AbstractSeveral studies have reported the development of undular bores over fringing coral reefs (e.g, Gallagher, 1976; Nwogu and Demirbilek, 2010) but the importance of this phenomenon for reef hydrodynamics has never been studied. Yet, the transformation of a long wave (e.g., swell or infragravity wave) into an undular bore leads to significant modifications of the wave field. The formation of undulations is for example associated to a significant increase of the leading bore height. Moreover, if the undulations have enough time to develop (i.e. if the reef flat is wide enough), the initial long wave will ultimately split into a series of solitons (e.g., Grue et al., 2008). All this is likely to affect wave run-up. As reeffronted coastlines are particularly vulnerable to flooding, a good understanding of long wave transformation over the reef flat, including their possible transformation into undular bores, is crucial. In this study, we investigate undular bore development over reef-type profiles based on a series of laboratory experiments. More specifically, we aim to characterize the conditions under which undular bores develop, and analyse how their development affect the hydrodynamics at the toe of the reef-lined beach and the resulting wave run-up.
Dekkers (2017): Experimental study on undular bore
development over coral reefs, MSc thesis, TU Delft.
Grue et al. (2008): Formation of undular bores and
solitary waves in the Strait of Malacca caused by the 26
December 2004 Indian Ocean tsunami, Journal of
Geophysical Research, 113 (C05008).
Gallagher (1972): Some quantitative aspects of nonlinear
wave radiation in a surf zone, Geophysical&
Astrophysical Fluid Dynamics.
Nwogu and Demirbilek (2010): Infragravity Wave Motions
and Runup over Shallow Fringing Reefs, J. Waterway,
Port, Coastal, Ocean Eng.