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Jennings tdec stream small
Jennings tdec stream small
Jennings tdec stream small
Jennings tdec stream small
Jennings tdec stream small
Jennings tdec stream small
Jennings tdec stream small
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Jennings tdec stream small
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Jennings tdec stream small
Jennings tdec stream small
Jennings tdec stream small
Jennings tdec stream small
Jennings tdec stream small
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Jennings tdec stream small

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  • 1. Understanding and Restoring StreamsGreg Jennings, PhD, PEProfessor, Biological & Agricultural EngineeringNorth Carolina State Universityjennings@ncsu.edu
  • 2. What is a Stream?… a body of water with a current,confined within a bed andstreambanksSynonyms: bayou, beck, branch,brook, burn, creek, crick, kill, lick,rill, river, rivulet, run, slough, sykeA stream is:• conduit in the water cycle• critical habitat• connected to a watershed
  • 3. Fluvial Geomorphology:The study of landforms and fluvial processesFluvial processes are associated with flowing water, including sediment erosion, transport, deposition
  • 4. Fluvial Forms• Bar• Channel• Confluence• Cutoff channel• Delta• Floodplain• Gorge• Gully• Meander• Oxbow lake• Pool• Riffle• Stream• Valley• Waterfall• Watershed
  • 5. Meandering Stream: Alluvial FormsRiffle Point Bar (deposition)Glide Run Pool
  • 6. Bankfull
  • 7. Bankfull Stage “corresponds to the discharge at which channel maintenance is the most effective, that is, the discharge at which moving sediment, forming or removing bars, forming or changing bends and meanders, and generally doing work results in the average morphologic characteristics” (Dunne and Leopold,1978)Stream Corridor Restoration: Principles, Processes, and Practices. 1998. Federal Interagency Stream Restoration Working Group.
  • 8. Stream Ecosystems• Channel (bed & banks)• Floodplain• Water & Sediment• Plants & Animals Photo Credit: Eve Brantley, Auburn University
  • 9. Stream Functions & Services1. Transport water2. Transport sediment3. Habitat (aquatic & terrestrial)4. Recreation & aesthetics5. Safe Water Supply
  • 10. Effects of Urbanization on Streams (US EPA)
  • 11. Urban Stream Syndrome (USS)• Response to watershed changes• Loss of natural functions & values• Causes problems locally & downstream• Requires systematic assessment & treatment
  • 12. Symptoms of USS• Erosion & incision• Water quality decline• Habitat loss• Ecosystem degradation• Flooding• Land loss• Infrastructure damage• Recreation impaired• Aesthetics impaired• Economic loss
  • 13. Urban Stream: Incision & bank erosion
  • 14. Causes of USS• Watershed impervious• Channelization• Impoundments• Diversions• Floodplain filling• Pollution discharges• Sedimentation• Stormwater runoff• Utilities & culverts• Buffer loss• Neglect & Ignorance
  • 15. Urban Disturbances to Hydrologic Cycle University of Central Florida
  • 16. Hydrograph Changes Due to Urbanization Higher Peak Flow Urban More Runoff Volume Flashier Response Lower Baseflow Rural
  • 17. Runoff: moreInfiltration: lessFlooding: moreBaseflow: less
  • 18. Constraints: Utilities, Road, Bridges, Culverts
  • 19. What Makes a Stream Healthy?1. Bed stability & diversity2. Sediment transport balance3. In-stream habitat & flow diversity4. Bank stability (native plant roots)5. Riparian buffer (streamside forest)6. Active floodplain7. Healthy watershed
  • 20. 1. Bed Stability & Diversity• Appropriate size sediments to resist shear stress• Riffle/Pool sequences in alluvial streams• Step/Pool sequences in high- gradient streams Photo Credit: Eve Brantley, Auburn University
  • 21. Riffles• Steep slope• High velocity & shear stress• Large substrate• High porosity & groundwater exchangePools• Flat slope• Low velocity & shear stress• Small substrate• Scour during high flow
  • 22. Problems: Bed Stability & Diversity• Headcut and excess scour• Plane bed – filling of pools• Armoring
  • 23. 2. Sediment Transport Balance• Minor erosion & deposition• Alluvial bars and benches• Sufficient stream power to avoid aggradation
  • 24. Problems: Sediment Transport Balance• Excess stream power – eroding bed• Insufficient stream power – aggradation
