Wave overtopping-caused disasters have occurred around revetments in Okinawa islands, which are one of the typhoon-prone areas in Japan and are mainly surrounded by coral reefs. To take countermeasures against wave overtopping are important from the viewpoint of disaster prevention and the design of coastal structures. The main purpose of this study is, therefore, to numerically examine wave deformation over a natural reef and wave overtopping around a road revetment in main Okinawa Island using a two-dimensional numerical wave flume “CADMAS-SURF”. The numerical results reveal that the CADMAS-SURF is able to simulate wave deformation over the reef including wave breaking and wave overtopping around the revetment appropriately and wave overtopping characteristics are greatly affected by bottom topography in front of the revetment. In addition, two methods to estimate the wave overtopping quantity are proposed in this study. The time variations of the wave overtopping quantities calculated by the two methods are found to be similar in the case of large overtopping quantity.
