comparing the overtopping curves. Although in many situations increasing the 

 height of a seawall would be unacceptable, Figure 22 shows that the effective- 

 ness of a cap can be equivalent to placing a great amount of stone in front of 

 the seawall. 



Methods to Evaluate Effectiveness of Seawalls 



28. Figure 22 provides an easy way to evaluate and compare the effec- 

 tiveness of various strategies to reduce overtopping. An extension of using 

 the figure to evaluate strategies would be to compare the area under the 

 curves. The more effective the strategy the less area under the curve. The 

 following parameter is defined to rank the various strategies based on the 

 area under the data trend curves: 



A = Q o J e 



r f' 



Q C.F'. 

 o 1 mm 

 dF = - — e 



F'. 

 mm 



The values of A are shown in Table 1 using F' . = 0.3 . A minimum value 

 q mm 



of F' = 0.3 is used since for F' = 0.3 overtopping rates would probably be 

 dominated by the inundation mode which would create serious problems in con- 

 ducting the laboratory work and would probably cause difficulties in evalu- 

 ating strategies which would be viable at somewhat lower water depths and wave 

 heights. The parameter A is not intended to be used to calculate over- 

 topping rates; rather, it is a measure of the hydraulic performance of a 

 seawall/revetment configuration and can be used to roughly compare the effec- 

 tiveness of various configurations. 



29. Using the values of A in Table 1 and the data trend curves in 



q 



Figure 22, it is easy to recognize the value of various strategies to reduce 

 wave overtopping. Since most of the data shown was collected to solve a site- 

 specific problem, this one set of data may not be ideal for quantifying the 

 effectiveness of one strategy versus another, but the potential of the evalua- 

 tion method presented in this section can be clearly perceived from this 

 review. Further studies using this evaluation method will be used along with 



32 



