Tokyo Metropolitan - Flood Control Integrated Information System (Bureau of Construction River Division) Provide

This website provides rainfall amount and river water level information observed in Tokyo, as well as the warnings, alarms and special alarms in real time.

Glossary

10-min rainfall

The amount of rainfall in the past 10 minutes up to the last ten minutes of each hour (1:00, 1:10, 1:20, 1:30, etc.) before the displayed time

1-hour rainfall

The amount of rainfall in the past 1 hour up to the hour (1:00, 2:00, 3:00, etc.) immediately before the displayed time

1-min rainfall

The amount of rainfall in the past 1 minute up to the displayed time

24-hour rainfall

The amount of rainfall in the past 24 hours up to the hour (1:00, 2:00, 3:00, etc.) immediately before the displayed time

Accumulated rainfall

Rainfall from the start of the rain until the displayed time
When there is no rainfall for 6 hours, the accumulated rainfall is reset, and after that when rainfall is detected, it will be considered a new rain (start of the rain).

Alarm

Information to be announced by the Japan Meteorological Agency when a serious disaster may occur due to heavy rain or strong winds

Displayed water level

Approximation of water level of general rivers

Flood alarm river

Flood alert information

Flood danger information

Flood danger water level

Water level that poses a risk of flooding which results in considerable damages such as flooded houses and buildings

Flood forecast river

Flood inundation information

Flood inundation water level

Flood warning information

Flood warning water level

Water level at which flood defense organizations are mobilized to prevent flood damage

Hourly maximum rainfall

Maximum rainfall for any hour from the beginning of the rainfall

Hourly maximum rainfall duration

An hour during which a maximum rainfall is recorded

Normal

Water level which does not require special attention for flood prevention activities

Sediment-related disaster alert information

Disaster prevention information jointly announced by the prefectures and the Japan Meteorology Agency so that the heads of municipalities can make judgments on issuing evacuation recommendation and the local citizens can voluntarily evacuate.

Stand-by water level for Flood Defense

Water level in the flood alarm river that each flood defense organization makes preparation for flood defense activities

Warnings

Information to be announced by the Japan Meteorological Agency when a disaster may occur due to heavy rain or strong winds

Water level

Height from the riverbed to water surface at a water level observatory

Water level fluctuation

Rise
A condition in which the water level has risen 1 cm or more compared to a minute ago

No fluctuation
A condition in which the water level has fluctuated less than 1 cm compared to a minute ago

Fall
A condition in which the water level has fallen 1 cm or more compared to a minute ago

Water level from top of the dike

Height from the top of the levee or revetment to the water surface

Water level well-known river

Water level which requires evacuation

Water level which requires special alert regarding the occurrence of disaster caused by the flood