SAITAMA (Kyodo) An underground tunnel built to take in river water overflow and release it into another river to mitigate flood damage was shown to the media Monday in Kasukabe, Saitama Prefecture.
The 6.3 km long conduit is 50 meters underground in Kasukabe and connects the Otoshifurutone and Edo rivers.
If the Otoshifurutone River or nearby Naka River flood, excess water can be channeled into the tunnel from five locations and temporarily stored in a gigantic reservoir before being pumped up and released into the Edo River.
The water chamber, dubbed the "underground palace," features 59 columns, each 25 meters high, that can store 670,000 cu. meters of water, according to the Land, Infrastructure and Transport Ministry.
The government project began in 1993 with a budget of 240 billion yen, and part of the tunnel became ready for use in 2002. The system will begin full operation in June.
Historically, the eastern part of Saitama Prefecture has been prone to floods. The government says the flood-management system will significantly reduce the danger of floods in the area.
