Experimental Study on Hydrodynamic Characteristics of Vegetated Ecological Honeycomb Revetment Under Irregular Waves

With the comprehensive consideration of natural environment and the requirements for bank slope protection, the research on the hydrodynamic characteristics of vegetated ecological revetments is crucial for the development of ecological revetments, as well as the management and protection of bank slopes. To study the hydrodynamic characteristics of a composite revetment system combining flexible vegetation and honeycomb structures under irregular waves, a revetment system consisting of Suaeda salsa which is typical in the coastal area of Tianjin and honeycomb structures is taken as a research object in this paper, and water-tank model experiments were conducted under irregular waves, so as to examine the effects of plant density and plant height on the irregular wave run-up, overtopping and near-bed flow velocity. Results demonstrate that both the wave run-up and the overtopping of irregular waves decreased with the increasing plant density and plant height. The attenuation rates of irregular wave run-up ranged from 10% to 50% across the tested conditions, while the maximum attenuation rate of overtopping exceeded 90%. At the design high-water level, a smaller plant height was found to slightly increase the near-bed flow velocity, whereas a greater plant height can effectively reduce the velocity, thereby mitigating the impact of potential slope scour. Compared with the experimental results under regular waves, the attenuation rate of irregular wave run-up was as low as 40%, while the attenuation rate of overtopping can reach over 90%. These findings confirm that the plants are more effective for the attenuation of irregular wave run-up, but they are conducive to the attenuation of overtopping under both the regular and irregular waves. Therefore, the vegetated ecological honeycomb revetment can effectively dissipate the incoming wave energy under both waves, and its protective performance can be enhanced by increasing the plant density and height. The exploration of the effects of the density and height of flexible vegetation on the hydrodynamic characteristics of ecological honeycomb revetments can provide a reference for the design and construction of similar ecological revetment engineering.