Designing for Aquatic Organism Passage at Road-Stream Crossings 5. Fluvial Processes and Channel Characteristics Important in Stream Simulation Design
5. Fluvial Processes and Channel Characteristics Important in Stream Simulation Design
Dan Cenderelli USDA Forest Service 1 Stream Systems Technology Center
April 2009 5-1 USDA-FS: Wayne NF, Eastern Region Ohio Department of Transportation Designing for Aquatic Organism Passage at Road-Stream Crossings 5. Fluvial Processes and Channel Characteristics Important in Stream Simulation Design
Acknowledgements
Traci Sylte, P.E. Bob Gubernick, P.E. Hydrologist, Engineering Geologist, Lolo NF, Montana Tongass NF, Alaska 2
April 2009 5-2 USDA-FS: Wayne NF, Eastern Region Ohio Department of Transportation Designing for Aquatic Organism Passage at Road-Stream Crossings 5. Fluvial Processes and Channel Characteristics Important in Stream Simulation Design
Presentation Outline
• Watershed Context • Discharge and Channel Characteristics • Channel Characteristics and Fluvial Processes • Channel slope • Channel shape, confinement, entrenchment • Channel planform • Channel slope, shape, and planform • Channel-bed material • Channel bedforms • Channel Classifications • Understanding and Predicting Channel Adjustments/Responses
3
April 2009 5-3 USDA-FS: Wayne NF, Eastern Region Ohio Department of Transportation Designing for Aquatic Organism Passage at Road-Stream Crossings 5. Fluvial Processes and Channel Characteristics Important in Stream Simulation Design
Feb 2003 Presentation Objectives
• A better understanding and appreciation of channel features, fluvial processes, and channel dynamics at a Culvert Characteristics road-stream crossing. • built in late 1950’s • diameter 1.83 m • length 27 m • gradient 2.1 percent June 2007 • Understand the importance of integrating fluvial geomorphology with engineering principles to design a road-stream crossing that contains a Replacement Culvert Characteristics •Bottomless Structure natural and dynamic channel •Span: 5.49 m; Height: 2.25 m through the structure. •Length: 29 m 4 •Design channel gradient: 4.4 percent
April 2009 5-4 USDA-FS: Wayne NF, Eastern Region Ohio Department of Transportation Designing for Aquatic Organism Passage at Road-Stream Crossings 5. Fluvial Processes and Channel Characteristics Important in Stream Simulation Design
Earth’s Surface Is Not Static… Alpine Mt. Everest Glacier
Glacial-lake outburst flood Max extent of glaciers 12,000 • Gravity years ago • Wind Pastures, • Water farms •Ice
…the agents of change 5
April 2009 5-5 USDA-FS: Wayne NF, Eastern Region Ohio Department of Transportation Designing for Aquatic Organism Passage at Road-Stream Crossings 5. Fluvial Processes and Channel Characteristics Important in Stream Simulation Design
Presentation Outline
• Watershed Context • Discharge and Channel Characteristics • Channel Characteristics and Fluvial Processes • Channel slope • Channel shape, confinement, entrenchment • Channel planform • Channel slope, shape, and planform • Channel bedforms • Channel-bed material • Channel Classifications • Understanding and Predicting Channel Adjustments/Responses 6
April 2009 5-6 USDA-FS: Wayne NF, Eastern Region Ohio Department of Transportation Designing for Aquatic Organism Passage at Road-Stream Crossings 5. Fluvial Processes and Channel Characteristics Important in Stream Simulation Design
Influence Of Geology, Climate, and Land Use On Fluvial Systems
Watershed Scale -runoff volume -sediment supply -basin size -basin shape -drainage density -basin gradient -vegetation type -vegetation density Channel Scale -discharge magnitude, duration, and frequency -channel-bed composition and structure -channel form (width and depth) -channel gradient
-sediment transport and deposition 7
April 2009 5-7 USDA-FS: Wayne NF, Eastern Region Ohio Department of Transportation Designing for Aquatic Organism Passage at Road-Stream Crossings 5. Fluvial Processes and Channel Characteristics Important in Stream Simulation Design
Hydrologic Differences Between Arid and Humid Climates
8 From Knighton (1998)
April 2009 5-8 USDA-FS: Wayne NF, Eastern Region Ohio Department of Transportation Designing for Aquatic Organism Passage at Road-Stream Crossings 5. Fluvial Processes and Channel Characteristics Important in Stream Simulation Design
Relevance of Drainage Pattern to Road-Stream Crossing Designs
The downstream delivery of sediment and wood by debris flows
9 from FISRWG (1998)
April 2009 5-9 USDA-FS: Wayne NF, Eastern Region Ohio Department of Transportation Designing for Aquatic Organism Passage at Road-Stream Crossings 5. Fluvial Processes and Channel Characteristics Important in Stream Simulation Design
Relevance of Drainage Pattern to Road- Stream Crossing Designs
The downstream delivery of sediment and wood by debris flows (think about runout length)
10 from FISRWG (1998)
April 2009 5-10 USDA-FS: Wayne NF, Eastern Region Ohio Department of Transportation Designing for Aquatic Organism Passage at Road-Stream Crossings 5. Fluvial Processes and Channel Characteristics Important in Stream Simulation Design
11 fromFrom Lancaster Lancaster, et al. et (2001) al, 2000
April 2009 5-11 USDA-FS: Wayne NF, Eastern Region Ohio Department of Transportation Designing for Aquatic Organism Passage at Road-Stream Crossings 5. Fluvial Processes and Channel Characteristics Important in Stream Simulation Design
Relevance of Drainage Shape to Road-Stream Crossing Designs
The timing, magnitude, and duration of peak discharge is influenced by drainage shape
from Patton (1988) 12
April 2009 5-12 USDA-FS: Wayne NF, Eastern Region Ohio Department of Transportation Designing for Aquatic Organism Passage at Road-Stream Crossings 5. Fluvial Processes and Channel Characteristics Important in Stream Simulation Design
Channel Position in Watershed
s ource tran sport resp from FISRWG (1998) onse
13
April 2009 5-13 USDA-FS: Wayne NF, Eastern Region Ohio Department of Transportation Designing for Aquatic Organism Passage at Road-Stream Crossings 5. Fluvial Processes and Channel Characteristics Important in Stream Simulation Design
Watershed Position and Geomorphic Processes
Aa
A,B,G B C,E,F
14 From Montgomery & Buffington, 1993
April 2009 5-14 USDA-FS: Wayne NF, Eastern Region Ohio Department of Transportation Designing for Aquatic Organism Passage at Road-Stream Crossings 5. Fluvial Processes and Channel Characteristics Important in Stream Simulation Design
Transport Reach Cascade (Aa) channel
15
April 2009 5-15 USDA-FS: Wayne NF, Eastern Region Ohio Department of Transportation Designing for Aquatic Organism Passage at Road-Stream Crossings 5. Fluvial Processes and Channel Characteristics Important in Stream Simulation Design
Transport Reach Step-pool (B) channel
16
April 2009 5-16 USDA-FS: Wayne NF, Eastern Region Ohio Department of Transportation Designing for Aquatic Organism Passage at Road-Stream Crossings 5. Fluvial Processes and Channel Characteristics Important in Stream Simulation Design
Response Reach, Pool-Riffle (C) channel
17
April 2009 5-17 USDA-FS: Wayne NF, Eastern Region Ohio Department of Transportation Designing for Aquatic Organism Passage at Road-Stream Crossings 5. Fluvial Processes and Channel Characteristics Important in Stream Simulation Design
Response Reach, Pool-Riffle (E) channel
18
April 2009 5-18 USDA-FS: Wayne NF, Eastern Region Ohio Department of Transportation Designing for Aquatic Organism Passage at Road-Stream Crossings 5. Fluvial Processes and Channel Characteristics Important in Stream Simulation Design
Watershed-Scale Processes Watershed-Scale Processes • Floods • Fire • Landslides/Debris Flows What it means to • Debris Torrents the crossing design • Wind Throw • Water Transport • Drought • Anthropogenic Activities/ • Sediment Transport Impacts • Wood Transport • Organism Passage
19
April 2009 5-19 USDA-FS: Wayne NF, Eastern Region Ohio Department of Transportation Designing for Aquatic Organism Passage at Road-Stream Crossings 5. Fluvial Processes and Channel Characteristics Important in Stream Simulation Design
Spatial Scale of Stream Channels
from FISRWG, 1998
20
April 2009 5-20 USDA-FS: Wayne NF, Eastern Region Ohio Department of Transportation Designing for Aquatic Organism Passage at Road-Stream Crossings 5. Fluvial Processes and Channel Characteristics Important in Stream Simulation Design
Presentation Outline
• Watershed Context • Discharge and Channel Characteristics • Channel Characteristics and Fluvial Processes • Channel slope • Channel shape, confinement, entrenchment • Channel planform • Channel slope, shape, and planform • Channel bedforms • Channel-bed material • Channel Classifications • Understanding and Predicting Channel Adjustments/Responses 21
April 2009 5-21 USDA-FS: Wayne NF, Eastern Region Ohio Department of Transportation Designing for Aquatic Organism Passage at Road-Stream Crossings 5. Fluvial Processes and Channel Characteristics Important in Stream Simulation Design
Channel-Forming Discharges
Q25 yr
2/3 Qbankfull
A range of flows (2/3 bankfull to the 25-year flood) are most 22 influential in forming and maintaining the channel
April 2009 5-22 USDA-FS: Wayne NF, Eastern Region Ohio Department of Transportation Designing for Aquatic Organism Passage at Road-Stream Crossings 5. Fluvial Processes and Channel Characteristics Important in Stream Simulation Design
What is the Purpose/Significance of Identifying Bankfull Flow Conditions?
