Strategize a Smooth Tenant-to-tenant Migration and Copilot Takeoff
Rc101 day1
1. Stream Assessment Greg Jennings, PhD, PE Professor, Biological & Agricultural Engineering North Carolina State University jennings@ncsu.edu Jason Zink, PE Zan Price, PE Mike Shaffer, PE Dave Penrose Barbara Doll, PE Kris Bass, PE Karen Hall Mitch Woodward
8. Watershed: “Area of land that drains water, sediment, and dissolved materials to a common outlet at some point along a stream channel” Dunne and Leopold, 1978 Watershed form is influenced by: Climate Geology & Soils Fluvial Geomorphology Vegetation Land Uses
10. From Webster's Revised Unabridged Dictionary (1913) : Watershed, n [Cf. G. wasserscheide; wasserwater + scheidea place where two things separate, fr. scheidento separate.] The whole region or extent of country which contributes to the supply of a river or lake. 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. Other Terms: Catchment, Drainage basin, River basin
11. North Carolina River Basins River basins include watersheds of varying sizes and shapes, each with a network of streams delivering water to an outlet
14. Water Transport to Streams Rainfall moves across the land as runoff or through the ground toward streams to provide baseflow Stream Corridor Restoration: Principles, Processes, and Practices. 1998. Federal Interagency Stream Restoration Working Group.
15. Groundwater Influences Streamflow Losing Stream Gaining Stream Groundwater Recharge Groundwater Discharge Stream Corridor Restoration: Principles, Processes, and Practices. 1998. Federal Interagency Stream Restoration Working Group.
16. Streamflow Duration and Frequency: Classification based on connection to groundwater Perennial (gaining stream) Ephemeral (losing stream) Intermittent (sometimes losing)
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18. Strahler Stream Order: Classification system describing position within the drainage network First order streams may be ephemeral, intermittent, or perennial in relation to groundwater connection Stream Corridor Restoration: Principles, Processes, and Practices. 1998. Federal Interagency Stream Restoration Working Group.
19. Stream Functions Transport water Transport sediment Habitat (aquatic & terrestrial) Recreation Aesthetics Safe Water Supply
20. Water Transport & Storage Hydrology: The study of the flow of the earth’s waters through the hydrologic cycle Hydrograph: Displays change in flow (discharge, Q, over time) Peak Flow Rising Limb Falling Limb Mean Daily Flow www.Geology.com
21. Hydrologic Responses to Urbanization Increased discharge Increased peak discharge Increased velocities Shorter time to peak flow More frequent bankfull events Increased flooding Lower baseflow Less ground water recharge
22. Hydrograph Changes Due to Urbanization Increased impervious surface results in more runoff and higher peak flow Urban Rural
23. Stream Condition Related to Impervious Surface Water quality and stream health decline in relation to impervious surface percentage Good Fair Poor Protected Impaired Urban Drainage Network Degraded Source: Center for Watershed Protection
24. Channel incision and bank erosion increase due to channelization and increased stormwater runoff
25. Urban streams have special challenges due to urban infrastructure (storm sewer and sanitary sewer)
26. In addition to stormwater and sewer systems, urban streams are also challenged by confinement
51. Stream Ecosystems Mostly downstream fluxes of energy and matter Lateral and vertical connections to the riparian and hyporheic zones Courtesy of Francois Birgand, NCSU
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53. Biological communities upstream and downstreamStream Corridor Restoration: Principles, Processes, and Practices. 1998. Federal Interagency Stream Restoration Working Group.
61. What makes a stream healthy? Bed stability & diversity Sediment transport balance In-stream habitat & flow diversity Bank stability (native plant roots) Riparian buffer (streamside forest) Active floodplain Healthy watershed
105. Stream Functions Transport water Transport sediment Habitat (aquatic & terrestrial) Recreation & aesthetics Safe Water Supply
106. Velocity & Discharge Q = VA = Discharge (cfs) V = Velocity (ft/s) A = Cross-Section Area (ft2) V related to slope, channel shape, and channel roughness Stream Corridor Restoration: Principles, Processes, and Practices. 1998. Federal Interagency Stream Restoration Working Group.
109. A = 40 sq ft W = 22 ft R = 1.7 ft S = 0.010 ft/ft n = 0.040 V = 5.0 ft/s Q = 200 cfs A = 220 sq ft W = 55 ft R = 3.5 ft S = 0.004 ft/ft n = 0.035 V = 6.1 ft/s Q = 1350 cfs
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111. Stream Corridor Longitudinal Profile Stream Corridor Restoration: Principles, Processes, and Practices. 1998. Federal Interagency Stream Restoration Working Group.
117. Abrasion of heavy materials rolling on bottomhttp://www.uwsp.edu/gEo/faculty/ritter/geog101/textbook/fluvial_systems/geologic_work_of_streams.html
118. Transportation: Movement of material by water Stream Load includes: dissolved + suspended + bed load Capacity: maximum load that can be transported for a given discharge (increases with velocity and turbulence) Competence: largest size material that can be transported for a given discharge http://www.uwsp.edu/gEo/faculty/ritter/geog101/textbook/fluvial_systems/geologic_work_of_streams.html
120. Deposition: Aggradation: Raising the bed elevation Bars: Depositional areas that may change flow directions http://www.uwsp.edu/gEo/faculty/ritter/geog101/textbook/fluvial_systems/geologic_work_of_streams.html
121. Bed Material (Substrate) Silt/Clay: < 0.062 mm Sand: 0.062 – 2 mm Gravel: 2 – 64 mm Cobble: 64 – 256 mm Boulder: 256 – 2048 mm
123. High Slope Moderate Slope Low Slope Stream Corridor Restoration: Principles, Processes, and Practices. 1998. Federal Interagency Stream Restoration Working Group.
