Process Inference from Coastal-Protection Structures to Boulder Beaches

Because boulder beaches and rubble coastal-protection structures have environmental and compositional similarities, beach-boulder movement is examined in the light of engineering studies of protection-structure stability. On a studied boulder beach, sediment transport occurred during 11 storms over a period of 2 years. Wave conditions from these 11 storms are used in two no-damage design formulae in an attempt to mathematically predict boulder movement. The design formulae over-predict the movement threshold of smaller sized beach sediment and under-predict the movement threshold of the larger sediment, however the Hedar formula (developed for low-angle protection structures) yielded the more realistic prediction.