Wave breaking in wave groups

Experiments were conducted with periodic wave groups incident on a plane beach with a slope of 1:35. The wave groups were composed of a series of cnoidal waves with varying wave heights. Emphasis was on obtaining a number of measurements inside the surf zone. The analysis of the data shows that the location of the start of breaking of the individual wave in a group is affected by the groupiness of the waves. The H/h ratio at breaking was seen to have a wider variation for the individual waves in the group than for monochromatic waves. In all cases, some groupiness was conserved inside the surf zone, but in some cases it was reversed in the sense that the higher waves in the group before breaking became the smallest after and vice versa. It was also found that even inside the surf zone, nonlinear interactions result in energy at frequencies that are multiples of the group frequency, although, as expected, the energy is more evenly distributed between the different frequencies than in the waves originally generated.