Rc101 day1

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Rc101 day1

  1. 1. Stream Assessment<br />Greg Jennings, PhD, PE<br />Professor, Biological & Agricultural Engineering<br />North Carolina State University<br />jennings@ncsu.edu<br />Jason Zink, PE<br />Zan Price, PE<br />Mike Shaffer, PE<br />Dave Penrose<br />Barbara Doll, PE<br />Kris Bass, PE<br />Karen Hall<br />Mitch Woodward<br />
  2. 2. What is a Stream?<br />… a body of water with a current, confined within a bed and streambanks<br />Synonyms:  bayou, beck, branch, brook, burn, creek, crick, kill, lick, rill, river, rivulet, run, slough, syke<br />A stream is:<br /><ul><li>conduit in the water cycle
  3. 3. critical habitat
  4. 4. connected to a watershed</li></li></ul><li>Hydrologic (Water) Cycle: describes the flow of water on the planet in response to solar energy and gravity<br />Stream Corridor Restoration: Principles, Processes, and Practices. 1998. Federal Interagency Stream Restoration Working Group.<br />
  5. 5. Water Cycle Components:<br /> Precipitation<br /> Runoff<br /> Infiltration<br /> Evapotranspiration<br />Groundwater flow<br />
  6. 6. Average annual precipitation is highly variable and the timing of rainfall each year is unpredictable<br />
  7. 7. Extreme Weather!<br />
  8. 8. Watershed:<br /> “Area of land that drains water, sediment, and dissolved materials to a common outlet at some point along a stream channel”<br /> Dunne and Leopold, 1978<br />Watershed form is influenced by:<br />Climate<br />Geology & Soils<br />Fluvial Geomorphology<br />Vegetation<br />Land Uses<br />
  9. 9. Watersheds include many land uses affecting flow and water quality<br />
  10. 10. From Webster's Revised Unabridged Dictionary (1913) :<br />Watershed, n [Cf. G. wasserscheide; wasserwater + scheidea place where two things separate, fr. scheidento separate.]<br />The whole region or extent of country which contributes to the supply of a river or lake.<br />The line of division between two adjacent rivers or lakes with respect to the flow of water by natural channels into them; the natural boundary of a basin.<br />Other Terms: Catchment, Drainage basin, River basin<br />
  11. 11. North Carolina River Basins<br />River basins include watersheds of varying sizes and shapes, each with a network of streams delivering water to an outlet <br />
  12. 12. Watershed Stream Network<br />Neuse River Basin, NC<br />
  13. 13. Watershed Functions:<br />Transport & Storage:<br />Water<br />Sediment<br />Dissolved Materials<br />Habitat:<br />Animals<br />Plants<br />Humans<br />
  14. 14. Water Transport to Streams<br />Rainfall moves across the land as runoff or through the ground toward streams to provide baseflow<br />Stream Corridor Restoration: Principles, Processes, and Practices. 1998. Federal Interagency Stream Restoration Working Group.<br />
  15. 15. Groundwater Influences Streamflow<br />Losing Stream Gaining Stream<br />Groundwater Recharge Groundwater Discharge<br />Stream Corridor Restoration: Principles, Processes, and Practices. 1998. Federal Interagency Stream Restoration Working Group.<br />
  16. 16. Streamflow Duration and Frequency:<br />Classification based on connection to groundwater<br />Perennial<br />(gaining stream)<br />Ephemeral<br />(losing stream)<br />Intermittent<br />(sometimes losing)<br />
  17. 17.
