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

10-min rainfall
The amount of rainfall in the past 10 minutes of the current time (1:00, 1:10, 1:20, 1:30...). For e.g, current time: 2:15, rainfall displayed: 2:00 - 2:10; current time: 2:21, rainfall displayed: 2:10 - 2:20...
1-hour rainfall
The amount of rainfall in the past 1 hour of the current time (1:00, 2:00, 3:00...). For e.g, current time: 2:15 pm, rainfall displayed: 1:00 pm - 2:00 pm.
1-min rainfall
The rainfall of the past 1 minute of the current time
24-hour rainfall
The amount of rainfall in the past 24 hours of the current time (1:00, 2:00, 3:00...)
Accumulated rainfall
Rainfall from the start of the rain until the current 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 announced by the Japan Meteorological Agency in the event of serious disasters such as heavy rain or strong wind
Displayed water level
Approximation of water level of general river
・Caution
40 - 60% of the height of the revetment depending on the width of the river
・Alert
70 - 90% of the height of the revetment depending on the width of the river
Flood alarm river
・A river which indicates the water level information of the rivers to the Flood Defense to carry out flood prevention measures when there is a risk of flood
・Among the rivers managed by the city of Tokyo, those are Sakai river, Tsurumi river, Onda river, Shinkoji river
Flood alert information
・The information regarding the flood forecast river announced when the water has reached the level which requires evacuation, or when it is projected that the water will reach the flood danger level based on the water level prediction
・Among the flood forecast rivers in Tokyo, those are Shiba river and Shin Shiba river only
Flood danger information
・The information regarding the flood forecast river announced when it is projected that the water level is going reach the surface of the revetment, or when the water level has reached the flood danger level and is projected to continue to rise higher.
・The information regarding water level well-known river announced when it has reached the flood danger level
Flood danger water level
The water level posing a risk of flood which results in damages such as considerable houses and buildings flood
Flood forecast river
・A river which indicates to the citizens that there is a risk of flooding
・Among the rivers managed by the city of Tokyo, those are the Kanda river, Meguro river, Shibuya river, Furukawa river, Nogawa river, Senkawa river, Shiba river, Shin Shiba river, Myoshoji river,
・For the Kanda river, Meguro river, Shibuya river, Furukawa river, Nogawa river, Senkawa river, Myoshoji river, only the flood danger information is announced.
Flood inundation information
・The information regarding flood forecast river in case flood has occurred
・Among the flood forecast rivers in Tokyo, those are Shiba river and Shin Shiba river only
Flood inundation water level
・The water level in the vicinity of the water level observatory which indicates that flood will occur and cause damage to houses and buildings
Flood warning information
・The information regarding flood forecast rivers, announced when the water has reached the flood warning water level and is projected to continue to rise higher
・Among the flood forecast rivers in Tokyo, those are Shiba river and Shin Shiba river only
Flood warning water level
The water level which requires flood defense committee to carry out flood prevention measures
Hourly maximum rainfall
Maximum rainfall for any hour from the beginning of the rain
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 JMA so that the head of municipality can make judgements on issuing evacuation recommendation and the local citizens can carry out flood prevention measures.
Stand-by water level for Flood Defense
The water level in the flood alarm river that alerts flood defense committee to stand by for flood fighting activities
The water level which requires evacuation
The water level which requires special alert regarding the occurrence of disaster caused by the flood
Warnings
Information to be announced by the Japan Meteorological Agency in the event of disaster due to heavy rain or strong wind
Water level
Height from the riverbed to the 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 1 minute ago
No fluctuation
A condition in which the water level has risen less than 1 cm compared to 1 minute ago
Fall
A condition in which the water level has fallen 1 cm or more compared to 1 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
・A river which indicates to the citizens the water level of rivers which pose risk to cause flood but is not "flood forecast river"
・Among the rivers managed by the city of Tokyo, those are Shakujii river, Zenpukuji river, Nomigawa river, Tsurumi river, Onda river, Shinkoji river, Sakai river


The condition of rainfall and river water level in Tokyo is displayed every 5 minutes. Please refresh the page to get the latest information.
Tokyo Metropolitan Bureau of Construction - River Division - Diaster prevention department S0000386@section.metro.tokyo.jp
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