Metropolitan Area Outer Underground Discharge Channel
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The Metropolitan Area Outer Underground Discharge Channel (首都圏外郭放水路 shutoken gaikaku hōsuiro?), is an underground water infrastructure project in Kasukabe, Saitama, Japan. It is the world's largest underground flood water diversion facility, built to mitigate overflowing of the city's major waterways and rivers during rain and typhoon seasons.
Work on the project started in 1992 and was completed by early 2009. It consists of five concrete containment silos with heights of 65 m and diameters of 32 m, connected by 6.4 km of tunnels, 50 m beneath the surface, as well as a large water tank with a height of 25.4 m, with a length of 177m, with a width of 78m, and with 59 massive pillars connected to 78 10MW pumps that can pump up to 200 tons of water (the approximate equivalent of a standard 25 meter pool) into the Edo River per second.
"Ryukyukan" for Underground Exploration Museum of The Metropolitan Area Outer Underground Discharge Channel is also a tourist attraction and can be visited for free; however, as the tours are conducted in Japanese, a Japanese speaker must be present in the group to act as a translator for non-Japanese speakers.
The main water tank resembles a temple and has been used in some movies and TV programs to create mystic scenes. In 2006, a Land Rover television commercial and print campaign was produced using Metropolitan Area Outer Underground Discharge Channel as a location.
The Dutch TV program Wie is de Mol? had an assignment taking place in the water tank.
In 2014, Australia's ABC TV science show Catalyst broadcast a short technical documentary (12'40") titled "Tokyo Flood Prevention" about this and associated flood mitigation structures, buried 50 metres beneath the teeming megacity of Tokyo. Its underworld river system—6.4km of tunnels, colossal water tanks, massive pillars, giant pumps that remove 200 tonnes of floodwater every second—is an engineering marvel built to protect Tokyo against the increasing threat of climate-change related flooding. The ABC programme includes the English-subtitled dialogue of the Japanese technicians.
- "LAIR OF THE BALROG". Accessed 10 January 2015
- "G-Cans Project, Kasukabe, Saitama, Greater Tokyo Area, Japan". Retrieved 10 January 2015
- "Catalyst: Tokyo Flood Prevention - ABC TV Science". ABC - Australian Broadcasting Corporation (Video Documentary). 2014-10-23. Retrieved 2015-03-20.
- Official website (including photos) (Japanese)