PART VI: RESULTS 



44. All results were calculated using overtopping rates from the phys- 

 ical model Phase II tests with the wall configured as shown in Figure 6 

 (Heimbaugh et al. 1988). Appendix A presents the water levels and overtopping 

 rates from these tests. The tabulated data include three different storm 

 surge levels of 9.5, 8.0, and 7.0 ft above NGVD for both the hurricane and 

 extratropical storm. These data were then used to obtain an overtopping 

 hydrograph necessary for determining flooding potential behind the structure. 

 The STHM described in Section V was employed for these calculations. 



45. At the request of NAG, overtopping rates for a beach elevation of 

 +3.4 ft NGVD in front of the seawall were developed using a numeric approach 

 because time constraints did not permit returning to the physical model. 

 These adjusted results are presented following the results of the Phase II 

 model tests. 



46. Maximum overtopping rates calculated by the STHM for a +1.0-ft 

 beach elevation are summarized in Table 7. Complete overtopping hydrographs 

 are in Appendix B. The overtopping rates (in cubic feet per second per linear 

 foot of seawall) do not include any contribution due to wind-induced 

 overtopping. 



Table 7 



Summary of Phase II Overtopping Rates 



+1.0-Ft Beach Elevation 



Overtopping 

 Maximum Swl* Rate** 



Storm Event ft cfs/ft 



Extratropical storm 7.0 0.07 



Extratropical storm 7.1 0.10 



Extratropical stormt 8.0 0.36 



Hurricane 8.0 0.45 



Hurricane 8.7 0.67 



Hurricane 9.5 0.94 



* Swl is in feet referenced to NGVD. 

 ** Overtopping rate in cubic feet per second per linear foot 

 of seawall. 

 t Not considered a design storm event. 



30 



