ASSESSMENT OF METHODS FOR MEASURING EMBEDDEDNESS: APPLICATION TO SEDIMENTATION IN FLOW REGULATED STREAMS1 |
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Authors: | Kelly M Sennatt Nira L Salant Carl E Renshaw Francis J Magilligan |
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Institution: | Respectively, Student, Dartmouth College, HB 6105 Earth Sciences, Hanover, New Hampshire 03755;Graduate Student, Department of Geography, University of British Columbia, No. 217 1984 West Mall, Vancouver, British Columbia V6T 122, Canada;Professor, Dartmouth College, HB 6105 Earth Sciences, Hanover, New Hampshire 03755;and Professor, Dartmouth College, HB 6017 Geography, Hanover, New Hampshire 03755 (E-Mail/Salant: ). |
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Abstract: | Abstract: Five commonly used methods for measuring embeddedness the — degree to which fine particles surround coarse substrate on the surface of the streambed — are assessed and used to evaluate the sedimentation pattern resulting from impoundment on tributaries of the Connecticut River. Results show that the U.S. Environmental Protection Agency (USEPA) method best reflects the sediment regime on these rivers. On the Ompompanoosuc River, regulated by a run-of-the-river/flood control dam, embeddedness increases significantly directly downstream of the dam. On the unregulated White River, no downstream trends in embeddedness are observed. The USEPA results on the Ompompanoosuc River reflect the movement of a local decrease in embeddedness, interpreted as a moving region of scour, with a calculated transport rate of approximately 5 to 25 m/day. Observed transport rates are similar to previously measured sediment transport rates and consistent with results from a multifraction sediment transport model. Application of the USEPA method to an additional regulated tributary demonstrates the effects of dam management on embeddedness. Flow regulation with high sediment trapping efficiency results in a decrease in embeddedness downstream of the dam. Results provide insight into the utility of available methods for evaluating the effects of management practice on streambed composition. |
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Keywords: | dams flow regulation deposition fluvial processes sediment transport watershed management |
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