Reinforcement Method of Detached Breakwaters for External Force Increase

There are 8,000 detached breakwaters in Japan. Even if the scale of offshore wave does not change, the front water depth of detached breakwaters is enlarged due to the sea level rise caused by the global warming. The necessary mass of blocks composing detached breakwaters, therefore, increases, and the existing detached breakwaters should be enhanced to satisfy the standard.The assumed external force of the Shimoniikawa coast was increased in 2008, when a disastrous wave hit a record high. As a result, there is a lack in existing block mass against the assumed external force, and the safety performance cannot be kept under the present condition.The paper shows the results of hydraulic model experiments in regards to the enforcement of existing detached breakwaters according to the increase of the assumed external force.