Artificial reefs

Introduction

An artificial reef (AR) is a man-made submerged structure whose main goal is to reduce incident waves by inducing wave breaking. However ARs are often constructed as multipurpose structures, i.e. not only to defend the coast from erosion but also to maximise secondary objectives such as to improve spot surfability, to stabilize nourishment material and to create marine parks of increased biodiversity. The design criteria for this structures are not easy to be defined a priori.

Materials

Stones

Stones are used especially for rubble mound structures whose hydraulic stability is verified through the formulae available in literature for low-crested structures (Burcharth et al., 2007).Un-corrected design of the structure (and thus a wrong selection of stone size) causes a low efficiency of the AR. Structure reshaping induced by wave breaking over the reef may occur and produce instability, with stones rolling down from the structure. Stones are relatively cheaper than other materials but can be more dangerous for surfing safety.