Wiyono, R.U.A., Sasaki, J. and Suzuki, T., 2013. Numerical Assessment of the 2011 Tohoku Earthquake Tsunami in Ports of Tokyo Bay with the Effectiveness of Floodgates

Floodgates were effective in reducing tsunami inundation at Funabashi and Kisarazu ports in Tokyo Bay during the 2011 Tohoku Tsunami. A numerical simulation utilizing a Finite Volume Coastal Ocean Model was carried out to demonstrate this conclusion. For the simulation, an unstructured mesh covering the tsunami propagation area was constructed. Detailed unstructured meshes at 5-m resolution were also constructed in ports and surrounding land area. Meshes were constructed using a 5-m resolution Digital Elevation Model and 50-m resolution bathymetry data. To evaluate floodgate effectiveness, potential impacts from the failure to close floodgates were investigated. An MPI HA8000 supercomputer at The University of Tokyo was utilized to execute the simulation. Simulation results were validated using inundation height data from a field survey. The effectiveness of floodgates at preventing the surrounding area from inundation is shown. When floodgates close, the surrounding area is safe from inundation. However, when floodgates do not close, the surrounding area can be inundated, and the extent of inundation can reach 620 m from the river at Funabashi Port and 450 m from the river at Kisarazu Port.