A series of model experiments are conducted in a wave flume. The profiles of overtopping waves are measured by a high speed video camera, current meters, etc. The pressures and total forces are measured by pressure transducers and load cells. The major conclusions are as follows:
1) The wave overtopping can be divided into two stages; Green Wave and Ovetopping Flow. Green Wave is the initial motion of overtopping wave, starting from jumping in front of the breakwater to hitting on the horizontal surface of breakwater superstructure. Overtopping Flow is a motion of overtopping wave after hitting the breakwater top. The overtopping wave becomes a flow toward harbor side.
2) The paraments to describe the Green Wave and Overtopping Flow are fomulated based on the experiments. The water depth and current intensity can be evaluated by the paraments.
3) Wave force acting on the flat surface and facilities of the breakwater top are fomulated at the both stage. The wave force at the stage of green wave is relatively impulsive, while the wave force during the overtopping flow is a slowly varying force.