Changes to wave parameters in the surf zone due to wind effects

Abstract

Wind/wave interactions in the surf zone were studied using a wave tank and environmental wind tunnel. Waves were modelled at approximately 1/50 scale and broke on a model scale beach of 1/20 slope. The wind was simulated using accelerated growth techniques over a relatively short fetch, and a model scale of roughly 1/100 was achieved. Thus there was some scaling mis-match between wind and wave simulations.

Results show that the wind has a significant effect on the breaking of the waves. Both breaker location and breaker type are affected, and the results agree with those of Douglass [10 and 11], The main findings, common to both studies, were that offshore winds promote plunging waves and delay the moment of breaking (reducing surf zone width), whereas onshore winds encourage early wave breaking, generally by spilling. Wave heights at breaking were not generally affected, but due to changes in breaker depth, the height-to-depth ratio is shown to be affected by the wind.

Additionally, studies of the motions of suspended particles, offshore of the surf zone, indicate wind effects on the drift velocities of these particles, although the precise nature of the wind effect was not clear.