Modeling of Barrier Breaching During Hurricanes Sandy and Matthew

Abstract

Morphological changes to barrier islands have long been understood and evaluated within the context of the Sallenger (2000) storm impact scale, which identifies regimes of storm-induced changes based on comparison of total water levels to the elevations of the dune toe and dune crest. Significant morphological changes to the nearshore, beach face and berm, dune, and back-barrier occur as ocean water levels increase through swash, collision, overwash, and inundation regimes (Sallenger, 2000). During collision, sediment is eroded from the dune toe and beach face and transported offshore, often accumulating in shore-parallel nearshore bars. During overwash and inundation, sediment transport is primarily directed toward the back-barrier, creating washover fans that are critical to barrier island evolution over long time scales (decades to millenia; Donnelly et al., 2006). Modifications to barrier island topography during hurricanes, for example, breaching, can influence flooding dynamics

Entrainment and Transport of Well‐Sorted and Mixed Sediment Under Wave Motion

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Predicting hydrodynamic evolution and the underlying morphodynamics shoreward of the wave shoaling zone is an ongoing challenge in coastal oceanography. Considerable effort has been made using regional-scale modeling tools to predict the hydrodynamics and the beach response to high energy storm events as well as beach recovery under low energy waves (Hegermiller et al, 2022;Rafati et al, 2021;Van der Lugt et al, 2019). These modeling frameworks, formulated as short-wave-averaged models, are not designed to simulate wave-by-wave hydrodynamic and sediment transport processes.

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Development and Application of an Infragravity Wave (InWave) Driver to Simulate Nearshore Processes

“…This modeling system can resolve the mesoscale oceanic features and downscale to coastal areas including IG waves and nearshore circulation. For example, Hegermiller et al (2022) used the InWave-ROMS model to demonstrate that water level variations due to IG waves were essential to be able to numerically reproduce breach generation during Hurricane Matthew (2016). The modeling system can also be applied to estuaries and inlets where the vertical structure of the flow might be relevant.…”

“…The reader is referred again to Bertin et al (2018) for a detailed description of their dynamics and implications. Recent publications (e.g., Hegermiller et al, 2022;Sherwood et al, 2022) highlight the relevance of IG waves to correctly estimate the coastal erosion, breach generation, and flooding processes associated with extreme storms. Here, we present InWave, a new IG wave driver within the COAWST modeling system.…”

Drivers of dune formation control ecosystem function and response to disturbance in a barrier island system

“…A range of different methods exist to predict water dynamics and sediment movement on coastal beaches. Numerous process-based models exist to simulate factors like wave setup, swash processes, beach and dune evolution, dune breaching, and overwash processes 54 – 56 . XBeach 57 is among the most widely used tools for storm forecasting of overwash processes, although models such XBeach have been shown to be highly sensitive to pre-storm bathymetric inputs 58 ; data which are not available for this field study.…”