Experimental study on wave attenuation and cross-shore profiles by submerged flexible vegetation

Research on the wave dynamics in vegetated zones, encompassing the force interaction, the wave attenuation, and the subsequent morphological evolution behind the vegetation, helps evaluate the role of vegetation. In this study, artificial leafy mimics were employed in flume experiments to investigate the influence of vegetation on regular wave attenuation and beach profile evolution. Variations in the wave height and force were analysed in the vegetation zone. Results show that flexible vegetation substantially attenuates waves, leading to a reduction in wave height ranging from 11.6% to 46.1% and a decrease in drag force ranging from 36.0% to 90.2%. The empirical formulae for CD with KC and Re were obtained. Furthermore, the final cross-shore beach profiles of the vegetated and unvegetated were analysed, and the presence of vegetation prevented further erosion of the beach, resulting in a reduction of 26.5% in experiments. Vegetation not only reduced the erosion depth but also brought the eroded regions nearer to the shoreline by dampening wave energy. Additionally, dimensionless parameters were formulated to characterize the response of the cross-shore beach profile under the shelter of flexible vegetation, and three empirical equations relating to erosion volume, distance, and depth were developed.