Q25 year Qbankfull 2/3 Qbankfull
• Bankfull discharge is an index of the range of flows that shape the channel and floodplain • Usually transports more sediment over time than any other discharge 23 • Typically occurs on average every 1 – 3 years
April 2009 5-23 USDA-FS: Wayne NF, Eastern Region Ohio Department of Transportation Designing for Aquatic Organism Passage at Road-Stream Crossings 5. Fluvial Processes and Channel Characteristics Important in Stream Simulation Design
Why are bankfull discharge and bankfull width important at road-stream crossings?
culvert inlet
Culverts less than bankfull width can lead to debris and/or24 bedload blockage and structure failure
April 2009 5-24 USDA-FS: Wayne NF, Eastern Region Ohio Department of Transportation Designing for Aquatic Organism Passage at Road-Stream Crossings 5. Fluvial Processes and Channel Characteristics Important in Stream Simulation Design
Why are bankfull discharge and bankfull width important at road-stream crossings?
• Crossing widths less than bankfull width increase channel velocities through the structure and form perches at the culvert outlet, which in turn cause aquatic organism 25 passage problems
April 2009 5-25 USDA-FS: Wayne NF, Eastern Region Ohio Department of Transportation Designing for Aquatic Organism Passage at Road-Stream Crossings 5. Fluvial Processes and Channel Characteristics Important in Stream Simulation Design
Presentation Outline
• Watershed Context • Discharge and Channel Characteristics • Channel Characteristics and Fluvial Processes • Channel slope • Channel shape, confinement, entrenchment • Channel planform • Channel slope, shape, and planform • Channel bedforms • Channel-bed material • Channel Classifications • Understanding and Predicting Channel Adjustments/Responses 26
April 2009 5-26 USDA-FS: Wayne NF, Eastern Region Ohio Department of Transportation Designing for Aquatic Organism Passage at Road-Stream Crossings 5. Fluvial Processes and Channel Characteristics Important in Stream Simulation Design
Channel Slope Considerations: Longitudinal Profile
channel-bed profile pool top of bank/floodplain 2 cross section location grade control ptc-H pool tail crest, high stability ptc-M pool tail crest, moderate stability 101 Existing culvert st-H st-H step, high stability diameter 3.1 m ptc-H
lw-M log weir, moderate stability 100 length 22 m lw-M lw-M lw-L log weir, low stability lw-M 99 ptc-M culvert lw-L ptc-M
2 lw-L 3 98 4 rock weir
97 5 ptc-H 6 tributary 96 bedrock ptc-M
95 ptc-M 8 ptc-H bedrock 7 94 channel ptc-H elative elevation (m) elevation elative 9 r
bedrock along ptc-H bedrock, left bank 93 right bank 10 of plunge pool 92 vertical exaggeration = 10 91 27 0 50 100 150 200 250 300 dis tance downstream (m)
April 2009 5-27 USDA-FS: Wayne NF, Eastern Region Ohio Department of Transportation Designing for Aquatic Organism Passage at Road-Stream Crossings 5. Fluvial Processes and Channel Characteristics Important in Stream Simulation Design
Channel Slope Considerations: Longitudinal Profile Shapes
Zone of ideal, preferred setting deposition
concave uniform
Zone of potential deposition potential headcut headcut
concave/convex convex
28
April 2009 5-28 USDA-FS: Wayne NF, Eastern Region Ohio Department of Transportation Designing for Aquatic Organism Passage at Road-Stream Crossings 5. Fluvial Processes and Channel Characteristics Important in Stream Simulation Design
Channel Slope Considerations: Longitudinal Profile Shapes
Qbankfull
Vertical Qbankfull offset
The longitudinal profile can identify possible system-wide29 channel degradation.
