2025 Volume 81 Issue 13 Article ID: 24-13531
Based on the database of “Statistics on Water Supply” during the fiscal years 2008 through 2021, vulnerability factors of water distribution pipelines in Japan were evaluated reflecting pipe material, joint types and diameter. The long-term trend of the vulnerability factors was also compiled. While the ratios of both earthquake-resistant pipes and earthquake-resistance compatible pipes to all pipes increased by a factor of two for 14 years, vulnerability factors only decreased by a factor of around 0.8. A new index called “restoration difficulty factor” was defined as the product of vulnerability factor and the extension of water distribution pipelines per capita and evaluated based on 2021 version of “Statistics on Water Supply.” In the municipalities in the hard-hit area of the 2024 Noto Peninsula earthquake, both of vulnerability factors and the extension of water distribution pipelines per capita significantly exceed the nation-wide averages. Consequently, restoration difficulty factors were approximately six times as large as the average, resulting in lengthening of restoration works from water outage.
