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Geomorphic response of sandbars to the March 2008 high-flow experiment on the Colorado River downstream from Glen Canyon Dam

Proceedings of the 2nd Joint Federal Interagency Conference on Sedimentation and Hydrologic Modeling

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Abstract

The completion of Glen Canyon Dam in 1963 drastically altered the downstream flow regime and resulted in more than a 90 percent reduction of sand supply to the Colorado River in Grand Canyon National Park. Sandbars that were maintained by annual floods and a large sediment supply are now fewer in number and smaller in area and volume. Efforts to maintain sandbars in the current era of dam management utilize controlled floods timed to occur during brief periods of sediment enrichment that result from tributary floods. Repeat surveys of 22 sandbars made before and after controlled floods conducted in 1996, 2004, and 2008 document changes in sandbar volume; and repeat surveys at more than 100 sites document changes in sandbar elevation and morphology for the 2008 event. Each of the controlled floods resulted in sandbar deposition that was followed by erosion in the 6-month post-flood period. Erosion rates are positively correlated with post-flood dam release volumes and negatively correlated with post-flood tributary sediment supply volume. October 2008 sandbar volume was similar or larger than sandbar volume in February 1996, before the first of the three controlled floods. Deposition during the 2008 controlled flood was also associated with increases in the quantity of backwater habitat, which is used by native and non-native fish.

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Additional Publication Details

Publication type:
Book
Publication Subtype:
Conference publication
Title:
Geomorphic response of sandbars to the March 2008 high-flow experiment on the Colorado River downstream from Glen Canyon Dam
Series title:
Proceedings of the 2nd Joint Federal Interagency Conference on Sedimentation and Hydrologic Modeling
Year Published:
2010
Language:
English
Publisher:
Advisory Committee on Water Information
Contributing office(s):
Southwest Biological Science Center
Description:
12 p.
Larger Work Type:
Article
Larger Work Subtype:
Journal Article
Number of Pages:
12
Time Range Start:
1996-02-01T12:00:00
Time Range End:
2008-10-31T12:00:00
Conference Title:
Hydrology and Sedimentation for a Changing Future Existing and Emerging Issues
Conference Location:
Reston, VA
Conference Date:
27-JUN-10
Country:
United States
State:
Arizona
Datum:
NAD 1983
Projection:
Stateplane, Arizona Central Zone