April 2009 5-29 USDA-FS: Wayne NF, Eastern Region Ohio Department of Transportation Designing for Aquatic Organism Passage at Road-Stream Crossings 5. Fluvial Processes and Channel Characteristics Important in Stream Simulation Design
Channel Slope Considerations: Geomorphic Processes
Aa
A,B,G B C,E,F
30 From Montgomery & Buffington, 1993
April 2009 5-30 USDA-FS: Wayne NF, Eastern Region Ohio Department of Transportation Designing for Aquatic Organism Passage at Road-Stream Crossings 5. Fluvial Processes and Channel Characteristics Important in Stream Simulation Design
Channel Slope Considerations: Longitudinal Profile Information
channel-bed profile pool top of bank/floodplain 2 cross section location grade control ptc-H pool tail crest, high stability ptc-M pool tail crest, moderate stability 101 Existing culvert st-H st-H step, high stability diameter 3.1 m ptc-H
lw-M log weir, moderate stability 100 length 22 m lw-M lw-M lw-L log weir, low stability lw-M 99 ptc-M culvert lw-L ptc-M
2 lw-L 3 98 4 rock weir
97 5 ptc-H 6 tributary 96 bedrock ptc-M
95 ptc-M 8 ptc-H bedrock 7 94 channel ptc-H elative elevation (m) elevation elative 9 r
bedrock along ptc-H bedrock, left bank 93 right bank 10 of plunge pool 92 vertical exaggeration = 10 91 31 0 50 100 150 200 250 300 dis tance downstream (m)
April 2009 5-31 USDA-FS: Wayne NF, Eastern Region Ohio Department of Transportation Designing for Aquatic Organism Passage at Road-Stream Crossings 5. Fluvial Processes and Channel Characteristics Important in Stream Simulation Design
Channel Slope Considerations: Longitudinal Profile Information % gradient difference maximum elevation segment between residual number distance between change length successive pool depth of grade grade controls channel-bed profile segment (m) (m) gradient segments (m) controls (m) pool top of bank/floodplain A 0.29 16.21 0.0178 n/a 0.47 2 16.2 2 cross section location B 0.12 24.85 0.0050 -71.9 0.10 2 24.9 grade control C 0.82 56.45 0.0145 190.4 0.33 4 18.9, 31.0, 6.6 ptc-H pool tail crest, high stability D 0.54 28.25 0.0193 32.9 0.70 3 17.6, 10.6 ptc-M pool tail crest, moderate stability E 0.22 3.35 0.0665 245.2 0.30 2 3.4 st-H step, high stability culvert 0.08 21.97 0.0037 -94.4 1.34 2 22.0 lw-M log weir, moderate stability lw-L log weir, low stability F 1.74 71.40 0.0243 551.5 0.25 3 44.4, 27.0 G 0.39 20.19 0.0192 -21.0 0.52 2 20.2 slope segments (A,B,C,D,E,F,G,H) a F,G 2.12 91.60 0.0232 -4.6 0.52 4 44.4, 27.0, 20.2 H 1.43 46.12 0.0309 60.8b,c 0.21 3 28.1, 18.0 a. Percent gradient difference when compared to slope segment F. b. Percent gradient difference when compared to slope segment G. c. When compared to combined slope segments of F and G, the percent gradient difference is 33.3% 101 Existing culvert st-H diameter 3.1 m ptc-H 100 lw-M length 22 m A lw-M
B lw-M 99 C ptc-M culvert lw-L ptc-M
2 lw-L D 98 3 4 E rock weir
97 5 ptc-H 6 tributary 96 bedrock F ptc-M
95 ptc-M 8 ptc-H G bedrock 7 94 channel 9 ptc-H relative elevation (m) elevation relative
bedrock along ptc-H bedrock, left bank H 93 right bank 10 of plunge pool 92 vertical exaggeration = 10 91 0 50 100 150 200 250 300 distance do wnstream (m)
The longitudinal profile determines bedform spacing, 32key grade controls, gradient variability, and scour depth ranges
April 2009 5-32 USDA-FS: Wayne NF, Eastern Region Ohio Department of Transportation Designing for Aquatic Organism Passage at Road-Stream Crossings 5. Fluvial Processes and Channel Characteristics Important in Stream Simulation Design
Channel Slope Considerations: Longitudinal Profile Information
Existing culvert diameter 3.1 m
lw-M length 22 m lw-M lw-M C ptc-M culvert lw-L ptc-M D lw-L 3 4 E rock weir
5 ptc-H 6 tributary bedrock { F sediment ptc-M
wedge ptc-M 8 7 bedrock along plunge 9 bedrock, left bank right bank pool of plunge pool
100 150 200 250 distance downstream (m)
The longitudinal profile determines local degradation33 and aggradation associated the culvert.
April 2009 5-33 USDA-FS: Wayne NF, Eastern Region Ohio Department of Transportation Designing for Aquatic Organism Passage at Road-Stream Crossings 5. Fluvial Processes and Channel Characteristics Important in Stream Simulation Design
Channel Slope Considerations: Geomorphic Processes
downstream
H Existing culvert design elevation c
t diameter 3.1 m p
lw-M control point length 22 m lw-M
B lw-M C ptc-M culvert rock lw-L ptc-M
2 lw-L D weir 3 4 E reference reach 5 ptc-H 6 tributary bedrock { F sediment ptc-M
wedge ptc-M 8 G upstream 7 plunge 9 design elevation bedrock along right bank pool bedrock, left bank control point 1 of plunge pool n = 10
50 100 150 200 250 distance downstream (m)
The longitudinal profile is used to develop the design channel34 profile and spacing of bedforms through the structure.
April 2009 5-34 USDA-FS: Wayne NF, Eastern Region Ohio Department of Transportation Designing for Aquatic Organism Passage at Road-Stream Crossings 5. Fluvial Processes and Channel Characteristics Important in Stream Simulation Design
Presentation Outline
• Watershed Context • Discharge and Channel Characteristics • Channel Characteristics and Fluvial Processes • Channel slope • Channel shape, confinement, entrenchment • Channel planform • Channel slope, shape, and planform • Channel bedforms • Channel-bed material • Channel Classifications • Understanding and Predicting Channel Adjustments/Responses 35
April 2009 5-35 USDA-FS: Wayne NF, Eastern Region Ohio Department of Transportation Designing for Aquatic Organism Passage at Road-Stream Crossings 5. Fluvial Processes and Channel Characteristics Important in Stream Simulation Design
Channel Shape Considerations
Qfp
Qbf Qbw Qlf
• Establishes the natural dimensions of the channel • Delineates the width and depth of low flow, the streambed, bankfull flow, floodplain inundation, and channel/slope interactions 36
April 2009 5-36 USDA-FS: Wayne NF, Eastern Region Ohio Department of Transportation Designing for Aquatic Organism Passage at Road-Stream Crossings 5. Fluvial Processes and Channel Characteristics Important in Stream Simulation Design
Channel Confinement Considerations
Confined channels •High energy •Straight, high gradient channels •minimal floodplain development •Channel migration low •Slope/channel interactions high
Unconfined channels •low energy •Sinuous, low-gradient channels •Well-developed floodplain •Channel migration high •Slope/channel interactions low
37 From Knighton, 1998
April 2009 5-37 USDA-FS: Wayne NF, Eastern Region Ohio Department of Transportation Designing for Aquatic Organism Passage at Road-Stream Crossings 5. Fluvial Processes and Channel Characteristics Important in Stream Simulation Design
Channel Entrenchment Considerations
38
April 2009 5-38 USDA-FS: Wayne NF, Eastern Region Ohio Department of Transportation Designing for Aquatic Organism Passage at Road-Stream Crossings 5. Fluvial Processes and Channel Characteristics Important in Stream Simulation Design
Confinement/Entrenchment Considerations: Floodplain Connectivity/Conveyance
39
April 2009 5-39 USDA-FS: Wayne NF, Eastern Region Ohio Department of Transportation Designing for Aquatic Organism Passage at Road-Stream Crossings 5. Fluvial Processes and Channel Characteristics Important in Stream Simulation Design
