OUTER CONTINENTAL SHELF SEDIMENT DISTRIBUTION AND DYNAMICS: A SUMMARY OF THE PRESENT STATE OF KNOWLEDGE

The US Outer Continental Shelf (OCS) consists of sediment that spans a wide range of sizes and composition as a result of previous sea levels and ongoing oceanographic processes. The OCS is also a sediment source for the common practice of beach nourishment or restoration in an effort to mitigate erosion, increase coastal resilience to storm impacts, provide habitat, and support the economy. Sediment placed on the beach is often required by state regulations to closely match the native grain size distribution and composition. Thus, understanding the nature and distribution of OCS sediment is also important in cost consideration of obtaining sediment for beach nourishment projects. This study examines the present state-of-knowledge on the availability, distribution, and characteristics of the sediment on the OCS under normal conditions, after storms, and post-dredging. Under normal conditions sediment in deltas and sand ridges are easily located and characterized as potential borrow sites. Storms can induce enough sediment transport to change the boundaries of borrow areas and the location of known sand ridges. Once dredged, OCS dynamics can include sediment infilling of the dredge pit and impact benthic infauna depending on the geometry and nearshore proximity of the excavation. The results of this study will also identify gaps in the present knowledge and identify research needs to further the scientific and coastal management community’s knowledge of OCS sediments and dynamics.