LAUSR

Abstract The 2011 Tohoku Tsunami induced sediment deposition of 334,000 m3 mainly in the basin and 9 m erosion at the tips of a breakwater and a groin in Oarai Port, Japan. The tsunami-induced bathymetry change was simulated using a numerical model and the simulated bathymetry change was compared with the measured one. The comparison showed that the simulated bathymetry change quantitatively agreed with the measured one including the sediment deposition and the erosion mentioned above although the erosion measured along the breakwater was not well reproduced by the model. The time series of simulated bathymetry change, water level, current and suspended sediment concentration showed that the sediment deposition in the center of the basin was mostly induced by the sediments that moved into the basin through its entrance between the breakwater and the groin and were redistributed by counterclockwise vortices. The severe erosion at the tip of the breakwater was mainly induced by the strong southward currents.