A Sea Level Rise Resilient Design for the Royal Hawaiian Groin, Waikiki, Hawaii

The Royal Hawaiian groin is located on Waikiki Beach, Hawaii, and anchors 1,730 linear ft (527 m) of critical beach in the heart of Waikiki. The groin was originally constructed in 1927, and by 2012 was in very obvious need of replacement. Rock rubble mound breakwater and groin construction has been traditionally used in Hawaii, and is aesthetically the desired construction methodology for coastal structures. Oceanographic design parameters were based on a potential direct hurricane strike and likely future sea level rise. The groin design is a hybrid structure; the base is composed of armor stone, and the crest is made of cast-in-place fiber-reinforced concrete. The groin is also adaptable to sea level rise by permitting a relatively easy increase in the concrete crest cap elevation without the need for heavy equipment to dismantle and reconstruct the groin. Construction in normally densely crowded Waikiki was going to be difficult; however, when construction started in May 2020 Hawaii was in COVID-19 lockdown, the hotels were closed, and Waikiki was empty, with no one to be impacted by closed beach access or construction noise.