Since over half the world's population lives in coastal zones, climate change and its consequences, like sea-level rise and intensifying tropical cyclones, are known as escalating threats. As a result, coastal areas experience higher storm waves, which increases vulnerability to coastal hazards. Despite the fact that hard engineering solutions are often effective in protecting coastal zones from high waves, they may produce substantial drawbacks for the natural environment. As a possible sustainable alternative, natural-based soft-engineering utilizing natural infrastructure, like oyster reefs, has attracted interest for its ability to protect coastlines while mitigating climate impacts.

Artificial oyster reefs are often compared to traditional low-crested breakwaters, which have been extensively studied. However, because of the variations in reef types, porosity, and rough surfaces, it is still uncertain whether their effects on wave attenuation and hydrodynamics are consistent across different conditions. To address this gap,  this study will conduct a physical experiment to assess the wave attenuation capabilities of multiple artificial oyster reefs with different geometric parameters when encountering various regular wave conditions. Besides, impermeable and porous configurations are compared to investigate the energy dissipation over the porous oyster shells. A series of dimensionless variables, such as the relative submergence and the relative length and distance of oyster reefs, are analyzed for their impact on wave reflection, transmission, and dissipation. The wave attenuation mechanisms on artificial oyster reefs will be revealed as a result.

The findings indicate that artificial oyster reefs can effectively reduce wave energy, helping to protect the coastal shoreline. They also have the added benefit of minimizing seabed scour in their vicinity. These results are valuable for understanding how artificial oyster reefs attenuate waves and for optimizing their layout in the future.

wave attenuation,transmission coefficient,Artificial oyster reefs,Porous media,physical model