Surf Reefs – Physical Modelling Results, Not Pipe Dreams

This paper discusses the diverse needs for near-shore reefs required to serve for both coast protection and to improve surfing, and how they impact on each other when a multi-purpose reef is designed. Two case studies using extensive physical modelling are discussed. At Borth, the modelling looked at optimising the design of two offshore multi-purpose reefs as part of a wider coastal defence scheme. Initial designs were changed to a single multi-purpose reef after the physical modelling showed that wave interactions between the reefs reduced their overall surfability, further contribution to coast protection were provided by an additional low crested breakwater. At Jumeirah, the modelling tested a single multi-purpose reef and its effect on the shoreline position in its lee. The modelling showed that the reef was able to produce a degree of surfable waves and also had an impact on the coast protection behind it. The authors of this paper believe that the physical modelling of the reefs allowed beneficial design refinement of the multi-purpose reefs to increase their effectiveness for both surfing and coast protection.