Rc101 day1
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Transcript of Rc101 day1
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Greg Jennings, PhD, PE
Professor, Biological & Agricultural Engineering
North Carolina State University
Jason Zink, PE
Zan Price, PE
Mike Shaffer, PE
Dave Penrose
Barbara Doll, PE
Kris Bass, PE
Karen Hall
Mitch Woodward
Stream Assessment
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… 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:
• conduit in the water cycle
• critical habitat
• connected to a watershed
What is a Stream?
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Hydrologic (Water) Cycle: describes the
flow of water on the planet in response
to solar energy and gravity
Stream Corridor Restoration: Principles, Processes, and Practices.
1998. Federal Interagency Stream Restoration Working Group.
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Water Cycle Components:
Precipitation
Runoff
Infiltration
Evapotranspiration
Groundwater flow
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Average annual precipitation is highly variable and the timing of
rainfall each year is unpredictable
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Extreme Weather!
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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:
1. Climate
2. Geology & Soils
3. Fluvial Geomorphology
4. Vegetation
5. Land Uses
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Watersheds include many
land uses affecting flow and
water quality
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From Webster's Revised Unabridged Dictionary (1913) :
Watershed, n [Cf. G. wasserscheide; wasser water + scheide a place where two things separate, fr. scheiden to separate.]
1. The whole region or extent of country which contributes to the supply of a river or lake.
2. 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
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North Carolina River Basins
River basins include watersheds of varying sizes and shapes, each with a network of streams delivering water to an outlet
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Watershed Stream Network
Neuse River Basin, NC
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Watershed Functions:
Transport & Storage:
1. Water
2. Sediment
3. Dissolved Materials
Habitat:
1. Animals
2. Plants
3. Humans
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Water Transport to StreamsRainfall 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.
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Losing Stream Gaining StreamGroundwater Recharge Groundwater Discharge
Groundwater Influences Streamflow
Stream Corridor Restoration: Principles, Processes, and Practices.
1998. Federal Interagency Stream Restoration Working Group.
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Streamflow Duration and Frequency:Classification based on connection to groundwater
Intermittent(sometimes losing)
Perennial(gaining stream)
Ephemeral(losing stream)
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Strahler Stream Order:Classification system describing position within the drainage network
Stream Corridor Restoration: Principles, Processes, and Practices. 1998.
Federal Interagency Stream Restoration Working Group.
First order
streams may
be
ephemeral, inte
rmittent, or
perennial in
relation to
groundwater
connection
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Stream Functions
1. Transport water
2. Transport sediment
3. Habitat (aquatic & terrestrial)
4. Recreation
5. Aesthetics
6. Safe Water Supply
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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)
www.Geology.com
Mean Daily Flow
Falling
Limb
Rising
Limb
Peak Flow
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Hydrologic Responses to
Urbanization
1. Increased discharge
2. Increased peak discharge
3. Increased velocities
4. Shorter time to peak flow
5. More frequent bankfull events
6. Increased flooding
7. Lower baseflow
8. Less ground water recharge
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Hydrograph Changes Due to Urbanization
Increased impervious surface results in more runoff and higher peak flow
Rural
Urban
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0 10 20 30 40 50 60 70 80
% Impervious
Urban
Drainage
Network
Stream Condition Related to Impervious Surface
Water quality and stream health decline in relation to impervious surface percentage
Good
Fair
Poor
Impaired
Protected
Degraded
Source: Center for Watershed Protection
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Channel incision and bank erosion increase due to channelization
and increased stormwater runoff
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Urban streams have special challenges due to urban
infrastructure (storm sewer and sanitary sewer)
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In addition to stormwater and sewer systems, urban streams are
also challenged by confinement
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Fluvial Geomorphology:
study of landforms and the fluvial processes
that shape them
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Fluvial Processes:
associated with flowing water, including sediment
erosion, transport, and deposition
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• Channel (bed & banks)
• Floodplain
• Water
• Sediment
• Plants & animals
Stream: A system of
fluvial forms & habitats
Photo Credit: Eve Brantley, Auburn University
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Fluvial Forms• Bar
• Channel
• Confluence
• Cutoff channel
• Delta
• Floodplain
• Gorge
• Gully
• Meander
• Oxbow lake
• Pool
• Riffle
• Stream
• Valley
• Waterfall
• Watershed
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Fluvial Processes and Landforms
1. How do stream systems work?
2. What determines stream size & shape
(i.e. morphology)?