  18. 18. Strahler Stream Order:<br />Classification system describing position within the drainage network <br />First order streams may be ephemeral, intermittent, or perennial in relation to groundwater connection<br />Stream Corridor Restoration: Principles, Processes, and Practices. 1998. Federal Interagency Stream Restoration Working Group.<br />
  19. 19. Stream Functions<br />Transport water<br />Transport sediment<br />Habitat (aquatic & terrestrial)<br />Recreation<br />Aesthetics<br />Safe Water Supply<br />
  20. 20. Water Transport & Storage<br />Hydrology: The study of the flow of the earth’s waters through the hydrologic cycle<br />Hydrograph: Displays change in flow (discharge, Q, over time)<br />Peak Flow<br />Rising Limb<br />Falling Limb<br />Mean Daily Flow<br />www.Geology.com <br />
  21. 21. 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 />
  22. 22. Hydrograph Changes Due to Urbanization<br />Increased impervious surface results in more runoff and higher peak flow<br />Urban<br />Rural<br />
  23. 23. Stream Condition Related to Impervious Surface<br />Water quality and stream health decline in relation to impervious surface percentage<br />Good<br />Fair<br />Poor<br />Protected<br />Impaired<br />Urban Drainage Network<br />Degraded<br />Source: Center for Watershed Protection<br />
  24. 24. Channel incision and bank erosion increase due to channelization and increased stormwater runoff<br />
  25. 25. Urban streams have special challenges due to urban infrastructure (storm sewer and sanitary sewer)<br />
  26. 26. In addition to stormwater and sewer systems, urban streams are also challenged by confinement<br />
  27. 27. Fluvial Geomorphology:<br />study of landforms and the fluvial processes that shape them<br />
  28. 28. Fluvial Processes:<br />associated with flowing water, including sediment erosion, transport, and deposition<br />
  29. 29. Stream: A system of fluvial forms & habitats<br /><ul><li>Channel (bed & banks)
  30. 30. Floodplain
  31. 31. Water
  32. 32. Sediment
  33. 33. Plants & animals</li></ul>Photo Credit: Eve Brantley, Auburn University<br />
  34. 34. Fluvial Forms<br /><ul><li>Bar
  35. 35. Channel
  36. 36. Confluence
  37. 37. Cutoff channel
  38. 38. Delta
  39. 39. Floodplain
  40. 40. Gorge
  41. 41. Gully
  42. 42. Meander
  43. 43. Oxbow lake
  44. 44. Pool
  45. 45. Riffle
  46. 46. Stream
  47. 47. Valley
  48. 48. Waterfall
  49. 49. Watershed</li></li></ul><li>Fluvial Processes and Landforms<br />How do stream systems work?<br />What determines stream size & shape (i.e. morphology)?<br />
  50. 50. Streams are ecosystems<br /><ul><li>Communities of organisms and their physical, chemical, and biological environments</li></ul>Courtesy of Francois Birgand, NCSU<br />
  51. 51. Stream Ecosystems<br />Mostly downstream fluxes of energy and matter<br />Lateral and vertical connections to the riparian and hyporheic zones<br />Courtesy of Francois Birgand, NCSU<br />
  52. 52. River Continuum Concept<br />Connections<br /><ul><li>Watershed to Corridor to Stream
  53. 53. Biological communities upstream and downstream</li></ul>Stream Corridor Restoration: Principles, Processes, and Practices. 1998. Federal Interagency Stream Restoration Working Group.<br />
  54. 54. Hyporheic Zone<br />
  55. 55. Field Investigations<br />What is living in the stream?<br />What are the physical and chemical conditions of the stream?<br />
  56. 56. Ecosystem Services<br /><ul><li>Provisioning – food, energy, industry
  57. 57. Regulating – climate, waste, nutrients
  58. 58. Supporting – water quality, pest control
  59. 59. Cultural – recreation, inspiration
  60. 60. Preserving – species diversity</li></li></ul><li>Self-Design<br /> The reorganization, substitution and shifting of an ecosystem (dynamics and functional processes) whereby it adapts to the environment superimposed upon it. (Mitsch & Jorgensen, Ecological Engineering)<br />
  61. 61. What makes a stream healthy?<br />Bed stability & diversity<br />Sediment transport balance<br />In-stream habitat & flow diversity<br />Bank stability (native plant roots)<br />Riparian buffer (streamside forest)<br />Active floodplain<br />Healthy watershed<br />
