Storm-Related Barrier Island Morphological Evolution

Science Center Objects

Storms quickly and dramatically alter barrier island environments by changing adjacent seafloor morphology, eroding beaches, scarping or leveling dunes, and sometimes creating new inlets. Measuring the magnitude of barrier island sediment movement during and after storms allows us to track rates of beach recovery, dune growth, and inlet-related alterations to barrier island sediment supply.

Introduction

Storms affect barrier islands immediately and dramatically, but they also drive sediment fluxes that help barriers adjust to changes in sea level. As part of the Coastal Sediment Availability and Flux project, we measure the changes storms make to barrier islands, such as how the volume of beaches and dunes change, where that sediment goes (either offshore or landward), and how developed and undeveloped parts of barrier islands respond differently. This information, coupled with an estimate of storm frequency, gives us some insight into the potential magnitude of long-term fluxes which we can integrate with models to make predictions about long-term barrier island vulnerability.

 

Barrier-estuary system change from Hurricane Sandy

Estuarine deposition (green) after Hurricane Sandy breached the island in two places (arrows).

Big storms move sediment from the front of the barrier to the top and the back of the barrier through a process called overwash. In addition to causing a lot of overwash, Hurricane Sandy also cut through (breached) the island in two places on Island Beach near Mantoloking, NJ, resulting in deposition (shown in green shades) in the estuary.

(Credit: Jennifer Miselis, USGS. Public domain.)

Vulnerability of Island Beach due to varying rates of sea-level rise (SLR). Top: lower SLR rate. Bottom: higher SLR rate.

Predictions of future vulnerability of Island Beach, NJ based on sediment flux estimates from Hurricane Sandy. The two panels display black and white vertical lines overlayed on a map of Island Beach, NJ. The top panel represents a sea-level rise rate of 7mm/year shows mostly black lines, while the bottom panel, represents a sea-level rise rate of 10mm/year, shows mostly white and gray lines. Black lines indicate that it is possible for the barrier to keep up with sea-level rise, whereas as white and gray lines indicate the barrier may be vulnerable to sea-level rise.

(Credit: Jennifer Miselis, USGS. Public domain.)