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Views Water in Japan
“Underground Temple” Safeguards Greater Tokyo from Floods

The Metropolitan Area Outer Underground Discharge Channel was completed 10 years ago and has helped reduced flood damage around the nation’s capital on more than 100 occasions. The world-class underground flood control system not only drains rainwater from low-lying areas but has a pressure adjusting tank that, with its huge columns, has been likened to a giant underground temple.

A Popular Filming Location

Walk down 116 steps from a small hut standing in a corner of a soccer pitch along the Edo River, and you will come upon a cavernous opening 177 meters long, 78 meters wide, and 18 meters high. In it are arrayed 59 concrete columns, each weighing 500 tons. This is the pressure adjusting tank of Tokyo’s Metropolitan Area Outer Underground Discharge Channel. From its solemn, awe-inspiring atmosphere, it has been likened to an “underground temple” and has been attracting visitors from around the world. Located in the city of Kasukabe in Saitama Prefecture north of Tokyo, it is frequently used for photo shoots for fashion magazines and is a well-known location for filming movies, music videos, and TV shows such as tokusatsu (special effects) superhero serial Kamen Rider (Masked Rider).

The templelike atmosphere of the pressure adjusting tank.

The pressure adjusting tank is part of the Shōwa Drainage Pump Station, which is also home to the Ryūkyūkan underground exploration museum. There, after listening to an explanation about the facilities and viewing the exhibits, visitors can take guided tours down to the floor of the tank. These tours are immensely popular and reservations are hard to secure. Despite being open to the public only on weekdays and one Saturday a month and the possibility of reservations being suddenly cancelled when the facility goes into operation after heavy rainfall or undergoes maintenance or checks, the number of visitors has exceeded 40,000. Many visitors—both young and old—enjoy posing for photos with figures or model weapons used by heroes in the many films and TV episodes shot at the facility.

Upper left: The entrance to the pressure adjusting tank sits in a corner of a soccer pitch. Upper right: The “underground temple” is reached by descending 116 steps. Bottom: Part of the roof is opened to lower maintenance equipment, providing a rare opportunity to see the tank illuminated with natural light.

“People have been awed by the colossal scale of the pressure adjusting tank, and this has increased interest in the actual function of the underground discharge channel,” notes Yabe Takayuki, who works in the local office of the Ministry of Land, Infrastructure, Transport and Tourism’s Kantō Regional Development Bureau. “Participating in the tour and seeing the exhibitions and videos in the Ryūkyūkan not only deepens understanding of the benefits of this system and what it has accomplished but also heightens people’s awareness of disaster prevention when they see how frightening floods can be. That’s why we always try to cooperate with the media in reporting and filming.”

Upper left: Yabe Takayuki of the Metropolitan Outer Floodway Management Office offered a guide of the facility. Upper right: Yabe stands next to a pillar to give an idea of its size. Bottom: The floor is covered with sediment carried in with water just a few steps away from the tourist area, suggesting how frightening floods can be.

  • [2017.04.04]
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