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USGS Studies Sediment Transport at Cape Hatteras, North Carolina
Reports of hundreds of ships that have sunk in these waters over the past several hundred years have earned the area extending along the Outer Banks of the North Carolina coastline the title "graveyard of the Atlantic." This area is dangerous because ships traveling along coastal currents close to shore can be driven into shallow waters by severe weather and become grounded. Diamond Shoals is a large, shifting sand deposit along the Outer Banks off Cape Hatteras, North Carolina.The shoal is approximately 10 km wide and extends offshore 30 km to the edge of the continental shelf. The abruptly rising shallow depths and crashing waves have battered apart many a grounded vessel.
The U.S. Geological Survey (USGS) Coastal and Marine Geology Program in Woods Hole, Massachusetts, is leading an effort to understand the regional sediment dynamics along the coastline of North and South Carolina. As part of the Carolinas Coastal Change Processes Project, we are investigating the processes that control the dynamics of sediment transport at Diamond Shoals. During the week of January 9-15, 2009, the research vessel (R/V) Connecticut and its five crew members transported USGS personnel John Warner, Marinna Martini, Jonathan Borden, Brandy Armstrong, Neil Ganju, Elizabeth Pendleton, and Sandy Baldwin to deploy oceanographic equipment at Diamond Shoals. Tripods were deployed at three sites along the outer perimeter of the shoal. Mounted on the tripods were instruments to measure surface waves, pressure, current velocity, bottom turbulence, suspended-sediment profiles, and sea-floor sand-ripple bedforms; one tripod also held a visual camera system. The measurements will be used to explore the oceanographic and sediment-transport processes responsible for maintaining the offshore sand shoal. The tripods were positioned with guidance from data collected during recent cruises by the USGS Sea Floor Mapping Group in Woods Hole. These data were used to identify locations for tripod deployment and to provide navigational assistance to the vessel during deployment.
Surficial grab samples of sediment were obtained at the deployment locations to determine characteristics of the seabed. The samples will be analyzed by the USGS Sediment Lab in Woods Hole for grain-size distribution, information that is critical to understanding the formation of the shoal and the regional sediment dynamics. We greatly thank the crew of the R/V Connecticut for their efforts, and the University of South Carolina and Dalhousie University, who provided additional equipment for the deployment.
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in this issue:
Modeling Climate Change and Ocean Acidification Sediment Transport at Cape Hatteras
Oceanographer Joins NOAA's Integrated Ocean Observing System Program |
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U. S. Department of the Interior | U.S. Geological Survey
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