Sand ridge morphology and bedform migration patterns derived from bathymetry and backscatter on the inner-continental shelf offshore of Assateague Island, USA

Continental Shelf Research
By: , and 

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Abstract

The U.S. Geological Survey and the National Oceanographic and Atmospheric Administration conducted geophysical and hydrographic surveys, respectively, along the inner-continental shelf of Fenwick and Assateague Islands, Maryland and Virginia over the last 40 years. High resolution bathymetry and backscatter data derived from surveys over the last decade are used to describe the morphology and presence of sand ridges on the inner-continental shelf and measure the change in the position of smaller-scale (10–100 s of meters) seafloor features. Bathymetric surveys from the last 30 years link decadal-scale sand ridge migration patterns to the high-resolution measurements of smaller-scale bedform features. Sand ridge morphology on the inner-shelf changes across-shore and alongshore. Areas of similar sand ridge morphology are separated alongshore by zones where ridges are less pronounced or completely transected by transverse dunes. Seafloor-change analyses derived from backscatter data over a 4–7 year period show that southerly dune migration increases in magnitude from north to south, and the east-west pattern of bedform migration changes ~ 10 km north of the Maryland-Virginia state line. Sand ridge morphology and occurrence and bedform migration changes may be connected to observed changes in geologic framework including topographic highs, deflated zones, and sand availability. Additionally, changes in sand ridge occurrence and morphology may help explain changes in the long-term shoreline trends along Fenwick and Assateague Islands. Although the data presented here cannot quantitatively link sand ridges to sediment transport and shoreline change, it does present a compelling relationship between inner-shelf sand availability and movement, sand ridge occurrence and morphology, geologic framework, and shoreline behavior.

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Additional publication details

Publication type Article
Publication Subtype Journal Article
Title Sand ridge morphology and bedform migration patterns derived from bathymetry and backscatter on the inner-continental shelf offshore of Assateague Island, USA
Series title Continental Shelf Research
DOI 10.1016/j.csr.2017.06.021
Volume 144
Year Published 2017
Language English
Publisher Elsevier
Contributing office(s) Woods Hole Coastal and Marine Science Center
Description 18 p.
First page 80
Last page 97
Country United States
Other Geospatial Assateague Island