Estimation of Extreme Marine Surface Wind Speed and Storm Surge in Closed Bays in West Japan by Using Stochastic Typhoon Model

Since the terrible storm surge disaster by the Typhoon Vera in 1959, many storm surge defense facilities have been constructed on the coast of bays with disastrous storm surges. The occurrence probability of a higher tidal level than the design tidal level seems to be small, but it may increase due to global warming effects such as the mean sea level rise and typhoon intensification. This study, therefore, gave the value of typhoon parameters under current and future climates by a stochastic typhoon model, and estimated the extreme marine surface depression and wind speed, storm surge, and tidal level with a return period of 10 to 1, 000 years in West Japan. The typhoon development region for the stochastic typhoon model was assumed to move toward the north by 1.5 degrees in latitude from the current to future climate. The simulation result shows that large storm surge and high tidal level over the design condition may appear even under the current climate and that the return period may decrease significantly at some locations.