Urban Watersheds

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Bankfull Indicators

• Flat, Depositional Surface Adjacent to Active
  Channel
• Height of Depositional Features (Point Bars)
• Change in Vegetation
• Slope or Topographic Breaks or Changes Along the
  Bank

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Past Attempts at Designing Streams
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Past Attempts at Designing Streams
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Designing Channels to be Natural
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Designing Channels to be Natural
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Natural Stream Systems
Terrace
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Terrace
Terrace
Terrace
Floodplain
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Entrenched Channel
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Shear Stresses in Streams
Channelized Stream
100-Year Storm
D100
2-Year Storm

D2
Natural Stream
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Differences
CONCEPT TRADITIONAL
GEOMORPHOLOGICAL
Time Short-term
Long-term
Model Theoretical Field
Measurement
Water Clear Sediment
Laden
Spatial Scale Reach
Watershed
Boundary Rigid
Mobile
Maintenance High
Sustainable
Design Flow 100 yr.
Bankfull Flow
Factor of Safety Conservative Balance of
Forces
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Natural Channel Design
Process by which new or re-constructed stream
channels and their associated floodplain riparian
systems are designed to be naturally functional,
stable, healthy, productive and sustainable.
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Soil Bioengineering

• The Use of Living and Non-Living Materials to
  Provide Soil Reinforcement and Prevent Erosion

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Comparison of Natural Channel Design and Soil
Bioengineering
Soil
Natural
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Rosgen Stream Classification
Source D. L. Rosgen
Function of
? Entrenchment ? Width/Depth Ratio ?
Slope

• ? Sinuosity ? Number of channels ? Channel
  Materials

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Rosgen Stream Classification System
Source D. L. Rosgen
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Channel Materials
Rosgen Stream Classification System

• Based on the D50 of the Dominant Bed Material

1 - Bedrock 2 - Boulder 3 - Cobble
4 - Gravel 5 - Sand 6 - Silt/Clay
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STREAM TYPE - C5
Rosgen Stream Classification System

• Well Defined Floodplain
• Meandering Point-Bars
• Good Riffle/Pool Distribution
• Entrenchment Ratio gt 2.2
• W/D Ratio gt 12
• M/W Ratio 4-20
• Sinuosity gt 1.2
• Slope lt 0.02

Source D. L. Rosgen
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Stream Evolution Models

• Key Tool Used for Stream Assessments
• Predictor of Current Future Stream Stability
• Useful for Prioritization of Restoration
  Activities

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Simons Modification of Schumms Model
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Use of Rosgens Classification System to Predict
Channel Evolution
Source D. L. Rosgen
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Use of Rosgens Classification System to Predict
Channel Evolution
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Use of Rosgens Classification System to Predict
Channel Evolution
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Geomorphic Approach to NCD

• Stable Reference Stream in Same
  Hydro-Physiographical Region
• Streams Exist in Dynamic State of Equilibrium
• Requires a Number of Geomorphic Measurements from
  a Reference Reach
• Range of Dimensionless Ratios
• Check that Designed Stream Can Handle Sediment
  Delivered by Watershed

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Reference Reach Criteria

• Stable Reference Stream in Same
  Hydro-Physiographical Region
• Must be Same Stream Type as Intended Design and
  Consistent w/ Existing Valley Type
• Must be Stable for a Minimum of Two Meander
  Wavelengths (20 Bankfull Widths)
• Best if Similar Valley Slope and Sediment Regime
  as Impacted Reach

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Locating Reference Reaches

• Same Stream as Impacted Reach
• Same General Watershed
• Review Gazetteer Maps for Similar Pattern Streams
  as Intended Design
• Be Prepared to Drive to Numerous Sites
• Reference Reaches are Typically not Found at
  Bridges and Culverts!!!!

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Dimensionless Ratios
Wbkf 20
Lm 200 Feet
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Dimensionless Ratios
Lm/Wbkf 200/2010
Wbkf 20
Lm 200 Feet
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Dimensionless Ratios
Reference Reach
Designed Reach
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Stream Restoration Techniques
Reference Reach NCD Process

• Determine Site Constraints Design Parameters
• Predict Stable Geometry Based on Reference Reach
• Check Sediment Transport Competency Capacity
  Equations
• Iterative Design Until Geometry and Calculated
  Depths Converge

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Sediment Transport Validation

• Verify Sediment Delivered to the System Will be
  Transported
• Procedures for Gravel Systems Typically Based on
  Sediment Transport Competency and Capacity
• Procedures for Sand Systems Typically Based on
  Sediment Transport Capacity

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Wbkf
In-Stream Structures
Cross-Vane
1/3
1/3
1/3
C
B
A
D
Approx. Half Wbkf
20-30 Degrees
B
C
Cross Section View
A
A
2-7 Slope
D
B
Longitudinal Profile
Flow
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Wbkf
Design of Vane Structures
1/4
1/2
1/4
W-Weir
D
B
20-30 Degrees
A
C
E
Scour Pools
Profile View
Flow
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Design of Vane Structures
J-Hook Vane
20-30 Degrees
Scour Pool
Flow
Cross Section View
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Rio Blanco

• J-Hook Vane

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Rootwad - Log Vane - J-Hook Combo

• Daves new go to player

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Latest Innovations in Stream Restoration