Abstract: To understand the role of reef crest in wave transformation and wave-induced setup over fringing reef, a series of experiments were carried out in a wave flume using idealized models that simulate a field fringing reef with the presence of a reef crest. Experimental results were reported for four water depths and for a variety of regular wave conditions. Preliminary analysis showed that the presence of the reef crest significantly alters the wave transformation process near the reef edge, especially the intensity of wave breaking and the generation of high harmonic waves. Wave setup was found to increase with the increase of incident wave height and wave period, but decrease with the increase of water depth. The reef crest controls the water level above the reef flat in a way similar to that a submerged breakwater controls the water level on the leeside of the breakwater; wave setup over a reef flat with a crest is generally much larger than that without; and a new dimensionless parameter to analyze the wave setup is introduced in order to take the crest configuration into consideration.

Key words: wave transformation, wave-induced setup, reef crest, laboratory experiment, dimensionless parameter