Flood History (Actual Records)

Actual flood records from 1896–2019, based on MLIT's National Land Survey "Disaster History Maps." Only major, wide-area disasters are recorded — the absence of a record does not mean an area has never flooded.

Only records from within the past 30 years contribute to the Hazard Score, adding a flat +5 points. Older records (e.g. the 1947 Kathleen Typhoon) are excluded from the bonus, since subsequent flood-control work may have since changed the situation.

*This is a separate indicator from the future flood-simulation zones used in the Hazard Score's "Flood Risk," and is based instead on actual past records. There are areas where the two disagree — for example, where the simulation shows no risk but an actual flood record exists.