| Summary: | Source: https://erdc-library.erdc.dren.mil/jspui/ The purpose of this study is to provide an analysis of hindcast and measured wave and wind data to estimate the long-term extreme wave heights for the St. Paul Harbor area at Kodiak, Alaska. This study included the development of the deepwater extreme wave climate, the derivation of a wave energy attenuation factor for deep- to shallow-water transition of extreme waves, and an analysis of collateral wind data to support the results of the analysis of hindcast wave data. The Wave Information Study (WIS) hindcast data applicable to the Kodiak area was surveyed'for extreme wave conditions. This survey resulted in a sample of 62 significant wave heights for the years 1956 through 1975 (Appendix A). The 62 significant wave heights were scaled and plotted according to several extreme probability models. The Extremal Type I or Fisher-Tippett Type I model demonstrated a better fit with the data than did the other models (Figure 1). Extrapolated significant wave heights based on the Extremal Type I model are listed versus return period in Table 7. The extreme wave predictions computed using monthly maximum significant wave height values from measured wave data (Table 9) tended to be smaller than the hindcast predictions. This difference was best explained by the fact that the measured data covered a time span of about 2 years; whereas, the hindcast data represented 20 years of wave climate. The longer record had a better chance of capturing a representative sample of extreme events than the short record. Extreme wave heights computed with long-term wind data provided by the National Weather Service agreed well with results from the analysis of WIS hindcast data and supported the overall validity of the study. Measured wave data provided by the Alaska Coastal Data Collection Program were analyzed to obtain a wave energy attenuation factor for the longperiod swell crossing the reefs into St. Paul Harbor at Kodiak. The attenuation factor represented the fraction of ...
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