On September 24, 1999, the typhoon No.9918 induced the storm surge disaster in the west of Japan,which is the most enormous one in Japan since the typhoon No.5915 in l959. The levels of the inundation traces were surveyed along the coast of Yatsushiro-kai Sea and Suo-nada Sea. The storm surge in Yatsushiro-kai Sea, Suo-ruda Sea, and Kagoshima Bay were simulated by a numerical model. The main conclusions are as follows :
(1)In Yatsushiro-kai Sea, the meteorological tide anomaly became nearly I meter in the southerm region around Minamata, about 2 meters in th northern region around Yatsushiro, and more than 3 meters in the innermost region around Shiranui mainly due to wind drift effect. The meteorological tide anomaly became the maximum near the astronomical high tide, therefore the total tidal level became very high. Consequently the water level went up to the roofs of the first stories of the houses at the Matsuai Section of Shiranui.
(2)In Suo-nada Sea, the meteorological tide anomaly became about 2 meters in the northern coast between Kanda and Tokuyama. The meteorological tide anomaly became the maximum at the astronomical high tide. Consequently many seawalls were damaged, and the residential areas at the backward were flooded.
(3)In Kagoshima Bay, the meteorological tide anomaly became about 0.5 meter in the entrance region and about I meter in the innermost region around Kagoshima.
(4)In the present numerical model, marine wind is estimated by a general assumption of wind velocity and direction. However, in the western region of Suo-nada Sea, the meteorological tide anomaly is underestimated by the model. It is necessary to consider the effect of the land topography on the marine wind.
(5)The maximum meteorological tide anomaly by the typhoon No.9918 is almost same as that by the typhoon No.9119 in 1991, however the darnage was more enormous because the astronomical tidal level was higher. The occurrence time of the inundation, evacuation advice, inundation elevation seem to be principal factors to vary the human damage.