large masses of "green" water. It is hard to imagine any surface feature of 

 the wall or fine tuning of the fronting revetment being particularly effective 

 for this extreme situation. For the tests conducted in this study, the 

 inundation mode of overtopping occurred primarily when F' was less than 

 about 0.3. Because changes in the geometry of the various seawall/revetment 

 configurations is not very important when overtopping is in the inundation 

 mode, it was not deemed necessary to make comparisons of data trends for F' 

 less than 0.3. 



17. One simple way to evaluate the effectiveness of a seawall/revetment 

 configuration is to use the area under the data trend curve. The less area 

 under the curve the more effective the configuration. Because of the discus- 

 sion given above, a logical lower limit for integration is 0.3, although other 

 limits could be used. The overtopping ranking coefficient A is defined 



- C.F' Q C.F 1 . 

 « n f i jt-.i o 1 min ,_. 



A q = Q Q j e dF' = - g- e (3) 



pi ' 



min 



A is shown in Table 1 using F' m i n = 0.3 . As with any complex phenomenon 

 no single parameter can be used to evaluate performance without considerable 

 care; but because this parameter seems to be such a logical extension of the 

 method of computing overtopping rates developed in this report, it is pre- 

 sented here. When evaluating structures, the smaller the value of A the 

 more effective the seawall configuration. 



18. At the request of NED, overtopping coefficients and overtopping 

 ranking coefficients were calculated for a previous monochromatic wave over- 

 topping study conducted by Saville (1955). Discussion of this effort and 

 tabulation of the coefficients are given in Appendix B. 



Stability of Armor Stone 



19. All configurations tested used the 2, 551 -lb median stone weight, 

 except Configuration 9 which used 4,718-lb medium stone weight (as described 

 in paragraph 5). Occasionally during testing, one or two armor stones would 

 be dislodged, but this movement was not significant; and the armor stone for 

 all configurations, except the double berm in Configuration 5 was observed to 



17 