  62. 62. 1. Bed Stability & Diversity<br /><ul><li>Appropriate size sediments to resist shear stress
  63. 63. Riffle/Pool sequences in alluvial streams
  64. 64. Step/Pool sequences in high-gradient streams</li></ul>Photo Credit: Eve Brantley, Auburn University<br />
  65. 65. Bed Stability & Diversity – Problems<br /><ul><li>Headcut and excess scour
  66. 66. Plane bed – filling of pools
  67. 67. Armoring</li></li></ul><li>2. Sediment Transport Balance<br /><ul><li>Minor erosion & deposition
  68. 68. Alluvial bars and benches
  69. 69. Sufficient stream power to avoid aggradation</li></li></ul><li>2. Sediment Transport Balance<br /><ul><li>Excess stream power – eroding bed
  70. 70. Insufficient stream power – aggradation</li></li></ul><li>3. In-stream Habitat & Flow Diversity<br />Overhanging Bank<br />Roots<br />Wood<br />Pool<br />Leaf Pack<br />Plants<br />Riffle<br />Rocks<br />
  71. 71. Stream Habitats<br />Macrohabitats: riffles, runs, pools, glides, steps, side channels<br />Microhabitats: roots, leaf packs, wood, rocks, plants, hyporheic zone <br />
  72. 72. Food Web<br />
  73. 73. Diversity of habitats<br />
  74. 74. What habitats do you see?<br />Pool<br />Leaf Pack<br />Wood<br />Rocks<br />Roots<br />Riffle<br />
  75. 75. 3. In-stream Habitat – Problems<br /><ul><li>Uniform flow – lack of diversity
  76. 76. Lack of wood, leaves, roots
  77. 77. Water quality –DO, nutrients, toxics</li></li></ul><li>4. Bank Stability<br /><ul><li>Dense native plant roots
  78. 78. Low banks with low stress</li></li></ul><li>4. Bank Stability – Problems<br /><ul><li>Loss of vegetation
  79. 79. High, steep banks – channelization</li></li></ul><li>5. Riparian Buffer (Streamside Forest)<br /><ul><li>Diverse native plants
  80. 80. Food and shade</li></li></ul><li>5. Riparian Buffer – Problems<br /><ul><li>Mowers and moo’ers
  81. 81. Invasive plants
  82. 82. Armoring and impervious surfaces</li></li></ul><li>6. Active Floodplain<br /><ul><li>Regular (every year) flooding to relieve stress
  83. 83. Riparian wetlands
  84. 84. Stormwater retention & treatment</li></li></ul><li>6. Active Floodplain – Problems<br /><ul><li>Channel incision
  85. 85. Floodplain fill and encroachment</li></li></ul><li>7. Healthy Watershed<br /><ul><li>Stormwater management
  86. 86. Wastewater management
  87. 87. Upstream sediment control</li></li></ul><li>7. Healthy Watershed – Problems<br /><ul><li>Stormwater energy and volume
  88. 88. Point and nonpoint source pollution
  89. 89. Erosion and sediment</li></li></ul><li>Stream Impairments<br /><ul><li>Straightening & dredging
  90. 90. Floodplain filling
  91. 91. Watershed manipulation
  92. 92. Sedimentation & stormwater
  93. 93. Pollution discharges
  94. 94. Utilities & culverts
  95. 95. Buffer removal
  96. 96. Disdain & neglect</li></li></ul><li>Stream Impairment Causes (US EPA)<br />Pathogens<br />Sediment<br />Nutrients<br />Organic Enrichment<br />Habitat Alterations<br />PCBs<br />Metals<br />Flow Alterations<br />Temperature<br />Mercury<br />
  97. 97. Why Restoration?<br /><ul><li>Water quality impairments
  98. 98. Habitat loss
  99. 99. Ecosystem degradation
  100. 100. Land loss
  101. 101. Safety concerns
  102. 102. Infrastructure damage
  103. 103. Flooding
  104. 104. Aesthetics</li></li></ul><li>Restoring Stream Health<br />Watershed management<br />Floodplain reconnection<br />Channel morphology – dimension, pattern, profile<br />Sediment transport balance<br />Habitat enhancements<br />Bank stabilization<br />Riparian buffer – native plants<br />
  105. 105. Stream Functions<br />Transport water<br />Transport sediment<br />Habitat (aquatic & terrestrial)<br />Recreation & aesthetics<br />Safe Water Supply<br />
  106. 106. Velocity & Discharge<br />Q = VA = Discharge (cfs)<br />V = Velocity (ft/s)<br />A = Cross-Section Area (ft2)<br />V related to slope, channel shape, and channel roughness<br />Stream Corridor Restoration: Principles, Processes, and Practices. 1998. Federal Interagency Stream Restoration Working Group.<br />
  107. 107. Manning Formula<br />
  108. 108.
