0.3 0.34 0.38 0.42 0.46 05 0.54 058 0.62 



RELATIVE FREEBOARD, F' 



Figure 11. Overtopping rate versus relative freeboard for the Roughans 

 Point seawall fronted by a wave absorber revetment with a berm and a 

 1.0-ft cap on wall (configuration RP-7) 



report are listed in Table 1. Table 1 also gives the value of the overtopping 

 coefficients used in Equation 2 and an overtopping rating coefficient for the 

 configuration (to be discussed later). For the Roughans Point seawall tests 

 the number in the designation is consistent with the configuration number 

 given by Ahrens, Heimbaugh, and Davidson (1986). 



20. Onshore winds can increase the overtopping rate by blowing spray 

 over the seawall or by wind stress on the runup mass on sloped structures. If 

 a seawall is being heavily overtopped by "green water," the additional amount 

 carried over the crest by wind effects is probably not important. However, 

 the portion of overtopping contributed by wind can be expected to increase as 

 the proportion of waves overtopping the wall decreases. The only quantitative 

 guidance on wind effects is in the SPM (1984). A recent brief study* suggests 



* "Assessment of Wind Effects on Wave Overtopping of Proposed Virginia Beach 

 Seawall," Memorandum from Donald T. Resio to Joan Pope, Coastal Engineering 

 Research Center, US Army Engineer Waterways Experiment Station. 



19 