124. Velocity & Particle Size Determine Process V = 5 ft/s V = 1 ft/s http://www.uwsp.edu/gEo/faculty/ritter/geog101/textbook/fluvial_systems/geologic_work_of_streams.html
125. Shear Stress: fluid force per unit area acting on the streambed = Rs = Shear Stress (lb/ft2) = Unit Weight of Water = 62.4 lb/ft3 R = Hydraulic Radius (ft) = A / P S = Average Water Surface Slope (ft/ft) A = Riffle Cross-Section Area (ft2) P = Wetted Perimeter (ft) P = Wbkf +2*Dbkf (approx)
139. Meandering Stream: Alluvial Forms Flow Downstream Floodplain Scarp Bankfull Stage Point Bar Pool Left Bank Right Bank Riffle Thalweg
140. 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.
147. Valley type affects stream morphology Colluvium is loose sediment transported by gravity and deposited at the bottom of a slope. Alluvium is sediment deposited by a river in the channel or floodplain Alluvial valleys occur where sediment particles are dropped by slow-moving water.
148. Valley Types: (www.epa.gov/watertrain/stream_class) Valley Type II Moderately steep, gentle sloping side slopes often in colluvial valleys From EPA Watershed Academy: Fundamentals of the Rosgen Stream Classification System
149. Valley Types: (www.epa.gov/watertrain/stream_class) Valley Type VIII Wide, gentle valley slope with well-developed floodplain adjacent to river terraces From EPA Watershed Academy: Fundamentals of the Rosgen Stream Classification System
150. Stream Corridor Lateral Profile Stream Corridor Restoration: Principles, Processes, and Practices. 1998. Federal Interagency Stream Restoration Working Group.
161. Pool Cross-Section (Meandering Stream) Stream Corridor Restoration: Principles, Processes, and Practices. 1998. Federal Interagency Stream Restoration Working Group.
162. Natural Stream Channel Stability (from Leopold) River has a stable dimension, pattern and profile Maintains channel features (riffles, pools, steps) Does not aggrade (fills) or degrade (erodes)
174. 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 above thalweg dmbkf Wbkf
176. Rocky Branch Phase II Reach 2: Priority 2 (floodplain excavation, C channel) Entrenchment Ratio = Wfpa / Wbkf = 90/20 = 4.5 Wfpa Wbkf Flood water flows onto floodplain several times each year
177. Rocky Branch Phase II Reach 1: Priority 3 (floodplain excavation, Bc channel) Entrenchment Ratio = Wfpa / Wbkf = 40/20 = 2 Wfpa Wbkf
178. Bank Height Ratio BHR = LBH / dmbkf LBH= Low Bank Height (Max Depth to thalweg) dmbkf= Max Depth from bankfull stage to thalweg Bankfull LBH dmbkf
179. BHR = 5.3 / 2.5 = 2.1 Top of Bank Bankfull dmax tob dmax
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182. Pattern (plan form) Alluvial (low-gradient) streams naturally meander across a valley with a somewhat predictable pattern
183. Meandering Stream: Alluvial Forms Riffle Point Bar (deposition) Run Glide Pool
184. Stream Corridor Restoration: Principles, Processes, and Practices. 1998. Federal Interagency Stream Restoration Working Group.
185. Oxbow Formation in Meandering Streams Stream Corridor Restoration: Principles, Processes, and Practices. 1998. Federal Interagency Stream Restoration Working Group.
191. Meander Length Ratio = meander length / width = 78/15 = 5.2 Meander Width Ratio = belt width / width = 57/15 = 3.8 Radius of Curvature Ratio = radius / width = 23/15 = 1.5 Belt Width Meander Length
192. Profile (bedform) Water Surface Riffle Slope Run Slope Glide Slope Pool Slope Thalweg Pool Spacing, Lp-p Riffle Slope Ratio, Srif / Sav Pool Slope Ratio, Spool/ Sav Pool-to-Pool Spacing Ratio, Lp-p/ Wbkf
208. Stream Corridor Restoration: Principles, Processes, and Practices. 1998. Federal Interagency Stream Restoration Working Group.
209. Step Pool Streams (high gradient) Stream Corridor Restoration: Principles, Processes, and Practices. 1998. Federal Interagency Stream Restoration Working Group.
226. Bankfull Discharge Flow fills active channel and spreads onto floodplain Represents break between channel & floodplain processes For channel in equilibrium, assumed to equal the effective discharge Return Period typically 1 to 2 years
227. 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.
![What is a Stream? … a body of water with a current, confined within a bed and streambanks Synonyms: bayou, beck, branch, brook, burn, creek, crick, kill, lick, rill, river, rivulet, run, slough, syke A stream is: ,[object Object]](data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7)