ESTIMATION OF THE RECURRENCE PERIOD OF THE STORM SURGE CAUSED BY TYPHOON JEBI AND THE ASSUMED MAXIMUM STORM SURGE IN OSAKA BAY

Abstract

 The risk of storm surge disasters is increasing due to the sea level rise and the increase in typhoon intensity caused by climate change. In order to enhance the evacuation framework against the maximum possible storm surge, the flood prevention law has been amended, and then local governments create a storm surge inundation hazard map. However, there is no estimation of the recurrence period of the maximum storm surge. In this study, an ensemble storm surge simulation is conducted in Osaka Bay using a nonlinear shallow water model with the aid of a global stochastic typhoon model to estimate the return period of storm surges caused by Typhoon Jebi, the largest typhoon ever recorded, and by the assumed maximum storm surge. The storm surge during Typhoon Jebi is simulated with sufficient accuracy. The estimated returen period of the storm surge caused by Typhoon Jebi is 50 to 100 years. The estimated return period of the assumed maximum storm surge is more than 2500 years, indicating that the local governments are assuming a very rare event.