G-Cans 首都圏外郭放水路
The underground canal system
Tokyo is equipped on its outskirts with an immense water drainage system for the various rivers that cross the territory of the metropolis. The reserves and the canals that support this underground system are impressive in their size and are open to the public for tours!
Protection against the fury of the waters
The work of the G-Cans, or "shutoken gaikaku hosuiro" in Japanese meaning "anti-flood tunnel of the outer metropolitan area" began in 1993, to be put into service 13 years later, in 2006.
Built between Showa in Tokyo and Kasukabe in Saitama prefecture, north of the capital, the complex extends over 6.4 kilometers, 50 meters below the surface of the earth.
- Read also: Typhoon season in Japan
G-Cans tank
Wikipedia
During typhoons or torrential rains, it diverts the overflowing waters of various rivers, such as Kuramatsu, Arakawa, or Nagakawa, to send them back to the Edo River, which then flows into Tokyo Bay.
The largest system in the world
The G-Cans is considered the largest water diversion system in the world. It is composed of :
- 5 concrete containment silos 62 meters high and 32 meters in diameter.
- 6.4 kilometers of tunnels, with a diameter of 10.6 meters, which connect the silos to the water reservoir when their capacity is exceeded.
- A huge water reservoir is 25.4 meters high, 177 meters long, and 78 meters wide. It is nicknamed the "underground temple" because of its 59 massive pillars reminiscent of the colonnades of a Greek temple.
- 78 turbines with a power of 10 MW each pumping 200 tons of water per second into the Edo River.
A place of tourist passage
This system works during heavy rains. During the dry period, unused, it can be visited. However, certain constraints are imposed.
It is indeed necessary to reserve your place in advance, a visiting group cannot number more than 50 people, and it is necessary to speak Japanese or to be accompanied by an interpreter who can translate the explanations and inform the visitors in case of need for evacuation.
Tourists in the G-Cans
Wiki commons
The large reservoir and its pillars have also been the scene of numerous television productions and evocations in popular culture. One of the best known is the filming of several scenes from the movie Hunger Games: Mockingjay (Part 2).
Address, timetable & access
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Address
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Phone
048-746-0748 -
Timetable
From Shibuya station, take the Hanzomon line to Kasukabe station (about 1h10). Take the Noda line and stop at Minami-Sakurai station (7 min) from where a bus line leads to G-Cans. -
Price
1,000 yen (about $8.50/8€) -
Access
Monday to Sunday: 10 am to 4 pm.
