Coastal wetlands such as salt marshes and mangroves provide a promising solution to future sea level rise and increased storminess. The growing interests in understanding and modeling of wave-current interaction with coastal wetlands have increased recently for Natural-based costal protection. The SWAN (Simulating Waves Nearshore) model has achieved good simulating results on vegetation-induced wave dissipation in the condition of pure waves, while the effects of the tidal currents are ignored. A revised formula based on Hu Suzuki, Zitman, Uittewaal and Stive (2014) formulation, in which the influences of currents and an empirical relationship of Re-CD are involved, is implemented into the full spectrum model SWAN. Results show the optimized numerical model has the ability to calculate wave damping due to plants in the condition of the pure waves or the combined of waves and currents. The numerical model can provide a better tool to assess the valuable protection services provided by coastal wetlands.
Coastal vegetation such as mangroves and salt marshes plays a significant role in dissipating waves energy and reducing shoreline erosion as the sea level rises (SLR) and the frequency and intensity of storms increases (Gabler, Osland and Grace,2017; Jankowski, Törnqvist and Fernandes,2016). Furthermore, aquatic vegetation existing in the coastal wetlands can also provide a critical ecosystem services including water purification, carbon sequestration, biogeochemical cycles controlling and sediment trapping (Ros et al., 2014). The wetlands and estuary region are always in a complex hydrodynamic environment with the coexistence of waves and currents which may be tidal current, ocean current, local wind generated current, river current and wave generated current. Many studies have shown that wave-current interactions produce different wave damping patterns in comparison with the pure wave conditions. But to date, there is still a lack of research on the mechanism of wave dissipation by plants in the case of wave-current coupling and most of the relevant numerical models can only calculate wave energy attenuation under pure wave conditions.