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Marsh barrier beaches form a line of defense against storm surges and sea level rise for coastal communities. Along the Massachusetts coastline near Boston, USA, there are several beaches composed of coarse pebbles and cobbles, transitioning into a diverse intertidal zone with mud flats, sand, gravel, and boulders. However, their low elevation and proximity to the ocean render them susceptible to erosion and coastal inundation. Winter storms and Nor'easter events further intensify these threats, posing challenges for both the natural habitats within the system and nearby infrastructure. To address these challenges and optimize coastal protection strategies, advanced numerical modeling techniques are increasingly being used.

One approach to coastal protection is beach nourishment, which involves adding sand or compatible material to replenish the beach profile. This study utilizes the SWAN (Simulating WAves Nearshore) and XBeach coastal modeling tools to evaluate the effectiveness of different beach nourishment strategies under various forcing conditions. SWAN, a third-generation wave model, computes wind-generated waves providing insights for setting boundary conditions in XBeach. SWAN operates by solving the spectral action balance equation, accounting for wave generation, propagation, transformation, and dissipation. XBeach is a process-based numerical model capable of simulating morphological changes during storm events. It computes radiation stress gradients and employs a generalized Lagrangian mean formulation to account for short wave-induced mass fluxes and return flows in shallow waters. Sediment transport rates are calculated via an advection-diffusion equation, incorporating the Soulsby-Van Rijn formulation for equilibrium concentration source-sink terms.

Our study selected four beach profiles, capturing variations in morphology and sediment composition in the area. ÑÇÐÇÓÎÏ·¹ÙÍø then conducted simulations to explore three nourishment scenarios, facilitating a comparison of coastal resilience strategies. Incorporating potential sea-level rise projections, our simulations provided data on key metrics such as post-nourishment wave runup levels, overwash extents, and predicted beach profile changes post-storm. Our analysis extended to evaluating the associated costs of implementing and maintaining each nourishment approach, ensuring a balanced approach between protection benefits and economic feasibility. Furthermore, we identified strategies aimed at minimizing disruption to sensitive habitats, such as adjacent salt marshes, and even incorporated techniques to enhance their overall health and resilience.

Our study utilizes a data-driven methodology to assess nourishment strategies for marsh barrier beaches in Massachusetts. ÑÇÐÇÓÎÏ·¹ÙÍø analyze various factors, including effectiveness, cost-efficiency, and ecological impact. The simulation-derived data aids decision-making and facilitates the adoption of evidence-based coastal protection measures. By integrating environmental, social, and economic considerations, our study contributes to the development of resilient coastal communities. Ultimately, our findings aim to empower decision-makers with the insights needed to implement sustainable and effective coastal protection strategies in the greater Boston area.