Text / Channel Evolution on the Lower Elwha River, Washington, 1939-2006

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Item Information.

Title
Channel Evolution on the Lower Elwha River, Washington, 1939-2006
Alternative Title
Scientific Investigations Report 2008-5127
Creator
Amy E. Draut
Jonathan Warrick
Joshua B. Logan
Michael McHenry
Randall E. McCoy
Date Created and/or Issued
2008
Publication Information
USGS
Contributing Institution
UC Riverside, Library, Water Resources Collections and Archives
Collection
Clearinghouse for Dam Removal Information (CDRI)
Rights Information
Copyrighted
Transmission or reproduction of materials protected by copyright beyond that allowed by fair use requires the written permission of the copyright owners. Works not in the public domain cannot be commercially exploited without permission of the copyright owner. Responsibility for any use rests exclusively with the user.
Description
Scope/Content: Abstract: Analyses of historical aerial photographs of the lower Elwha River, Clallam County, Washington, reveal rates and patterns of channel change in this dammed, anabranching river between 1939 and 2006. Absolute positional changes of the active-floodplain margins, which commonly exceeded 50 m over that interval, have exceeded 400 m locally. Annualized rates of channel movement were typically ~2 to 10 m/yr; higher annualized rates over some time intervals are attributable to the formation of new channels by episodic avulsion. Channel movement by more gradual lateral meander migration was also common. Anthropogenic modification of the floodplain between the 1940s and 1980s substantially altered channel form and position. This analysis of rates and patterns of channel change over nearly 70 years on the lower Elwha River is intended to characterize the evolution of the river throughout most of the time interval when two large dams have been in place upstream. Channel morphology and rates of channel movement are expected to change significantly in response to removal of the dams and re-establishment of the upstream sediment supply during a major river-restoration project.
Scope/Content: Author affiliation: USGS
Type
text
Identifier
ark:/86086/n2xs5v0h
1132
Subject
Sediment and channel dynamics
Dams
Dam retirement
Place
Elwha River, WA
Elwha Dam
Glines Canyon Dam

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