Confinement/Entrenchment Considerations: Floodplain Connectivity/Conveyance
Existing Conditions Design option 1 • undersized culvert • bankfull width sized culvert • no floodplain culverts • no floodplain culverts
Design option 2 Design option 3 • bankfull width sized culvert • valley spanning structure • floodplain culverts
40
April 2009 5-40 USDA-FS: Wayne NF, Eastern Region Ohio Department of Transportation Designing for Aquatic Organism Passage at Road-Stream Crossings 5. Fluvial Processes and Channel Characteristics Important in Stream Simulation Design
Presentation Outline
• Watershed Context • Discharge and Channel Characteristics • Channel Characteristics and Fluvial Processes • Channel slope • Channel shape, confinement, entrenchment • Channel planform • Channel slope, shape, and planform • Channel bedforms • Channel-bed material • Channel Classifications • Understanding and Predicting Channel Adjustments/Responses 41
April 2009 5-41 USDA-FS: Wayne NF, Eastern Region Ohio Department of Transportation Designing for Aquatic Organism Passage at Road-Stream Crossings 5. Fluvial Processes and Channel Characteristics Important in Stream Simulation Design
Channel Planform Considerations
Scour zone Riprap reinforcement
42
April 2009 5-42 USDA-FS: Wayne NF, Eastern Region Ohio Department of Transportation Designing for Aquatic Organism Passage at Road-Stream Crossings 5. Fluvial Processes and Channel Characteristics Important in Stream Simulation Design
Channel Planform Considerations • If possible, locate crossings on straight channel segments • Accept small skews in channel-road alignment and reinforce banks if necessary • Interpret and predict the natural planform pattern at the crossing • May need to perform channel restoration to recreate natural geometries 43
April 2009 5-43 USDA-FS: Wayne NF, Eastern Region Ohio Department of Transportation Designing for Aquatic Organism Passage at Road-Stream Crossings 5. Fluvial Processes and Channel Characteristics Important in Stream Simulation Design
XS3 Channel Planform t
d Considerations a rf/nm o
r
g
n
i
g
g
o XS4 l
d
l
O
t existing XS5 Interpreted culvert channel XS6 pattern rf/nm 220 S Rd 2 SF U rf/nm XS7 rf/nm N
XS8 fp/lt EXPLANATION valley margin t bedrock bankfull flow floodprone width fp/lt XS9 large woody debris pool tail crest t step t terrace fp/lt floodplain or low terrace rf/nm road fill or 44native material culvert XS10 log weir
April 2009 5-44 USDA-FS: Wayne NF, Eastern Region Ohio Department of Transportation Designing for Aquatic Organism Passage at Road-Stream Crossings 5. Fluvial Processes and Channel Characteristics Important in Stream Simulation Design
Channel-Bank Patterns
step step
step
step bankline bankline
45
April 2009 5-45 USDA-FS: Wayne NF, Eastern Region Ohio Department of Transportation Designing for Aquatic Organism Passage at Road-Stream Crossings 5. Fluvial Processes and Channel Characteristics Important in Stream Simulation Design
Channel-Bank Patterns
lateral scour pool bankline pool
riffle bankline
46
April 2009 5-46 USDA-FS: Wayne NF, Eastern Region Ohio Department of Transportation Designing for Aquatic Organism Passage at Road-Stream Crossings 5. Fluvial Processes and Channel Characteristics Important in Stream Simulation Design
Presentation Outline
• Watershed Context • Discharge and Channel Characteristics • Channel Characteristics and Fluvial Processes • Channel slope • Channel shape, confinement, entrenchment • Channel planform • Channel slope, shape, and planform • Channel bedforms • Channel-bed material • Channel Classifications • Understanding and Predicting Channel Adjustments/Responses 47
April 2009 5-47 USDA-FS: Wayne NF, Eastern Region Ohio Department of Transportation Designing for Aquatic Organism Passage at Road-Stream Crossings 5. Fluvial Processes and Channel Characteristics Important in Stream Simulation Design
Channel Slope, Shape, and Planform
Cascade
Step-Pool Plane Bed Step-Pool Anasta- Pool-Riffle Braided mosing Pool-Riffle Pool-Riffle Step-Pool
48 From Rosgen 1996
April 2009 5-48 USDA-FS: Wayne NF, Eastern Region Ohio Department of Transportation Designing for Aquatic Organism Passage at Road-Stream Crossings 5. Fluvial Processes and Channel Characteristics Important in Stream Simulation Design
Channel Slope, Shape, and Planform channel bends straight channel
49 from FISRWG, 1998
April 2009 5-49 USDA-FS: Wayne NF, Eastern Region Ohio Department of Transportation Designing for Aquatic Organism Passage at Road-Stream Crossings 5. Fluvial Processes and Channel Characteristics Important in Stream Simulation Design
Channel Slope, Shape, and Planform • Fluvial processes in meandering, pool-riffle channels
50 from FISRWG, 1998
April 2009 5-50 USDA-FS: Wayne NF, Eastern Region Ohio Department of Transportation Designing for Aquatic Organism Passage at Road-Stream Crossings 5. Fluvial Processes and Channel Characteristics Important in Stream Simulation Design
Channel Slope, Shape, and Planform
upstream view of XS in culvert
point pool along bar outer bend
Channel migration
Fluvial processes and channel shape is 51 dependant on where it occurs in the planform
April 2009 5-51 USDA-FS: Wayne NF, Eastern Region Ohio Department of Transportation Designing for Aquatic Organism Passage at Road-Stream Crossings 5. Fluvial Processes and Channel Characteristics Important in Stream Simulation Design
Pool-Riffle Channel Flow Patterns and Energy Dissipation
Profile View
pool riffle Plan View
bar deposit
bar deposit
52
April 2009 5-52 USDA-FS: Wayne NF, Eastern Region Ohio Department of Transportation Designing for Aquatic Organism Passage at Road-Stream Crossings 5. Fluvial Processes and Channel Characteristics Important in Stream Simulation Design
Step-Pool Channel Flow Patterns and Energy Dissipation Profile View
step step step pool pool Plan View
53
April 2009 5-53 USDA-FS: Wayne NF, Eastern Region Ohio Department of Transportation Designing for Aquatic Organism Passage at Road-Stream Crossings 5. Fluvial Processes and Channel Characteristics Important in Stream Simulation Design
Presentation Outline
• Watershed Context • Discharge and Channel Characteristics • Channel Characteristics and Fluvial Processes • Channel slope • Channel shape, confinement, entrenchment • Channel planform • Channel slope, shape, and planform • Channel bedforms • Channel-bed material • Channel Classifications • Understanding and Predicting Channel Adjustments/Responses 54
April 2009 5-54 USDA-FS: Wayne NF, Eastern Region Ohio Department of Transportation Designing for Aquatic Organism Passage at Road-Stream Crossings 5. Fluvial Processes and Channel Characteristics Important in Stream Simulation Design
Channel Bedforms Considerations • Are the bedforms significant along the longitudinal profile? step pool • Are the bedforms stable, permanent step pool features or are they temporary step pool features? step pool • Do the bedforms form step-pool or riffle-pool sequences along the channel? riffle • How do the bedforms affect channel pool roughness? riffle riffle crest • Are the bedforms important for pool dissipating flow energy during floods?
