How Climate Change Increases Flood Risk
Global warming has fundamentally altered rainfall patterns across Japan. Japan Meteorological Agency data shows that intense downpours exceeding 100mm per hour have increased by 1.4 times over the past 30 years. Typhoon intensity has also strengthened. These changing weather patterns have led to more frequent and severe flooding and landslide disasters.
Major Rivers and Flood Risk
Japan's principal rivers—the Tone, Kiso, Yodo, and Ishikari rivers—were engineered based on historical flood data. However, climate change is now producing rainfall exceeding these historical projections. The 2019 Typhoon 19 breach of the Chikuma River in Nagano Prefecture destroyed numerous homes. Concentrated downpours now affect both urban and rural areas with devastating consequences.
Regional Flood Risk Mapping
The Ministry of Land, Infrastructure, Transport and Tourism publishes comprehensive flood risk data for all major waterways. Low-lying regions like the Kanto Plain, Osaka Plain, and Nagoya Plain face particularly severe inundation risks. Historical flood events underscore the critical importance of consulting hazard maps before purchasing property or establishing business operations in flood-prone areas.