Maximum Annually Recurring Wave Heights in Hawai‘i1

Abstract

The goal of this study was to determine the maximum annually recurring wave height approaching Hawai‘i. The motivation was scientific as well as administrative: to enhance understanding of the recurring nature of dominant swell events, as well as to inform the Hawai‘i administrative process of determining the “upper reaches of the wash of the waves” (Hawai‘i Revised Statutes [H.R.S.] § 205-A), which delineates the shoreline. We tested three approaches to determine the maximum annually recurring wave, including log-normal and extremal exceedance probability models and Generalized Extreme Value (GEV) analysis using 25 yr of buoy data and long-term wave hindcasts. The annual recurring significant wave height was found to be 7.7 ±0.28 m (25 ft ±0.9 ft), and the top 10% and 1% wave heights during this annual swell was 9.8 ±0.35 m (32.1 ft ±1.15 ft) and 12.9 ±0.47 m (42.3 ft ±1.5 ft), respectively, for open North and Northwest Pacific swell. Directional annual wave heights were also determined by applying hindcasted swell direction to observed buoy data lacking directional information.