riffle
pool riffle crest transverse rib
particle cluster 55
April 2009 5-55 USDA-FS: Wayne NF, Eastern Region Ohio Department of Transportation Designing for Aquatic Organism Passage at Road-Stream Crossings 5. Fluvial Processes and Channel Characteristics Important in Stream Simulation Design
Channel Bedforms
step • Steps and Pools pool step pool step • Riffles and Pools pool step pool • Large Woody Debris • Transverse Ribs
riffle • Particle Clusters pool riffle • Gravel Bars riffle crest pool
riffle
pool riffle crest transverse rib
particle cluster 56
April 2009 5-56 USDA-FS: Wayne NF, Eastern Region Ohio Department of Transportation Designing for Aquatic Organism Passage at Road-Stream Crossings 5. Fluvial Processes and Channel Characteristics Important in Stream Simulation Design
Channel Bedforms: Steps and Pools
step step pool pool step pool step pool bankline bankline
57
April 2009 5-57 USDA-FS: Wayne NF, Eastern Region Ohio Department of Transportation Designing for Aquatic Organism Passage at Road-Stream Crossings 5. Fluvial Processes and Channel Characteristics Important in Stream Simulation Design
Channel Bedforms: Riffles and Pools
riffle pool riffle
riffle crest pool
riffle
58
April 2009 5-58 USDA-FS: Wayne NF, Eastern Region Ohio Department of Transportation Designing for Aquatic Organism Passage at Road-Stream Crossings 5. Fluvial Processes and Channel Characteristics Important in Stream Simulation Design
Channel Bedforms: Transverse Ribs and Particle Clusters
pool riffle crest transverse rib
particle cluster
59
April 2009 5-59 USDA-FS: Wayne NF, Eastern Region Ohio Department of Transportation Designing for Aquatic Organism Passage at Road-Stream Crossings 5. Fluvial Processes and Channel Characteristics Important in Stream Simulation Design
Channel Bedforms: Large Woody Debris
60
April 2009 5-60 USDA-FS: Wayne NF, Eastern Region Ohio Department of Transportation Designing for Aquatic Organism Passage at Road-Stream Crossings 5. Fluvial Processes and Channel Characteristics Important in Stream Simulation Design
Channel Bedforms: Gravel Bars, Riffles, Pools
riffle
gravel bar pool
61
April 2009 5-61 USDA-FS: Wayne NF, Eastern Region Ohio Department of Transportation Designing for Aquatic Organism Passage at Road-Stream Crossings 5. Fluvial Processes and Channel Characteristics Important in Stream Simulation Design
Presentation Outline
• Watershed Context • Discharge and Channel Characteristics • Channel Characteristics and Fluvial Processes • Channel slope • Channel shape, confinement, entrenchment • Channel planform • Channel slope, shape, and planform • Channel bedforms • Channel-bed material • Channel Classifications • Understanding and Predicting Channel Adjustments/Responses 62
April 2009 5-62 USDA-FS: Wayne NF, Eastern Region Ohio Department of Transportation Designing for Aquatic Organism Passage at Road-Stream Crossings 5. Fluvial Processes and Channel Characteristics Important in Stream Simulation Design
Channel-Bed Material
step Considerations pool step
pool step • Does channel-bed substrate
pool step size vary spatially between pool and within channel units (i.e., pools versus steps, pool riffle crest transverse rib riffles versus pools, within
particle cluster riffles)? • Is the channel-bed substrate well sorted or poorly sorted (uniformly or non-uniformly graded)? • Does the channel-bed substrate vary vertically (i.e., surface layer versus the subsurface layer)? 63
April 2009 5-63 USDA-FS: Wayne NF, Eastern Region Ohio Department of Transportation Designing for Aquatic Organism Passage at Road-Stream Crossings 5. Fluvial Processes and Channel Characteristics Important in Stream Simulation Design
Channel-Bed Material: Steps and Pools
step step pool pool step pool step pool bankline bankline
64
April 2009 5-64 USDA-FS: Wayne NF, Eastern Region Ohio Department of Transportation Designing for Aquatic Organism Passage at Road-Stream Crossings 5. Fluvial Processes and Channel Characteristics Important in Stream Simulation Design
Channel-Bed Material: Riffles and Pools
riffle pool riffle
riffle crest pool
riffle
65
April 2009 5-65 USDA-FS: Wayne NF, Eastern Region Ohio Department of Transportation Designing for Aquatic Organism Passage at Road-Stream Crossings 5. Fluvial Processes and Channel Characteristics Important in Stream Simulation Design
Channel-Bed Material: Transverse Ribs and Particle Clusters
pool riffle crest transverse rib
particle cluster
66
April 2009 5-66 USDA-FS: Wayne NF, Eastern Region Ohio Department of Transportation Designing for Aquatic Organism Passage at Road-Stream Crossings 5. Fluvial Processes and Channel Characteristics Important in Stream Simulation Design
Channel-Bed Material: Vertical Variability
67
April 2009 5-67 USDA-FS: Wayne NF, Eastern Region Ohio Department of Transportation Designing for Aquatic Organism Passage at Road-Stream Crossings 5. Fluvial Processes and Channel Characteristics Important in Stream Simulation Design
Channel-Bed Material: Vertical Variability subsurface layer
surface percent finer layer
particle size
surface layer
subsurface layer
68 from Bunte and Abt, 2001
April 2009 5-68 USDA-FS: Wayne NF, Eastern Region Ohio Department of Transportation Designing for Aquatic Organism Passage at Road-Stream Crossings 5. Fluvial Processes and Channel Characteristics Important in Stream Simulation Design
Types of Flow Resistance or Channel Roughness • Boundary Resistance • Particle roughness
step (particle size, sorting, etc.) pool step • Vegetation roughness pool step • Channel Resistance pool step • Slope variability pool • Bedform sequences • (step-pool, pool-riffle, etc.) • Bank irregularity riffle • Channel alignment pool riffle
• Free Surface Resistance riffle crest • Surface waves pool • Hydraulic jumps
riffle
pool riffle crest transverse rib
particle cluster 69
April 2009 5-69 USDA-FS: Wayne NF, Eastern Region Ohio Department of Transportation Designing for Aquatic Organism Passage at Road-Stream Crossings 5. Fluvial Processes and Channel Characteristics Important in Stream Simulation Design
Channel Roughness and Culvert Roughness
Natural channel
Culvert
Culvert roughness 0.023 – 0.027
70
April 2009 5-70 USDA-FS: Wayne NF, Eastern Region Ohio Department of Transportation Designing for Aquatic Organism Passage at Road-Stream Crossings 5. Fluvial Processes and Channel Characteristics Important in Stream Simulation Design
Typical velocity profiles
100 Natural channel
90 boulder channel bed gravel channel bed 80 unembedded culvert
70
60
50 Culvert depth (cm) depth 40
30
20
10
0 -1.0 0.0 1.0 2.0 3.0 4.0 velocity (m/s) 71
April 2009 5-71 USDA-FS: Wayne NF, Eastern Region Ohio Department of Transportation Designing for Aquatic Organism Passage at Road-Stream Crossings 5. Fluvial Processes and Channel Characteristics Important in Stream Simulation Design
Particle Movement and Culverts
ert ulv d c ze rsi de annel un stream ch
rt lve cu ed Initiation of siz ly particle movement Increasing er Shear Stress p pro
Bankfull Q Increasing Flow 72
April 2009 5-72 USDA-FS: Wayne NF, Eastern Region Ohio Department of Transportation Designing for Aquatic Organism Passage at Road-Stream Crossings 5. Fluvial Processes and Channel Characteristics Important in Stream Simulation Design
Presentation Outline
• Watershed Context • Discharge and Channel Characteristics • Channel Characteristics and Fluvial Processes • Channel slope • Channel shape, confinement, entrenchment • Channel planform • Channel slope, shape, and planform • Channel bedforms • Channel-bed material • Channel Classifications • Understanding and Predicting Channel Adjustments/Responses 73
April 2009 5-73 USDA-FS: Wayne NF, Eastern Region Ohio Department of Transportation Designing for Aquatic Organism Passage at Road-Stream Crossings 5. Fluvial Processes and Channel Characteristics Important in Stream Simulation Design
Channel Classification
• Many of the channel features and fluvial processes discussed in this presentation are encompassed in the channel classification systems developed by Montgomery and Buffington (1993, 1997) and Rosgen (1994, 1996). • Both of these classification systems provide a common framework for: – understanding channel morphology and fluvial processes – predicting channel responses to natural or anthropogenic disturbances • Classifying channels encourage and require field observations of channel characteristics and interpretation fluvial processes and channel dynamics. • Don’t limit yourself to one channel classification: Each
have strengths and weaknesses. 74
April 2009 5-74 USDA-FS: Wayne NF, Eastern Region Ohio Department of Transportation Designing for Aquatic Organism Passage at Road-Stream Crossings 5. Fluvial Processes and Channel Characteristics Important in Stream Simulation Design
