Author(s): Paran Pourteimouri; Suzanne J.M.H. Hulscher; Bas W. Borsje
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Keywords: No Keywords
Abstract: Living Dikes, which combine engineered dikes with vegetated foreshores such as salt marshes, are increasingly recognized as a sustainable alternative to traditional coastal defenses (Möller et al., 2014). Vegetation on foreshores attenuates waves before they reach the dike, reducing hydrodynamic loading on the dike and thereby lowering the required dike height and maintenance needs, while enhancing ecological and climate-resilience benefits. As sea-level rise and storm intensification increase pressure on flood defenses, understanding the underlying bio-physical mechanisms and optimizing nature-based solutions are crucial for ensuring long-term coastal resilience. A key factor determining the effectiveness of Living Dikes is the influence of vegetation traits on wave attenuation. Characteristics such as height, stem thickness, root spacing, branch density, intertwining length, and flexibility strongly affect drag forces, bed shear stress, and turbulence around stems, thereby controlling wave energy dissipation (Nepf, 2012). Although experiments have shown that vegetation can substantially reduce wave impacts (Möller et al., 2014; Keimer et al., 2021; Vettori et al., 2025), few numerical models capture the coupled wave–vegetation–dike interactions or systematically quantify the influence of vegetation traits on flow mechanisms and wave attenuation. This study investigates how branch density within vegetation patches influences flow characteristics that govern wave energy dissipation and, consequently, hydrodynamic loading on dikes. The findings provide practical insights for the design of Living Dikes and for improving vegetation parameterizations in large-scale coastal models.
Year: 2026