# Physical modelling of the removal of Glines Canyon Dam & Lake Mills By Chris Bromley, Gordon Grant, Colin Thorne University of Nottingham / Oregon State.

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Physical modelling of the removal of Glines Canyon Dam & Lake Mills By Chris Bromley, Gordon Grant, Colin Thorne University of Nottingham / Oregon State University

Source: National Park Service

Elwha River Project “…the full restoration of the Elwha River ecosystem and the native anadromous fisheries…’ Elwha River Ecosystem and Fisheries Restoration Act, 1992 (P.L. 102-495)

Lake Aldwell ~ 2.98 million m 3 Lake Mills ~ 11.85 million m 3

Image courtesy of National Park Service Baselevel

2.29 m = 2.8 cm

Research hypotheses The greater the magnitude of the drop in baselevel, a. The greater the incision and lateral adjustment that will occur within the original delta area b. The more rapidly sediment will erode from the delta surface c. The greater the total volume of original delta sediment will be eroded

Dam

Horizontal scale = 1 : 310 Vertical scale = 1 : 81.7 Vertical distortion = 3.79

3.3 km = 10.65 m

1.067 km = 3.44 m

45.72 m = 0.56 m

Similitude of Froude No. & Shields No. Assume uniform steady flow

Q m = Q p * H V 1.5 Q m  growth = 110 l/min → Q p = 420 m 3 /s (14,825 cfs)

R11 3x - center R7 3x - left 0 - 21

R11 3x - center R7 3x - left 3 - 21

R11 3x - center R7 3x - left 6 - 21

R11 3x - center R7 3x - left 9 - 21

R11 3x - center R7 3x - left 12 - 21

R11 3x - center R7 3x - left 15 - 21

R11 3x - center R7 3x - left 18 - 21

R11 3x - center R7 3x - left 21 - 21

RunFrom (mins.) To (mins.) Prototype Sediment- transporting time (Weeks) % total sediment volume passing Downstream Yrs-worth of Sediment Transport 1x Left 734577657.08.416.6 3x Left 34303730514.5711.5 3x Centre 3470436014.832.6925.8 3x Right 279029402.53.722.9

RunFrom (mins.) To (mins.) Prototype Sediment- transporting time (Weeks) % total sediment volume passing downstream Yrs-worth of Sediment transport 1x Left 7345797510.513.5410.7 3x Left 3430403510.12620.5 3x Centre 3470472020.840.0831.7 3x Right 2790343010.715.5412.3

Conclusions 1 Volumes and rates of original delta erosion increase with, -central incisional channels -increasing magnitudes of removal

Conclusions 2 Beyond 3x C, relationships less clear, -peak rates and volumes very high during very early stages of removal -increasing channel lengths d/s of original delta may represent negative feedback between original delta erosion and delta progradation

Acknowledgements St. Anthony Falls Laboratory & NCED Dianna Smith, Jason Lundheim, Mike Plante, Dick Christopher, Ben Erickson, Jeremy Schultz, Josh Brand, Matt Leuker Brett Otteson, Ben Freisen, Corey Markfort Alessandro Cantelli, Gary Parker, Chris Paola, Greg Stewart, Tim Randle, Gordon Grant, Colin Thorne Brian Winter, Bill Jackson, Reclamation

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