[1] On 30 October 2012, Hurricane Sandy made landfall near Brigantine New Jersey bringing widespread erosion and damage to the coastline. We have obtained a unique set of high-resolution before and after storm measurements of seabed morphology and in situ hydrodynamic conditions (waves and currents) capturing the impact of the storm at an inner continental shelf field site known as the ''Redbird reef''. Understanding the signature of this storm event is important for identifying the impacts of such events and for understanding the role that such events have in the transport of sediment and marine debris on the inner continental shelf. As part of an ONR-sponsored program designed to understand and characterize the ripple dynamics and scour processes in an energetic, heterogeneous inner-shelf setting, a series of high-resolution geoacoustic surveys were conducted before and after Hurricane Sandy. Our overall goal is to improve our understanding of bedform dynamics and spatio-temporal length scales and defect densities through the application of a recently developed fingerprint algorithm technique. Utilizing high-resolution swath sonar collected by an AUV and from surface vessel sonars, our study focuses both on bedforms in the vicinity of manmade seabed objects and dynamic natural ripples on the inner shelf in energetic coastal settings with application to critical military operations such as mine countermeasures.

Bottom trawl fishing presents a severe yet largely unquantified threat to shipwreck sites. Here we present a quantification of damage to sites from the Aegean and Black seas through high resolution imaging of 45 shipwrecks discovered by the E/V Nautilus expeditions, 2009-2012. These shipwrecks are part of a modern submarine landscape that is heavily damaged by trawls, which also remove sediment and smooth out natural features of the seabed. We quantify the severity of this threat to archaeological sites through repeat visits to one ancient shipwreck and quantify the change to the seabed over a period of eleven months. The results illustrate the benefits of enforced areas of restricted bottom trawling (Marine Protected Areas) to the in situ preservation of shipwreck sites and to natural seabed features and benthic habitats. Careful marine spatial planning and coordinated management of fishing activity can mitigate this destructive activity. In addition, we counter the claim made by some commercial salvors who use trawl damage as an excuse to salvage artifacts from wrecks, further destroying historically significant sites for profit.

Ripple bedform response to near bed forcing has been found to be asynchronous with rapidly changing hydrodynamic conditions. Recent models have attempted to account for this time variance through the introduction of a time offset between hydrodynamic forcing and seabed response with varying success. While focusing on temporal ripple evolution, spatial ripple variation has been partly neglected. With the fingerprint algorithm ripple bedform parameterization technique, spatial variation can be quickly and precisely characterized, and as such, this method is particularly useful for evaluation of ripple model spatio-temporal validity. Using time-series hydrodynamic data and synoptic acoustic imagery collected at an inner continental shelf site, this study compares an adapted time-varying ripple geometric model to observed field observations in light of the fingerprint algorithm results. Multiple equilibrium ripple predictors are tested within the time-varying model, with the algorithm results serving as the baseline geometric values. Results indicate that ripple bedforms, in the presence of rapidly changing high-energy conditions, reorganize at a slower rate than predicted by the models. Relict ripples were found to be near peak-forcing wavelengths after rapidly decaying storm events, and still present after months of sub-critical flow conditions.

Munitions and explosives of concern (MEC) in U.S. waters can present a risk to the development and operation of offshore wind energy resources. Therefore, the U.S. Bureau of Ocean Energy Management requires offshore wind energy developers to evaluate the risk MEC poses to the development, operation, and maintenance of offshore wind energy generation and transmission systems. This article describes an MEC risk management framework consisting of the following steps: (1) MEC hazard assessment, (2) MEC risk assessment, (3) MEC risk validation, and (4) MEC risk mitigation. The MEC hazard assessment involves historical research to identify MEC potentially present in the development area. The MEC risk assessment evaluates the development activities and provides a relative MEC risk ranking for those activities. The developer determines the acceptability of these risks, and any potentially unacceptable MEC risks undergo risk validation through field surveys. The developer then considers the tolerability of the validated risks and develops and implements an appropriate MEC risk mitigation strategy based on actual site conditions. A risk framework provides a structured method to plan and operationalize the identification, evaluation, and mitigation of MEC risk throughout the development, operation, and maintenance life cycle of an offshore wind energy generation and transmission project.

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.