Velocity moments in nearshore

Recent models for nearshore sediment transport suggest the importance of various moments of the fluid velocity field in determining transport rates. Using two days of field data from a low slope beach with moderate wave heights (H∼70cm), some low order, normalized moments are compared to results from simple monochromatic and linear random wave models. Not surprisingly, the random wave model is substantially more accurate than the monochromatic model. However, wave breaking and other nonlinearities introduce effects not explained by either formalism. The observed cross‐shore velocity variance is decomposed into wind wave and surf beat components. The surf beat contribution is maximum at the shoreline, while the wind wave component is maximum offshore. The total variance is nearly constant across the surf zone. This observation contradicts assumptions that are fundamental to many models of surf zone dynamics and sediment transport. Analysis of a wider range of wave conditions is needed to assess the general...

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