RECENT GEOPHYSICAL AND MORPHODYNAMIC OBSERVATIONS ALONG THE ASSATEAGUE ISLAND INNER CONTINENTAL SHELF IN RELATION TO SUPERSTORM SANDY

In response to the impacts of Superstorm Sandy a series of related regional studies on inner shelf geology and benthic habitat mapping were initiated by the USGS and the National Parks Service, and faculty and students from the University of Delaware have been involved in gathering and interpreting geophysical and hydrodynamic related the surface morphology, benthic communities, sediment patterns along Assateague Island National Seashore. During the 2014 and 2015 field seasons over 75 km² of high-resolution side-scan sonar and collocated bathymetry were collected spanning the beach in depths of less than 2 m out to a distance of approximately 1 nm and depths of 10-12 m.

Specifically, we have mapped the offshore area of the park boundary with surface vessel mounted bathy side-scan sonar at a resolution ~50 cm/pixel for comparison to that of the pre-storm survey, (2) resampled a subset of the benthic stations that represent all sediment strata previously identified, (3) obtained novel data with our ROV and AUV assets, including bottom video and multibeam bathymetry, at specifically chosen locations on a much finer scale in order to enhance understanding of the benthic habitat and bottom type changes, and (4) compared our newly obtained data to recent USGS partner collected data and to that from the pre-storm survey in order to examine changes that occur over season and inter-annual time frames and in order to asses what may be attributable to Superstorm Sandy. To additionally support the interpretation of these data,, two instrumented moorings comprised of acoustic Doppler current profilers (ADCPs) and rotary sonar sensors were deployed at 3 locations along the island capturing in situ measurements of directional waves, tidal currents, and 2-dimensional acoustic imagery of seabed morphology.