  • 25. Streams convey water and sedimentLane’s Balance (Lane, 1955) Channel Evolution Model (Schumm, 1984)
  • 26. 3. In-stream Habitat & Flow DiversityMacrohabitats: riffles, runs, pools, glides, steps, side channels, scour holesMicrohabitats: roots, leaf packs, wood, rocks, plants, hyporheic zone
  • 27. Problems: In-stream Habitats• Uniform flow – lack of diversity• Lack of wood, leaves, roots• Water quality – DO, nutrients, toxics
  • 28. 4. Bank Stability• Dense native plant roots• Low banks with low stress
  • 29. Problems: Bank Stability• Loss of vegetation• High, steep banks – channelization
  • 30. 5. Riparian Buffer (Streamside Forest)• Diverse native plants• Food and shade
  • 31. Problems: Riparian Buffer• Mowers and moo’ers• Invasive plants• Armoring and impervious surfaces
  • 32. 6. Active Floodplain• Regular (every year) flooding to relieve stress• Riparian wetlands• Stormwater retention & treatment
  • 33. Problems: Active Floodplain• Channel incision• Floodplain fill and encroachment
  • 34. 7. Healthy Watershed• Stormwater management• Wastewater management• Upstream sediment control
  • 35. Problems: Healthy Watershed• Stormwater energy and volume• Point and nonpoint source pollution• Erosion and sediment
  • 36. Ecosystem Restoration:“activities that initiate or accelerate the recovery ofecosystem health, integrity, and sustainability”(SER, 2004)
  • 37. Planning a Stream Project:• Goals? Stability, Habitat, Recreation?• Constraints? Access, Land Availability, Utilities?• Feasibility? Will it Work?• Constructability? Equipment, Materials, Time/$?
  • 38. Case Study: Long Creek (1995-2005)• Dairy Farm: Fencing, Bank Stabilization, Planting 10 years later
  • 39. Roaring River, Stone Mt State Park (2000-10)• Trout Stream: Channel Realignment, Structures, Planting 10 years later
  • 40. Rocky Branch, NCSU Campus• Urban Stream: Channel Realignment, Structures, Planting
  • 41. Restoration Components 1. Channel morphology 2. Floodplain structure 3. Hydrologic & hydraulic analysis 4. In-stream structures 5. Habitats & vegetation 6. Site & watershed conditions 7. Monitoring, maintenance, educ ation
  • 42. 1. Channel Morphology • Dimension (baseflow, bankfull, flood flows) • Pattern (meandering, straight, braided) • Profile (bedform – riffle, run, pool, glide, step) Photo Credits: Darrell Westmoreland, North State Environmental, Inc.2005 South Fork Mitchell River 2006
  • 43. 2011 South Fork Mitchell River
  • 44. 2011 South Fork Mitchell River
  • 45. High-quality“reference”streams serve asdesign templates
  • 46. Bankfull Width, Wbkf = 9.3 ft; Bankfull Area, Abkf = 13.9 ft2Mean Depth, dbkf = Abkf / Wbkf = 13.9 / 9.3 = 1.5 ftWidth to Depth Ratio, W/d = Wbkf / dbkf = 9.3 / 1.5 = 6.2
  • 47. Morphologic Stream Classification Systems• Schumm (1977) – Alluvial channels – Meandering, straight, braided – Type related to channel stability & sediment transport• Montgomery & Buffington (1993) – Alluvial, colluvial, bedrock channels – Channel response related to sediment inputs – 6 classes of alluvial channels: cascade, step- pool, plane-bed, riffle-pool, regime, and braided• Rosgen (1994) www.wildlandhydrology.com
  • 48. Rosgen Classification of Natural Rivers• Based on physical characteristics (empirical)• Requires field measurements• Requires bankfull dimensions www.wildlandhydrology.com
  • 49. www.wildlandhydrology.com
  • 50. G4 Eastern NC
  • 51. 2000 2001 2003 2003
  • 52. 2. Floodplain Structure• Regular (every year) flooding to relieve stress• Floodwater retention & riparian wetlands• Stormwater discharge retention & treatment
  • 53. Entrenchment Ratio ER = Wfpa / Wbkf Wfpa = Width of Flood Prone Area measured at the elevation twice bankfull max depth above thalweg Wbkf = Width of Bankfull Channel Wfpa Bankfull 2 x dmbkf dmbkfabove thalweg Wbkf
  • 54. Priority 1: Raise channel to existing valley and construct new meandering channel ER = 15; W/d = 12Rain will come during andimmediately following construction!2006 Town Creek Tributary 2007
  • 55. 2008 Town Creek Tributary
  • 56. Priority 1: lift channel Incised Stream Priority 2 & 3:lower floodplainStream Corridor Restoration: Principles, Processes, and Practices.1998. Federal Interagency Stream Restoration Working Group.
