Vulnerability assessment and adaptation to sea level rise in high-wave environments: A case study on O'ahu, Hawai'i

High energy waves intensify the impacts of sea level rise and threaten coastal communities, requiring measures to prevent harmful consequences. Vulnerability assessments using NOAA's assessment guide were performed in a high wave environment, accounting for the impacts of sea level rise on coastal inundation, longshore transport, benthic habitat as well as on beach users and homeowners. This case study of the North Shore region of Oahu, Hawai'i' uses multi-criteria evaluation and cost-benefit analysis based on vulnerabilities, impacts, and protective actions such as shoreline hardening, beach nourishment and dunes, vegetative cover, and elevation or relocation of structures. Geomorphology and natural habitats dramatically affect coastal exposure in high energy wave environments. The most viable adaptation strategies include expansion of artificial reefs in benthic habitat dominated areas while the vegetative cover and beach nourishment are most appropriate in developed locations and surf tourism areas. Suitable adaptation strategies were determined based on differences in the biophysical environment and community perceptions. The value of this approach lies in both a generalized method for compiling and analyzing large amounts of data as well as customizing the proposed framework to identify crucial elements necessary for effective adaptation to sea level rise in high-energy wave environments.