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World’s largest dam removal reverses coastal erosion

September 27, 2019

Coastal erosion outpaces land generation along many of the world’s deltas and a significant percentage of shorelines, and human-caused alterations to coastal sediment budgets can be important drivers of this erosion. For sediment-starved and erosion-prone coasts, large-scale enhancement of sediment supply may be an important, but poorly understood, management option. Here we provide new topographic measurements that show the patterns and trends of beach accretion following the restoration of sediment supply from a massive dam removal project. River sediment was initially deposited in intertidal-to-subtidal deltaic lobes, and this sediment was reworked by ocean waves into subaerial river mouth bars over time scales of several months. These river mouth bars welded to the shoreline and then initiated waves of sediment accretion along adjacent upcoast and downcoast beaches. Although the downcoast shoreline has a high wave-angle setting, the sedimentation waves straightened the downcoast shoreline rather than forming self-organized quasi-periodic instabilities, which suggests that simple coastal evolution theory did not hold under these conditions. Combined with other mega-nourishment projects, these findings provide new understanding of littoral responses to the restoration of sediment supplies.

Publication Year 2019
Title World’s largest dam removal reverses coastal erosion
DOI 10.1038/s41598-019-50387-7
Authors Jonathan Warrick, Andrew W. Stevens, Ian M. Miller, Shawn R Harrison, Andrew C. Ritchie, Guy R. Gelfenbaum
Publication Type Article
Publication Subtype Journal Article
Series Title Scientific Reports
Index ID 70208192
Record Source USGS Publications Warehouse
USGS Organization Pacific Coastal and Marine Science Center