Study on Characteristics of Wave Deformation and Transport of Coral Gravels Around Swash Zone

This study investigates characteristics of wave deformation on a coral beach and behavior of coral gravels under such forward-leaning waves through two different laboratory experiments. All these experiments were captured by multiple video cameras mounted beside the glass wall of the flume and water surface fluctuations, topography change, nearbottom current velocities and gravel velocities were quantitatively extracted through the analysis of recorded images. Primary findings of the experiments are as follows: (i) deformation of nearshore waves and bed profiles dynamically interacted with each other and developed steeply sloping coral bed around the swash zone enhanced the formation of partial standing waves; (ii) initiation of motion of the gravels depends not only on the local bottom shear stress but also on the positions of each gravel relative to the others; (iii) after the initiation of motion, behavior of gravels were dominantly determined by the surrounding flow velocity but not by the bed conditions.