Development and Installation of Flap-gate Type Seawall Against Tsunami and Storm Surge

A flap-gate type movable seawall, which usually lies down on the ground, rises up automatically by buoyancy during inundation by tsunamis or storm surges, and then it forms a continuous seawall. This structure keeps lying in usual time to secure traffic and landscape. In emergence time, it protects a target area against inundation without power machineries and human operation. This structure is named as NEORISE which means No Energy and no Operation RIsing SEawall. The 2011 Tohoku Earthquake gave damages to power machineries and communication systems of tsunami-barrier gates and these tsunamis caused many casualties who tried to operate and close these gates. Structures for tsunami protection are required so as to avoid machinery failure and risk of operators. The NEORISE satisfies both of these requirements. In Japan 78 systems have been already constructed and this technology will contribute toward preventing and mitigating flood disaster.