REANALYSIS OF REGULAR AND RANDOM BREAKING WAVE STATISTICS

Statistics of breaking waves across the surf zone are reanalyzed on the basis of various sets of field and laboratory data so as to provide coastal engineers with reliable information on breaking waves. The breaker index or the ratio of wave height to water depth is to be expressed as a function of the two parameters of beach slope and relative depth, and Goda's breaker index formula is revised slightly to reduce the slope effect. The breaker index for regular waves has inherent variability as expressed with the coefficient of variability, which increases from 6% to 14% as the beach slope becomes steep up to 1/10. The incipient breaking height of the significant wave is about 30% lower than that of regular waves, but the ratio of significant wave height to water depth gradually increases within the surf zone toward the shoreline. The wave height distribution is the narrowest in the middle of the surf zone, but it returns to the Rayleigh distribution near the shoreline owing to wave regeneration after breaking. The nonlinearity of random waves is strongest at the outer edge of the surf zone, but it is destroyed by the wave breaking process inside the surf zone. The ratios of statistical wave heights H-1/10, H-1/3 and H-rms to the spectral significant wave height H-m0 are shown to increase as the wave nonlinearity parameter increases up to the outer edge of the surf zone.