Rc101 Day 3 Jennings 10

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Rc101 Day 3 Jennings 10

  1. 1. What Makes a Stream Healthy?<br /><ul><li>Bed stability & diversity
  2. 2. Sediment transport balance
  3. 3. In-stream habitat & flow diversity
  4. 4. Bank stability (native plant roots)
  5. 5. Riparian buffer (streamside forest)
  6. 6. Active floodplain</li></li></ul><li>Bed Stability & Diversity<br /><ul><li>Appropriate size sediments to resist shear stress
  7. 7. Riffle/Pool sequences in alluvial streams
  8. 8. Step/Pool sequences in high-gradient streams</li></ul>Photo Credit: Eve Brantley, Auburn University<br />
  9. 9. Sediment Transport Balance<br /><ul><li>Minor erosion & deposition
  10. 10. Alluvial bars and benches
  11. 11. Sufficient stream power to avoid aggradation</li></li></ul><li>In-stream Habitat & Flow Diversity<br />Overhanging Bank<br />Roots<br />Wood<br />Pool<br />Leaf Pack<br />Plants<br />Riffle<br />Rocks<br />
  12. 12. Bank Stability<br /><ul><li>Dense native plant roots
  13. 13. Low banks with low stress</li></li></ul><li>Riparian Buffer (Streamside Forest)<br /><ul><li>Diverse native plants
  14. 14. Food and shade</li></li></ul><li>Active Floodplain<br /><ul><li>Regular (every year) flooding to relieve stress
  15. 15. Riparian wetlands
  16. 16. Stormwater retention & treatment</li></li></ul><li>What is a “Stable” Stream?<br />“Graded” Stream: Condition of “balance between erosion and deposition attained by mature rivers” (Davis, 1902)<br />“Dynamic Equilibrium”: Stream form & character unchanged while continuous inflow of water/sediment (Strahler, 1957)<br />“Equilibrium Controlling Factors”: Width, depth, velocity, slope, discharge, sediment size, sediment concentration, channel roughness (Leopold, 1964)<br />“Regime Channels”: Some erosion and deposition but no net change in dimension, pattern, and profile (Hey, 1997)<br />“Stream Channel Stability”: ability of a stream, over time, in the present climate, to transport the sediment and flows produced by its watershed in such a manner that the stream maintains its dimension, pattern, and profile without either aggrading or degrading (Rosgen, 1996)<br />
  17. 17. Lane’s Stream Balance Relationship<br />
  18. 18. Causes of Instability<br /><ul><li>Increase runoff
  19. 19. Increase slope
  20. 20. Changes in sediment load
  21. 21. Loss of riparian buffer
  22. 22. Floodplain filling
  23. 23. Instream modification</li></li></ul><li>Increase Runoff: Land Use Changes<br />
  24. 24. 10%<br />50%<br />Development Impacts on the Water Cycle<br />55%<br />15%<br />Courtesy NEMO, Univ. of CT<br />
  25. 25. Impervious Surfaces Across the Landscape<br />Center for Watershed Protection<br />Sidewalks<br />Roads<br />Parking<br />Driveways<br />Buildings<br />
  26. 26. More Runoff<br />Arriving Faster<br />NEMO<br />The Science of Stormwater…<br />
  27. 27. Hydrologic Responses to Urbanization<br />Increased discharge<br />Increased peak discharge<br />Increased velocities<br />Shorter time to peak flow<br />More frequent bankfull events<br />Increased flooding<br />Lower baseflow<br />Less ground water recharge<br />
  28. 28.
  29. 29.
  30. 30.
  31. 31.
  32. 32. Increase Slope<br /><ul><li>Channelization
  33. 33. Lower Reservoir Water Surface
  34. 34. Dam Break
  35. 35. Geologic Uplift</li></li></ul><li>Simon Channel Evolution Model<br />Source:<br />Simon, 1989, USACE 1990<br />
  36. 36.
  37. 37.
  38. 38. Head Cut<br />
  39. 39.
  40. 40.
  41. 41.
  42. 42.
  43. 43.
  44. 44.
  45. 45.
  46. 46. I<br />I<br />I<br />I<br />I<br />I<br />I<br />II<br />II<br />I<br />I<br />III<br />III<br />IV<br />I<br />III<br />Original Nickpoint<br />IV<br />V<br />I<br />VI<br />
  47. 47. G4c Alabama<br />
  48. 48. Changes in Sediment Load<br /><ul><li>Development
