Tsunami attacks land-area in a few minutes just after earthquake shaking or it is transmitted just after the coastal
structure and ground are damaged by earthquake motion. The time required for any prevention system operation is very
short and the power source may be malfunctioned by an earthquake before tsunami arrival. The hydro-plane type
removable breakwater is designed to be operated without any external power supply but with powerful flux of tsunami
itself. Hydro-Plane Type Removable Breakwater has the following characteristics;
1) It works and flows up in tsunami flux. Its operation does not need any human check nor any equipment even if
infrastructure is destructed by an earthquake.
2) The breakwater system and the ground base are independent each other. The influence of ground deformation is small.
3) The breakwater system is applicable to both landward and seaward waves in the same mechanism. It is easy set the
required operation according to the request of the administrator.
4) The implementation of system is easy and working time for installation is short. These merits are suitable to the
construction inside the navigation cannel.
5) The system is simple structure composed from relatively few members. Therefore, the reliability is high and the
material and maintenance management is easy.
6) The breakwater system is laid on the seabed during inactive state and is no obstacle in the navigation channel. It does
not change the surrounding scenery.
The performance tests with a scale of 1/200 and 1/50 were carried out in the basins of Kyoto and Osaka Prefecture
Universities during 2012 to 2015 to investigate the abilities of Hydro-plane type Breakwater with above
characteristics. The experimental results demonstrated that the breakwater was effective to reduce tsunami energy, to
be applicable in the practical site. Continuously a large scale (1/10) model test was carried out at the large Geo-Flume
on 2015 in the Port and Airport Research Institute to investigate the performance in detail.
Additionally we proposed “Design Manual for Hydro-plane Removable Breakwater” on the basis of the
performance design methodology. The manual part includes the maintenance occurrence, check method of
connection belt, action to emergency, standard for long term-stability etc.

Key Wards: Hydro-Plane Type Removable Breakwater, Tsunami, Run-up Tsunami, Hazard Reduction, Particle
Computation Method, Destructive-performance Simulation-