External Forces of Sediment Transport in Surf and Swash Zones Induced by Wave Groups and Their Associated Long Waves

This study investigates the coupling field of grouped wind waves and their associated long waves in the surf and swash zones. Based on the calculated wave fields, the contributions of the wind waves and the long waves on the sediment transport efficiency axe discussed. Spatial variations of the incident grouped wind waves propagating over a plane slope are calculated based on time-dependent mild slope equation. Generation of the long waves is reproduced based on a time-varying breakpoint model proposed by Symonds et al. [1982]. In order to obtain the long wave solutions extending over the landward region from the still water shoreline, calculations using nonlinear shallow water equations are connected to the Symonds' model invoking a moving boundary treatment. The Shields parameters under composition of the grouped wind waves and the associated long waves are evaluated to assess the mobility of the bottom sediment. The results show that the long waves have greater sediment transport efficiency over the grouped wind waves in the swash zone.

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