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Shinjuku City Official Website > Foreign Language Top Page > Employment and Status of Residence > Being Ready for a Flood in Urban Areas

Being Ready for a Flood in Urban Areas

Inquiries: Security Affairs Section, Security Affairs Division

Flooding Can Occur Even in Places Far from Rivers

The number of typhoons and concentrated heavy rain that exceed the capacity of sewerage systems has been increasing recently in Japan. In Shinjuku City, basements and streets may have been flooded, while sand and earth have entered some buildings because of typhoons and heavy rain.

●Typhoons
Typhoons are concentrated between July and September in Japan, causing landslides and floods. Take the following precautions to prepare against typhoons.

  • To fight the strong wind, reinforce glass doors and close windows and shutters.
  • Don’t leave items outdoors that are likely to be blown away.
  • Purchase flashlights and a portable radio as typhoons sometimes cause blackouts.
  • Listen carefully to weather forecasts on television, radio and websites for information on approaching typhoons.

Wind Levels and Anticipated Damage

Wind speed10~15m/s Utility pole lines and trees start to sway.
Wind speed15~20m/s Roof tiles, signs and galvanized plates become loose.
Wind speed20~25m/s Roof tiles, signs and galvanized plates start to fly off.
Items blown in the wind break glass windows.
Wind speed25~30m/s Temporary scaffolds that are inadequately maintained will collapse.
Wind speed30m/s or higher Rooftops are blown off and wooden houses start to collapse.

(According to the Japan Meteorological Agency. Average wind speed over a 10-minute period.)

●Concentrated Heavy Rain
Concentrated heavy rain refers to a heavy downpour that falls on a limited area for a limited time. This type of rain has been increasing in Tokyo in recent years. Since it typically occurs suddenly in a limited area, it is difficult to predict when and where such a downpour will occur.
Sewerage systems and small rivers may overflow and cause severe damage. Please pay attention to weather forecasts, such as on TV, radio and websites, and be extra careful when it starts to rain suddenly.

Amount of Rain per Hour and Its Description

Amount of rain per hour Description
10-20mm Splashing rain. It is difficult to hear others.
20-30mm Downpour. Side ditches, sewage systems, small rivers flood.
30-50mm Rain buckets. Roads become like a river.
50-80mm Waterfall-like rain. An avalanche of rocks and earth can occur. Driving is dangerous.
More than 80 mm A major disaster may occur due to the rain. Extreme caution is necessary.

(According to Japan Meteorological Agency)

In Basements

Since rain water from heavy rainfall or torrential rains can easily flow into basements, it is a good idea to have sandbags and boards that can halt the flow of water available. In addition, as it is sometimes difficult to realize the gravity of a situation when you are indoors, look outside from time to time and listen to the latest news on the TV or radio.

◎Shinjuku City distributes sandbags. If you need sandbags, please contact any of the following offices and come pick up the sandbags.

For those who live east of Meiji-dori Avenue
Inquiries: Tobu Public Works Office
Address: 2-42 Ichigaya-Nakano-cho, Shinjuku-ku
Tel: 03-5361-2454
For those who live west of Meiji-dori Avenue
Inquiries: Seibu Public Works Office
Address: 1-9-8 Shimo-Ochiai, Shinjuku-ku
Tel: 03-3364-2422

On the Street

Backed-up sewage may open up manholes, creating large holes underwater that cannot be seen. It is best to avoid walking through flooded streets. Sometimes, waters form pools in V-shaped streets, and they may cause accidents, such as submerging cars.

Flood Hazard Map

This map shows the estimated flood damage when Shinjuku City has a torrential maximum rainfall of 153 mm per hour and total rainfall of 690 mm.

Evacuating during a Typhoon or Torrential Rain

Preparation is vital to avoiding storm and flood damage. It is a good idea to check the hazard map and confirm any potentially high-risk locations. It is also important to listen carefully to the information that public institutions provide, and to take appropriate action for evacuating to a safer place depending on the weather conditions and your own location.

●Evacuation Procedures
○ Taking shelter
If a disaster is predicted, refrain from going out if you are in a location that is safe until the typhoon or rainstorm passes.
○ Moving laterally
If you are able to move to another location and take shelter at a friend’s house or a safer location in the neighborhood, such as an evacuation site established by the city, do so.
○ Moving vertically
If a storm or flood is fast approaching and moving to another location is dangerous, evacuate to the second floor or higher.

●Evacuation Information
When there is a risk of a major disaster due to a typhoon or torrential rain, the City Office will issue evacuation preparation information/evacuation advisories for the elderly, an evacuation advisory or an emergency evacuation directive. Evacuation preparation information/evacuation advisories for the elderly encourage residents to prepare to evacuate, announcing that the possibility of a disaster occurring is high. Those who might take a lot of time preparing for evacuation—such as the elderly, the disabled and other people who need special assistance—should begin to evacuate at this point. An evacuation advisory is an announcement recommending evacuation to local residents who live in an area where damage due to the coming disaster is predicted. An emergency evacuation directive is issued when the situation is more urgent, such as when people’s lives are at high risk.

Weather Information for Shinjuku City

Shinjuku City provides disaster prevention weather information, such as a 48-hour weather forecast for the city, the amount of rain in six locations of the city, and the river level. Please take advantage of this service.

• From computers
Weather Information for Shinjuku City
URL: www.micosfit.jp/snjk/

• From cell phones
Shinjuku City Disaster Prevention Weather Information E-mail System
You can receive disaster prevention weather information via e-mail.
URL: www.bousai-mail.jp/snjk/

April 1, 2019