PART VII: SUMMARY AND CONCLUSIONS 



51. The WIS hindcast data applicable to Chiniak Bay were surveyed 

 for extreme wave conditions. The resulting 62 significant wave heights were 

 found to fit the Extremal Type I distribution. The resulting extrapolated 

 significant wave heights are reported in Table 7. The associated reliability 

 analysis indicates that if the Extremal Type I is the proper model, then the 

 standard error in estimating the extremes is about one-tenth of a meter. It 

 should be stressed that the major source of error is due to the choice of the 

 model and is thus not included in this number. 



52. Measured data from the area were also found to fit an Extremal 

 Type I distribution. The results from this analysis tend to underestimate 

 long-term conditions such as the 10- to 50-year events. This is mostly due 

 to the short data record length (2 years). Extremes computed using the NWS 

 wind data are similar to those given by the hindcast analysis. For the 

 50-year event they differ by about six-tenths of a meter, and for the 

 100-year event they are approximately the same. 



53. The peak wave period that most accurately represents the local 

 weather patterns is that computed by the WIS hindcast. The wave period asso- 

 ciated with the 20-year extreme event is 14.3 sec. This value should be suf- 

 ficient for the 50- and 100-year events as well. The deepwater to intermedi- 

 ate water depth (77 m at the outer buoy) wave height correction for l4.3-sec 

 periods is 0.929. This correction was applied to the significant wave 

 heights listed in Table 7 and the values listed in Table 23 were obtained. 



Table 23 



Depth Corrected to Outer Buoy (77 m) Significant 



Wave Heights Versus Return Period 



Return Period Significant Wave 



years Height, m 



5 9.22 



10 9.85 



20 10.48 



40 11.10 



50 11.31 



60 11.47 



100 11.93 



55 



