Influence of a dam on fine-sediment storage in a canyon river

Hazel Jr., Joseph E and Topping, David J and Schmidt, John C and Kaplinski, Matt (2006) Influence of a dam on fine-sediment storage in a canyon river. Journal of Geophysical Research Earth Surface, 111 (F01025). ISSN 0148-0227

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Abstract

Glen Canyon Dam has caused a fundamental change in the distribution of fine sediment storage in the 99-km reach of the Colorado River in Marble Canyon, Grand Canyon National Park, Arizona. The two major storage sites for fine sediment (i.e., sand and finer material) in this canyon river are lateral recirculation eddies and the main-channel bed. We use a combination of methods, including direct measurement of sediment storage change, measurements of sediment flux, and comparison of the grain size of sediment found in different storage sites relative to the supply and that in transport, in order to evaluate the change in both the volume and location of sediment storage. The analysis shows that the bed of the main channel was an important storage environment for fine sediment in the predam era. In years of large seasonal accumulation, approximately 50% of the fine sediment supplied to the reach from upstream sources was stored on the main-channel bed. In contrast, sediment budgets constructed for two short-duration, high experimental releases from Glen Canyon Dam indicate that approximately 90% of the sediment discharge from the reach during each release was derived from eddy storage, rather than from sandy deposits on the main-channel bed. These results indicate that the majority of the fine sediment in Marble Canyon is now stored in eddies, even though they occupy a small percentage ( similar to 17%) of the total river area. Because of a 95% reduction in the supply of fine sediment to Marble Canyon, future high releases without significant input of tributary sediment will potentially erode sediment from long-term eddy storage, resulting in continued degradation in Marble Canyon.

Item Type:	Article
Publisher’s Statement:	Copyright 2006 by the American Geophysical Union
ID number or DOI:	10.1029/2004JF000193
Keywords:	Canyon river; sediment erosion; sediment storage; Colorado river; predam; postdam; sand patters; silt; clay; fine-sediment;
Subjects:	Q Science > QE Geology
NAU Depositing Author Academic Status:	Faculty/Staff
Department/Unit:	College of Engineering, Forestry, and Natural Science > School of Earth Sciences and Environmental Sustainability
Date Deposited:	18 Oct 2015 19:53
URI:	http://openknowledge.nau.edu/id/eprint/920

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