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• Communities of organisms and their physical,
chemical, and biological environments
Streams are ecosystems
Courtesy of Francois Birgand, NCSU
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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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River Continuum
Concept
Connections
• Watershed to
Corridor to Stream
• Biological
communities
upstream and
downstream
Stream Corridor Restoration: Principles, Processes, and Practices.
1998. Federal Interagency Stream Restoration Working Group.
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Hyporheic Zone
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Field Investigations
What is living in the
stream?
What are the physical and
chemical conditions of the
stream?
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Provisioning – food, energy, industry
Regulating – climate, waste, nutrients
Supporting – water quality, pest control
Cultural – recreation, inspiration
Preserving – species diversity
Ecosystem Services
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Self-Design
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)
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1. Bed stability & diversity
2. Sediment transport balance
3. In-stream habitat & flow diversity
4. Bank stability (native plant roots)
5. Riparian buffer (streamside forest)
6. Active floodplain
7. Healthy watershed
What makes a stream healthy?
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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
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1. Bed Stability & Diversity – Problems
• Headcut and excess scour
• Plane bed – filling of pools
• Armoring
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2. Sediment Transport Balance
• Minor erosion & deposition
• Alluvial bars and benches
• Sufficient stream power to avoid aggradation
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2. Sediment Transport Balance
• Excess stream power – eroding bed
• Insufficient stream power – aggradation
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PoolRoots Wood
Leaf Pack
RiffleRocks
3. In-stream Habitat & Flow Diversity
Plants
Overhanging Bank
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Stream Habitats
Macrohabitats: riffles,
runs, pools, glides,
steps, side channels
Microhabitats: roots,
leaf packs, wood,
rocks, plants,
hyporheic zone
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Food Web
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Diversity of habitats
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What habitats do you see?
Pool
Roots
Wood
Leaf Pack
Riffle
Rocks
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3. In-stream Habitat – Problems
• Uniform flow – lack of diversity
• Lack of wood, leaves, roots
• Water quality – DO, nutrients, toxics
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4. Bank Stability
• Dense native
plant roots
• Low banks with
low stress
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4. Bank Stability – Problems
• Loss of vegetation
• High, steep banks – channelization
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5. Riparian Buffer (Streamside Forest)
• Diverse native plants
• Food and shade
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5. Riparian Buffer – Problems
• Mowers and moo’ers
• Invasive plants
• Armoring and impervious surfaces
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6. Active Floodplain
• Regular (every year) flooding to relieve stress
• Riparian wetlands
• Stormwater retention & treatment
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6. Active Floodplain – Problems
• Channel incision
• Floodplain fill and encroachment
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7. Healthy Watershed
• Stormwater management
• Wastewater management
• Upstream sediment control
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7. Healthy Watershed – Problems
• Stormwater energy and volume
• Point and nonpoint source pollution
• Erosion and sediment
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Stream Impairments
• Straightening & dredging
• Floodplain filling
• Watershed manipulation
• Sedimentation & stormwater
• Pollution discharges
• Utilities & culverts
• Buffer removal
• Disdain & neglect
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Stream Impairment
Causes (US EPA)
1. Pathogens
2. Sediment
3. Nutrients
4. Organic Enrichment
5. Habitat Alterations
6. PCBs
7. Metals
8. Flow Alterations
9. Temperature
10. Mercury
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Why Restoration?
• Water quality impairments
• Habitat loss
• Ecosystem degradation
• Land loss
• Safety concerns
• Infrastructure damage
• Flooding
• Aesthetics
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1. Watershed management
2. Floodplain reconnection
3. Channel morphology –
dimension, pattern, profile
4. Sediment transport balance
5. Habitat enhancements
6. Bank stabilization
7. Riparian buffer – native
plants
Restoring Stream Health
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Stream Functions
1. Transport water
2. Transport sediment
3. Habitat (aquatic & terrestrial)
4. Recreation & aesthetics
5. Safe Water Supply
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Q = V A = Discharge (cfs)
V = Velocity (ft/s)
A = Cross-Section Area (ft2)
V related to slope, channel shape, and channel
roughness
Velocity &
Discharge
Stream Corridor Restoration: Principles, Processes, and Practices. 1998. Federal Interagency Stream Restoration Working Group.
