High resolution field monitoring in coastal wetlands of the U.S. Mid-Atlantic to support quantification of storm surge attenuation at the regional scale

Abstract:

Hurricane Sandy (2012) demonstrated the vulnerability of the US East Coast to extreme events, and motivated the exploration of resilient coastal defenses that incorporate both hard engineering and natural strategies such as the restoration, creation and enhancement of coastal wetlands and marshes. Past laboratory and numerical studies have indicated the potential of wetlands to attenuate storm surge, and have demonstrated the complexity of the surge hydrodynamic interactions with wetlands. Many factors control the propagation of surge in these natural systems including storm characteristics, storm-induced hydrodynamics, landscape complexity, vegetation biomechanical properties and the interactions of these different factors. While previous field studies have largely focused on the impact of vegetation characteristics on attenuation processes, few have been undertaken with holistic consideration of these factors and their interactions. To bridge this gap of in-situ field data and to support the calibration of storm surge and wave numerical models such that wetlands can be correctly parametrized on a regional scale, we are carrying out high resolution surveys of hydrodynamics (pressure, current intensity and direction), morphology (topo-bathymetry, micro-topography) and vegetation (e.g. stem density, height, vegetation frontal area) in 4 marshes along the Chesapeake Bay. These areas are representative of the ecosystems and morphodynamic functions present in this region, from the tidal Potomac marshes to the barrier-island back-bays of the Delmarva Peninsula. The field monitoring program supports the investigation of the influence of different types of vegetation on water level, swell and wind wave attenuation and morphological evolution during storm surges. This dataset is also used to calibrate and validate numerical simulations of hurricane storm surge propagation at regional and local scales and to support extreme weather coastal resilience planning in the region.

Figure 1 shows an area prone to storm surge impact within one of the 4 study sites: the Dameron Marsh Natural Area Preserve, located on the shoreline of the Northern Peninsula of Virginia, along the Chesapeake Bay.