Review of Long Wave Dynamics over Reefs and into Ports with Implication for Port Operations

Abstract

This paper reviews the dynamics of infragravity (long-period) waves over reef systems and the consequences of these waves for operations in ports located behind reefs with particular attention to Western Australia. Swells which originate in the Southern Ocean generate long (infragravity) waves, which propagate to the coast. On the reef edge, the swell waves are largely dissipated, transferring energy to turbulence and heat but also in that process generating long wave energy. The remaining swell waves are dominated by the infragravity waves and propagate towards the mainland and into port basins where they cause moored ship motions with consequences for the operational downtime of the port's operations. When contemplating solutions to mitigate the impact of the long wave problems, these may be addressed from two sides: from the load side (waves) and the strength side (mooring). The former will be discussed in this paper.

Nonhydrostatic and surfbeat model predictions of extreme wave run-up in fringing reef environments

“…Fringing reefs are characterized by a seaward sloping reef face leading up to a shallow reef flat platform that extends towards the beach. Wave transformation in these environments is subject to several simultaneous and interacting processes [15], which include: shoaling; dissipation by wave breaking [16]; wave-induced setup [5,17]; nonlinear energy transfer to higher and/or lower (infragravity) frequencies [18][19][20]; dissipation by bottom friction [21]; low-frequency wave reflection; and resonance [22],…”

“…Given that low-frequency motions often dominate near the shoreline of fringing reef environments, it is imperative that the numerical model applied be able to correctly describe the non-linear transfer of wave energy to the infragravity (low-frequency) band [28,33,20]. For this study, we consider the XBeach numerical model that combines both phase-resolving and phase-averaged approaches.…”