On the wave attenuation properties of seagrass meadows

The wave attenuation properties of seagrass meadows were investigated in aflume facility using dynamically-scaled models of seagrass exposed to regularlong crested waves. Experiments were conducted for 66 wave conditions andwith four plant densities; waves were measured with eight resistance wavegauges. The data collected represent the most-comprehensive dataset of itskind. They reveal that the wave attenuation coefficient KD of a seagrassmeadow reaches a uniform value after a distance of approximately 1.5 - 3times the water depth from the meadow start and that both KD and the dragcoefficient Cd depend significantly on the plant density. An improved modelof KD based on the work of Lei and Nepf (2019) is proposed that takes intoaccount the effects of the solid volume fraction of the plant model through acorrection on Cd and that of plant density via an effective vegetation frontalarea av-e. The effective vegetation frontal area is described as a power lawof the roughness density ?f . The model, which was validated with the dataof KD obtained from the laboratory experiments described herein, displaysan excellent agreement with data from the literature. It can predict KDaccurately also for cases whereby the maximum wave orbital excursion iscomparable with the blade length, despite this condition violates the model'sassumptions. This work provides a comprehensive dataset and a new modelthat can be used to improve the prediction of wave attenuation of seagrass meadows.