Field study of wave transmission through a rubble-mound breakwater

Characteristics of sea and swell incident at a permeable rubblemound breakwater located in Monterey Harbor, California, are resolved into reflected and transmitted components.The wave characteristics are studied by analyzing synchronized wave records of three underwater sensors judiciously placed, two to seaward and one to landward of the breakwater.Power spectra and cross spectra are calculated for various characteristic sea states selected from three months of observations.Amplitude and phase are determined for the spectral wave components comprising the partial standing wave phenomena.This study was unique in that it entails experiments conducted in the field on a prototype structure in the natural environment.Transmission has been studied heretofore exclusively with scale models.The coefficients of transmission are considerably less for the prototype than predicted by a Corps of Engineers model study of the Monterey Breakwater.The differ- ences are apparently related to more wave energy scattering and dissipation due to turbulence than predicted by the model.