COMPARATIVE CONSIDERATION OF HORIZONTAL AND VERTICAL EVACUATION RISKS IN LARGE-SCALE FLOODS WITH INLAND FLOOD

Abstract

 In May 2021, the Basic Act on Disaster Control Measures was amended to add "emergency safety measures" that can direct not only horizontal evacuation but also vertical evacuation, but the choice of evacuation action in the stage of "evacuation order" is still left to the residents. Horizontal evacuation may become dangerous in situations where inland flood is occurring. In this study, we conducted flood simulations and inland flood simulations in the middle reaches of the Chikugo River, where inland floods frequently occur, and aimed to propose a mechanism for residents to make safer evacuation decisions by comparing the risks of horizontal evacuation and vertical evacuation. As a result, we found that the risk of horizontal evacuation and vertical evacuation differs greatly in each area, and that it is necessary to instruct appropriate evacuation behavior in each area, such as in some areas where the risk of horizontal evacuation increases faster when inland flood is considered.