Editorial: Deadly rains in east Japan highlight need to rethink flood preparedness

Japan faced a deadly wave of torrential rain, resulting in 13 fatalities and causing extensive damage across the country. A continuous band of heavy rainfall emerged in Chiba Prefecture, bringing unprecedented levels of precipitation that overwhelmed drainage systems and led to the inundation of thousands of buildings. Approximately 2,700 vehicles became stranded, trapped inside as water reached half the height of their tires, making them immobile.

The rapid rise in water levels was primarily due to internal flooding from overflowing sewers and drainage systems, which submerged basements of commercial buildings and apartment complexes. The impact of transportation disruptions was significant, with many residents unable to return home, and emergency shelters were set up at Narita Airport to accommodate around 7,000 people.

Despite a Level 5 Emergency Warning for heavy rain, issued for the first time since the reorganization of disaster-prevention weather information, the lack of timely forecasts for localized rainfall posed challenges. Authorities must improve communication to encourage safer actions, particularly in light of the increasing frequency of intense rainfall due to global warming.