Flume experiments were performed to test four plant mimics with different stiffness to reveal the effect of plant stiffness on the wave dissipation and turbulence process. The mimics were built of silica gel rod groups, and their bending elastic modulus was measured as a proxy for stiffness. The regular wave velocity distribution, turbulence characteristics, and wave dissipation effect of different groups were studied in a flume experiment. Results show that, when a wave ran through the flexible rod groups, the velocity period changed gradually from unimodal to bimodal, and the secondary wave peak was more apparent in the more flexible mimics. The change in the turbulence intensity in the different rod groups showed that the higher the rod stiffness, the greater the turbulence intensity. With an increase in the bending elastic modulus of a rod group, the wave dissipation coefficient increased. The increase in the wave dissipation coefficient was not linearly correlated with the bending elastic modulus, but it was sensitive within a certain range of the elastic modulus.Water 2019, 11, 109 2 of 15 study the effect of changes in the wave height and wave form. Incident wave height, plant densities, reflection, transmission coefficient, and the wave energy dissipation were investigated. Moller and Spencer discovered that wave height decreased exponentially in a vegetated area [19]. Quartel et al. [20] performed an experiment at the Red River Delta in Vietnam and found that the wave dissipation ability of mangrove areas is five to 7.5 times more than that produced due to bottom friction. Bradley and Houser [21] quantitatively analyzed the effect of the relative movement of flexible seaweed leaves on wave height reduction in a reversing current. Fonseca and Cahalan [22] and Augustin et al. [11] showed that, when the height of seaweed was greater than or close to the water depth, the wave dissipation effect was obvious, and when the plant was submerged, the wave dissipation effect decreased with increased water depth. Tschirky and Hall [23] and Lima et al. [24] performed experiments that indicated that an increase in plant density enhanced the wave dissipation effect. However, Mazda et al. [25] and Horstman et al. [26] found that when the water depth in the mangrove was more than the height of the aerial roots, an increase in water depth reduced the wave dissipation effect, and when the water depth increased to the height of the mangrove leaves, the wave dissipation effect increased. Cruise and Muslesh [27] used a rigid pole to simulate the emerged portion of rigid vegetation and studied the effect of plant diameter and arrangement on water depth and velocity. White and Nepf [28] also studied the plant drag force, flow turbulence, and diffusion with a rigid rod.Currently, there are many laboratory studies on vegetation under unidirectional currents and/or waves [29][30][31][32], field studies on wave dissipation through flexible vegetation [33][34][35][36], and turbulent flow through real mangrove roots [37]. However, ...