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Manning Formula
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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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R = 1.5 ft
S = 0.0012 ft/ft
n = 0.038
V = 1.8 ft/s
Q = 89 cfs
= 0.11 lb/sq ft
Competence = ~30 mm
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Stream Corridor Longitudinal Profile
Stream Corridor Restoration: Principles, Processes, and Practices.
1998. Federal Interagency Stream Restoration Working Group.
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Sediment Transport
Flowing water does work:
• Erosion
• Transportation
• Deposition (of alluvium)
http://www.uwsp.edu/gEo/faculty/ritter/geog101/textbook/fluvial_systems/geologic_work_of_streams.html
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Erosion: Detachment of material from bed and banks
95% of stream energy used to overcome friction
Remaining energy used for Erosion Processes:
• Flowing water dissolves materials
• Hydraulic action dislodges materials
• Abrasion of heavy materials rolling on bottom
http://www.uwsp.edu/gEo/faculty/ritter/geog101/textbook/
fluvial_systems/geologic_work_of_streams.html
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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
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Bedload is related to Discharge for Each River
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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
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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
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Substrate
Characterization
Wolman Pebble Count
![Page 75: Rc101 day1](https://reader034.fdocuments.us/reader034/viewer/2022050813/58a5cbe01a28ab6c2a8b57ab/html5/thumbnails/75.jpg)
Stream Corridor Restoration: Principles, Processes, and Practices. 1998. Federal Interagency Stream Restoration Working Group.
High Slope Moderate Slope Low Slope
![Page 76: Rc101 day1](https://reader034.fdocuments.us/reader034/viewer/2022050813/58a5cbe01a28ab6c2a8b57ab/html5/thumbnails/76.jpg)
Velocity & Particle Size Determine Process
http://www.uwsp.edu/gEo/faculty/ritter/geog101/textbook/fluvial_systems/geologic_work_of_streams.html
V = 5 ft/s
V = 1 ft/s
![Page 77: Rc101 day1](https://reader034.fdocuments.us/reader034/viewer/2022050813/58a5cbe01a28ab6c2a8b57ab/html5/thumbnails/77.jpg)
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)
![Page 78: Rc101 day1](https://reader034.fdocuments.us/reader034/viewer/2022050813/58a5cbe01a28ab6c2a8b57ab/html5/thumbnails/78.jpg)
Stream Competence (www.epa.gov/WARSSS)
![Page 79: Rc101 day1](https://reader034.fdocuments.us/reader034/viewer/2022050813/58a5cbe01a28ab6c2a8b57ab/html5/thumbnails/79.jpg)
A = 40 sq ft
W = 22 ft
R = 1.7 ft
S = 0.010 ft/ft
= 1.0 lb/sq ft
Competence = ~250 mm
A = 220 sq ft
W = 55 ft
R = 3.5 ft
S = 0.004 ft/ft
= 0.8 lb/sq ft
Competence = ~200 mm
![Page 80: Rc101 day1](https://reader034.fdocuments.us/reader034/viewer/2022050813/58a5cbe01a28ab6c2a8b57ab/html5/thumbnails/80.jpg)
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Sediment
Deposition:
• Point bar
• Lateral bar
• Mid-channel bar
• Transverse bar
• Delta bar
![Page 82: Rc101 day1](https://reader034.fdocuments.us/reader034/viewer/2022050813/58a5cbe01a28ab6c2a8b57ab/html5/thumbnails/82.jpg)
Stream Corridor Restoration: Principles, Processes, and Practices. 1998. Federal Interagency Stream Restoration Working Group.
