Hydrodynamic performance of Gabion Box Artificial Reefs

Naturally occurring shoals and near-shore reefs act as good wave attenuators. Artificial creations of such nature identical attenuators are called artificial reefs. They are being increasingly deployed since the past decade, as artificial reefs may be included under soft engineering approach to protect a coast in an environmentally friendly and aesthetically pleasing manner. Conventional hard approaches like construction of sea wall, groins, revetments, bulkheads and break waters have been known to create negative environmental impacts. Using artificial reefs as shore protection measure one may achieve wave energy dissipation without creating much destructive effects on coastline and its species compared to hard engineering approaches. As they are entirely off the shore and submerged, the aesthetics of the beach is not lost and these types of structures also have the potential to improve the local ecology and recreational amenity like snorkeling and diving. Hence they are often called multipurpose reefs combining the aspects of coastal protection, aquaculture and surfing. Past studies (Pilarczyk et al., 2003) (Shirlal et al., 2007) shows that the artificial reefs are viable shore protection elements dissipating wave energy which are capable of bringing down the transmitted wave height past the structure. Firth et al., (2014) indicate that the artificial reefs made of gabions were colonized by twelve to fourteen different benthic species depending on location of deployment. This author brings out that the Gabions potentially have important habitat-forming value as they are analogous to natural boulders. Black et al., (2001) had come out with the design aspects of narrow neck beach in gold coast and also for incorporating it for surfing, public amenity and coastal protection. Thus there appears to be several positive aspects in using artificial reefs for coastal protection. The objective of the present investigation is to examine the wave dissipation and transmission characteristics with reference to reef parameters. The results of physical model experiments to find the performance of the Gabion Box Artificial Reef will be brought out.