Montgomery and Buffington Channel Classification (1993, 1997) • Reach-scale classification based on channel morphology, flow hydraulics, and fluvial processes • Classification developed for mountain channels in the Pacific Northwest, but applicable in other mountainous environments • Six alluvial channel types: Braided, dune-ripple, pool-riffle, plane bed, step-pool, and cascade • Two non-alluvial channel types: bedrock and colluvial • Channels are distinguished from each other based based on characteristics such as bed-material size, channel slope, dominant roughness elements, pool spacing, bedform pattern, channel confinement, sediment supply, and transport capacity • Provides a framework for predicting the degree and style of channel response to changes in sediment and water inputs or
local controls for different channel types 75
April 2009 5-75 USDA-FS: Wayne NF, Eastern Region Ohio Department of Transportation Designing for Aquatic Organism Passage at Road-Stream Crossings 5. Fluvial Processes and Channel Characteristics Important in Stream Simulation Design
Montgomery & Buffington Profile View Plan View Alluvial Channel Types
A. Cascade
B. Step-pool
C. Plane bed
D. Pool-riffle
E. Dune-ripple 76 From Montgomery & Buffington, 1993
April 2009 5-76 USDA-FS: Wayne NF, Eastern Region Ohio Department of Transportation Designing for Aquatic Organism Passage at Road-Stream Crossings 5. Fluvial Processes and Channel Characteristics Important in Stream Simulation Design
General Channel Characteristics for Channel Types of Montgomery and Buffington
Frequency of Typical Typical effective Dominant Pool spacing sediment transport bedload Type of Typical bed Typical roughness (channel Typical Typical reach supply capacity of transport channel mat erial slope elements widths) Confinement type conditions stream (mobile bed) nonalluvial -colluvial variable > 0.20 grains, LWD variable confined source high high infrequent
-bedrock bedrock variable not applicable variable confined transport low high not applicable alluvial -cascade boulder 0.10 to 0.30 grains, banks < 1 confined transport low high infrequent
-step-pool cobble, 0.03 to 0.10 bedforms, 1 to 4 confined transport low high infrequent boulder grains, LWD, -plane bed 1 cobble 0.01 to 0.03 grains, banks none variable transport low high infrequent
-plane bed 2 gravel 0.01 to 0.03 grains, banks none variable response moderate moderate frequent
-pool-riffle gravel 0.001 to 0.02 bedforms, 5 to 7 unconfined response moderate moderate frequent grains, LWD, sinuosity, -dune-ripple sand < 0.001 sinuosity, 5 to 7 unconfined response high low very frequent bedforms -braided sand, gravel, < 0.030 bedforms variable unconfined response high low77 frequent cobble
April 2009 5-77 USDA-FS: Wayne NF, Eastern Region Ohio Department of Transportation Designing for Aquatic Organism Passage at Road-Stream Crossings 5. Fluvial Processes and Channel Characteristics Important in Stream Simulation Design
Montgomery & Buffington Channel Classification
Aa
A,B,G B C,E,F
78 From Montgomery & Buffington, 1993
April 2009 5-78 USDA-FS: Wayne NF, Eastern Region Ohio Department of Transportation Designing for Aquatic Organism Passage at Road-Stream Crossings 5. Fluvial Processes and Channel Characteristics Important in Stream Simulation Design
Rosgen Channel Classification (1994, 1996) • Reach-scale classification based on channel entrenchment, width to depth ratio, sinuosity, channel slope, and channel- bed material • Classification developed from measurements of 450 streams in different geographic settings • Identifies and differentiates eight major channel types (referred to as A, B, C, D, DA, E, F, or G channels) on the basis of degree of entrenchment, gradient, width to depth ratio, and sinuosity • Identifies six subcategories within each major channel type based on the dominant material composing the channel bed • Provides a framework for interpreting the various channel types in terms of sensitivity or responsiveness to disturbance, recovery potential after disturbance, sediment supply, susceptibility to bank erosion, and influence of vegetation on channel form 79
April 2009 5-79 USDA-FS: Wayne NF, Eastern Region Ohio Department of Transportation Designing for Aquatic Organism Passage at Road-Stream Crossings 5. Fluvial Processes and Channel Characteristics Important in Stream Simulation Design
Channel characteristics of Rosgen Channel Types Stream Type Channel characteristics A Step-pool, or cascading: plunge and scour pools, high energy, low sediment storage, stable; B Riffles and rapids: some scour pools, bars rare, stable; C Pool-riffle sequences: meandering, point bars, well-developed floodplain, banks stable or unstable; D Braided: multiple channels, shifting bars, scour, deposition, high sediment supply, eroding banks; DA Anastomosing: multiple channels, pool-riffle, vegetated floodplain, adjacent wetlands, stable banks; E Meadow meanders: well-developed floodplain, riffle-pool, relative high sediment conveyance; F Valley meanders: incised into valleys, poor floodplain, pool-riffle, banks stable or unstable; G Gullies: incised into hillslopes and meadows, high sediment supply, unstable banks, step-pool. 80
April 2009 5-80 USDA-FS: Wayne NF, Eastern Region Ohio Department of Transportation Designing for Aquatic Organism Passage at Road-Stream Crossings 5. Fluvial Processes and Channel Characteristics Important in Stream Simulation Design
Rosgens Channel Classification
from Rosgen 1996 Cascade
Step-Pool Plane Bed Step-Pool Anasta- Pool-Riffle Braided mosing Pool-Riffle Pool-Riffle Step-Pool
81
April 2009 5-81 USDA-FS: Wayne NF, Eastern Region Ohio Department of Transportation Designing for Aquatic Organism Passage at Road-Stream Crossings 5. Fluvial Processes and Channel Characteristics Important in Stream Simulation Design
Rosgen’s Channel Classification
82 from Rosgen, 1996
April 2009 5-82 USDA-FS: Wayne NF, Eastern Region Ohio Department of Transportation Designing for Aquatic Organism Passage at Road-Stream Crossings 5. Fluvial Processes and Channel Characteristics Important in Stream Simulation Design
Presentation Outline
• Watershed Context • Discharge and Channel Characteristics • Channel Characteristics and Fluvial Processes • Channel slope • Channel shape, confinement, entrenchment • Channel planform • Channel slope, shape, and planform • Channel bedforms • Channel-bed material • Channel Classifications • Understanding and Predicting Channel Adjustments/Responses 83
April 2009 5-83 USDA-FS: Wayne NF, Eastern Region Ohio Department of Transportation Designing for Aquatic Organism Passage at Road-Stream Crossings 5. Fluvial Processes and Channel Characteristics Important in Stream Simulation Design
Channel Adjustments and Responses
• Channels adjust their bedform configuration, width, depth, slope, and meander pattern in response to changes in discharge, sediment supply, and/or base level changes • Channel adjustments occur in response to naturally occurring events such as floods, landslides, etc. or land-use activities such as logging/road building, mining, urbanization, dam building, etc. • The rate of channel adjustment varies spatially and temporally along the channel in response to a disturbance; this reflects watershed- and local-scale differences in geomorphic setting, fluvial processes, channel characteristics, and past disturbances
84
April 2009 5-84 USDA-FS: Wayne NF, Eastern Region Ohio Department of Transportation Designing for Aquatic Organism Passage at Road-Stream Crossings 5. Fluvial Processes and Channel Characteristics Important in Stream Simulation Design
Channel Adjustments and Responses Sediment Stream (LOAD) X (SIZE) (SLOPE) X (DISCHARGE)
from Lane, 1955; in FISRWG, 1998 85
April 2009 5-85 USDA-FS: Wayne NF, Eastern Region Ohio Department of Transportation Designing for Aquatic Organism Passage at Road-Stream Crossings 5. Fluvial Processes and Channel Characteristics Important in Stream Simulation Design
Timescales of adjustment
Service life of structure
86 from Knighton, 1998
April 2009 5-86 USDA-FS: Wayne NF, Eastern Region Ohio Department of Transportation Designing for Aquatic Organism Passage at Road-Stream Crossings 5. Fluvial Processes and Channel Characteristics Important in Stream Simulation Design
Channel Response: Influenced by Location in Watershed
Aa
A,B,G B C,E,F
87 from Montgomery & Buffington, 1993
April 2009 5-87 USDA-FS: Wayne NF, Eastern Region Ohio Department of Transportation Designing for Aquatic Organism Passage at Road-Stream Crossings 5. Fluvial Processes and Channel Characteristics Important in Stream Simulation Design
Understanding and Predicting Channel Responses/Adjustments
long-term average Channel Dimension (width, depth, gradient, etc.) Time
Dynamic, Stable Channels: Steady State Equilibrium 88
