砕波帯・波打ち帯を統合的に捉えた風波・長周期波による底質移動外力の評価

Abstract

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 mobility are discussed. Spatial variations of the incident grouped wind waves propagating over a plane slope are calculated based on time-dependent mild slope equations. 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 non-linear 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 ability over the grouped wind waves in the swash zone.