California Sea Grant College Program

Wave breaking is a common phenomenon in nature. Along any coastline one can be impressed by the dramatic transformation of water waves as they advance onto a beach. The waves with a relatively smooth water surface offshore transform to those with rough white fronts of spray and bubbles when they arrive at the shoreline. Although there is no exact definition of wave breaking, the term "wave breaking" is generally used to describe the transformation process from a smooth wave to the quasi-steady state with a white­ water front rather than to any particular instant within the transition.

An approximate classification of breaker types was first made by Mason (1952 ). He divided breakers into two types: spilling and plunging. The generally employed classification. described by Galvin (1968,1972) according to empirical knowledge of the breaking process, has four types of breakers according to their initial motion: spilling, plunging, collapsing and surging. Of course. this division is approximate, and there often seems to be a smooth gradation between them. On the other hand, because of the existence of various environments. it is not difficult to find occasions when waves do not fit well into one of these descriptions.