![Page 83: Rc101 day1](https://reader034.fdocuments.us/reader034/viewer/2022050813/58a5cbe01a28ab6c2a8b57ab/html5/thumbnails/83.jpg)
Point Bars:
Inside meander
bends
![Page 84: Rc101 day1](https://reader034.fdocuments.us/reader034/viewer/2022050813/58a5cbe01a28ab6c2a8b57ab/html5/thumbnails/84.jpg)
Lateral Bars:
Formed in
straight channels
![Page 85: Rc101 day1](https://reader034.fdocuments.us/reader034/viewer/2022050813/58a5cbe01a28ab6c2a8b57ab/html5/thumbnails/85.jpg)
Lateral Bars:
Formed in
straight channels
![Page 86: Rc101 day1](https://reader034.fdocuments.us/reader034/viewer/2022050813/58a5cbe01a28ab6c2a8b57ab/html5/thumbnails/86.jpg)
Mid-channel Bars:
Formed in over-
wide channels
![Page 87: Rc101 day1](https://reader034.fdocuments.us/reader034/viewer/2022050813/58a5cbe01a28ab6c2a8b57ab/html5/thumbnails/87.jpg)
Transverse Bars:
Formed in straight
channels
![Page 88: Rc101 day1](https://reader034.fdocuments.us/reader034/viewer/2022050813/58a5cbe01a28ab6c2a8b57ab/html5/thumbnails/88.jpg)
Meandering Stream: Alluvial Forms
Point Bar
ScarpBankfull Stage
Thalweg
Flow DownstreamFloodplain
Riffle
Pool
Right
Bank
Left Bank
![Page 89: Rc101 day1](https://reader034.fdocuments.us/reader034/viewer/2022050813/58a5cbe01a28ab6c2a8b57ab/html5/thumbnails/89.jpg)
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.
![Page 90: Rc101 day1](https://reader034.fdocuments.us/reader034/viewer/2022050813/58a5cbe01a28ab6c2a8b57ab/html5/thumbnails/90.jpg)
Bankfull
![Page 91: Rc101 day1](https://reader034.fdocuments.us/reader034/viewer/2022050813/58a5cbe01a28ab6c2a8b57ab/html5/thumbnails/91.jpg)
Channel
Evolution
(Succession)
Response to
incising forces
Stream Corridor Restoration:
Principles, Processes, and Practices.
1998. Federal Interagency Stream
Restoration Working Group.
![Page 92: Rc101 day1](https://reader034.fdocuments.us/reader034/viewer/2022050813/58a5cbe01a28ab6c2a8b57ab/html5/thumbnails/92.jpg)
Bankfull
Terrace
![Page 93: Rc101 day1](https://reader034.fdocuments.us/reader034/viewer/2022050813/58a5cbe01a28ab6c2a8b57ab/html5/thumbnails/93.jpg)
Incised System: Floodplain Creation
Floodplain
Terrace
![Page 94: Rc101 day1](https://reader034.fdocuments.us/reader034/viewer/2022050813/58a5cbe01a28ab6c2a8b57ab/html5/thumbnails/94.jpg)
Stream Morphology:
size and shape of channel & floodplain
(dimension, pattern, profile)
![Page 95: Rc101 day1](https://reader034.fdocuments.us/reader034/viewer/2022050813/58a5cbe01a28ab6c2a8b57ab/html5/thumbnails/95.jpg)
![Page 96: Rc101 day1](https://reader034.fdocuments.us/reader034/viewer/2022050813/58a5cbe01a28ab6c2a8b57ab/html5/thumbnails/96.jpg)
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.
Valley type affects
stream morphology
![Page 97: Rc101 day1](https://reader034.fdocuments.us/reader034/viewer/2022050813/58a5cbe01a28ab6c2a8b57ab/html5/thumbnails/97.jpg)
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
![Page 98: Rc101 day1](https://reader034.fdocuments.us/reader034/viewer/2022050813/58a5cbe01a28ab6c2a8b57ab/html5/thumbnails/98.jpg)
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
![Page 99: Rc101 day1](https://reader034.fdocuments.us/reader034/viewer/2022050813/58a5cbe01a28ab6c2a8b57ab/html5/thumbnails/99.jpg)
Stream Corridor Lateral Profile
Stream Corridor Restoration: Principles, Processes, and Practices. 1998. Federal Interagency Stream Restoration Working Group.
