This incredibly huge pressure-adjusting reservoir was built 22 meters below ground level between 1993 and 2009, and it is really gigantic: 177 meters long, 78 meters wide, 25 meters high with a forest of 59 reinforced concrete pillars each weighing 500 tons supporting the ceiling.

Gigantic underground reservoirs reduce the threat of flooding in the enormous 30 million mega-city and capital of Japan.

A new gigantic underground reservoir in Tokyo

Every year, the low-lying northern areas of Tokyo are almost regularly flooded when the typhoon season drench the city with large amounts of water.

So it was until a few years ago when a giant plant was opened. The complex consists of five huge underground reservoirs into which rain or flood water is led down into.

From these reservoirs, the water is then pumped away and into a river that flows through Tokyo and empties into Tokyo Bay.

Flooding Decreased To One Third

The plant has not been cheap, at a cost of about 2 billion US dollar, in has in turn limited the number of floods to a third.

The plant is only one of the many measures that large cities around the world currently take to defend against flooding from storm surges, which is getting worse due to global warming and sea landings.