APPENDIX B: 



COMPARISON OF SEAWALL PERFORMANCE AND 

 BEACH EROSION EFFECTS 



1. To compare the relative effectiveness of the two seawall geometries 

 and to estimate the overtopping rates for a beach erosion level different from 

 the one that was tested, regression coefficients must be determined for Equa- 

 tion 3 (main text) for each data set. Table Bl lists the regression coeffi- 

 cients determined for the Phase I seawall data set (A) , the Phase II seawall 

 data set (B) , a partial Phase II data set (C) containing only the test results 

 for the 100 percent values of the design wave height at the wave board 

 (DWHAWB) , and a partial Phase II data set (D) containing test results for only 

 those tests with a 70 percent or less DWHAWB. 



Table Bl 

 Regression Coefficients for Phase I and Phase II Data Sets 



Regression Coefficient 



Data Set 



A, Phase I Seawall 

 30 to 70% DWHAWB 



B, Phase II Seawall 

 30 to 100% DWHAWB 



C, Phase II Seawall 

 100% DWHAWB 



D, Phase II Seawall 

 30 to 70% DWHAWB 



Q , cfs/ft 



52.3 



50.4 



7.78 



37.94 



-13.19 



-13.67 



-7.476 



-13.89 



The data curves for data sets A, B, C, and D have been drawn through the data 

 and are shown in Figures Bl , B2 , B3 , and B4 , respectively. 



2. Comparisons of the overtopping rates between the two seawall geome- 

 tries and the different beach erosion levels can be made by computing a maxi- 



mum zero-moment wave height H 



at the structure toe. From earlier wave 



tank tests (Ahrens and Heimbaugh, in publication*) it has been found that the 



* References cited in the Appendixes can be found in the References at the 

 end of the main text. 



Bl 



