TARGETING MARINE SAND RESOURCES FOR NOURISHMENT ON THE OUTER CONTINENTAL SHELF OF NORTH CAROLINA

Beach nourishment is a popular engineering with nature (EWN) strategy used globally for shoreline stabilization and coastal storm damage reduction. Following Hurricane Sandy in 2012, the Bureau of Ocean Energy Management (BOEM), initiated a collaborative effort with the 11 Atlantic Coast states to inventory sand resources and collect new data where coverage was lacking along the Outer Continental Shelf (3-8 nm), with the intention to augment the efficiency of beach project planning. Over 300 nm of high-resolution chirp sub-bottom data, sidescan sonar and vibracores were collected in 2015 and interpreted for geologic horizons and potential nourishment-compatible sand thickness across the Southern NC shelf. In addition, hundreds of paleochannels were mapped and evaluated for fill patterns and resource potential. Various forms of hardbottom were delineated, sometimes in close proximity to sand resources. To supplement the offshore data that is costly and challenging to collect, other reconnaissance tools (e.g., rugosity) were tested using available bathymetric datasets and geospatial analysis of the seafloor. Finally, the geophysical interpretations have been coupled with grain size analysis and 14C dating from cores collected along the geophysical lines to examine geologic context and potential depositional mechanisms of resource sands. Results show high spatial variability in the distribution of beach-compatible sands across the southern NC shelf, although some deposits exceed 10 feet. These findings provide a useful starting point for coastal managers seeking sufficient offshore sediment resources for nourishment in response to future storm events and sea level rise.