INCORPORATING CLIMATE CHANGE RESILIENCE INTO A BREAKWATER REPAIR: A CASE STUDY AT HILO, HAWAII

Abstract

The original breakwater at Hilo Harbor was completed in 1930 and consisted of a 10,080-foot-long rubble-mound breakwater built over Blonde Reef, protecting a 35-foot-deep basin. Recent repairs were completed in 1973, 1975, and 1981. The 1981 repair consisted of a layer of 7.5-ton tribar armor units along 900 feet of the breakwater along the trunk of the structure. The USACE Honolulu District intends to conduct repairs to the Hilo Harbor breakwater within the next 5 to 10 years. A multifaceted analysis has been conducted to optimize future repair design from both an economic investment standpoint, as well as to incorporate evaluation of risk of failure and reliability-based design under projected future forcing conditions. The results of this analysis will be presented including the following: 1) evaluation of breakwater damage using both visual inspection and remote sensing data; 2) an in-depth analysis of present and future breakwater overtopping rates due to extreme waves and sea level rise through the use of spectral phase-averaged wave modeling, Boussinesq phase-resolving models, and high fidelity, fully three-dimensional Computational Fluid Dynamics (CFD) wave modeling; and 3) initial results of reliability-based design to assess past and present performance and damage modes.