April 2009 5-88 USDA-FS: Wayne NF, Eastern Region Ohio Department of Transportation Designing for Aquatic Organism Passage at Road-Stream Crossings 5. Fluvial Processes and Channel Characteristics Important in Stream Simulation Design
Channel Responses to an Undersized Culvert Save CreekSave Creek OlympicOlympic NF, WA NF, WA
Sediment Wedge
Sediment Wedge Eroded Portion of Sediment Wedge
Inlet Culvert Span 2.1 m Constriction = = = Bankfull Width 9.7 m 0.22 89 Ratio
April 2009 5-89 USDA-FS: Wayne NF, Eastern Region Ohio Department of Transportation Designing for Aquatic Organism Passage at Road-Stream Crossings 5. Fluvial Processes and Channel Characteristics Important in Stream Simulation Design
Channel Responses to an Undersized Culvert Save Creek Olympic NF, WA
Sediment Wedge
Outlet Plunge Pool Expansion = Scour Width = 12.8 m = 1.3 90 Ratio Bankfull Width 9.7 m
April 2009 5-90 USDA-FS: Wayne NF, Eastern Region Ohio Department of Transportation Designing for Aquatic Organism Passage at Road-Stream Crossings 5. Fluvial Processes and Channel Characteristics Important in Stream Simulation Design
Channel Responses To An Undersized Culvert
91
April 2009 5-91 USDA-FS: Wayne NF, Eastern Region Ohio Department of Transportation Designing for Aquatic Organism Passage at Road-Stream Crossings 5. Fluvial Processes and Channel Characteristics Important in Stream Simulation Design
Channel Responses After the Replacement of a “Properly-Sized” Culvert
92
April 2009 5-92 USDA-FS: Wayne NF, Eastern Region Ohio Department of Transportation Designing for Aquatic Organism Passage at Road-Stream Crossings 5. Fluvial Processes and Channel Characteristics Important in Stream Simulation Design
Rate of Channel Adjustment
1998 – Siegel Ck, LNF 1979 – Siegel Ck, LNF
93
April 2009 5-93 USDA-FS: Wayne NF, Eastern Region Ohio Department of Transportation Designing for Aquatic Organism Passage at Road-Stream Crossings 5. Fluvial Processes and Channel Characteristics Important in Stream Simulation Design
Channel Changes in Response to Undersized Culverts
94 from FISRWG, 1998
April 2009 5-94 USDA-FS: Wayne NF, Eastern Region Ohio Department of Transportation Designing for Aquatic Organism Passage at Road-Stream Crossings 5. Fluvial Processes and Channel Characteristics Important in Stream Simulation Design
Recognizing Channel Instability and Disequilibrium Channel Dimension (width, depth, gradient, etc.) Time
Unstable Channels: Disequilibrium 95
April 2009 5-95 USDA-FS: Wayne NF, Eastern Region Ohio Department of Transportation Designing for Aquatic Organism Passage at Road-Stream Crossings 5. Fluvial Processes and Channel Characteristics Important in Stream Simulation Design
Site Risk Assessment: Channel Instability
• Important to recognize channel instability and disequilibrium
• Climate change, base-level changes, land-use practices, etc. can96 cause local and system-wide channel degradation and aggradation
April 2009 5-96 USDA-FS: Wayne NF, Eastern Region Ohio Department of Transportation Designing for Aquatic Organism Passage at Road-Stream Crossings 5. Fluvial Processes and Channel Characteristics Important in Stream Simulation Design
Site Risk Assessment: Channel Instability from FISRWG, 1998 • Channel Evolution Model
97
April 2009 5-97 USDA-FS: Wayne NF, Eastern Region Ohio Department of Transportation Designing for Aquatic Organism Passage at Road-Stream Crossings 5. Fluvial Processes and Channel Characteristics Important in Stream Simulation Design
Site Risk Assessment: Channel Instability • Channel Evolution Model
98 from FISRWG, 1998
April 2009 5-98 USDA-FS: Wayne NF, Eastern Region Ohio Department of Transportation Designing for Aquatic Organism Passage at Road-Stream Crossings 5. Fluvial Processes and Channel Characteristics Important in Stream Simulation Design
Site Risk Assessment: Channel Responses to Consider • Channel stability: Is the overall channel stable or unstable because of system-wide degradation and aggradation? • Vertical adjustment potential: What is the potential range of channel-bed elevations over the service life of the structure from scour and fill processes during floods, sediment and wood inputs from debris flows and/or debris torrents, loss or formation of debris jams, land-use changes, etc.? • Headcut potential: What are the ecological implications for allowing headcutting to occur as the channel adjusts to establish a new equilibrium condition? • Lateral adjustment potential: Can channel migration or lateral shifting over the service life of the structure affect stream/culvert alignment? • Floodplain inundation/connectivity: Is floodplain function and connectivity important to the fluvial system and ecological processes? 99
April 2009 5-99 USDA-FS: Wayne NF, Eastern Region Ohio Department of Transportation Designing for Aquatic Organism Passage at Road-Stream Crossings 5. Fluvial Processes and Channel Characteristics Important in Stream Simulation Design
Predicting Channel Responses When Replacing a Structure Channel stability: Is the overall channel stable or unstable because of system-wide degradation and aggradation?
Qbankfull
Vertical Qbankfull offset
100
April 2009 5-100 USDA-FS: Wayne NF, Eastern Region Ohio Department of Transportation Designing for Aquatic Organism Passage at Road-Stream Crossings 5. Fluvial Processes and Channel Characteristics Important in Stream Simulation Design
Predicting Channel Responses When Replacing a Structure Vertical adjustment potential: What is the potential range of channel-bed elevations over the service life of the structure from scour and fill processes during floods, sediment and wood inputs from debris flows and/or debris torrents, loss or formation of debris jams, land-use changes, etc.? % gradient channel-bed profile difference maximum pool elevation segment between residual number distance between top of bank/floodplain distance downstream (ft) change length successive pool depth of grade grade controls 2 cross section location 164.1grade control 328.1492.2segment (m) (m) 656.2 gradient segments (m) controls 820.3(m) 984. 3 ptc-H pool tail crest, high stability A 0.29 16.21 0.0178 n/a 0.47 2 16.2 ptc-M pool tail crest, moderate stability B 0.12 24.85 0.0050 -71.9 0.10 2 24.9 st-H step, high stability C 0.82 56.45 0.0145 190.4 0.33 4 18.9, 31.0, 6.6 lw-M log weir, moderate stability D 0.54 28.25 0.0193 32.9 0.70 3 17.6, 10.6 lw-L log weir, low stability E 0.22 3.35 0.0665 245.2 0.30 2 3.4 slope segments (A,B,C,D,E,F,G,H) culvert 0.08 21.97 0.0037 -94.4 1.34 2 22.0 upper vertical adjustment potential line downstream lower vertical adjustment potential line F 1.74 71.40 0.0243 551.5 0.25 3 44.4, 27.0 ExGisting 0.39 culv 20.19ert 0.0192design -21.0 0.52elevation 2 20.2 a design channel-bed profile 1 (S=0.0226) diameterF,G 2.12 3.1 91.60m 0.0232 -4.6 0.52 4 44.4, 27.0, 20.2 60.8b,c ptc-H H 1.43 46.12 0.0309 0.21 3 28.1, 18.0
lw-M design bedform locations (head of riffles) control point length 22 m A fill plungelw-M pool with channel-bed material a. Percent gradient difference when compared to slope segment F. base of footing of replacement structure (on bedrock) b. Percent gradient difference when compared to slope segment G. B lw-M predicted long-termC bed surface (headcut,ptc-M erosion) c. When comparedculvert to combined slope segmentsrock of F and G, the percent gradient difference is 33.3% lw-L ptc-M
2 lw-L D distance downstream (ft) weir 3 4 0 164.1 328.1492.2E 656.2 820.3reference 984.3 103 reach 337.9 5 ptc-H 102 6 334.7 tributary downstream 101 { Existing culvert st-H design elevation 331.4 bedrock diameter 3.1 m F ptc-M ptc-H
lw-M control point 100 sedimentlength 22 m A lw-M 328.1
B lw-M t) ptc-M ptc-M 99 C wedge culvert rock f lw-L
ptc-M 324.8 lw-L 2 ptc-H D weir 8 98 3 4 G ock E reference 321.5 upstream 7 reach nel 97 5 ptc-H 6 9 318.3 tributary plunge bedrock along { 96design elevation bedrock F right bank sedimentpool bedrock,ptc-M left bank 315.010 95 control point 1 wedge ptc-M elative elevation( 8 of plunge pool ptc-H 311.7 elative elevation (m) elevation elative r r G bedrock 7
upstream ptc-H 94 channel plunge 9 308.4 design elevation bedrock along H ptc-H eration = 10 93 right bank pool bedrock, left bank 10 control point 1 of plunge pool 305.1 92 301.9 vertical exaggeration = 10 101 5091 100 150 200 250298.6 300 0 50 100 150 200 250 300 distancedistance downstream downst ream (m) (m)
April 2009 5-101 USDA-FS: Wayne NF, Eastern Region Ohio Department of Transportation Designing for Aquatic Organism Passage at Road-Stream Crossings 5. Fluvial Processes and Channel Characteristics Important in Stream Simulation Design
Predicting Channel Responses When Replacing a Structure Headcut potential: What are the ecological implications for allowing headcutting to occur as the channel adjusts to establish a new equilibrium condition?
