Numerical study for conical wave propagation in slope vegetation waters

The numerical model for wave propagation in vegetation water was developed based on fully nonlinear Boussinesq equation in which the drag force due to vegetation was added. The model was verified by comparing between the numerical and experimental results for wave propagation in vegetation waters. The numerical results are in line with flume experiments. Then the model was used to test waves propagating through a finite patch of vegetation at the bank slope. An analysis is conducted to understand shoaling, breaking and wave-induced current by aquatic vegetation. It is found that the wave height in the vegetated zone is attenuated more rapidly than in the adjacent unvegetated region, which is induced by the damping effects of the vegetation. Compared with the vegetation away from the shoreline, the vegetation affects more on attenuation in the surf zone, no secondary crushing occuring. And wave phase speed and wave length of the broken wave are also decreased in the vegetated region compared to the unvegetated region, which leads to refraction effects bending wavecrests towards the patch in the exterior region. When vegetation is located in inthe surf zone, the wave setup is significantly reduced. In the outer part of the vegetation patch(close to the breaker line), the wave setup is relatively larger. The vegetation has a significant effect on the nearshore circulation, and the nearshore circulation and the large-scale vortex appear on the edge of the vegetation. The distribution of the offshore flow in shore is uniform, the flow velocity is small and the distribution range is relatively large. The farther the vegetation area is from the shoreline, the larger the vortex scale is, and the more intense the offshore flow is.