A Statistical Model for Frequency of Coastal Flooding in Honolulu, Hawaiʻi, During the 21st Century

Abstract (from AGU100): The state of Hawaiʻi and city of Honolulu experienced an unprecedented number of minor flooding episodes during 2017 due to the combination of seasonal high tides and record‐high mean sea levels. To quantify the impact of sea level rise on the tendency for flooding events to cluster in future years, we developed a hierarchical statistical model describing the number of days per year for which sea level exceeds a prescribed threshold in Honolulu as a function of annual mean sea level and the amplitude of the highest tides. Based on this model, we generate probabilistic projections of exceedance days per year for the 21st century, which show pronounced inflections in the frequency of exceedance...

Categories: Publication; Types: Citation; Tags: Pacific Islands CASC, Sea-Level Rise and Coasts, Water, Coasts and Ice

Rising sea levels and the increase of shoreline wave energy at American Samoa

American Samoa is experiencing rapid relative sea level rise due to increases in global sea level and significant post-2009 earthquake land subsidence, endangering homes and critical infrastructure. Wave and water-level observations collected over a fringing reef at Faga‘itua Bay, American Samoa, in 2017 reveal depth-limited shoreline sea-swell wave heights over the range of conditions sampled. Using field data to calibrate a one-dimensional, phase-resolving nonhydrostatic wave model (SWASH), we examine the influence of water level on wave heights over the reef for a range of current and future sea levels. Assuming a fixed reef bathymetry, model results predict rising sea levels will escalate nearshore extreme water...

Categories: Publication; Types: Citation

Final Report: Diagnosing and communicating the effect of climate variability on frequency of coastal inundation

Increased coastal flooding due to sea-level rise (SLR) threatens the culture, habitat, and essential infrastructure of the Hawaiian and U.S. Affiliated Pacific Islands. The purpose of this project was to respond to the needs of Pacific Island communities for improved information about the frequency of coastal flooding—both in the near term and throughout the 21st century. Seasonal sea-level and flooding forecasts were produced by combining multiple types of information into a single forecast that performs better out to six months than any individual forecast. The forecasts are provided on a website created for this project. Projections of tidal flooding for the 21st century were produced for 35 island locations...

Assessment of Future Flooding in Pu‘uhonua o H¯onaunau National Historical Park

This document contains planning materials for Pu‘uhonua O Hōnaunau National Historical Park (PUHO; an important Hawaiian cultural site) to address information gaps in sea level rise planning materials. This report focuses on planning horizons of 10-30 years and also provides information about the entire 21st century. Specific assets in the park are addressed and local/park knowledge was used to assess the level and frequency at which the any given structure can be inundated and still maintain its integrity.