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![Page 1: Channel Modification Washington Dept. Forestry, 2004, Channel Modification Techniques Katie Halvorson.](https://reader030.fdocuments.us/reader030/viewer/2022032709/56649e9e5503460f94ba0299/html5/thumbnails/1.jpg)
Channel ModificationWashington Dept. Forestry, 2004, Channel
Modification Techniques
Katie Halvorson
![Page 2: Channel Modification Washington Dept. Forestry, 2004, Channel Modification Techniques Katie Halvorson.](https://reader030.fdocuments.us/reader030/viewer/2022032709/56649e9e5503460f94ba0299/html5/thumbnails/2.jpg)
Purpose What makes for successful modification Channel form
• Planform
• Cross section
• Channel profile Sediment transport Design Bank reconstruction Monitoring
Overview:
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Purpose: “accelerate recovery to a stable, sustainable channel form that is in dynamic balance with its sediment, large-wood, and flow regime.”
Immediate benefits by creating improved habitats
Channel modification projects:
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Improved stability
Improved sorting of gravels for spawning habitats
Improved water access to floodplain
Greater diversity in channel bedforms
Improved riparian zones
Improved habitat quality
Successful channel modification will include:
![Page 5: Channel Modification Washington Dept. Forestry, 2004, Channel Modification Techniques Katie Halvorson.](https://reader030.fdocuments.us/reader030/viewer/2022032709/56649e9e5503460f94ba0299/html5/thumbnails/5.jpg)
Physical effects of channel modification
Alters way energy is dissipated through reach and it effects:
• Volume of sediment transported
• Hydraulic variables
• Large wood transport and retention
![Page 6: Channel Modification Washington Dept. Forestry, 2004, Channel Modification Techniques Katie Halvorson.](https://reader030.fdocuments.us/reader030/viewer/2022032709/56649e9e5503460f94ba0299/html5/thumbnails/6.jpg)
Planform
• Shape in map view
• Defined by sinuosity
Cross-section
• Width and depth from bank to bank and across floodplain
Profile
• Slope variability along channel bed
Channel Form
![Page 7: Channel Modification Washington Dept. Forestry, 2004, Channel Modification Techniques Katie Halvorson.](https://reader030.fdocuments.us/reader030/viewer/2022032709/56649e9e5503460f94ba0299/html5/thumbnails/7.jpg)
Channel form cont.
Integrated feature Modifications• Reconstruction of channel• Installation of structural feature to
induce change• Helps reduce bank erosion and control
channel migration
![Page 8: Channel Modification Washington Dept. Forestry, 2004, Channel Modification Techniques Katie Halvorson.](https://reader030.fdocuments.us/reader030/viewer/2022032709/56649e9e5503460f94ba0299/html5/thumbnails/8.jpg)
Planform
How to increase sinuosity:
• increase diversity of sizes and sorting of sediment
• Increase vertical topography
• Addition of point bars
![Page 9: Channel Modification Washington Dept. Forestry, 2004, Channel Modification Techniques Katie Halvorson.](https://reader030.fdocuments.us/reader030/viewer/2022032709/56649e9e5503460f94ba0299/html5/thumbnails/9.jpg)
Alter depth, shape, width and modification of banks and bars.
Accomplished by:
• narrowing channel by restoring vegetation that redirects flow
• removing levees
Cross section change
![Page 10: Channel Modification Washington Dept. Forestry, 2004, Channel Modification Techniques Katie Halvorson.](https://reader030.fdocuments.us/reader030/viewer/2022032709/56649e9e5503460f94ba0299/html5/thumbnails/10.jpg)
Channel profile
Refers to variation of slope in a channel bed
Influences the passage of fish
Placement of large woody debris
Reconfiguration of stream length
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Sediment transport
Can enhance and provide habitat
Size and shape will influence quality of habitat
Size and shape of channel will determine size and sorting of material
![Page 12: Channel Modification Washington Dept. Forestry, 2004, Channel Modification Techniques Katie Halvorson.](https://reader030.fdocuments.us/reader030/viewer/2022032709/56649e9e5503460f94ba0299/html5/thumbnails/12.jpg)
Analog- replicating channel from historical data
• Best used when watershed hydrologic and sediment have not been changed much
Empirical- uses equations
• Helps relate channel characteristics derived from universal data sets
Analytical- equations and models
• Used when sediment dynamics and hydrology are changing
Channel modification design
![Page 13: Channel Modification Washington Dept. Forestry, 2004, Channel Modification Techniques Katie Halvorson.](https://reader030.fdocuments.us/reader030/viewer/2022032709/56649e9e5503460f94ba0299/html5/thumbnails/13.jpg)
Bank reconstruction
Most channels will require reconstruction on at least one side
Will change hydraulic conditions
Can affect stability of other banks
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Not a large enough emphasis
“the importance of reporting project monitoring results cannot be overstated.”
Only way to learn what does and doesn’t work
Monitoring:
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Purpose: “accelerate recovery to a stable, sustainable channel form that is in dynamic balance with its sediment, large-wood, and flow regime.”
Look at channel form and specifics to come up with a design and continue to monitor during and after modifications.
In conclusion: