2022 Volume 78 Issue 2 Pages I_181-I_186
The 2011 Tohoku tsunami accompanied a large amount of silt and clay along the Sanriku coast and supplied them substantially onto the inland area. Such a tsunami containing silty materials could contribute to increasing coastal and human damage. However, characteristics of tsunami-induced suspension of silty materials and their effect on tsunami flows have not been sufficiently understood. This study conducted a laboratory experiment of sediment transport on a silty bottom and developed a numerical model to investigate the detailed processes and mechanisms. Results from the experiment indicated that a wave-induced flow suspended more silty materials for higher fluidities of bed materials. A vortical flow induced by wave breaking further contributed to enhancing the sediment suspension from the bottom. The sediment processes were reproduced by the numerical model with two empirical parameters of sediment entrainment calibrated with the experimental result. The numerical model reasonably reproduced a local scour on the bottom as well as the concentration of suspended materials.