CONSIDARATION OF SEAWALL EFFECT ON TSUNAMI EVACUATION

Abstract

 The purpose of this study is to verify the effect of the seawall height on successful evacuation rates. The relation between the height of seawalls and the mortality was analyzed using the data of past questionnaires. Furthermore, numerical tsunami and evacuation simulations were performed for two towns to verify the effect of different seawall heights on morality. Under Tohoku tsunami conditions, the results indicate that early evacuation is more effective in decreasing mortality rates than constructing higher seawalls. The numerical results show that the inundation area decreases by 5% and the mortality decreases by 10 to 20% when the seawall height increased. On the other hand, the mortality rate was reduced to zero when the start time to evacuation is within 10 min.