{Update} Bagged Oyster Shell Breakwater

A preliminary analysis of the data obtained during the wave basin testing of bagged oyster shell has been completed.  Forty-three experiments were conducted yielding unique combinations of structure height, structure length, and wave characteristics.  The ratio of incident and transmitted wave heights were compared to published methodologies for estimating wave transmission at low-crested rubble mound structures.  In general the equations, limits, and methodologies described in Van der Meer et al. (2005) tend to overestimate the transmission coefficients measured in the laboratory experiments, but a simple linear regression on a direct (one to one) comparison of predicted and measured values yields a coefficient of fit of 91%.

While the limited data suggests that existing methodologies for estimating wave transmission at rubble mound structures could potentially be used in the design of bagged oyster shell breakwaters, the following should be addressed through continued experimentation:

• An expanded test matrix should be developed that includes analysis of additional monochromatic waves, as well as simulation of random waves.
• The summative contributions of wave reflection and overtopping should somehow be segregated from actual transmission through the structure, and the overall contributions of each compared to one another.
• The frequency attenuation of such structures, regardless of their material composition, should be explored in more detail for regular and irregular waves since wave period places an important role in sediment transport.