Tokyo Metropolitan Storm Surge Training Site

Seawall: This is an installation that raises the existing ground using concrete or the like to prevent damage from flooding caused by storm surges and abnormal tidal levels. In the case of Tokyo Bay, this is maintained at a height of 4.6-8.0 m from the mean low tide level.

Floodgate: Floodgates are built at a boundary between the outer waters and the inner waters partitioned by the seawall. If the water level in the outer waters rises because of a high tide or the like, the floodgate is closed to prevent the water level in the inner waters from rising.

Interior Seawall: This is used to protect the inland from flooding, even when the seawall is destroyed by an earthquake. It is also used to protect inland from flooding even when inland water rises because of a storm surge occurs and the floodgate is closed.

Drainage Pumping Station: When the floodgates are closed because of a typhoon or the like, the drainage pump will begin operating to lower the water level in the inland waters if the water level in the inland waters is rising because of rain or sewage drainage.

Inland Lock: Inland locks are where storm surge barrier cross roads and paths to prevent the intrusion of sea water.

Atmospheric (Barometric) Pressure: Barometric pressure measured at each observation point

Wind Speed: Indicates wind speeds. Indicates the average 10-minute wind speed measured at each observation point. This is expressed as x.x m or x.x m/s.

Wind Direction: Direction in which the wind is blowing measured at each observation point

Spring Tide: The difference between tide levels at high tide and the low tide become greater at time of a new moon and full moon.

Low Tide: The tide level is minimal mainly due to the tide-generating force of our moon and sun. It appears twice a day on many coasts around the world.

Tide Level: Short-cycle fluctuations such as ocean waves are smoothly removed at sea level measured from the reference plane.

Tide Level Deviation: The difference (deviation) between the astronomical tide level calculated from the movement of the celestial bodies (estimated tide level) and the actual tide level which is affected by the weather and the like

Astronomical Tide: The phenomenon of sea-level rise and fall caused by the tide-generating forces of our moon and the sun. The actual observed tide level is the product of weather effects such as barometric pressure and wind on the astronomical tide.

Astronomical Tide Level: This mainly refers to tide levels predicting the astronomical tide. This is also called predicted sea level.

High Tide: The tide level is extremely high mainly due to the tide-generating forces of our moon and the sun. It appears twice a day on many coasts around the world.

Inland and Outlying Embankments: The side of the embankment where there is housing and agricultural land that is protected from high tides and flooding by the embankment is called inland embankment, and the side that is sandwiched by the embankment and where water flows is called the outlying embankment.

Abnormal Tide Level: A phenomenon in which the tide level continues to be higher (or lower) than normal for a relatively long period of time (about 1 week to 3 months).

Ａ. P.: A.P. (Arakawa Peil) refers to the datum level of port construction along the coast of Tokyo Bay.

Missing Data: A state in which observation data cannot be measured due to equipment inspection or a malfunction at observation equipment.

Suction Effect: Sea water is sucked up and the tide level rises due to the a drop in barometric pressure associated with strong meteorological disturbances, such as a typhoon or the like.

Storm Surge Special Warning Water Level: This is the standard water level to inform Tokyo residents of the risk of coastal and river flooding caused by the storm surge brought by the largest conceivable typhoon. When the water level at the standard Tatsumi Water Gate (Tatsumi, Koto Ward) reaches this storm surge special warning water level, Tokyo Metropolitan Government will issue a "storm surge flooding information (equivalent to alert level 5 in evacuation information, etc.)" and notify the relevant wards, and with the cooperation of media organizations, etc., will inform residents.

Storm Surge: Sea levels rise abnormally due to the suction effect of the sea level because of a drop in barometric pressure associated with strong meteorological disturbances such as a typhoons or the like and the blowing effect of sea water caused by the wind.

Special Storm Surge Warning: Forecasts released by the Japan Meteorological Agency are announced when a storm surge caused by an intense typhoon or similar extratropical low pressure that occurs every few decades is expected.

Storm Surge Warning: Forecasts released by the Japan Meteorological Agency are forecasts made by warning when a serious disaster is likely to occur.

Storm Surge Advisory: Forecasts released by the Japan Meteorological Agency are forecasts made with special care when a disaster is likely to occur.

Blowing Effect: Sea water is blown to the coast and the tide levels rise due to wind blowing toward the coast.

Terms Relating to Storm Surges