Estimating Overtopping Impacts in Los Angeles/Long Beach Harbors with a Distorted-Scale Physical Model

Recent topographic surveys of the breakwaters for Los Angeles/Long Beach Harbors revealed an average crest elevation of the San Pedro Breakwater of approximately 1.5 ft below the design crest of + 14 ft MLLW. A physical model study was conducted to estimate future impacts on harbor operations if crest loss continues or if the crest is restored to the design elevation. A 3-dimensional distorted-scale physical model (1:100 vertical, 1:400 horizontal) was used to investigate the change in total energy and low frequency wave energy (periods > ∼85 sec) at numerous locations within the harbor as a function of the breakwater crest elevation. Constraints of the distorted scale model were overcome to generate incident overtopping waves that induced low frequency oscillations in the harbor. Sensitivity of these oscillations to crest elevation is presented.