Interaction between waves and vegetation.

This paper investigates the complex interaction between wave hydrodynamics and aquatic vegetation, emphasizing its importance for the management of coastal ecosystems. Vegetation plays a crucial role in the dynamics of river and coastal flows, influencing their structure and turbulence, as well as the transport and distribution of nutrients, sediments, ecosystems, and habitats. For example, mangroves serve as a natural defense against tsunamis and extreme waves. Nature-based coastal defense technologies are increasingly being adopted, in alignment with the principles of ecohydraulics. Riparian vegetation represents one of the most effective nature-based solutions for coastal protection. In addition, lagoons and estuarine areas often feature structures such as mussel farms and boat guides, such as the Venetian Briccole. Therefore, accurate evaluation of wave transmission through cylindrical stem arrays is essential to assess their coastal protection capabilities and designing effective protective structures, such as mangrove restoration projects. This paper presents a theoretical study of wave attenuation for regular (Airy) and solitary waves propagating through rigid, emergent, and submerged cylindrical stems on horizontal and sloping bottoms. The theoretical model results are compared with numerical simulations obtained using the SPH (Smoothed Particle Hydrodynamics) Lagrangian numerical code, which does not rely on mesh-based methods. Furthermore, the bulk drag coefficients of rigid stem arrays are evaluated on the basis of stem density, diameter, and submersion ratio. This paper aims to engage a broad audience, including scientists and practitioners in ecohydrology, coastal hydrodynamics, and environmental management, providing actionable insights to improve the ecological resilience of coastal systems.