[Abstract]

The development of a flap gate movable breakwater is reaching the final stage of demonstration tests in the sea after 6 years of studies. This breakwater is based on a steel flap gate in hydraulic gates which has a number of adoption results domestically and abroad. The flap gate breakwater usually lies down on the seabed and rises up to the sea surface quickly with buoyancy in order to protect land from flood damage when a tsunami or storm surge occurs. The expectations for its practical use are big. In past studies for practical use, reflecting viewpoints of a large number of specialists, we conducted an improvement of certainty of the gate’s rising operation and confirmed its effectiveness by experiments and numerical analysis. This paper describes the characteristics of the flap gate movable breakwater in detail, and shows the application possibility to a head gate or seawall other than the tsunami and storm surge type. Furthermore, it shows the results of the latest model experiments regarding its main functions/abilities such as the flood prevention and the seakindliness, at the end of this paper, an outline of the ongoing demonstration project is shown.