  109. 109. A = 40 sq ft<br />W = 22 ft<br />R = 1.7 ft<br />S = 0.010 ft/ft<br />n = 0.040<br />V = 5.0 ft/s<br />Q = 200 cfs<br />A = 220 sq ft<br />W = 55 ft<br />R = 3.5 ft<br />S = 0.004 ft/ft<br />n = 0.035<br />V = 6.1 ft/s<br />Q = 1350 cfs<br />
  110. 110. R = 1.5 ft<br />S = 0.0012 ft/ft<br />n = 0.038<br />V = 1.8 ft/s<br />Q = 89 cfs<br /><ul><li> = 0.11 lb/sq ft</li></ul>Competence = ~30 mm <br />
  111. 111. Stream Corridor Longitudinal Profile<br />Stream Corridor Restoration: Principles, Processes, and Practices. 1998. Federal Interagency Stream Restoration Working Group.<br />
  112. 112. Sediment Transport<br />Flowing water does work:<br /><ul><li>Erosion
  113. 113. Transportation
  114. 114. Deposition (of alluvium)</li></ul>http://www.uwsp.edu/gEo/faculty/ritter/geog101/textbook/fluvial_systems/geologic_work_of_streams.html <br />
  115. 115. Erosion: Detachment of material from bed and banks<br />95% of stream energy used to overcome friction<br />Remaining energy used for Erosion Processes:<br /><ul><li> Flowing water dissolves materials
  116. 116. Hydraulic action dislodges materials
  117. 117. Abrasion of heavy materials rolling on bottom</li></ul>http://www.uwsp.edu/gEo/faculty/ritter/geog101/textbook/fluvial_systems/geologic_work_of_streams.html <br />
  118. 118. Transportation: Movement of material by water<br />Stream Load includes:<br />dissolved + suspended + bed load<br />Capacity: maximum load that can be transported for a given discharge (increases with velocity and turbulence)<br />Competence: largest size material that can be transported for a given discharge<br />http://www.uwsp.edu/gEo/faculty/ritter/geog101/textbook/fluvial_systems/geologic_work_of_streams.html <br />
  119. 119. Bedload is related to Discharge for Each River<br />
  120. 120. Deposition:<br />Aggradation: Raising the bed elevation<br />Bars: Depositional areas that may change flow directions<br />http://www.uwsp.edu/gEo/faculty/ritter/geog101/textbook/fluvial_systems/geologic_work_of_streams.html <br />
  121. 121. Bed Material (Substrate)<br />Silt/Clay: < 0.062 mm<br />Sand: 0.062 – 2 mm<br />Gravel: 2 – 64 mm<br />Cobble: 64 – 256 mm<br />Boulder: 256 – 2048 mm<br />
  122. 122. Substrate CharacterizationWolman Pebble Count<br />
  123. 123. High Slope Moderate Slope Low Slope<br />Stream Corridor Restoration: Principles, Processes, and Practices. 1998. Federal Interagency Stream Restoration Working Group.<br />
  124. 124. Velocity & Particle Size Determine Process<br />V = 5 ft/s<br />V = 1 ft/s<br />http://www.uwsp.edu/gEo/faculty/ritter/geog101/textbook/fluvial_systems/geologic_work_of_streams.html <br />
  125. 125. Shear Stress: fluid force per unit area acting on the streambed <br /> = Rs = Shear Stress (lb/ft2)<br /> = Unit Weight of Water = 62.4 lb/ft3<br />R = Hydraulic Radius (ft) = A / P<br />S = Average Water Surface Slope (ft/ft)<br />A = Riffle Cross-Section Area (ft2)<br />P = Wetted Perimeter (ft) <br />P = Wbkf +2*Dbkf (approx)<br />
  126. 126. Stream Competence (www.epa.gov/WARSSS)<br />
  127. 127. A = 40 sq ft<br />W = 22 ft<br />R = 1.7 ft<br />S = 0.010 ft/ft<br /><ul><li> = 1.0 lb/sq ft</li></ul>Competence = ~250 mm<br />A = 220 sq ft<br />W = 55 ft<br />R = 3.5 ft<br />S = 0.004 ft/ft<br /><ul><li> = 0.8 lb/sq ft</li></ul>Competence = ~200 mm<br />
  128. 128. A = 64 sqft<br />W = 32 ft<br />D = 2.0 ft<br />R = 1.8 ft<br />S = 0.012 ft/ft<br />n = 0.040<br />V = 5.7 ft/s<br />Q = 370 cfs<br /><ul><li> =1.2 lb/sq ft</li></ul>Competence = 100-300 mm <br />
  129. 129. Sediment Deposition:<br /><ul><li> Point bar
