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Title
A scaled physical modeling investigation of the potential response of the Lake Mills delta to different magnitudes and rates of removal of Glines Canyon Dam from the Elwha River, WA
Alternative Title
Managing Watersheds for Human and Natural Impacts: Engineering, Ecological, and Economic Challenges, EWRI and ASCE 2005 Watershed Management Conference, Williamsburg, Virginia, July 19-22, 2005
Creator
Chris Bromley
Gordon Grant, Colin R. Thorne
School of Geography, University of Nottingham, University Park, Nottingham, NG7 2RD, U.K.
Oregon State University
Date Created and/or Issued
2005
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: Glines Canyon Dam impounds about 8.5 m m3 of mixed grain size sediment in the Lake Mills delta. It is hypothesized that, up to a certain point, an increase in the magnitude and rate of dam removal (base level lowering) will result in increased volumes and rates of delta erosion and progradation into the reservoir. Beyond this point, though, it is unclear whether these volumes and rates will continue to increase at the same rate or whether negative feedback mechanisms will act to reduce the rates, and maybe even the total volumes, at which sediment is prograded. Negative feedback may occur if sediment is prograded progressively more quickly and further into the reservoir in the early stages of response to progressively larger increments of dam removal, thus increasing the ?y component of bed slope change more quickly than the ?x component decreases due to the upstream migration of incision. If so, the rate at which bed slope decreases may increase significantly, thus decreasing the flow's ability to erode sediment and causing more rapid system stabilization. Further, if progressively larger increments of dam removal cause more lateral channel movement to occur in the early stages of adjustment, this might recruit more gravel from the delta terrace deposits, thus enabling more of the channel to armor more rapidly and more completely than with smaller increments of removal. Finally, the armoring process will be exacerbated if the rate at which bed slope decreases does increase significantly, since a rapid decrease in slope will cause a rapid decrease in boundary shear stress and thus decrease the likelihood of gravel movement. A series of dam removal experiments was performed in a scaled physical model, which was built and operated at the St. Anthony Falls Laboratory, in order to address these research hypotheses.
Type
text
Form/Genre
digital copy
Identifier
ark:/86086/n2sf2vs0
116
Subject
Sediment and channel dynamics
Dams
Dam retirement
Place
Elwha River, WA
Glines Canyon Dam
US

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