Integrated Flood Measures for Urban Flooding
Overview
Following damage and challenges caused by inland flooding and other impacts in urban areas during the August 2026 Chiba downpour and heavy rain in the Tokai region in September, the Water Disaster Investigation and Countermeasures Committee compiled a policy for addressing urban flooding. The policy calls for promptly implementing comprehensive structural and non-structural measures based on three pillars: recognizing risks in advance, supporting evacuation actions that protect lives, and reducing flood damage through basin-wide water management.
Key points
- The policy calls for promptly implementing comprehensive structural and non-structural measures to address challenges specific to urban flooding.
- The measures are organized around three pillars: strengthening advance risk awareness, supporting evacuation actions that protect lives, and reducing flood damage through basin-wide water management.
- The policy was compiled in light of the August 2026 Chiba downpour and heavy rain in the Tokai region in September.
Overview
The Water Disaster Investigation and Countermeasures Committee examined flood damage and challenges, including inland flooding in urban areas, and compiled a policy for addressing urban flooding.
Impact
The stated objectives of the measures are to protect human lives and prevent catastrophic damage to urban functions.
Details
Under “Strengthening Advance Risk Awareness,” the policy calls for accurately identifying and communicating flood risks, taking into account the complex patterns of flooding in urban areas, including localized low-lying areas and underground spaces.
Under “Supporting Evacuation Actions That Protect Lives,” the policy calls for measures to encourage appropriate actions and evacuation in response to rapid changes in conditions caused by intense urban downpours, sudden road flooding, and inundation of low-lying areas.
Under “Reducing Flood Damage Through Basin-Wide Water Management,” the policy calls for measures to “store” and “convey” water across the entire basin, even in urban spaces where water has nowhere to go.
The compiled materials and the committee’s progress to date are published on the Ministry of Land, Infrastructure, Transport and Tourism website.