  130. 130. Lateral bar
  131. 131. Mid-channel bar
  132. 132. Transverse bar
  133. 133. Delta bar</li></li></ul><li>Stream Corridor Restoration: Principles, Processes, and Practices. 1998. Federal Interagency Stream Restoration Working Group.<br />
  134. 134. Point Bars: <br />Inside meander bends<br />
  135. 135. Lateral Bars: <br />Formed in straight channels<br />
  136. 136. Lateral Bars: <br />Formed in straight channels<br />
  137. 137. Mid-channel Bars: <br />Formed in over-wide channels<br />
  138. 138. Transverse Bars: <br />Formed in straight channels<br />
  139. 139. Meandering Stream: Alluvial Forms<br />Flow Downstream<br />Floodplain<br />Scarp<br />Bankfull Stage<br />Point Bar<br />Pool<br />Left Bank<br />Right Bank<br />Riffle<br />Thalweg<br />
  140. 140. Bankfull Stage<br />“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)<br />Stream Corridor Restoration: Principles, Processes, and Practices. 1998. Federal Interagency Stream Restoration Working Group.<br />
  141. 141. Bankfull<br />
  142. 142. Channel Evolution<br />(Succession)<br />Response to incising forces<br />Stream Corridor Restoration: Principles, Processes, and Practices. 1998. Federal Interagency Stream Restoration Working Group.<br />
  143. 143. Terrace<br />Bankfull<br />
  144. 144. Incised System: Floodplain Creation<br />Terrace<br />Floodplain<br />
  145. 145. Stream Morphology:size and shape of channel & floodplain (dimension, pattern, profile)<br />
  146. 146.
  147. 147. Valley type affects stream morphology<br />Colluvium is loose sediment transported by gravity and deposited at the bottom of a slope.<br />Alluvium is sediment deposited by a river in the channel or floodplain<br />Alluvial valleys occur where sediment particles are dropped by slow-moving water.<br />
  148. 148. Valley Types: (www.epa.gov/watertrain/stream_class)<br />Valley Type II Moderately steep, gentle sloping side slopes often in colluvial valleys<br />From EPA Watershed Academy: Fundamentals of the Rosgen Stream Classification System<br />
  149. 149. Valley Types: (www.epa.gov/watertrain/stream_class)<br />Valley Type VIII Wide, gentle valley slope with well-developed floodplain adjacent to river terraces<br />From EPA Watershed Academy: Fundamentals of the Rosgen Stream Classification System<br />
  150. 150. Stream Corridor Lateral Profile<br />Stream Corridor Restoration: Principles, Processes, and Practices. 1998. Federal Interagency Stream Restoration Working Group.<br />
  151. 151. Floodplains: Critical Stream Components<br />
  152. 152. Floodplain Functions<br /><ul><li>Floodwater storage
  153. 153. Reducing peak flows
  154. 154. Erosion prevention
  155. 155. Water quality
  156. 156. Groundwater recharge
  157. 157. Food & shade
  158. 158. Habitats</li></li></ul><li>
  159. 159. Terrace<br />Floodplain<br />Left Bank<br />Right Bank<br />Thalweg<br />Streambed<br />Downstream<br />
  160. 160. Terrace<br />Floodplain<br />Right Bank<br />Left Bank<br />Thalweg<br />Streambed<br />Downstream<br />
  161. 161. Pool Cross-Section (Meandering Stream)<br />Stream Corridor Restoration: Principles, Processes, and Practices. 1998. Federal Interagency Stream Restoration Working Group.<br />
  162. 162. Natural Stream Channel Stability<br />(from Leopold)<br />River has a stable dimension, pattern and profile<br />Maintains channel features (riffles, pools, steps)<br />Does not aggrade (fills) or degrade (erodes)<br />
  163. 163. Dimension (cross-section)<br /><ul><li>Area
  164. 164. Width
  165. 165. Depth
  166. 166. Width/Depth Ratio
