By Marjorie Wolfe, PE, CFM  Senior Engineer  Clean Water Services Tualatin River Tributaries Cohesive Stream Channel Erodi...
Outline <ul><ul><li>Clean Water Services </li></ul></ul><ul><li>What we’re about and where we are coming from </li></ul><u...
Tualatin River Watershed
Clean  Water  Services Facts <ul><li>Board of Directors is Washington County Commission </li></ul><ul><li>Serve a populati...
<ul><li>Mission </li></ul><ul><li>Enhance the environment and quality of life in the Tualatin River Watershed through visi...
<ul><li>Holistic Approach </li></ul><ul><li>Wastewater, stormwater  </li></ul><ul><li>Encourages watershed protection and ...
The Clean Water Course Swale Water Quality Treatment Stream Restoration Projects Watersheds 2000 Healthy Streams Plan Wate...
<ul><li>⇧ Public Awareness and  Expectations </li></ul><ul><li>⇧ Regulatory Requirements </li></ul><ul><li>⇧ Costs </li></...
Outline <ul><ul><li>Clean Water Services </li></ul></ul><ul><li>What we’re about and where we are coming from </li></ul><u...
Why this study? <ul><li>Given That … </li></ul><ul><li>Urbanization impacts streams </li></ul><ul><li>Stream health is imp...
<ul><ul><li>To ensure that surface water management strategies are cost effective and provide greatest ecological uplift t...
Cedar Mill Creek Watershed, 1984
Cedar Mill Creek Watershed, 1990
Cedar Mill Creek Watershed, 1994
Cedar Mill Creek Watershed, 1997
Cedar Mill Creek Watershed, 2002
<ul><ul><li>Clean Water Services </li></ul></ul><ul><li>What we’re about and where we are coming from </li></ul><ul><ul><l...
<ul><li>Understanding Stream Power and erosion </li></ul>Why this Approach?
<ul><li>References </li></ul><ul><li>Stage I </li></ul><ul><li>Stage VI </li></ul>Stream Response
What is different about cohesives?
What does flow have to do with it? (USEPA - after Wolman and Miller 1960)
<ul><ul><li>Clean Water Services </li></ul></ul><ul><li>What we’re about and where we are coming from </li></ul><ul><ul><l...
<ul><li>1. Determine critical shear stress and erodibility values  for typical cohesive soils. </li></ul><ul><li>2. Use th...
<ul><li>In depth measurement of erodibility and critical shear stress parameters of typical cohesive soils at 50 sites. </...
<ul><li>What:  Erodibility coefficient, and critical shear stress, and shear strength properties. </li></ul><ul><li>How:  ...
Obtained from jet-test device    =  k  (  o -   c )    = erosion rate (m/s) k   = erodibility coefficient (m 3 /N-s) ...
Jest Test Device Jet Nozzle Jet Nozzle As scour hole depth increases, shear stress decreases
From Relation between Shear Stress and Erosion We Can Calculate   c  and   Shear Stress, Pa Erosion Rate, cm 3 /sec  c
Determining shear strength
<ul><li>BSTEM :  Bank Stability Toe Erosion Model </li></ul><ul><li>Relates erodibility to flow rates over time </li></ul>...
Bank-Toe Erosion After First Flow Event Bank Stability and Toe Erosion Model (BSTEM)
Check for stability FS>1
Simulate Next Flow and Check Stability
 
<ul><li>What:  Rapid geomorphic assessments. </li></ul><ul><li>How:  Determine stage of channel evolution, incision, widen...
Cohesive Strength Meter (CSM ) The CSM consists of a water-filled chamber 30 mm in diameter that is pushed into the sedime...
Mapping Critical Shear Stress: Yalobusha River Basin, MS
<ul><li>What:  Determine effect of vegetation on stream bank stability. </li></ul><ul><li>How:  Measure root strength and ...