![Page 100: Rc101 day1](https://reader034.fdocuments.us/reader034/viewer/2022050813/58a5cbe01a28ab6c2a8b57ab/html5/thumbnails/100.jpg)
Floodplains: Critical Stream Components
![Page 101: Rc101 day1](https://reader034.fdocuments.us/reader034/viewer/2022050813/58a5cbe01a28ab6c2a8b57ab/html5/thumbnails/101.jpg)
Floodplain Functions
• Floodwater storage
• Reducing peak flows
• Erosion prevention
• Water quality
• Groundwater recharge
• Food & shade
• Habitats
![Page 102: Rc101 day1](https://reader034.fdocuments.us/reader034/viewer/2022050813/58a5cbe01a28ab6c2a8b57ab/html5/thumbnails/102.jpg)
![Page 103: Rc101 day1](https://reader034.fdocuments.us/reader034/viewer/2022050813/58a5cbe01a28ab6c2a8b57ab/html5/thumbnails/103.jpg)
Floodplain
Left BankRight Bank
Downstream
Terrace
Streambed
Thalweg
![Page 104: Rc101 day1](https://reader034.fdocuments.us/reader034/viewer/2022050813/58a5cbe01a28ab6c2a8b57ab/html5/thumbnails/104.jpg)
FloodplainLeft Bank Right
Bank
Downstream
Terrace
Streambed
Thalweg
![Page 105: Rc101 day1](https://reader034.fdocuments.us/reader034/viewer/2022050813/58a5cbe01a28ab6c2a8b57ab/html5/thumbnails/105.jpg)
Pool Cross-Section (Meandering Stream)
Stream Corridor Restoration: Principles, Processes, and Practices. 1998. Federal Interagency Stream Restoration Working Group.
![Page 106: Rc101 day1](https://reader034.fdocuments.us/reader034/viewer/2022050813/58a5cbe01a28ab6c2a8b57ab/html5/thumbnails/106.jpg)
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)
![Page 107: Rc101 day1](https://reader034.fdocuments.us/reader034/viewer/2022050813/58a5cbe01a28ab6c2a8b57ab/html5/thumbnails/107.jpg)
Dimension (cross-section)
• Area
• Width
• Depth
• Width/Depth Ratio
• Entrenchment Ratio
• Bank Height Ratio
![Page 108: Rc101 day1](https://reader034.fdocuments.us/reader034/viewer/2022050813/58a5cbe01a28ab6c2a8b57ab/html5/thumbnails/108.jpg)
Bankfull Stage: “incipient flooding”“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)
Stream Corridor Restoration: Principles, Processes, and Practices. 1998. Federal Interagency Stream Restoration Working Group.
![Page 109: Rc101 day1](https://reader034.fdocuments.us/reader034/viewer/2022050813/58a5cbe01a28ab6c2a8b57ab/html5/thumbnails/109.jpg)
Bankfull
Terrace
![Page 110: Rc101 day1](https://reader034.fdocuments.us/reader034/viewer/2022050813/58a5cbe01a28ab6c2a8b57ab/html5/thumbnails/110.jpg)
Dimension: Cross-Section
![Page 111: Rc101 day1](https://reader034.fdocuments.us/reader034/viewer/2022050813/58a5cbe01a28ab6c2a8b57ab/html5/thumbnails/111.jpg)
Riffle Dimensions
Bankfull
Wbkf
Abkf
Measure Bankfull Width (Wbkf) and Bankfull Area (Abkf)
Mean Depth, dbkf = Abkf / Wbkf
Width to Depth Ratio, W/d = Wbkf / dbkf
dbkf
![Page 112: Rc101 day1](https://reader034.fdocuments.us/reader034/viewer/2022050813/58a5cbe01a28ab6c2a8b57ab/html5/thumbnails/112.jpg)
Bankfull Width, Wbkf = 9.3 ft; Bankfull Area, Abkf = 13.9 ft2
Mean Depth, dbkf = Abkf / Wbkf = 13.9 / 9.3 = 1.5 ft
Width to Depth Ratio, W/d = Wbkf / dbkf = 9.3 / 1.5 = 6.2
![Page 113: Rc101 day1](https://reader034.fdocuments.us/reader034/viewer/2022050813/58a5cbe01a28ab6c2a8b57ab/html5/thumbnails/113.jpg)
