VERIFICATION OF WAVE OVERTOPPING MODEL BY FIELD DAMAGE OF TYPHOON NO.18

The Japanese western coastal areas were heavily damaged by storm surges and waves due to the Typhoon No. 18 on September 23~24 in 1999. The waves induced by the typhoon approach also were huge on the time when the storm surge became the maximum. Some coastal zones located on the west side of a target bay were perfectly flooded by the overtopped waves at the sea walls. The flooded area, inundation time and wave overtopping rate in the two districts were revealed by the field survey. One was protected by the sea wall covered with armor blocks and another by sea wall with a detached breakwater. A numerical scheme expecting wave overtopping rate was applied for investigating the effect of coastal barriers. The numerical results agreed with the flooded volumes obtained in the field survey and reproduced the reduction of wave overtopping rate in the detached breakwater.