Review of wave attenuation by artificial oyster reefs based on experimental analysis

In recent years, soft engineering coastal protection based on oyster reefs has emerged as a sustainable solution. However, the mechanism and quantification of wave attenuation by oyster reefs remain unclear. This review briefly presents the development process of wave attenuation by artificial oyster reefs in experiments, with the aim of providing a basis and reference for future studies and projects on wave attenuation by oyster reefs. The dimensionless height hs/d and dimensionless crest width B/Hi are considered essential parameters affecting wave attenuation. The wave transmission coefficient decreases as the dimensionless height or crest width of the reef increases. When the dimensionless height is greater than or equal to 1.0, the wave transmission coefficient is less than 0.5. The wave attenuation effect varies broadly among reefs. Compared to Reef Balls, Wave Attenuation Devices, and Reef BLK, Oyster Shell Bag exhibits a smaller wave transmission coefficient. Wave attenuation factors caused by oyster reefs include wave breaking, reflection, overtopping, and frictional dissipation; among them, wave breaking is considered the most essential mechanism for the energy attenuation of submerged structures. Finally, an outlook from the perspectives of the oyster reef wave attenuation mechanism, parameterised prediction, optimal layout, and monitoring is presented.