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.
Built between 1993 and 2006 at a cost of nearly $3 billion, the Water Discharge Tunnel 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.
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.
‘Incredible drain system’
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.
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.
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Source: Alex Zolbert | CNN
Image: Shine Your Light