Laboratory investigation of the breaking wave characteristics over a barrier reef under the effect of current

Abstract

ABSTRACTRecent field studies have increasingly recognized the importance of tides in dominating the coral reef hydrodynamics. Aside from the tidal level, it is also important to evaluate the effect of tidal current on wave breaking over coral reefs. In this study, a series of laboratory experiments were performed in a wave-current flume in the presence of both flooding and ebbing tides. Experimental results are reported for a variety of combined wave-current conditions based on an idealized barrier reef model. Results analyses show that the relative reef-flat submergence (the ratio of reef-flat submergence to deep-water wave height) is a key parameter to characterize such breaking-wave characteristics as the breaker type, the breaking location, the surfzone width, and the breaker depth index. The influences of the current flowrate on the breaking location, the surfzone width, and the breaker height index appear to be significant within our tested ranges. Empirical formulas to predict these characteristics in the existing literature are also improved to account for the current effect.