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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 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.|
|Wind speed25～30m/s||Temporary scaffolds that are inadequately maintained will collapse.|
|Wind speed30m/s or higher||Block walls and houses may 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||Water may pool on the ground after a heavy rainfall.|
|30-50mm||Rain buckets. Roads become like a river.|
|50-80mm||Waterfall-like heavy rain continues. Driving is dangerous.|
|More than 80 mm||You may sense pressure and fear, making it difficult to breathe. Heavy rainfall may also make it difficult to see.|
(According to Japan Meteorological Agency)
Shinjuku City 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.
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 in ten locations. Please take advantage of this service.
• From computers
Weather Information for Shinjuku City
• From cell phones
Shinjuku City Disaster Prevention Weather Information E-mail System
You can receive disaster prevention weather information via e-mail.
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.
○ Stay safe indoors
If a disaster is predicted, refrain from going out if you are in a location that is safe until the typhoon or rainstorm passes.
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.
○ Stay safe in an emergency
If a storm or flood is fast approaching and moving to another location is dangerous, evacuate to the second floor or higher.
When there is a risk of a major disaster due to a typhoon or torrential rain, the City Office will typically make two types of announcement: “evacuation for the elderly, etc.” or “evacuation instructions.” “Evacuation for the elderly, etc.” encourages 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. “Evacuation instructions” is an announcement recommending evacuation to all local residents who live in an area where damage due to the coming disaster is predicted.
After the City Office confirms that a disaster has struck, it will announce “stay safe in an emergency” in as much detail as possible. Please take proper action to protect lives.
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.
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
For those who live west of Meiji-dori Avenue
Inquiries: Seibu Public Works Office
Address: 1-9-8 Shimo-Ochiai, Shinjuku-ku
April 1, 2022