STUDY ON THE DRIFTING MECHANISM OF THE TSUNAMI DEBRIS AFFECTED BY THE WAVE BREAKING

Abstract

 When a tsunami with the wave breaking approaches a coastal area, it is necessary to consider the effect of the wave breaking in order to evaluate the impact of tsunami-borne debris on port facilities. However, there have been few studies that investigated the relationship between the motion of the floating tsunami-borne debris and the wave breaking. Addirionally, the mechanism of the moving behavior of the debris caused by the tsunami with the wave breaking has not been investigated in detail. This study aims to examine the mechanism of the tsunami-borne debris behavior affected by the wave breaking through a series of hydraulic experiments. By conducting spatially dense hydraulic measurements and trajectory analysis of the debris using image measurements, the results indicate that the presence or absence of wave breaking, as well as the relationship between the location of wave breaking and the initial position of debris, affect the characteristics of moving behavior of floating debris. This study also reveals that the debris drifts at a speed equivalent to the wave celerity, driven by the rapid water surface gradient caused by wave breaking.