学会誌「自然災害科学」

氾濫特性に応じた避難情報提供に関する研究

Study on Providing Evacuation Information Based on Flood Characteristics

矢部 浩規*

Hiroki YABE*

Abstract

Evacuation behavior at the time of floods is affected by characteristics of a flood and a region. However, information provided by government administrations, such as prior information on flood-prone areas and hazard maps, and information on a flood in progress, is sometimes uniform and inadequate. In addition, all residents find it hard to fully understand such information. This paper analyzes what evacuation information is appropriate to the characteristics of a flood and a region, in order to investigate ways of providing information to maximize evacuation effectiveness and minimize flood damage. A model was made which can evaluate the possibility of successful evacuation. The model was applied to cases of flooding on the left bank of the Toyohira River in Sapporo, the right bank of the Chubetsu River in Asahikawa, and the right bank of the Tokachi River in Obihiro. The main results obtained are as follows. (1) When the population that needs to be evacuated is large (e.g., in the center of a city) and when the flood stream velocity is high, or when a levee breach makes walking impossible, evacuation information must be provided rapidly. (2) When information is provided over a wide area (e.g., in a sparsely populated area), information provision measures that can overcome distance are effective. This is because the measures such as oral instructions and a public address vehicle take a relatively long time to disseminate information.
This study also quantitatively demonstrates that appropriate provision of evacuation information can mitigate flood damage.

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