Cold Season Exclusive: Explore Kannana Underground’s ‘Regulating Pond’ and Flood Protection Tunnel

Also featuring chamber music mini-concerts! What does this extraordinary Infrastructure Tour aim to convey?

The “Kanda River and Route 7 Loop Underground Regulation Ponds Infrastructure Tour,” conducted from autumn to winter, is gaining popularity. This tour takes visitors underground to explore a river facility created as a flood control measure against typhoons and heavy rainfall, located beneath the Route 7 loop. The highlight is a visit to a massive tunnel, approximately 4.5km long from north to south and 40m underground, with a storage capacity of 540,000 cubic meters.

Alongside the extraordinary experience, the tour aims to convey the purpose and effectiveness of river facilities. In fact, Tokyo has been hit by numerous water-related disasters in the past, prompting various countermeasures to be implemented up to the present day.

Children and adults alike can enjoy a tour of the “Giant Underground Tunnel”

This is an infrastructure tour of the Kanda River and Loop Route 7 Underground Regulating Basin, which has been held since before Corona and has been well received. The tours include a combination of tours of the underground control ponds and events such as classical music mini-concerts and yoga, as well as tours of popular spots in Tokyo such as Odaiba and Toyosu Market after the tour of the underground control ponds.

First, participants learn about the roles and mechanisms of the regulating reservoirs in a classroom lecture. After that, participants will see how the underground reservoirs work by flowing water through a model of the reservoirs.

A water control reservoir is a facility that takes in flood water when the water level exceeds a certain level during heavy rains, and temporarily stores it in an underground facility. By taking water from rivers that are about to overflow, flooding can be prevented mainly downstream of the reservoir.

There are three types of reservoirs: dug-in, underground box, and underground tunnel. The Zempukuji River Intake Basin has a huge underground tunnel-type reservoir that stretches 4.5 km from north to south. Now that we had a better understanding of the facility, it was time to visit the highlight of the tour, the underground control pond.

While descending about 40 meters underground and passing through the connecting pipe that serves as the entrance to the underground water control basin, a flow reduction basin that receives flood water taken from the river, the participants were repeatedly surprised by the sight of the tunnel.

When they arrived at the huge tunnel they wanted to visit, they confirmed its size and the traces of water storage. Afterwards, a special event that can only be experienced here begins.

In particular, the classical chamber music mini-concerts, which have been held since last year, are highly popular, offering performances with pleasant reverberation and resonance. Participants express excitement and feedback such as, “The sound is powerful and very satisfying to listen to!”