Cohesion due to roots is a function of the tensile strength of the roots and their distribution (root-area ratio)
<ul><li>Range of cohesive soil erodibility  </li></ul><ul><li>Effect of active floodplains and beaver activity </li></ul><...
Same creek different corridor
Summary <ul><li>Understand the erosion characteristics of Tualatin basin cohesive soils </li></ul><ul><li>Understand the r...
<ul><li>For more information: </li></ul><ul><li>Clean Water Services </li></ul><ul><li>www.cleanwaterservices.org </li></u...
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Asce Ewrg Presentation

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Tualatin river tributary stream erosion study in partnership with Andrew Simon of USDA.

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Asce Ewrg Presentation

  1. 1. By Marjorie Wolfe, PE, CFM Senior Engineer Clean Water Services Tualatin River Tributaries Cohesive Stream Channel Erodibility Study
  2. 2. Outline <ul><ul><li>Clean Water Services </li></ul></ul><ul><li>What we’re about and where we are coming from </li></ul><ul><ul><li>Why this Study? </li></ul></ul><ul><li>Drivers and objectives </li></ul><ul><ul><li>Review of stream erosion processes </li></ul></ul><ul><li>Cohesive vs non-cohesive </li></ul><ul><ul><li>The nuts and Bolts – technical details </li></ul></ul><ul><ul><li>Preliminary findings </li></ul></ul><ul><ul><li>Summary </li></ul></ul>
  3. 3. Tualatin River Watershed
  4. 4. Clean Water Services Facts <ul><li>Board of Directors is Washington County Commission </li></ul><ul><li>Serve a population of more than 500,000 inside the urban growth boundary </li></ul><ul><li>Regional SWM utility in cooperation with Washington County and 12 Cities </li></ul><ul><li>Tree for all challenge: two million native trees and shrubs to be planted over 20 years </li></ul><ul><li>FY 08-09 Budget </li></ul><ul><ul><li>$55.8 million Operating </li></ul></ul><ul><ul><li>$67 million Capital </li></ul></ul>
  5. 5. <ul><li>Mission </li></ul><ul><li>Enhance the environment and quality of life in the Tualatin River Watershed through visionary and collaborative management of water resources in partnership with others. </li></ul><ul><li>Vision </li></ul><ul><li>We provide cost-effective services and environmentally sensitive management of water resources for the Tualatin River watershed. </li></ul>A direct Connection
  6. 6. <ul><li>Holistic Approach </li></ul><ul><li>Wastewater, stormwater </li></ul><ul><li>Encourages watershed protection and enhancement Programs (Trading) </li></ul><ul><li>Incorporates Watershed assessment and monitoring activities </li></ul>Watershed based permit
  7. 7. The Clean Water Course Swale Water Quality Treatment Stream Restoration Projects Watersheds 2000 Healthy Streams Plan Watershed Based Permit Stream Erodibility Study Vegetated Corridor Standards
  8. 8. <ul><li>⇧ Public Awareness and Expectations </li></ul><ul><li>⇧ Regulatory Requirements </li></ul><ul><li>⇧ Costs </li></ul><ul><li>⇧ Environmental Quality including: </li></ul><ul><ul><li>Water Quality </li></ul></ul><ul><ul><li>Aquatic Habitat </li></ul></ul><ul><ul><li>Ecosystem diversity </li></ul></ul>Preparing for the Next Bend…
  9. 9. Outline <ul><ul><li>Clean Water Services </li></ul></ul><ul><li>What we’re about and where we are coming from </li></ul><ul><ul><li>Why this Study? </li></ul></ul><ul><li>Drivers and objectives </li></ul><ul><ul><li>Review of stream erosion processes </li></ul></ul><ul><li>Cohesive vs non-cohesive </li></ul><ul><ul><li>The nuts and Bolts – technical details </li></ul></ul><ul><ul><li>Preliminary findings </li></ul></ul><ul><ul><li>Summary </li></ul></ul>
