The dynamics of infragravity wave transformation over a fringing reef

A fringing reef at Ningaloo Coast, Western Australia, exhibits unique dynamics where infragravity waves—low-frequency ocean motions—dominate over short-period waves on the lagoon side due to efficient generation by breakpoint forcing on its steep fore-reef slope. This study, combining field observations and numerical simulations, revealed that while both wave types remain small (<0.3 m) in shallow reef waters (<2 m), infragravity waves persist further inland, their propagation modulated by tidal water levels. Frictional dissipation dampens these waves but at a slower rate than short waves, leading to the dominance of progressive (shoreward-moving) infragravity motions across the reef and lagoon. The findings challenge conventional assumptions about wave behavior in such environments, offering critical insights for understanding coastal processes in fringing reef systems.

Pomeroy, A., Lowe, R., Symonds, G., Van Dongeren, A., & Moore, C. (2012). The dynamics of infragravity wave transformation over a fringing reef. Journal of Geophysical Research: Oceans, 117(C11). Portico. https://doi.org/10.1029/2012jc008310