about this analysis is that the reef does not produce much shift in the peak 

 period of the spectrum. In fact, in only a few tests was the shift as much as 

 10 percent. 



Wave Reflection and Energy Dissipation 



36. The method developed by Goda and Suzuki (1976) to resolve the wave 

 spectrum into incident and reflected components is the method used in this 

 study to calculate the reflection coefficient. According to Goda and Suzuki, 

 the reflection coefficient is defined as 



where E and E are the reflected and incident wave energy of the spec- 

 trum, respectively. 



37. One variable, the reef reflection parameter, was found to be con- 

 spicuously better than others for predicting wave reflection and is formulated 

 as 



This parameter can be thought of as approximately the ratio of wave length to 



horizontal distance between the toe of the reef and the swl on the reef. 



Since, for many tests, the reefs are deformed and/or submerged, the quantity 



(A /h )d is sometimes only indicative of this horizontal distance. When K 

 \ t c/ s r 



is plotted versus the reef reflection parameter, a very strong data trend re- 

 sults (Figure 25) . Such a strong trend seems surprising considering the com- 

 plex nature of irregular wave reflection and the wide range of conditions 

 represented in Figure 25. A regression equation was fit to the data shown in 

 Figure 25 to provide a convenient rule-of-thumb method to estimate reflection 

 from a reef and to provide insight relating to wave reflection from coastal 

 structures in general. The equation is given by 



36 



