• Save
Asce Ewrg Presentation
Upcoming SlideShare
Loading in...5
×
 

Asce Ewrg Presentation

on

  • 1,631 views

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

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

Statistics

Views

Total Views
1,631
Views on SlideShare
1,615
Embed Views
16

Actions

Likes
0
Downloads
0
Comments
0

3 Embeds 16

http://www.linkedin.com 11
https://www.linkedin.com 4
http://www.docshut.com 1

Accessibility

Categories

Upload Details

Uploaded via as Microsoft PowerPoint

Usage Rights

© All Rights Reserved

Report content

Flagged as inappropriate Flag as inappropriate
Flag as inappropriate

Select your reason for flagging this presentation as inappropriate.

Cancel
  • Full Name Full Name Comment goes here.
    Are you sure you want to
    Your message goes here
    Processing…
Post Comment
Edit your comment

Asce Ewrg Presentation Asce Ewrg Presentation Presentation Transcript

  • By Marjorie Wolfe, PE, CFM Senior Engineer Clean Water Services Tualatin River Tributaries Cohesive Stream Channel Erodibility Study
  • Outline
      • Clean Water Services
    • What we’re about and where we are coming from
      • Why this Study?
    • Drivers and objectives
      • Review of stream erosion processes
    • Cohesive vs non-cohesive
      • The nuts and Bolts – technical details
      • Preliminary findings
      • Summary
  • Tualatin River Watershed
  • Clean Water Services Facts
    • Board of Directors is Washington County Commission
    • Serve a population of more than 500,000 inside the urban growth boundary
    • Regional SWM utility in cooperation with Washington County and 12 Cities
    • Tree for all challenge: two million native trees and shrubs to be planted over 20 years
    • FY 08-09 Budget
      • $55.8 million Operating
      • $67 million Capital
    • Mission
    • Enhance the environment and quality of life in the Tualatin River Watershed through visionary and collaborative management of water resources in partnership with others.
    • Vision
    • We provide cost-effective services and environmentally sensitive management of water resources for the Tualatin River watershed.
    A direct Connection
    • Holistic Approach
    • Wastewater, stormwater
    • Encourages watershed protection and enhancement Programs (Trading)
    • Incorporates Watershed assessment and monitoring activities
    Watershed based permit
  • 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
    • ⇧ Public Awareness and Expectations
    • ⇧ Regulatory Requirements
    • ⇧ Costs
    • ⇧ Environmental Quality including:
      • Water Quality
      • Aquatic Habitat
      • Ecosystem diversity
    Preparing for the Next Bend…
  • Outline
      • Clean Water Services
    • What we’re about and where we are coming from
      • Why this Study?
    • Drivers and objectives
      • Review of stream erosion processes
    • Cohesive vs non-cohesive
      • The nuts and Bolts – technical details
      • Preliminary findings
      • Summary
  • Why this study?
    • Given That …
    • Urbanization impacts streams
    • Stream health is important
    • Unknown characteristics of cohesive soils
    • Quantify the influence of floodplains and vegetated corridors
    • Introducing
    • Andrew Simon
    • USDA-ARS National Sedimentation Laboratory, Oxford, MS
      • To ensure that surface water management strategies are cost effective and provide greatest ecological uplift to Tualatin tributaries.
    • By providing data to inform…
      • Improved stream restoration designs
      • Effective stormwater management strategies
      • Demonstrate regulatory compliance
    The Goal of this Work is…
  • 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
      • Clean Water Services
    • What we’re about and where we are coming from
      • Why this Study?
    • Drivers and objectives
      • Review of stream erosion processes
    • Cohesive vs non-cohesive
      • The nuts and Bolts – technical details
      • Preliminary findings
      • Summary
    Outline
    • Understanding Stream Power and erosion
    Why this Approach?
    • References
    • Stage I
    • Stage VI
    Stream Response
  • What is different about cohesives?
  • What does flow have to do with it? (USEPA - after Wolman and Miller 1960)
      • Clean Water Services
    • What we’re about and where we are coming from
      • Why this Study?
    • Drivers and objectives
      • Review of stream erosion processes
    • Cohesive vs non-cohesive
      • The nuts and Bolts – technical details
      • Preliminary findings
      • Summary
    Outline
    • 1. Determine critical shear stress and erodibility values for typical cohesive soils.
    • 2. Use these results to estimate how potential changes in flow regime may impact erosion, sedimentation, and bank stability.
    • 3. Test a new, smaller version of the jet-test device being constructed by the USDA-ARS.
    • 4. Determine the influence of root reinforcement on streambank erodability provided by native riparian species.
    • 5. Conduct rapid geomorphic assessments of the tributaries to map the stability for various stream reaches.
    Study Objectives
    • In depth measurement of erodibility and critical shear stress parameters of typical cohesive soils at 50 sites.
    • Rapid geomorphic assessments at 300 sites.
    • Effect of vegetated corridor on stream bank stability 10 species.
    Field Data Gathering
    • What: Erodibility coefficient, and critical shear stress, and shear strength properties.
    • How: Bore hole shear stress, jet test (2 sizes), CSM.
    • Where: 50 sites
    • Why: Indicates how resistant cohesive soils are to hydraulic and geotechnical forces.
    Determining Erodibility
  • 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
  • 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
    • BSTEM : Bank Stability Toe Erosion Model
    • Relates erodibility to flow rates over time
    • Incorporates effect of vegetation
    Data Analysis
  • 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
  •  
    • What: Rapid geomorphic assessments.
    • How: Determine stage of channel evolution, incision, widening, deposition. Use CSM to correlate to in depth erodibility parameters.
    • Where: 300+ sites
    • Why: Map of stream reaches that identify sensitivity to erosion to inform effective surface water management strategies.
    Geomorphic Assessment Map
  • 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
  • Mapping Critical Shear Stress: Yalobusha River Basin, MS
    • What: Determine effect of vegetation on stream bank stability.
    • How: Measure root strength and density of specific species typical of vegetated corridors.
    • Where: 10 sites various age and species type.
    • Why: Determine short and long term benefits of vegetated corridors on stream bank stability.
    Vegetated Corridor Effects
  • Cohesion due to roots is a function of the tensile strength of the roots and their distribution (root-area ratio)
    • Range of cohesive soil erodibility
    • Effect of active floodplains and beaver activity
    • Effect of urban vegetated corridors vs agricultural activity
    • Urbanization effects on bed control
    Preliminary Findings
  • Same creek different corridor
  • Summary
    • Understand the erosion characteristics of Tualatin basin cohesive soils
    • Understand the relative influence of flow, floodplains, and vegetated corridors on urban stream health
    • Apply in sub-basin stormwater management strategies
      • Map stream incision, widening, and stability by reach
      • Asses alternatives: flow control, stream restoration, bypass
    • Support overall basin approach
    • Inform stream restoration design
    • For more information:
    • Clean Water Services
    • www.cleanwaterservices.org
    • USDA Agricultural Research Service
    • www.ars.usda.gov/research/projects
    Questions?