Typhoon-Induced Stage-Frequency and Overtopping Relationships for the Commercial Port Road, Territory of Guam

Abstract : This report describes the procedures and results of a typhoon overtopping-frequency analysis for a vulnerable section of the commercial port road along Cabras Island, U.S. Territory of Guam. Numerical modeling of typhoon winds, waves, storm surge, and nearshore processes is used to estimate wave overtopping rates due to historical storm events. Alternatives modeled include the existing fringing reef, beach, and protective seawall, and a plan configuration in which a low-crested, Core-Loc-armored berm is included in the nearshore profile. Model overtopping rates arc input to the Empirical Simulation Technique (EST) life-cycle stochastic model. Life-cycle simulations are postprocessed to generate overtopping rate frequency-of-occurrence relationships for return periods of up to 100 years. Model results indicate that the proposed low-crested berm to be built in the nearshore profile will significantly reduce the vulnerability of the road and port facilities to damage due to wave overtopping.