A numerical model for high resolution simulations of marine fluid dynamics and coastal morphodynamics

Coastal systems are among the most vulnerable areas on our planet, susceptible to both human and natural threats, including coastal erosion due to climate change related processes such as increasing sea level, waves height and storms. Such changes may lead to a shifted sediment dynamics and to exacerbated erosion patterns. In addition, coastal livelihoods in developing countries endure the strongest impact of coastal land loss, which is expensive to be restored by standard engineering, and will increasingly become so in the near future. Resilient, low-cost, and sustainable adaptation measures are clearly required to mitigate the effects of coastal regression in a changing climate. In this work, a novel quantitative method for the coastal zonation to wave-induced chronic erosion threat is developed, in order to overcome the limitations of wave energy underestimation (typically due to biased,large-scale, wave input in nested numerical models) and lack of sediment data. In addition, a new implementation in SWAN is developed to compute the wave damping due to flexible vegetation. It overcomes the parametrization of unresolved flexibility effects into a tunable drag coefficient. The new methods are successfully validated with experimental and field data. They are also combined to study a case of practical interest. Finally, a Nature-Based mitigation solution, focused on P.oceanica meadows restoration, is proposed and quantitatively analyzed the first time in a selected study area.