A coastal breakwater is an engineered offshore structure, usually made of concrete or rock that is designed to disperse wave energy and reduce shoreline erosion. Breakwaters are generally built parallel to the shoreline. They may be attached to the shore or unattached (as in barrier islands), and above water or fully submerged. They may be built as a single structure or a series of structures.
Living breakwaters, or artificial reefs, are structures designed to be colonized by coral or oysters and to provide habitat for other aquatic species. Living breakwaters can be designed to protect against the effects of storms and coastal erosion.
As waves break on the breakwater, energy is reduced. The waters on the shoreward side of the breakwater are calmer and the wave component of a storm-driven flood is reduced.
The City of Richmond, as a long-term component of its master diking plan and in collaboration with relevant agencies, is considering offshore barrier islands to help dissipate waves and protect the West Dike, minimize the need for future dike crest increases, and create intertidal habitat.