F = freeboard of the structure, h - d 



c s 



h = crest height of the seawall 

 c 



d = still-water depth at the toe of the wall or the toe of the 



revetment fronting the wall 



L = Airy wave length calculated using d and T 

 p s p 



H = incident zero moment wave height at or near the toe of the 

 mo 



structure 



Equation 1 can be thought of as the ratio of the freeboard to the severity of 



the local incident wave conditions. 



17. A very valuable characteristic of the freeboard parameter is that 



it combines a lot of information about the structure, water depth, and wave 



conditions into one variable. The parameter F' has higher correlation with 



the overtopping rate for the Roughans Point data than any other parameter 



which could be identified, including the parameter F/H , suggested by the 



work of Goda (1969) and Seelig (1980) or the dimensionless freeboard parameter 



F/(T gH ) used by Owen (1982b), where T is the zero-crossing wave period, 



g is the acceleration of gravity and, H is the significant wave height of 



the spectrum. Figure 10 shows a plot of the overtopping rate as a function of 



- 2 4 



-2.2 



-20 



PROFILE VIEW 



-V*- 



1.8 

 1.6 



I 4 

 I .2 

 I 

 - 8 

 -0.6 

 -0.4 

 -0.2 



45 0.55 



RELATIVE FREEBOARD. F' 



0.0 



0.75 



Figure 10. Overtopping rate versus relative freeboard for the Roughans 

 Point seawall with no revetment (configuration RP-1) 



17 



