Ky =Vi^To)^ -^ (Kn)2 = ^k'/^h 



Figure 1. Definition of terms for wave transmission 

 for permeable breakwaters. 



II. WAVE TRANSMISSION BY OVERTOPPING 



Wave transmission by overtopping occurs when wave energy is trans- 

 mitted by flow over the top of a structure. The transmission by over- 

 topping coefficient can be estimated using (Seelig, in preparation, 

 1979)^ : 



Ky^ = C (1-F/R) 



= for F/R greater than 1.0 



(2) 



where 

 R 

 F 



C 



(Ky^)max 



= wave runup 



breakwater freeboard, defined as the structure 

 height, h, minus the water depth, d 



= an empirical coefficient 



= 1.0 



Laboratory tests show that the value of C is related to the crest width 

 of the structure, B: 



0.51 - 0.11 B/h 



(3) 



Thus, a slight decrease in the transmission by overtopping occurs as the 

 structure crest width increases. 



3SEELIG, W.N., op. cit. , p. 7. 



