Palm Beach – Queensland

DHI Australia has completed an artificial reef for improving coastal protection and the surfing amenity at Palm Beach

Lifted from:
https://www.dhigroup.com/global/news/2019/11/construction_of_dhi_artificial_reef_design

Designing a complex artificial reef 
The reef design itself has evolved from a rectangular submerged breakwater rotated obliquely to the incident wave direction and with mild seaward facing slopes merging into a conical wave focusing toe.
The design used wave refraction to focus and intensify wave energy towards the shallow crest, and as a result of this, further increase wave dissipation. 
The crest level of the reef was set to 1.5 meters below mean sea level to make sure the reef crest remained submerged during low tide, while still being able to induce wave breaking on most swell conditions.
The shape of the reef was carefully designed to make sure that wave breaking on the reef occurred in a continuous and predictable fashion suitable to most surfers.

A rubble mound rock boulder design was chosen as the best option to assure that the design shape could be achieved in construction and that its structural integrity could be assured during large storms.