INFLUENCE OF WIND ON BREAKING WAVES

The influence of local wind on nearshore breaking waves was investigated in a laboratory wave-wind flume. The breaker location, geometry, and type were found to depend strongly upon the wind direction. Onshore winds cause waves to break earlier, to break in deeper water farther from shore, and to spill; offshore winds cause waves to break later, to break in shallower water closer to shore, and to plunge. For onshore winds, it was observed that breaking of the wind-generated ripples can initiate spilling breaking of the primary underlying wave by providing a perturbation on the crest of the underlying wave as it shoals. The implications of these results are that surf zone width, currents, and sediment transport can be affected by local winds. Thus, engineering estimates of these quantities could be improved by consideration of local wind. Surf zone dynamics models that ignore wind or include wind only as a surface shear may be missing a very important effect of the wind—its effect on the initiation and mechanics of wave breaking. © ASCE.