Bankfull Width, Wbkf = 36 ft; Bankfull Area, Abkf = 112 ft2
Mean Depth, dbkf = Abkf / Wbkf = 112 / 36 = 3.1 ft
Width to Depth Ratio, W/d = Wbkf / dbkf = 36 / 3.1 = 11.5
![Page 114: Rc101 day1](https://reader034.fdocuments.us/reader034/viewer/2022050813/58a5cbe01a28ab6c2a8b57ab/html5/thumbnails/114.jpg)
Entrenchment Ratio
ER = Wfpa / Wbkf
Bankfull
2 x dmbkf
above thalweg
Wfpa
Wbkf
dmbkf
Wfpa = Width of Flood Prone Area measured at the
elevation twice bankfull max depth above thalweg
Wbkf = Width of Bankfull Channel
![Page 115: Rc101 day1](https://reader034.fdocuments.us/reader034/viewer/2022050813/58a5cbe01a28ab6c2a8b57ab/html5/thumbnails/115.jpg)
ER = Wfpa / Wbkf = 75 / 15 = 5.0
![Page 116: Rc101 day1](https://reader034.fdocuments.us/reader034/viewer/2022050813/58a5cbe01a28ab6c2a8b57ab/html5/thumbnails/116.jpg)
Flood water flows onto floodplain
several times each year
Rocky Branch Phase II Reach 2:
Priority 2 (floodplain excavation, C channel)
Entrenchment Ratio = Wfpa / Wbkf = 90/20 = 4.5
![Page 117: Rc101 day1](https://reader034.fdocuments.us/reader034/viewer/2022050813/58a5cbe01a28ab6c2a8b57ab/html5/thumbnails/117.jpg)
Rocky Branch Phase II Reach 1:
Priority 3 (floodplain excavation, Bc channel)
Entrenchment Ratio = Wfpa / Wbkf = 40/20 = 2
![Page 118: Rc101 day1](https://reader034.fdocuments.us/reader034/viewer/2022050813/58a5cbe01a28ab6c2a8b57ab/html5/thumbnails/118.jpg)
Bank Height Ratio
BHR = LBH / dmbkf
BankfullLBH
dmbkf = Max Depth from bankfull stage to thalweg
dmbkf
LBH = Low Bank Height (Max Depth to thalweg)
![Page 119: Rc101 day1](https://reader034.fdocuments.us/reader034/viewer/2022050813/58a5cbe01a28ab6c2a8b57ab/html5/thumbnails/119.jpg)
BHR = 5.3 / 2.5 = 2.1
![Page 120: Rc101 day1](https://reader034.fdocuments.us/reader034/viewer/2022050813/58a5cbe01a28ab6c2a8b57ab/html5/thumbnails/120.jpg)
1
10
100
1000
10000
0.1 1 10 100
Ba
nk
full
D
isch
arg
e,
Q (
cfs
)
Drainage Area (sq mi)
Hydraulic Geometry Regional Curves
NC Piedmont
NC Mtn
MD Alleghany
MD
NY
VT
OH 01
OH 05
OK
SW OR
Pacific NW
AZ
AZ & NM
![Page 121: Rc101 day1](https://reader034.fdocuments.us/reader034/viewer/2022050813/58a5cbe01a28ab6c2a8b57ab/html5/thumbnails/121.jpg)
1
10
100
1000
0.1 1 10 100
Cro
ss-s
ect
ion
Are
a (
sq f
t)
Drainage Area (sq mi)
Hydraulic Geometry Regional Curves
NC Piedmont
NC Mtn
MD Alleghany
MD
NY
VT
OH 01
OH 05
OK
SW OR
Pacific NW
AZ
AZ & NM
![Page 122: Rc101 day1](https://reader034.fdocuments.us/reader034/viewer/2022050813/58a5cbe01a28ab6c2a8b57ab/html5/thumbnails/122.jpg)
Alluvial (low-gradient) streams
naturally meander across a
valley with a somewhat
predictable pattern
Pattern (plan form)
![Page 123: Rc101 day1](https://reader034.fdocuments.us/reader034/viewer/2022050813/58a5cbe01a28ab6c2a8b57ab/html5/thumbnails/123.jpg)
Pool
Run
Point Bar
(deposition)
Glide
Riffle
Meandering Stream: Alluvial Forms
![Page 124: Rc101 day1](https://reader034.fdocuments.us/reader034/viewer/2022050813/58a5cbe01a28ab6c2a8b57ab/html5/thumbnails/124.jpg)
Stream Corridor Restoration: Principles, Processes, and Practices. 1998. Federal Interagency Stream Restoration Working Group.
