Hydraulic Design of a Groyne System in Extreme Swell Conditions: a Case Study

Since suitable rock materials for groyne construction are often hard to find in remote areas, a case study has been performed to identify alternative designs for classic rock groynes with concrete elements. Moreover, since design conditions at the particular location are quite severe (Hs = 4.5 m nearshore for return period 50 years and Tp = 16 to 21 s), the required rock sizes would become very large for the available rock quality, and difficult to extract in a quarry without an excess of residual material. Even if such a design would be technically feasible, it would not be economically beneficial. Different alternative solutions have been studied and tested in a physical model. Specific attention has been given to the stability and deformations of the roundhead under the influence of these long waves. Armour elements varied from cubes, Xblocs, Antifers to Haros. Even a new element has been developed and tested for this particular problem: the Harocube.