Experimental Investigations Using Computer Vision for Debris Motion Generated by Solitary Waves

Abstract

A tsunami created by the momentary release of a large amount of energy accumulated in the ocean crust destroys coastal structures and generates considerable debris, posing a serious threat to coastal communities. Hence, understanding the movement characteristics of drifting attributed to tsunamis for coastal disaster prevention is necessary. In this study, a color-based Debris mOtion Tracking (DOT) model is developed to understand the behavioral characteristics of drifting caused by solitary waves. The behavioral characteristics of drifting are analyzed quantitatively based on the weight of the debris, scale of solitary waves, and revetment type, which have not been considered previously. The DOT model tracks the drifting behavior more accurately than the existing commercial programs. In a laboratory experiment, the kinetic energy, and maximum debris velocity increase with an increase in the magnitude of solitary waves. An analysis of the drifting characteristics based on revetment type reveals that the initial acceleration of drifting in the wave absorbing revetment (WAR) is higher than that in the vertical revetment (VR). Velocities of vertical and horizontal flow develop in VR and WAR, respectively, and thus the momentum flux acted more strongly. Further, overtopping the wave characteristics based on the revetment type determines the drifting behavior.