Coastal change from a massive sediment input: Dam removal, Elwha River, Washington, USA

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Abstract

The removal of two large dams on the Elwha River, Washington, provides an ideal opportunity to study coastal morphodynamics during increased sediment supply. The dam removal project exposed ~21 million cubic meters (~30 million tonnes) of sediment in the former reservoirs, and this sediment was allowed to erode by natural river processes. Elevated rates of sand and gravel sediment transport in the river occurred during dam removal. Most of the sediment was transported to the coast, and this renewed sediment supply resulted in hundreds of meters of seaward expansion of the river delta since 2011. Our most recent survey in January 2015 revealed that a cumulative ~3.5 million m3 of sediment deposition occurred at the delta since the beginning of the dam removal project, and that aggradation had exceeded 8 m near the river mouth. Some of the newly deposited sediment has been shaped by waves and currents into a series of subaerial berms that appear to move shoreward with time.

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Additional publication details

Publication type Conference Paper
Publication Subtype Conference Paper
Title Coastal change from a massive sediment input: Dam removal, Elwha River, Washington, USA
DOI 10.1142/9789814689977_0161
Year Published 2015
Language English
Publisher World Scientific Publishing Company
Publisher location Singapore
Contributing office(s) Pacific Coastal and Marine Science Center
Larger Work Type Book
Larger Work Subtype Conference publication
Larger Work Title The Proceedings of the Coastal Sediments 2015
Conference Title Coastal Sediments 2015
Conference Location San Diego, CA
Conference Date May 11-15, 2015
Country United States
State Washington
Other Geospatial Elwha River