  49. 49. Agriculture
  50. 50. Bank Erosion
  51. 51. Impoundments</li></li></ul><li>
  52. 52. Aggradation<br />
  53. 53.
  54. 54.
  55. 55.
  56. 56.
  57. 57. Mid-channel bar and transverse bar directing flow into a high bank causing erosion and slumping<br />
  58. 58. Debris Occurrence<br /><ul><li>Large Woody Debris
  59. 59. Depends on Riparian Stability
  60. 60. Beaver Dams</li></li></ul><li>Woody debris<br />
  61. 61. Impoundments<br />Upstream:<br /><ul><li>Decrease velocities
  62. 62. Deposition of fine material
  63. 63. Loss of habitat</li></ul>Downstream:<br /><ul><li>“Hungry water”
  64. 64. Change in flow</li></li></ul><li>Riparian Condition (Buffer)<br /><ul><li>Composition
  65. 65. Density
  66. 66. Potential</li></li></ul><li>Values of Vegetation<br />Habitats<br />Water Quality<br />Bank Stability<br />Shade & Food<br />Stream Corridor Restoration: Principles, Processes, and Practices, 10/98, by the <br />Federal Interagency Stream Restoration Working Group (FISRWG)." <br />
  67. 67. Streamside Forests (also known as riparian buffers)<br /><ul><li>Trees, shrubs, herbs, and grasses are critical to the health of streams
  68. 68. Buffers are the first line of defense against the impacts of polluted runoff
  69. 69. natural vegetation buffers are especially critical in urban areas</li></li></ul><li>
  70. 70.
  71. 71.
  72. 72. Altered States Due to Disturbance<br /><ul><li>Channelization
  73. 73. Straightening
  74. 74. Levees
  75. 75. Hardening
  76. 76. Mining</li></li></ul><li>Floodplain Filling<br />
  77. 77.
  78. 78. Stability Assessment<br />http://www.epa.gov/warsss/index.htm<br />
  79. 79. Entrenchment Ratio<br />
  80. 80. Lateral Stability<br /><ul><li>Meander Width Ratio
  81. 81. Bank Erosion (BEHI)</li></li></ul><li>G4c Alabama<br />
  82. 82. Stream Channel Succession (WARSSS)<br />
  83. 83. Stream Channel Succession (WARSSS)<br />http://www.epa.gov/WARSSS/sedsource/successn.htm<br />
  84. 84. Stability Assessment<br />http://www.epa.gov/warsss/index.htm<br />
  85. 85. Entrenchment Ratio<br />
  86. 86. Lateral Stability<br /><ul><li>Meander Width Ratio
  87. 87. Bank Erosion (BEHI)</li></li></ul><li>Meander Width Ratio<br />MWR = Wblt / Wbkf<br />Wblt = Belt Width<br />Wbkf = Bankfull Width of Riffle Cross-Section<br />Wbkf<br />Wblt<br />
  88. 88. Bank ErosionMonitoring <br />
  89. 89. Bank Erosion Hazard Index (BEHI)<br />
  90. 90. Bank Erosion Hazard Index (BEHI)<br />
  91. 91. Bank Erosion Hazard Index (BEHI)<br />
  92. 92. Bankfull Stage: Water fills the active channel and begins to spread onto the floodplain<br />Stream Corridor Restoration: Principles, Processes, and Practices. 1998. Federal Interagency Stream Restoration Working Group.<br />
  93. 93.
  94. 94. Bank Height RatioVery Low<br />
  95. 95. Bank Height RatioModerate<br />
  96. 96. Bank Height RatioVery High<br />
  97. 97.
  98. 98. Root Depth RatioVery Low BEHI<br />
  99. 99. Root Depth RatioModerate BEHI<br />
  100. 100. Root Depth RatioVery High BEHI<br />
  101. 101.
  102. 102. Root DensityVery Low BEHI<br />
  103. 103. Root DensityModerate<br />
  104. 104. Root DensityVery High BEHI<br />
  105. 105. Bank Angle (from horizontal)<br />
  106. 106. Bank AngleVery Low<br />
  107. 107. Bank AngleModerate - High<br />
  108. 108. Bank AngleVery High<br />
  109. 109.
  110. 110. Surface ProtectionVery Low BEHI<br />
  111. 111. Surface ProtectionModerate<br />
  112. 112. Surface ProtectionVery High BEHI<br />
  113. 113. Bank Materials<br />Very Low Risk<br />Extreme Risk<br />High Risk<br />
  114. 114.
  115. 115.
  116. 116.
  117. 117. Near Bank StressLow<br />
  118. 118. Near Bank StressModerate<br />
  119. 119. Near Bank StressHigh<br />
  120. 120. Near Bank StressVery High<br />

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