MEPS 456:63-72 (2012)  -  DOI: https://doi.org/10.3354/meps09754

ABSTRACT: We demonstrate the utility of using the equivalent bottom roughness for calculating the friction factor and the drag coefficient of a seagrass meadow for conditions in which the meadow height is small compared to the water depth. Wave attenuation induced by the seagrass Posidonia oceanica is evaluated using field data from bottom-mounted acoustic doppler velocimeters (ADVs). Using the data from one storm event, the equivalent bottom roughness is calculated for the meadow as k_s ~ 0.40 m. This equivalent roughness is used to predict the wave friction factor ƒ_w, the drag coefficient on the plant, C_D, and ultimately the wave attenuation for other storms. Root mean squared wave height (H_rms) is reduced by around 50% for incident waves of 1.1 m propagating over ~1000 m of a meadow of P. oceanica with shoot density of ~600 shoots m⁻².

KEY WORDS: Wave attenuation · Posidonia oceanica · Seagrass meadow · Bottom roughness · Friction coefficient · Drag coefficient · Wave damping