Impact of Storm-induced Sediment Transport and Depositional Processes in Essex Tidal Inlet and Backbarrier Bay System

Castle Neck spit and Essex Inlet and Bay system are part of a highly dynamic and interconnected sand transport regime that is governed by strong tidal currents and a southerly longshore transport system driven by northeast storms. Sand eroded from the southern spit of Castle Neck moves into Essex Bay where it fills nearby channels, such as Castle Neck River, and enlarges sand shoals, including the western flood-tidal delta. These changes have significant impacts on local communities, threatening infrastructure on the barrier and affecting fisheries in the Bay. The ability of the sand to be transported deep into the bay is illustrated by the deposition of 185,000 m3 of sand on the landward most flood delta between 2010 and 2016. The loss of sand from the spit and its delivery to the bay was likely related to a number of storm parameters including intensity, track, forward speed, and resulting storm surge and wave energy. Satellite imagery shows that extensive spit retreat between 2007 and 2016 was coincident with the large-scale expansion of the inner flood delta. This sedimentation process indicates that sand is highly mobile in Essex Bay and can be transported far inland from its original source during high energy storm events. Here, we investigate the contribution of storms to long-term morphological changes in Essex Tidal Inlet and Bay, and develop correlations between storm characteristics (intensity, approach angle, and storm forward speed) and corresponding morphological changes. Our results show a non-linear response of sediment transport volumes with storm characteristics. Slow moving storms, albeit similar size and track, lengthen the period of sediment entrainment and transport, compared to their fast-moving counterparts, while a variation on the storm intensity controls sediment transport by modulating water depth during the storm.