How giant tunnels protect Tokyo from flood threat
November 1, 2012 -- Updated 1317 GMT (2117 HKT)
- Japan's "Water Discharge Tunnel" complex drains floodwater into Edo River
- Underground complex is higher than five-story building, stretches nearly four miles
- System's heart is four turbines powered by jet engines similar to those in Boeing 737 plane
Tokyo (CNN) -- On the outskirts of Tokyo, behind a small government building, underneath a soccer field and skateboard park, sits a remarkable feat of engineering.
It's an example of how Japan's capital, which lies in a region at high risk from flooding and tropical cyclones, is trying to figure out how to contain the elements to protect its 13 million inhabitants.
The entrance, which is locked at all times, is so nondescript a visitor may walk past dozens of times without ever noticing it.
But today, we are given a tour down below of the so-called "Water Discharge Tunnel."
Read: Long slog to clean up after Sandy
Sandy floods New York City subways
Staten Island devastated by Sandy
Frustration, Desperation after Sandy
Built between 1993 and 2006 at a cost of nearly $3 billion, the stunning complex is far more impressive than its name suggests.
Winding down a series of stairs, you soon come upon a massive hall, resembling an underground Parthenon, or a scene out of a science fiction film.
In pictures: Sandy's trail of destruction
The initial water tank stretches more than 320 feet in length and towers higher than a five-story building.
When you add it all up, the complex features five massive shafts, or tanks, that are able to move water along a tunnel that stretches nearly four miles.
Special: Tokyo battles the elements
In this area of Saitama prefecture, heavy rains would often flood the Naka River Basin. But now, that valuable farmland has an incredible drain system sitting below.
When the tanks and tunnel fill, engineers are able to turn on the heart of the system, which is a series of four turbines powered by jet engines similar to those used in a Boeing 737 airplane. The turbines are then able to rapidly funnel floodwaters to the nearby Edo River.
It's worth noting that this part of suburban Tokyo can hardly be compared to the dense underground of New York City, which is a maze of subway tunnels, sewage systems and power lines.
The engineers here are the first to point out that their system, while remarkable, is meant to deal with heavy rains -- and that it would struggle to cope with a Sandy-type storm surge coming from the Atlantic Ocean into New York's Upper Bay.
Still, the underground marvel could inspire engineers to look for new ways to try to contain Mother Nature in the future.
Huge plugs could have spared subways from flooding, developers say
Today's five most popular stories
Part of complete coverage on
February 6, 2013 -- Updated 1526 GMT (2326 HKT)
Advocates say the exam includes unnecessarily invasive and irrelevant procedures -- like a so-called "two finger" test.
February 6, 2013 -- Updated 0009 GMT (0809 HKT)
Supplies of food, clothing and fuel are running short in Damascus and people are going hungry as the civil war drags on.
February 6, 2013 -- Updated 1801 GMT (0201 HKT)
Supporters of Richard III want a reconstruction of his head to bring a human aspect to a leader portrayed as a murderous villain.
February 5, 2013 -- Updated 1548 GMT (2348 HKT)
Robert Fowler spent 130 days held hostage by the same al Qaeda group that was behind the Algeria massacre. He shares his experience.
February 6, 2013 -- Updated 0507 GMT (1307 HKT)
As "We are the World" plays, a video shows what looks like a nuclear attack on the U.S. Jim Clancy reports on a bizarre video from North Korea.
The relationship is, once again, cold enough to make Obama's much-trumpeted "reset" in Russian-U.S. relations seem thoroughly off the rails.
Ten years on, what do you think the Iraq war has changed in you, and in your country? Send us your thoughts and experiences.
February 5, 2013 -- Updated 1215 GMT (2015 HKT)
Musician Daniela Mercury has sold more than 12 million albums worldwide over a career span of nearly 30 years.
Photojournalist Alison Wright travelled the world to capture its many faces in her latest book, "Face to Face: Portraits of the Human Spirit."
February 6, 2013 -- Updated 0006 GMT (0806 HKT)
Europol claims 380 soccer matches, including top level ones, were fixed - as the scandal widens, CNN's Dan Rivers looks at how it's done.
February 6, 2013 -- Updated 1237 GMT (2037 HKT)
That galaxy far, far away is apparently bigger than first thought. The "Star Wars" franchise will get two spinoff movies, Disney announced.
July 25, 2014 -- Updated 2327 GMT (0727 HKT)
It's an essential part of any trip, an activity we all take part in. Yet almost none of us are any good at it. Souvenir buying is too often an obligatory slog.