  167. 167. Entrenchment Ratio
  168. 168. Bank Height Ratio</li></li></ul><li>Bankfull Stage: “incipient flooding”<br />“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 &Leopold,1978)<br />Stream Corridor Restoration: Principles, Processes, and Practices. 1998. Federal Interagency Stream Restoration Working Group.<br />
  169. 169. Terrace<br />Bankfull<br />
  170. 170. Dimension: Cross-Section<br />
  171. 171. Riffle Dimensions<br />Wbkf<br />Bankfull<br />Abkf<br />dbkf<br />Measure Bankfull Width (Wbkf) and Bankfull Area (Abkf)<br />Mean Depth, dbkf = Abkf / Wbkf<br />Width to Depth Ratio, W/d = Wbkf / dbkf<br />
  172. 172. Bankfull Width, Wbkf = 9.3 ft; Bankfull Area, Abkf = 13.9 ft2<br />Mean Depth, dbkf= Abkf / Wbkf= 13.9 / 9.3 = 1.5 ft<br />Width to Depth Ratio, W/d = Wbkf / dbkf = 9.3/ 1.5 = 6.2<br />Wbkf<br />dbkf<br />Abkf<br />
  173. 173. Bankfull Width, Wbkf = 36 ft; Bankfull Area, Abkf = 112 ft2<br />Mean Depth, dbkf= Abkf / Wbkf= 112 / 36 = 3.1 ft<br />Width to Depth Ratio, W/d = Wbkf / dbkf = 36/ 3.1 = 11.5<br />Wbkf<br />Abkf<br />dbkf<br />
  174. 174. Entrenchment Ratio<br />ER = Wfpa / Wbkf<br />Wfpa= Width of Flood Prone Area measured at the elevation twice bankfull max depth above thalweg<br />Wbkf= Width of Bankfull Channel<br />Wfpa<br />Bankfull<br />2 x dmbkf<br />above thalweg<br />dmbkf<br />Wbkf<br />
  175. 175. ER = Wfpa / Wbkf = 75/ 15 = 5.0 <br />Wfpa<br />Wbkf<br />
  176. 176. Rocky Branch Phase II Reach 2:<br />Priority 2 (floodplain excavation, C channel)<br />Entrenchment Ratio = Wfpa / Wbkf = 90/20 = 4.5<br />Wfpa<br />Wbkf<br />Flood water flows onto floodplain several times each year<br />
  177. 177. Rocky Branch Phase II Reach 1:<br />Priority 3 (floodplain excavation, Bc channel)<br />Entrenchment Ratio = Wfpa / Wbkf = 40/20 = 2<br />Wfpa<br />Wbkf<br />
  178. 178. Bank Height Ratio<br />BHR = LBH / dmbkf<br />LBH= Low Bank Height (Max Depth to thalweg)<br />dmbkf= Max Depth from bankfull stage to thalweg<br />Bankfull<br />LBH<br />dmbkf<br />
  179. 179. BHR = 5.3 / 2.5 = 2.1 <br />Top of Bank<br />Bankfull<br />dmax tob<br />dmax<br />
  180. 180.
  181. 181.
  182. 182. Pattern (plan form)<br />Alluvial (low-gradient) streams naturally meander across a valley with a somewhat predictable pattern<br />
  183. 183. Meandering Stream: Alluvial Forms<br />Riffle<br />Point Bar (deposition)<br />Run<br />Glide<br />Pool<br />
  184. 184. Stream Corridor Restoration: Principles, Processes, and Practices. 1998. Federal Interagency Stream Restoration Working Group.<br />
  185. 185. Oxbow Formation in Meandering Streams<br />Stream Corridor Restoration: Principles, Processes, and Practices. 1998. Federal Interagency Stream Restoration Working Group.<br />
  186. 186. Chute cutoff across tight meander bend<br />
  187. 187. Oxbows<br />
  188. 188. Oxbows<br />
  189. 189. Sinuosity = stream length / valley length<br />K = 1850 / 980 = 1.9 <br />Valley Length<br />
  190. 190. Plan Form Relationships<br />
  191. 191. Meander Length Ratio = meander length / width = 78/15 = 5.2<br />Meander Width Ratio = belt width / width = 57/15 = 3.8<br />Radius of Curvature Ratio = radius / width = 23/15 = 1.5<br /> Belt Width<br /> Meander Length<br />
  192. 192. Profile (bedform)<br />Water Surface<br />Riffle Slope<br />Run Slope<br />Glide Slope<br />Pool Slope<br />Thalweg<br />Pool Spacing, Lp-p<br />Riffle Slope Ratio, Srif / Sav<br />Pool Slope Ratio, Spool/ Sav<br />Pool-to-Pool Spacing Ratio, Lp-p/ Wbkf<br />
  193. 193. Stream Bedform Variability:Slope Substrate size Velocity OxygenationShear stress Habitats<br />