  10. 10. Why this study? <ul><li>Given That … </li></ul><ul><li>Urbanization impacts streams </li></ul><ul><li>Stream health is important </li></ul><ul><li>Unknown characteristics of cohesive soils </li></ul><ul><li>Quantify the influence of floodplains and vegetated corridors </li></ul><ul><li>Introducing </li></ul><ul><li>Andrew Simon </li></ul><ul><li>USDA-ARS National Sedimentation Laboratory, Oxford, MS </li></ul>
  11. 11. <ul><ul><li>To ensure that surface water management strategies are cost effective and provide greatest ecological uplift to Tualatin tributaries. </li></ul></ul><ul><li>By providing data to inform… </li></ul><ul><ul><li>Improved stream restoration designs </li></ul></ul><ul><ul><li>Effective stormwater management strategies </li></ul></ul><ul><ul><li>Demonstrate regulatory compliance </li></ul></ul>The Goal of this Work is…
  12. 12. Cedar Mill Creek Watershed, 1984
  13. 13. Cedar Mill Creek Watershed, 1990
  14. 14. Cedar Mill Creek Watershed, 1994
  15. 15. Cedar Mill Creek Watershed, 1997
  16. 16. Cedar Mill Creek Watershed, 2002
  17. 17. <ul><ul><li>Clean Water Services </li></ul></ul><ul><li>What we’re about and where we are coming from </li></ul><ul><ul><li>Why this Study? </li></ul></ul><ul><li>Drivers and objectives </li></ul><ul><ul><li>Review of stream erosion processes </li></ul></ul><ul><li>Cohesive vs non-cohesive </li></ul><ul><ul><li>The nuts and Bolts – technical details </li></ul></ul><ul><ul><li>Preliminary findings </li></ul></ul><ul><ul><li>Summary </li></ul></ul>Outline
  18. 18. <ul><li>Understanding Stream Power and erosion </li></ul>Why this Approach?
  19. 19. <ul><li>References </li></ul><ul><li>Stage I </li></ul><ul><li>Stage VI </li></ul>Stream Response
  20. 20. What is different about cohesives?
  21. 21. What does flow have to do with it? (USEPA - after Wolman and Miller 1960)
  22. 22. <ul><ul><li>Clean Water Services </li></ul></ul><ul><li>What we’re about and where we are coming from </li></ul><ul><ul><li>Why this Study? </li></ul></ul><ul><li>Drivers and objectives </li></ul><ul><ul><li>Review of stream erosion processes </li></ul></ul><ul><li>Cohesive vs non-cohesive </li></ul><ul><ul><li>The nuts and Bolts – technical details </li></ul></ul><ul><ul><li>Preliminary findings </li></ul></ul><ul><ul><li>Summary </li></ul></ul>Outline
  23. 23. <ul><li>1. Determine critical shear stress and erodibility values for typical cohesive soils. </li></ul><ul><li>2. Use these results to estimate how potential changes in flow regime may impact erosion, sedimentation, and bank stability. </li></ul><ul><li>3. Test a new, smaller version of the jet-test device being constructed by the USDA-ARS. </li></ul><ul><li>4. Determine the influence of root reinforcement on streambank erodability provided by native riparian species. </li></ul><ul><li>5. Conduct rapid geomorphic assessments of the tributaries to map the stability for various stream reaches. </li></ul>Study Objectives
  24. 24. <ul><li>In depth measurement of erodibility and critical shear stress parameters of typical cohesive soils at 50 sites. </li></ul><ul><li>Rapid geomorphic assessments at 300 sites. </li></ul><ul><li>Effect of vegetated corridor on stream bank stability 10 species. </li></ul>Field Data Gathering
  25. 25. <ul><li>What: Erodibility coefficient, and critical shear stress, and shear strength properties. </li></ul><ul><li>How: Bore hole shear stress, jet test (2 sizes), CSM. </li></ul><ul><li>Where: 50 sites </li></ul><ul><li>Why: Indicates how resistant cohesive soils are to hydraulic and geotechnical forces. </li></ul>Determining Erodibility
