Forecasting of damage level of damaged maritime structures and estimation of degree of risk on coasts due to storm surge and wind waves caused by typhoons

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Typhoons which pass through the Kyushu Island have many courses. Typhoons strike the Kyushu Island a few times a year. Damage of the maritime structures by storm surge and wind waves frequently occurs in the western two prefectures, Kumamoto and Nagasaki Prefectures. The coastline in these prefectures is complex. It faces open and closed seas. The coastline facing these areas has different topographical characteristics.The author proposes four kinds of method for forecasting the damage level of maritime structures along the coastline at each coast for each path of typhoon. The first one is the MWS (maximum wind speed) Method. The MWS Method is based on the maximum wind speed near typhoon center at latitude of 30°N. The second one is the Magnitude Method. The Magnitude Method is defined based on the maximum wind speed and the typhoon size. The third one is the EWE (equivalent wave energy) Method. The EWE Method is defined based on the maximum wind speed and the duration of wind blowing … More of typhoon. The fourth one is the CP (central pressure) Method. The CP Method is defined based on the central pressure of the typhoon at latitude of 30°N.The index of vulnerability of each coast for the typhoons of same rank at latitude of 30°N is estimated by the method mentioned above. By using this vulnerability index, the damage level of maritime structures by a coming typhoon at each coast can be estimated when the typhoon passes through at latitude of 30°N.In 1999, Typhoon 9918 struck Kyushu Island. Due to the storm surge and wind waves, the typhoon caused enormous damage to maritime structures. The four kinds of forecasting method, which is proposed by author, is examined to estimate the damage level of damaged maritime structures along the coast caused by Typhoon 9918. The result shows that the forecasting method can be used to estimate the damage level of maritime structures that will occur along the coast before a typhoon strikes.The method, which developed in this time, shows possibility of the estimation of degree of the risk and influence of typhoon on the coasts. The forecasting method will be used for the purpose of coastal zone management in disasters prevention works. Further, it is useful for information of storm warning and evacuation for residents along the coastlines. Less