“Underground Temple” Safeguards Greater Tokyo from Floods

The templelike atmosphere of the pressure adjusting tank.

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.

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.

The same intersection in Satte, Saitama Prefecture—downstream of the Metropolitan Area Outer Underground Discharge Channel—in July 2000 (left) and October 2004 (right), before and after the Discharge Tunnel was opened. They show the flood situation after similar amounts of rainfall. (Photo provided by the Edogawa River Office, Ministry of Land, Infrastructure, Transport, and Tourism.)

Overall view of the Metropolitan Area Outer Underground Discharge Channel. (Photo provided by the Edogawa River Office, Ministry of Land, Infrastructure, Transport, and Tourism.)

Upper left: Water flowing into a containment silo. Upper right: Inside the huge, 10-meter diameter underground tunnel. Bottom: Looking down into silo No. 1, which could easily house the space shuttle. The opening in the upper part of the photo is the pressure adjusting tank. (Upper two photos provided by the Edo River Office, Ministry of Land, Infrastructure, Transport, and Tourism.)

Upper left: The pressure adjusting tank can regulate water pressure when the drainage station turbine pumps are operating or are suddenly shut down. (Photo provided by the Edo River Office, Ministry of Land, Infrastructure, Transport, and Tourism.) Upper right. The four turbine pumps of the drainage station. Bottom left: Sluice gates that discharge water into the Edo River. Bottom right: The Edo River is wide enough to accommodate water discharged from the drainage station.

Upper left: The Ryūkyūkan on the grounds of the Shōwa Drainage Pump Station contains an exhibition hall and is the gathering place for tours of the pressure adjusting tank. Upper right: Visitors hear an explanation of the facilities from a staff member. Bottom left: A room showing videos on three screens. Bottom right: Visitors can look into the actual control room.

Containment silo No. 1 seen from the pressure adjusting tank. The view of this side is also very popular.

The pressure adjusting tank viewed from the top of the stairs.