Abstract

In Japan, natural disasters occur frequently and both structural and non-structural measures are essential for disaster prevention. However, the social, economic and natural conditions are different in each region and therefore it has been difficult to evaluate natural disaster risks comprehensively considering various natural disaster such as earthquakes and torrential rainfall. From these backgrounds, the GNS (Gross National Safety for natural disasters) was originally developed by Kikumoto et al. and prefectural disaster risks were also evaluated using GNS_2015 (year 2015 version of GNS). However, structural and non-structural countermeasures for disaster prevention and mitigation are usually planned and carried out in various administrative units such as the country, prefectures and/or municipalities. Therefore, the disaster risks should be evaluated in multi-scale (from country to municipality scales) to increase the effectiveness investment against disaster prevention. Hence, to evaluate natural disaster risks in municipality scale, it is necessary to increase resolution of the damage estimation maps and use consistent statistical data. In this study, the new calculation methodology using GIS (Geographic Information System) was introduced to evaluate “exposure” of natural disaster more precisely in municipality scale. The newly extended GNS was applied to evaluate natural disaster risks of each municipalities in 6 prefectures (Osaka, Hyogo, Kyoto, Nara, Wakayama and Shiga prefectures) in the Kinki district, Japan. The evaluated natural disaster risks are compared with the ones evaluated by the conventional method. Additionally, the “exposure” of flood can be evaluated by superposing damage estimation maps and population distribution using GIS. The disaster risk evaluation results using GNS clearly shows that more comprehensive evaluation of natural disaster risks is important and evacuation/movement from region with high natural hazard exposure will be one of the most effective ways to reduce natural disaster risks.

1. Introduction

Japan is prone to natural disasters. There is a fundamental need for creating a kind of safety index against potential natural disasters to guide us to transform our land into truly safe land. The index must indicate how effective current hard and soft (structural and non-structural) measures are to resist against potential natural disasters, and what measures are inadequate. Immediately after Great East Japan Earthquake on March 11, 2011, an urgent need to create such an index of nation-wide safety index was advocated, together with Gross Domestic Product (GDP) and Gross National Happiness (GNH), to steadily transform Japan to safe land.

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