The Giant Underground Tunnels Protecting Tokyo From Floods
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The Giant Underground Tunnels Protecting Tokyo From Floods

February 28, 2020

The city of Tokyo is built
around and over rivers. When you travel around here, it is striking
just how often you cross water. And from up above, you can see this
whole area is flat, low-lying coastal land. Some parts of Tokyo even sit below sea level. They’ve sunk because of decades of
pumping out groundwater. The two and a half million people
in those low-lying areas are protected by a network of
flood gates and aging levees, which’ll be fine unless sea levels rise. But even inland, a huge part of this megacity is built
in river basins and flood plains. And as the climate breaks down, rain storms here are getting more intense
and more frequent. If you want to prevent river flooding, or drain neighbourhoods
that are starting to flood: where do you put the water? If you pump it out of that neighbourhood, you’re likely just moving the flood next door. The best plan would, in theory, be to pump the floodwater
all the way to the ocean, or at least to a tidal river
that can deal with it. But for that, you would need tunnels and
buffer tanks on an almost unimaginable scale. Now, despite what some
breathless blog posts might claim, the whole metropolis doesn’t have that. But there is one place, about an hour
north of the centre of Tokyo, that does. This is the Metropolitan Area
Outer Underground Discharge Channel, or at least, one part of it: the holding tank. It is almost impossible to convey the scale
of this on camera. [IN JAPANESE:] If the Otoshifurutone and Naka rivers
start to flood, this is where the water will drain to. Actually, where the water
is sort-of still draining to. There was a massive rainstorm about two days ago, and there is still water in the system. I am not allowed down on the floor,
just in case. [IN JAPANESE:] This tank, and the kilometres of tunnels and
all the silos that bring water to it, cost nearly a quarter of a trillion yen, that’s about two billion US dollars,
at the end of the 20th century. That was when the Japanese government was
spending money to finance enormous
infrastructure projects like this, to try and stimulate the economy. Which, for long-term security, is great: but it took a national recession
to make this happen. A plan like this only works if a government
wants to spend a colossal amount of money, and in the 21st century, there aren’t many governments
willing to do that. Thank you to all the team here
for letting me down in the tank, and up on these catwalks.
You can find out more about them and their work
at the link in the description. Echo! [echoes continue and fade] That goes for a long time.

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  1. -Land has sunk from pumping ground water
    -Storms are now more intense since land is below sea level

  2. Location coordinates at each cutscene:

    00:00 = 35.6698, 139.7828 (looking NNE)
    00:03 = 35.6949, 139.7880 (NE)
    00:05 = 35.6961, 139.7852 (SSE)
    00:07 =
    00:09 = 35.6844, 139.8645 (WNW)
    00:14 = 35.6698, 139.7828 (NNE)
    00:22 = 35.6730, 139.7815 (S)
    00:24 =
    00:26 = 35.6698, 139.7828 (NNE)
    00:39 =
    00:44 = 35.6698, 139.7828 (NNE)
    01:12 = 35.9972, 139.8123 (W)

    01:15 = 35.9955, 139.8105 (NE)
    The rest are all underground at the last timestamp. I have no idea why I spent time doing this.

  3. tom, could you please make a video on how you get access to all of these random things? how do you get permission to get in these tunnels for example?
    just an idea for a video.

  4. 3:15 “thank you to all the team for letting me down”

    replace “all the team” with “life” and you have the story of my life

  5. Not a bad idea! I wonder if something like that could be constructed in Arkansas to protect the farmland from flooding?? We had a flood like i've never experienced earlier this year. Took out a BUNCH of crops and at least 1 hog farm.

  6. Japan, where the whole country is willing to take a recession for 137 hectares of land and its inhabitants. Be more like Japan.

  7. "there arent many governments willing to do that"

    yup and thats why in the uk we have a housing crisis and the government is building more luxury housing than council housing

  8. I could imagine something like this could be retrofitted to also make power.
    Like adding turbines to the inlets for when a storm comes to make backup power, or making large storage tanks above ground or uphill to be used for power later..

    A system like this is intriguing and full of amazing possibilities.

  9. I personally understand how harsh it is in the desert. The lack of water is serious. The help combat this I am personally working to increase rain and changes in weather. I have an almost 24 hour a day 7 days a week tire and styrofoam fire burning and will continue to for as long as I can.

  10. Props to Japan though, instead of wasting money with smaller projects, many of which get funding only to be cancelled or scaled back halfway through, they have the drive to actually go all the way and spend the money to do it properly. Just look at their maglev train line, tunneling entirely though a massive mountain range, 90%of the track is underground, and meanwhile us Brits are still debating weather or not to even go ahead with HS2, and the Americans have bridges failing due to lack of maintenance funding.

  11. hiding in a tunnel in a flood sounds like a recipe for disaster… no thanks, ill head for the hills or a strong tall building.

  12. Young people are all for the green new deal until they find out that all modern life's luxuries will be lost…no phone, A/C, no hamburgers and god forbid that their entire family may have to live in a house that is the size of the room they now inhabit alone…suddenly it becomes screw the planet but leave my facebook alone.
    It may become so awful that they will need to wear their pants until holes appear in the material instead of buying new pants with holes already installed.

  13. $2 Billion is a "colossal" amount of money? We spend $500 Billion a year on military in the US. We could make 250 projects of this scale, every year.

  14. 1:30 The series finally of Kamen Rider Fiaz was filmed in a place like this! Seeing people on the ground and then looking up… it's amazing.

  15. Am I a weirdo or is anyone else really satisfied from huge concrete structures like underground tunnels, huge dams and other things

  16. There aren't many government willing to do that indeed. Now we have flooding in Jakarta, people losing lives and up to 700 million USD damage in 1 flooding. Is that a fair trade?

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