地区単位の警戒避難行動に対する土砂災害対策の効果に関する試論

抄録

Studies of countermeasures against sediment-related disasters often focus on structural measures; however, nonstructural measures, including warning and evacuation, also play important roles in protecting human lives. Such nonstructural measures were enacted in Japan in 2001; however, since human responses to sediment-related disasters are influenced by many factors, the effects of these measures are typically studied in terms of a small number of individual cases, and remain poorly understood. Therefore, in this study, we conducted in-person interviews and questionnaire surveys to examine the effects of non-structural measures implemented before disasters occurred in five municipalities of Nagano Prefecture, where Typhoon Hagibis caused sediment-related disasters with no human injury or loss of life. The survey results indicate that co-operation and information exchange within and outside the regional unit were required for effective warning and evacuation actions in each regional unit. Therefore, we scored the measures in terms of their effects on information provision and communication opportunities. As the scores of these effects increased, the evacuation rates during disasters increased, although sex differences among regional units may have had an influence. In areas that had experienced severe property damage following sediment-related disasters, evacuation rates were found to be related only to communication opportunities. To improve the effects of non-structural sediment-related disaster countermeasures, we propose that the numbers of disaster prevention drills and seminars should be increased, and that more organisations should be involved in their implementation, ensuring the use of a wider range of methods. Furthermore, showing the importance of communication opportunities provided by incorporating non-structural measures into law would also be effective for preventing human losses.