This study utilizes repeated geoacoustic mapping to quantify the morphodynamic response of the nearshore to storm-induced changes. The aim of this study was to quantitatively map the nearshore zone of Assateague Island National Seashore (ASIS) to determine what changes in bottom geomorphology and benthic habitats are attributable to storm events including hurricane Sandy and the passage of hurricane Joaquin. Specifically, (1) the entire domain of the National Parks Service offshore area was mapped with side-scan sonar and multibeam bathymetry at a resolution comparable to that of the existing pre-storm survey, (2) a subset of the benthic stations were resampled that represented all sediment strata previously identified, and (3) newly obtained data were compared to that from the pre-storm survey to determined changes that could be attributed to specific storms such as Sandy and Joaquin. Capturing event specific dynamics requires rapid response surveys in close temporal association of the before and after period. The time-lapse between the pre-storm surveys for Sandy and our study meant that only a time and storm integrated signature for that storm could be obtained whereas with hurricane Joaquin we could identify impacts to the habitat type and geomorphology more directly related to that particular storm. This storm impacts study provides for the National Park Service direct documentation of storm-related changes in sediments and marine habitats on multiple scales: From large scale, side-scan sonar maps and interpretation of acoustic bottom types, to characterize as fully as possible habitats from 1 to 10 m up to many kilometer scales, as well as from point benthic samples within each sediment stratum and these results can help guide management of the island resources.

This study utilizes repeated geoacoustic mapping to quantify the morphodynamic response of the nearshore to storm-induced changes. The aim of this study was to quantitatively map the nearshore zone of Assateague Island National Seashore (ASIS) to determine what changes in bottom sediments, benthic fauna and fish habitat are attributable to storm events including hurricane Sandy and the passage of hurricane Joaquin. Specifically, (1) the entire domain of the National Parks Service offshore area was mapped with side-scan sonar and multibeam bathymetry at a resolution comparable to that of the existing pre-storm survey, (2) a subset of the benthic stations were resampled that represented all sediment strata previously identified, and (3) newly obtained data were compared to that from the pre-storm survey to determined changes that could be attributed to specific storms such as Sandy and Joaquin. Capturing event specific dynamics requires rapid response surveys in close temporal association of the before and after period. The time-lapse between the pre-storm surveys for Sandy and our study meant that only a time and storm integrated signature for that storm could be obtained whereas with hurricane Joaquin we could identify impacts to the habitat type and geomorphology more directly related to that particular storm. This storm impacts study provides for the National Park Service direct documentation of storm-related changes in sediments and marine habitats on multiple scales: from large scale, side-scan sonar maps and interpretation of acoustic bottom types, to characterize as fully as possible habitats from 1 to 10 m up to many kilometer scales, as well as from point benthic samples within each sediment stratum and these results can help guide management of the island resources.

Assateague Island is a barrier island complex that stretches 37 miles along the Atlantic coast of Maryland and Virginia. The island's location along the eastern seaboard makes for a highly dynamic system that not only changes over long temporal scale through longshore transport and sea level transgression/ regression, but also over short seasonal scales due to strong currents and storm events such as Hurricane Sandy in late October 2012 and Hurricane Joaquin in October 2015. Geologically speaking, both hurricanes gave us a rare opportunity to quantify large spatial scale sea-floor changes over a short temporal scale because of the vast amount of energy that moved through the region in 2012 and 2015. This coastal geomorphological study will aim to quantify the macro-scale changes that took place over time by utilizing data collected via bathymetric sea-floor mapping surveys that took place in 2011 and 2014. The first data set was collected by the Maryland Geological Survey pre-Hurricane Sandy (2011), using a Versar single-beam echosounder. This will be compared to multi-phase bathymetric data that was collected by the University of Delaware utilizing an Edgetech 6205 multi-phase echosounder (2015). Comparing these two data sets allows us to measure large spatial scale changes over a short temporal scale. This will aim to quantify the amount of substrate changes and overall sediment movement based off each storm event. This study will have implications for quantifying near shore sand resource movement during storm events.