coefficients also increase with increasing relative reef height 



h /d and increasing relative freeboard F/H until the 

 c s mo 



crest height reaches the upper limit of wave runup. 



Wave energy dissipation characteristics of a reef are difficult 

 to summarize briefly because of the complexity of the phenome- 

 non. One surprising finding was that for short-period waves 



d /L > 0.12 which do not overtop the crest the reef will dis- 

 s p 



sipate 80 to 90 percent of incident wave energy. For reefs 



with the lowest relative crest height tested 0.63 < h /d 



c s 



< 0.70 , the structure would dissipate about 30 percent of 

 incident wave energy. Reefs with their crests near the still- 

 water level will dissipate between 30 to 70 percent of incident 



wave energy depending on the relative reef width A /d L 



t s p 



The model developed in this study was found to make good esti- 

 mates of energy dissipation. 



44 