  26. 26. Obtained from jet-test device  = k (  o -  c )  = erosion rate (m/s) k = erodibility coefficient (m 3 /N-s)  o = boundary shear stress (Pa)  c = critical shear stress (Pa) (  o -  c ) = excess shear stress Critical shear stress is the stress required to initiate erosion. The Equation
  27. 27. Jest Test Device Jet Nozzle Jet Nozzle As scour hole depth increases, shear stress decreases
  28. 28. From Relation between Shear Stress and Erosion We Can Calculate  c and  Shear Stress, Pa Erosion Rate, cm 3 /sec  c
  29. 29. Determining shear strength
  30. 30. <ul><li>BSTEM : Bank Stability Toe Erosion Model </li></ul><ul><li>Relates erodibility to flow rates over time </li></ul><ul><li>Incorporates effect of vegetation </li></ul>Data Analysis
  31. 31. Bank-Toe Erosion After First Flow Event Bank Stability and Toe Erosion Model (BSTEM)
  32. 32. Check for stability FS>1
  33. 33. Simulate Next Flow and Check Stability
  34. 35. <ul><li>What: Rapid geomorphic assessments. </li></ul><ul><li>How: Determine stage of channel evolution, incision, widening, deposition. Use CSM to correlate to in depth erodibility parameters. </li></ul><ul><li>Where: 300+ sites </li></ul><ul><li>Why: Map of stream reaches that identify sensitivity to erosion to inform effective surface water management strategies. </li></ul>Geomorphic Assessment Map
  35. 36. Cohesive Strength Meter (CSM ) The CSM consists of a water-filled chamber 30 mm in diameter that is pushed into the sediment. The jet of water comes from a downward directed nozzle in the chamber. The velocity of the jet is increased systematically through each experiment. Bed erosion is inferred from the drop in the transmission of infrared light across the chamber caused by the suspension of sediment. Lighter, Faster, not as robust, indirect measurement
  36. 37. Mapping Critical Shear Stress: Yalobusha River Basin, MS
  37. 38. <ul><li>What: Determine effect of vegetation on stream bank stability. </li></ul><ul><li>How: Measure root strength and density of specific species typical of vegetated corridors. </li></ul><ul><li>Where: 10 sites various age and species type. </li></ul><ul><li>Why: Determine short and long term benefits of vegetated corridors on stream bank stability. </li></ul>Vegetated Corridor Effects
  38. 39. Cohesion due to roots is a function of the tensile strength of the roots and their distribution (root-area ratio)
  39. 40. <ul><li>Range of cohesive soil erodibility </li></ul><ul><li>Effect of active floodplains and beaver activity </li></ul><ul><li>Effect of urban vegetated corridors vs agricultural activity </li></ul><ul><li>Urbanization effects on bed control </li></ul>Preliminary Findings
  40. 41. Same creek different corridor
  41. 42. Summary <ul><li>Understand the erosion characteristics of Tualatin basin cohesive soils </li></ul><ul><li>Understand the relative influence of flow, floodplains, and vegetated corridors on urban stream health </li></ul><ul><li>Apply in sub-basin stormwater management strategies </li></ul><ul><ul><li>Map stream incision, widening, and stability by reach </li></ul></ul><ul><ul><li>Asses alternatives: flow control, stream restoration, bypass </li></ul></ul><ul><li>Support overall basin approach </li></ul><ul><li>Inform stream restoration design </li></ul>
  42. 43. <ul><li>For more information: </li></ul><ul><li>Clean Water Services </li></ul><ul><li>www.cleanwaterservices.org </li></ul><ul><li>USDA Agricultural Research Service </li></ul><ul><li>www.ars.usda.gov/research/projects </li></ul>Questions?

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