APPENDIX C: WIND-INDUCED OVERTOPPING EVALUATION 



1. A sample calculation of wind-induced overtopping, using the method 

 described in the SPM (1984), is presented in this appendix. No adaptations 

 were made to include wind-induced setup in these calculations. Following the 

 example is a summary of total estimated maximum overtopping rates for the 

 Virginia Beach seawall design as modeled in the Phase II model tests. These 

 estimates include both wave-induced and wind-induced overtopping. The summary 

 presents results for the cases with the +1.0 ft NGVD elevation and the +3.4 ft 

 elevation. 



2. To estimate wind-induced overtopping (as described in Chapter 7 of 



the SPM) runup on the seawall must be calculated first. For this example a 



storm surge of +8.0 ft above NGVD will be used. To calculate runup the ratios 



2 

 of H'/gT and d /H' must be determined for use with Figure 7-18 in the 

 o s o * 



SPM, where H' is the deepwater wave height, g is gravity, T is the wave 

 period of 13.7 sec, and d is the depth from the swl to the toe of the 

 structure, in this case 7.0 ft (8.0 - 1.0 = 7.0). 



3. To determine the deepwater wave height the ratio of breaking wave 

 height to deepwater wave height (IL /H') is evaluated. Breaking wave height 



2 

 K, is found by calculating d /gT and entering Figure 7-4 using a slope of 



0.05 (1 on 20). This value d /gT^ is 0.00116 and yields a value of H, /d 



s b s 



of 1.35, or IL equals 9.5 ft. 



4. With H, known, another ratio, d /L , occurs where L is the 



2 ^ 

 deepwater wave length equal to 5.12T and where d /L equals 0.0073. From 



Table CI in Appendix C of the SPM the ratio of H/H' equals to 1.546 is 



° 2 

 found. This allows for the original ratios of H'/gT and d /H' to be 



o so 



determined as follows: 



and 



H' 



° = til = 0.0010 



gT 32.2(13.7) 



w-'d-^-^"" 



CI 