  194. 194. Riffles<br /><ul><li>Steep slope
  195. 195. High velocity
  196. 196. High shear stress
  197. 197. Large substrate
  198. 198. High porosity</li></li></ul><li>Importance of Riffles<br />Areas of oxygenation<br />Highly diverse substrate and habitat<br />Diverse macroinvertebrate population<br />
  199. 199. Pools<br /><ul><li>Flat slope
  200. 200. Low velocity
  201. 201. Low shear stress
  202. 202. Small substrate
  203. 203. Scour during high flow</li></li></ul><li>Importance of Pools<br />Refuge for fish during low flow, drought periods<br />Rest stop and food area for fish<br />Predator refuge for young fish<br />
  204. 204. River Dimensions<br />
  205. 205. Velocities:Low flow and Flood flow<br />Little Garvin Creek, Clemson, SC<br />
  206. 206. Channel dimensions in a meandering stream<br />www.uwsp.edu/gEo/faculty/lemke/geomorphology/lecture_outlines/04_fluvial_landforms.html<br />
  207. 207. Profile is related to Pattern<br />
  208. 208. Stream Corridor Restoration: Principles, Processes, and Practices. 1998. Federal Interagency Stream Restoration Working Group.<br />
  209. 209. Step Pool Streams<br />(high gradient)<br />Stream Corridor Restoration: Principles, Processes, and Practices. 1998. Federal Interagency Stream Restoration Working Group.<br />
  210. 210. Grade Controls<br />Nickpoints<br />
  211. 211. Flow diversity improves habitat:<br /><ul><li> Riffles
  212. 212. Steps
  213. 213. Pools</li></li></ul><li>Natural Stream Channel Stability<br />(from Leopold)<br />River has a stable dimension, pattern and profile<br />Maintains channel features (riffles, pools, steps)<br />Does not aggrade (fills) or degrade (erodes)<br />
  214. 214. Equilibrium Controlling Variables<br /><ul><li>Width
  215. 215. Depth
  216. 216. Slope
  217. 217. Velocity
  218. 218. Discharge
  219. 219. Flow resistance
  220. 220. Sediment size
  221. 221. Sediment load</li></ul>Leopold et al (1964)<br />
  222. 222. Channel Forming Discharges<br />and Regional Curves<br />
  223. 223. Channel-forming (dominant) discharge<br />Estimated using:<br /><ul><li>Effective discharge
  224. 224. Bankfull discharge
  225. 225. Discharge associated with recurrence interval (typically 1 to 2 year)</li></li></ul><li>Effective Discharge<br />Transports the most sediment over a long time<br />
  226. 226. Bankfull Discharge<br />Flow fills active channel and spreads onto floodplain<br />Represents break between channel & floodplain processes<br />For channel in equilibrium, assumed to equal the effective discharge<br />Return Period typically 1 to 2 years<br />
  227. 227. Bankfull Stage<br />“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)<br />Stream Corridor Restoration: Principles, Processes, and Practices. 1998. Federal Interagency Stream Restoration Working Group.<br />
  228. 228. Bankfull<br />
  229. 229. Bankfull Indicators<br /><ul><li>Top of streambank (floodplain)
  230. 230. Break in slope on streambank
  231. 231. Top of point bar</li></ul>Bankfull<br />Bankfull<br />
  232. 232. Bankfull<br />
  233. 233. Bankfull<br />
  234. 234. Bankfull<br />
  235. 235. Bankfull<br />
  236. 236. Channel Evolution<br />(Succession)<br />Response to incising forces<br />Stream Corridor Restoration: Principles, Processes, and Practices. 1998. Federal Interagency Stream Restoration Working Group.<br />
  237. 237. Terrace<br />Bankfull<br />
  238. 238. Bankfull<br />
  239. 239.
  240. 240. Bankfull<br />
  241. 241. Bankfull<br />

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