Models of alongshore sediment transport during quiescent conditions, storm‐driven barrier island morphology, and poststorm dune recovery are integrated to assess decadal barrier island evolution under scenarios of increased sea levels and variability in storminess (intensity and frequency). Model results indicate barrier island response regimes of keeping pace, narrowing, flattening, deflation (narrowing and flattening), and aggradation. Under lower storminess scenarios, more areas of the island experienced narrowing due to collision. Under higher storminess scenarios, more areas experienced flattening due to overwash and inundation. Both increased sea levels and increased storminess resulted in breaching when the majority of the island was not keeping pace and deflation was the dominant regime due to increased overtopping. Under the highest storminess scenario, the island was unable to recover elevation after storms and drowned in just 10 years.

This study presents a broad overview of surface gravity wave dynamics in Delaware Bay and the adjacent continental shelf by employing the wave model Simulating Waves Nearshore one‐way coupled to the ocean model Regional Ocean Modeling System for a period from 2006 to 2012. The distributions of simulated wave statistics agree well with observations obtained from three wave buoys located on the shelf, in the bay near the open ocean, and about 35 km up the bay. A partitioning analysis to separate the two‐dimensional wave height spectrum into wind‐forced and swell parts reveals that waves on the shelf are predominantly remotely generated swell. Bathymetric refraction shelters the bay from energetic open ocean waves, which is supported by an idealized ray tracing analysis. Waves near the bay entrance are also refracted by oblique tidal currents, whose refraction characteristics critically depend on the detailed spatial distributions of the currents. Opposing tidal currents, flowing against the wave propagation direction, focus wave energy outside the bay entrance and in the deeper bay channels, where currents are relatively strong. A spectral partitioning analysis for waves in the bay indicates that less energetic wave fields are likely not directly forced by the wind. More energetic waves, on the other hand, are dominantly driven by winds and the wave response in the bay depends on the fetch‐setting wind direction. Our results for wind‐driven waves in the bay are consistent with previous fetch‐limited observations, but we find a systematic bias between wind and wave directions due to bathymetric refraction.

The effects of interior headland restoration on estuarine sediment transport processes were assessed through process-based numerical modeling. Three proposed interior headland restoration scenarios in the Grand Bay estuary (Mississippi/Alabama) were modeled using Delft3D to understand impacts on suspended sediment concentrations, bed level morphology, and sediment fluxes under present-day conditions and a sea level rise (SLR) of 0.5 m, representing a high projection of SLR by the year 2050. Model results showed localized differences in bed levels near the restored features after a year of simulated morphologic change. The restored headland features acted as a sediment source to the immediate surroundings while also providing some non-significant sheltering effect of backshore shoals and marsh shorelines. Sediment fluxes were sensitive to wind directions and the presence of the restored headlands. However, regardless of wind direction, mean sea level, or restoration action, the greatest sediment fluxes were always export fluxes from the estuary, which were further increased with increased sea level. Suspended sediment concentrations were highly influenced by SLR in a non-linear manner. Sediment concentrations both increased and decreased depending on depth under SLR. Furthermore, SLR allowed for the suspension and deposition of sediments on the marsh platform. Overall, the influence of SLR was more impactful to changing sediment dynamics than the influence of the restoration features.

Forecasting barrier island evolution provides coastal managers and stakeholders the ability to assess the resiliency of these important coastal environments that are home to both established communities and existing natural habitats. This study uses an established coupled model framework to assess how Dauphin Island, Alabama, responds to various storm and sea-level change scenarios, along with a suite of restoration measures, over the course of a decade. The coupled model framework uses validated models for long-term alongshore sediment transport (Delft 3D), short-term storm induced impacts (XBeach), as well as dune building and recovery (empirical dune growth model). This model framework was simulated with the various storm and sea-level change scenarios on a non-restored Dauphin Island, then a subset of the storm and sea-level change scenarios were applied to a suite of seven different restoration measures to determine how they would influence the morphologic evolution over a decadal period. Topographic and bathymetric changes captured in post-simulation digital elevation models were then passed on to partners for various simulations to determine the effects on habitat evolution and water quality as it relates to oyster reef and submerged aquatic vegetation.