Existing culvert design elevation diameter 3.1 m ptc-H
lw-M control point length 22 m A lw-M
B lw-M C ptc-M culvert rock lw-L ptc-M
2 lw-L D weir 3 4 E reference reach 5 ptc-H 6
tributary { bedrock F sediment ptc-M
wedge ptc-M
8 ptc-H G ck upstream 7 nel plunge 9 design elevation bedrock along right bank pool bedrock, left bank control point 1 of plunge pool eration = 10 102 50 100 150 200 250 distance downstream (m)
April 2009 5-102 USDA-FS: Wayne NF, Eastern Region Ohio Department of Transportation Designing for Aquatic Organism Passage at Road-Stream Crossings 5. Fluvial Processes and Channel Characteristics Important in Stream Simulation Design
XS3 Predicting Channel Responses t
When Replacing a Structure d a
rf/nm o
r
g
n
i
• Lateral Adjustment Potential: g
g
o XS4 l
d
l
Can channel migration or O lateral shifting over the service t existing XS5 Interpreted life of the structure affect culvert channel stream/culvert alignment? XS6 pattern rf/nm 220 S Rd 2 SF U rf/nm XS7 rf/nm N Proposed
placement XS8 fp/lt of structure EXPLANATION valley margin t bedrock bankfull flow floodprone width fp/lt XS9 large woody debris pool tail crest t step t terrace fp/lt floodplain or low terrace rf/nm road fill103 or native material culvert XS10 log weir
April 2009 5-103 USDA-FS: Wayne NF, Eastern Region Ohio Department of Transportation Designing for Aquatic Organism Passage at Road-Stream Crossings 5. Fluvial Processes and Channel Characteristics Important in Stream Simulation Design
Stevens Creek Olympic NF Washington Predicting Channel Responses fp/lt When Replacing a Structure
XS2 Floodplain inundation/connectivity: Is floodplain tributary fp/lt Interpreted function and connectivity important to the fluvial channel system and ecological processes? XS3 pattern pond fp/lt
XS4
XS5 N
0 20 m XS6 berm
existing culvert pond XS7
EXPLANATION tributary valley margin rm bankfull flow er XS8 b fp/lt floodplain/lo w terrace
fp/lt debris jam pond
XS9 berm
fp/lt
debris jam 104
April 2009 5-104 USDA-FS: Wayne NF, Eastern Region Ohio Department of Transportation Designing for Aquatic Organism Passage at Road-Stream Crossings 5. Fluvial Processes and Channel Characteristics Important in Stream Simulation Design
Stevens Creek Olympic NF Predicting Channel Responses Washington fp/lt When Replacing a Structure
XS2 Floodplain inundation/connectivity:
tributary fp/lt XS3 Interpreted channel XS3 pattern fp/lt pond fp/lt pond XS4 construct XS4 side channels
XS5 N XS5 N 0 20 m XS6 berm 020 m
existing culvert XS6
XS7 remove
EXPLANATION berm
tributary valley margin
bankfull flow XS8 fp/lt floodplain/lo w terrace remove culvert
fp/lt debris jam pond XS7
XS9 berm install wider structure fp/lt EXPLANATION debris jam tributary construct valley margin 105 channel bankfull flow S
April 2009 5-105 USDA-FS: Wayne NF, Eastern Region Ohio Department of Transportation Designing for Aquatic Organism Passage at Road-Stream Crossings 5. Fluvial Processes and Channel Characteristics Important in Stream Simulation Design
Summary • Watershed-scale and local-scale processes influence channel conditions at the crossing; consideration of these processes at both scales are needed for understanding channel conditions, fluvial processes, and channel responses at the road-stream crossing. • The gradient, planform pattern, dimensions, bedforms, and sediment size of the natural channel must be evaluated at the road-stream crossing in order to design a structure that contains a natural and dynamic channel. • A road-stream crossing channel design that has dimensions and characteristics similar to those in the natural channel will ensure that the design channel will be able to laterally and vertically adjust its form to a wide range of floods and sediment/debris inputs without compromising the movement and habitat needs of fish and other aquatic organisms. 106
April 2009 5-106 USDA-FS: Wayne NF, Eastern Region Ohio Department of Transportation Designing for Aquatic Organism Passage at Road-Stream Crossings 5. Fluvial Processes and Channel Characteristics Important in Stream Simulation Design
Selected References and Recommended Readings • Federal Interagency Stream Restoration Working Group (FISRWG). 1998. Stream Corridor Restoration: Principles, Processes, and Practices. Federal Interagency Stream Restoration Working Group (15 Federal agencies of the United States Government). ISBN-0-934213-59-3. • Knighton, D. 1998. Fluvial Forms and Processes. New York: John Wiley and Sons. 383 p. • Montgomery, D.R.; Buffington, J.M. 1997. Channel-reach morphology in mountain drainage basins. Geological Society of America Bulletin. 109. 596- 611. • Montgomery, D.R.; MacDonald, L.H. 2002. Diagnostic approach to stream channel assessment and monitoring. Journal of the American Water Resources Asssociation. 38. 1-16. • Ritter, D.F.; Kochel, R.C.; Miller, J.R. 1995. Process Geomorphology. Dubuque, IA: Brown Publishers. 538 p. • Rosgen, D. 1996. Applied River Morphology. Pagosa Springs, CO: Wildland Hydrology. • Simon, A. 1989. A model of channel response in disturbed alluvial channels. Earth Surface Process and Landforms. 14. 11-26. • Simon, A.; Downs, P.W. 1995. An interdisciplinary approach to evaluation of potential instability in alluvial channels. Geomorphology. 12. 215-232. • Thorne, C.R.; Hey, R.D.; Newsom, M.D. 1997. Applied Fluvial Geomorphology for River Engineering and Management (Editors). John Wiley 107 and Sons. New York, NY.
April 2009 5-107 USDA-FS: Wayne NF, Eastern Region Ohio Department of Transportation