![Page 125: Rc101 day1](https://reader034.fdocuments.us/reader034/viewer/2022050813/58a5cbe01a28ab6c2a8b57ab/html5/thumbnails/125.jpg)
Oxbow
Formation in
Meandering
Streams
Stream Corridor Restoration:
Principles, Processes, and Practices. 1998.
Federal Interagency Stream Restoration Working
Group.
![Page 126: Rc101 day1](https://reader034.fdocuments.us/reader034/viewer/2022050813/58a5cbe01a28ab6c2a8b57ab/html5/thumbnails/126.jpg)
Chute cutoff across tight meander bend
![Page 127: Rc101 day1](https://reader034.fdocuments.us/reader034/viewer/2022050813/58a5cbe01a28ab6c2a8b57ab/html5/thumbnails/127.jpg)
Oxbows
![Page 128: Rc101 day1](https://reader034.fdocuments.us/reader034/viewer/2022050813/58a5cbe01a28ab6c2a8b57ab/html5/thumbnails/128.jpg)
Oxbows
![Page 129: Rc101 day1](https://reader034.fdocuments.us/reader034/viewer/2022050813/58a5cbe01a28ab6c2a8b57ab/html5/thumbnails/129.jpg)
Sinuosity = stream length / valley length
K = 1850 / 980 = 1.9
Valley Length
![Page 130: Rc101 day1](https://reader034.fdocuments.us/reader034/viewer/2022050813/58a5cbe01a28ab6c2a8b57ab/html5/thumbnails/130.jpg)
Plan Form Relationships
![Page 131: Rc101 day1](https://reader034.fdocuments.us/reader034/viewer/2022050813/58a5cbe01a28ab6c2a8b57ab/html5/thumbnails/131.jpg)
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
Meander
Length
Belt
Width
![Page 132: Rc101 day1](https://reader034.fdocuments.us/reader034/viewer/2022050813/58a5cbe01a28ab6c2a8b57ab/html5/thumbnails/132.jpg)
Glide Slope
Riffle Slope
Run Slope
Pool Slope
Water Surface
Thalweg
Pool Spacing, Lp-p
Profile (bedform)
Riffle Slope Ratio, Srif / Sav
Pool Slope Ratio, Spool / Sav
Pool-to-Pool Spacing Ratio, Lp-p / Wbkf
![Page 133: Rc101 day1](https://reader034.fdocuments.us/reader034/viewer/2022050813/58a5cbe01a28ab6c2a8b57ab/html5/thumbnails/133.jpg)
Stream Bedform Variability:
Slope Substrate size
Velocity Oxygenation
Shear stress Habitats
![Page 134: Rc101 day1](https://reader034.fdocuments.us/reader034/viewer/2022050813/58a5cbe01a28ab6c2a8b57ab/html5/thumbnails/134.jpg)
Riffles
• Steep slope
• High velocity
• High shear stress
• Large substrate
• High porosity
![Page 135: Rc101 day1](https://reader034.fdocuments.us/reader034/viewer/2022050813/58a5cbe01a28ab6c2a8b57ab/html5/thumbnails/135.jpg)
Importance of Riffles
• Areas of oxygenation
• Highly diverse substrate and habitat
• Diverse macroinvertebrate population
![Page 136: Rc101 day1](https://reader034.fdocuments.us/reader034/viewer/2022050813/58a5cbe01a28ab6c2a8b57ab/html5/thumbnails/136.jpg)
Pools
• Flat slope
• Low velocity
• Low shear stress
• Small substrate
• Scour during high flow
![Page 137: Rc101 day1](https://reader034.fdocuments.us/reader034/viewer/2022050813/58a5cbe01a28ab6c2a8b57ab/html5/thumbnails/137.jpg)
Importance of Pools
• Refuge for fish during
low flow, drought
periods
• Rest stop and food
area for fish
• Predator refuge for
young fish
![Page 138: Rc101 day1](https://reader034.fdocuments.us/reader034/viewer/2022050813/58a5cbe01a28ab6c2a8b57ab/html5/thumbnails/138.jpg)
River Dimensions
![Page 139: Rc101 day1](https://reader034.fdocuments.us/reader034/viewer/2022050813/58a5cbe01a28ab6c2a8b57ab/html5/thumbnails/139.jpg)
Velocities:
Low flow and
Flood flow
Little Garvin
Creek, Clemson, SC
![Page 140: Rc101 day1](https://reader034.fdocuments.us/reader034/viewer/2022050813/58a5cbe01a28ab6c2a8b57ab/html5/thumbnails/140.jpg)
Channel dimensions in a meandering stream
www.uwsp.edu/gEo/faculty/lemke/geomorphology/lecture_outlines/04_fluvial_landforms.html
![Page 141: Rc101 day1](https://reader034.fdocuments.us/reader034/viewer/2022050813/58a5cbe01a28ab6c2a8b57ab/html5/thumbnails/141.jpg)
Profile is related to Pattern
![Page 142: Rc101 day1](https://reader034.fdocuments.us/reader034/viewer/2022050813/58a5cbe01a28ab6c2a8b57ab/html5/thumbnails/142.jpg)
Stream Corridor Restoration: Principles, Processes, and Practices. 1998. Federal Interagency Stream Restoration Working Group.
