WAVE DYNAMICS AND REVETMENT DESIGN ON A NATURAL REEF

Abstract

In connection with hydraulic studies of a new coastal resort development on the south-east coast ofBali in Indonesia, a three-dimensional (3D) physical model study was carried out. The study was aimed at the determination of the wave transformation over a shallow natural reef in front of the resort and for the design of the rubble mound revetments to be builtfor coastal protection. Due to the heavy wave breaking on the reef, physical model tests were the only viable avenue for obtaining a reliable design of the revetment structures located behind the shallow reef area. The stability of the armour layer as well as the overtopping of the revetments were equally important aspects of this part of the study, since not only should the resort be protected against storm waves, but visitors should also be able to comfortably visit the coastal areas during more normal wave conditions. This paper mainly concerns the wave dynamics on the reef. Due to the limited water depth the wave conditions were dominated by heavy wave breaking and the associated release of the bound long-period wave components in the wave groups of the incident wave train. These long-period wave components caused a dynamic water level set-up with long-period variations in front of the revetments (surf beats). The depthlimited wave conditions on the reef and the dynamic water level set-up had major influence on the evolution of damage and overtopping of the revetments and made the design of the revetments particularly complex.