| Abstract | Scaled laboratory experiments were conducted to investigate the relative performance of hybrid shore protection systems composed of various coastal dyke designs fronted by marsh platforms. The experiments were used to identify reductions in incident wave height, wave run-up and overtopping, and damage to armour stone resulting from different marsh vegetation configurations. Model dyke and marsh platform features, loosely based on archetypes found in Atlantic Canada, were constructed in a wave basin at 1:20 scale and exposed to a range of waves and water level conditions. The experiments were conducted using idealized surrogate vegetation, and the model setup featured four parallel flumes which made it possible to investigate alternative marsh-dyke systems simultaneously under identical conditions. The results illustrate the sensitivity of wave attenuation, overtopping, and damage (stone movement) to different components of the hybrid system, including the cross-shore width of the vegetation field, vegetation characteristics (including stem density, height and flexibility), and alternative dyke designs. For the range of wave and water level conditions investigated, the presence of a high-density vegetation field reduced wave heights at the dyke toe by almost 50%, which led to significant reductions in damage to the dyke, and more than a 10-fold reduction in mean wave overtopping discharges. |
|---|