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Step Pool Streams
(high gradient)
Stream Corridor Restoration: Principles, Processes, and Practices. 1998. Federal Interagency Stream Restoration Working Group.
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Grade Controls
Nickpoints
![Page 145: Rc101 day1](https://reader034.fdocuments.us/reader034/viewer/2022050813/58a5cbe01a28ab6c2a8b57ab/html5/thumbnails/145.jpg)
Flow diversity
improves habitat:
• Riffles
• Steps
• Pools
![Page 146: Rc101 day1](https://reader034.fdocuments.us/reader034/viewer/2022050813/58a5cbe01a28ab6c2a8b57ab/html5/thumbnails/146.jpg)
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)
![Page 147: Rc101 day1](https://reader034.fdocuments.us/reader034/viewer/2022050813/58a5cbe01a28ab6c2a8b57ab/html5/thumbnails/147.jpg)
Equilibrium Controlling Variables
• Width
• Depth
• Slope
• Velocity
• Discharge
• Flow resistance
• Sediment size
• Sediment load
Leopold et al (1964)
![Page 148: Rc101 day1](https://reader034.fdocuments.us/reader034/viewer/2022050813/58a5cbe01a28ab6c2a8b57ab/html5/thumbnails/148.jpg)
Channel Forming
Discharges
and Regional
Curves
![Page 149: Rc101 day1](https://reader034.fdocuments.us/reader034/viewer/2022050813/58a5cbe01a28ab6c2a8b57ab/html5/thumbnails/149.jpg)
Channel-forming (dominant) discharge
Estimated using:
• Effective discharge
• Bankfull discharge
• Discharge associated with
recurrence interval
(typically 1 to 2 year)
![Page 150: Rc101 day1](https://reader034.fdocuments.us/reader034/viewer/2022050813/58a5cbe01a28ab6c2a8b57ab/html5/thumbnails/150.jpg)
Effective Discharge
Transports the
most sediment
over a long time
![Page 151: Rc101 day1](https://reader034.fdocuments.us/reader034/viewer/2022050813/58a5cbe01a28ab6c2a8b57ab/html5/thumbnails/151.jpg)
Bankfull Discharge
Return Period typically 1 to 2 years
Flow fills active channel and spreads onto floodplain
Represents break between channel & floodplain processes
For channel in equilibrium, assumed to equal the effective discharge
![Page 152: Rc101 day1](https://reader034.fdocuments.us/reader034/viewer/2022050813/58a5cbe01a28ab6c2a8b57ab/html5/thumbnails/152.jpg)
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.
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Bankfull
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Bankfull Indicators
• Top of streambank (floodplain)
• Break in slope on streambank
• Top of point bar
Bankfull
Bankfull
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Bankfull
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Bankfull
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Bankfull
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Bankfull
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Channel
Evolution
(Succession)
Response to
incising forces
Stream Corridor Restoration:
Principles, Processes, and Practices.
1998. Federal Interagency Stream
Restoration Working Group.
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Bankfull
Terrace
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Bankfull
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Bankfull
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Bankfull