  • 57. Priority 2: Excavate lower floodplain and construct new meandering channel ER = 6; W/d = 112008 White Slough 2010
  • 58. Entrenchment Ratio = Wfpa / Wbkf = 90/15 = 6 White Slough 2010
  • 59. Priority 2: Excavate lower floodplain and construct new meandering channel2004 NCSU Rocky Branch 2005
  • 60. Rocky Branch Phase II Reach 2: Priority 2 (floodplain excavation, C channel) Entrenchment Ratio = Wfpa / Wbkf = 90/20 = 4.5Flood water flows onto floodplainseveral times each year
  • 61. Priority 3: Excavate narrow floodplain benches in confined systems ER = 2.2; W/d = 122005 NCSU Rocky Branch 2006
  • 62. Rocky Branch Phase II Reach 1:Priority 3 (floodplain excavation, Bc channel)Entrenchment Ratio = Wfpa / Wbkf = 40/20 = 2
  • 63. 2008 NCSU Rocky Branch
  • 64. Priority 3: Excavate narrow floodplain benches in confined systems ER = 1.6; W/d = 152009 Little Shades Creek 2010
  • 65. Entrenchment Ratio = Wfpa / Wbkf = 60/38 = 1.6
  • 66. Little Shades Creek 2010
  • 67. In-Stream Structures (Logs & Rocks)• Streambank protection• Habitat enhancement (pools, aeration, cover)• Grade control• Sediment transport
  • 68. Structure Criteria:• Natural materials• Habitats & passage for aquatic organisms• Natural sediment transport (alluvial systems) Do you like these?
  • 69. Boulder J-Hook Vane
  • 70. Runaway Truck Ramp
  • 71. Boulder J-Hook Vane• 3-5 % arm slopes• 20-25 degree arm angles• Boulder footers & non-woven geotextile• 0.5 ft drops over j-hook inverts
  • 72. Boulder Vane 20-25 degree angles 3-5 % arm slopes20-25 degrees3-5 % arm slopes
  • 73. BoulderJ-Hook Vane
  • 74. Log Vane• 2-4 % arm slopes• 20 degree arm angles• Sealed with woven geotextile & backer logs
  • 75. Log J-Hook Vane• Direct flow away from bank around bend• Grade control and scour pool• Brush toe buried under log vane• Backer logs & geotextile
  • 76. Log J-Hook Vane• Hook boulders control grade• Footer boulders and geotextile• Boulder sills
  • 77. Log J-Hook Vane• Hook boulders control grade• Footer boulders and geotextile• Boulder sills
  • 78. Log J-Hook Vane
  • 79. Multiple Log Vanes Saugahatchee Creek2007 2008
  • 80. Multiple Log Vanes Saugahatchee Creek2009 January 2009 July Photo Credit: Dan Ballard, Town of Auburn
  • 81. Multiple Log Vanes: Saugahatchee Creek Photo Credit: Dan Ballard, Town of Auburn
  • 82. Boulder Cross Vane
  • 83. Cross Vane• Direct flow in new channel alignment• Grade control and scour pool• Footer boulders & geotextile
  • 84. Cross Vane (logs embedded)• Undercut bed 2 ft and backfill with gravel, cobble, boulders, wood• Cut thalweg 0.5 ft deep
  • 85. Double-Drop Boulder Cross Vane Photo Credit: Darrell Westmoreland, North State Environmental, Inc.
  • 86. Double-Drop Boulder Cross Vane
  • 87. Offset Boulder Cross Vane at a Bridge
  • 88. Boulder W-Vane
  • 89. Boulder Double Wing Deflector
  • 90. Constructed Riffle
  • 91. 1st Order Streambed Transplant• Substrate transfer from old channel to new channel
  • 92. Constructed Riffle• Undercut bed 2 ft and backfill with gravel, cobble, boulders, wood• Cut thalweg 0.5 ft deep
  • 93. Constructed Riffle• Undercut bed 2 ft and backfill with gravel, cobble, boulders, wood• Cut thalweg 0.5 ft deep
  • 94. Riffles withBouder/Log Steps
  • 95. Wood• Food sources• Cover• Scour pools• Flow diversity
  • 96. Brush Toe• Layers of logs and brush under water in pools• Live cuttings above water (silky dogwood, elderberry)• Matting, seed, transplanted alders on top
  • 97. Brush Toe• Layers of logs and brush under water in pools• Live cuttings above water (silky dogwood, elderberry)• Matting, seed, transplanted alders on top
  • 98. Summary: Plan for Success1. Plan for floods -- immediately & often2. Plan for dry weather3. Plan for vegetation maintenance4. Understand constraints5. Expect the Unexpected

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