
Tokyo's Underground Discharge Channel - aashaykumar92
https://en.wikipedia.org/wiki/Metropolitan_Area_Outer_Underground_Discharge_Channel
======
60654
These enormous underground projects are so interesting.

I've been following the Chicago Deep Tunnel project, which is nearing
completion after half a century of work.[1] Because Chicago was built on
swampland and next to the lake, rainwater used to be a huge problem because it
didn't have anywhere to go when it rains, except into sewers - which used to
be well under capacity for burst rainfall, which led to basement flooding etc.

So the city is building (and almost finished with) a set of _huge_ tunnels
across the entire city that regular sewers will drain into during flash
floods, and then pump the water out to reservoirs repurposed from abandoned
quarries on the edge of town. The target capacity is 17 billion gallons, which
is apparently the volume of twelve football stadiums stacked together? [2]

I'd love to tour that construction. Not sure they offer public tours though.
:)

[1] [https://interestingengineering.com/chicagos-deep-tunnel-
proj...](https://interestingengineering.com/chicagos-deep-tunnel-project-
holds-17-5-billion-gallons-sewage-underground) [2]
[https://www.mwrd.org/irj/portal/anonymous?NavigationTarget=n...](https://www.mwrd.org/irj/portal/anonymous?NavigationTarget=navurl://9c5c7fe35c89b6ac5694df01de50b07c)

~~~
NullPrefix
>twelve football stadiums stacked together

I understand that football stadium play area is standard, but how do you
measure height? Is it a foul to kick the ball too high in the air? The play
area, I assume isn't limited vertically.

~~~
wlesieutre
It says "volume of twelve stadiums" so maybe by treating an entire stadium as
a giant bowl up to the top of the seating? But who knows what stadium is the
reference stadium - that's not a consistent thing like the size of a football
field.

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zeptomu
Fun fact:

There is a software for modelling drainage systems called SWMM (Stormwater
Management Model) that has been around since 1970s (!) and is programmed in C
and released as free software. Still most modern drainage and sewer research
is modelled via this software and there are several companies that built a GUI
for simpler usage. However the core is often still based on this nearly 50
year old software which I find amazing [edit: it has been updated since then
and originally it was written in Fortran].

The model has hydraulics and hydrology capabilities [0], i.e. it can model
stuff like pipe pressure but also takes infiltration of stormwater (aka
"rain") into the surface into account. When using it you have to define your
sewer (which is mostly a directed graph) and so called catchments where you
define which areas drain into which nodes (inlets) by defining parameters like
impervious area, slope, etc. You can then let it rain on your area of interest
(e.g. a city) and find out which nodes get flooded at specific points in time
(or hopefully not).

[0]
[https://en.wikipedia.org/wiki/Storm_Water_Management_Model#H...](https://en.wikipedia.org/wiki/Storm_Water_Management_Model#Hydrology_and_hydraulics_capabilities)

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jhurwitz
As of last year, they now offer hourly guided tours 7 days a week for about
USD$10. (In fact, I was just there earlier today!)

Note: it's about 1.5 hrs (each way) from Tokyo, and you need someone in your
group who can speak Japanese.

Reservations here:
[https://reserva.be/guidetour](https://reserva.be/guidetour)

~~~
240dl
Here are some pics from when I took this tour last year:

[http://www.lucashayas.com/journal/2018/11/18/maoudc](http://www.lucashayas.com/journal/2018/11/18/maoudc)

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SmellyGeekBoy
It's amazing just how much stuff there is under Tokyo - not just
infrastructure like this and the usual transport links but entire multi-storey
shopping malls. There's almost a whole city beneath the city. It's possible to
travel for miles without ever seeing daylight!

~~~
Iv
My favorite part is the JSDF underground bunkers where they store the giant
robots used for disaster relief.

~~~
bamboozled
Where is this and how do I see it ?

~~~
barry-cotter
It’s a joke, a mecha robot reference.

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melling
Saw this BBC story on it last year:

[http://www.bbc.com/future/story/20181129-the-underground-
cat...](http://www.bbc.com/future/story/20181129-the-underground-cathedral-
protecting-tokyo-from-floods)

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amluto
> 78 10 MW (13,000 hp) pumps that can pump up to 200 tons of water into the
> Edo River per second.[4]

Wow, I hope the grid can handle the relatively sudden appearance of 780 MW of
load. I assume they have some protocol in which why turn on one pump at a time
and coordinate with the grid operators.

~~~
gmueckl
I'm a bit worried that systems like this make the continued existence of large
cities dependent on the availability of power and the resilience of power
grids. It all works well enough usually, but when things go wrong, systems
like that can make a bad situation a lot worse.

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needle0
I've been there. The containment tank is positively MASSIVE, way more huge
than what can be conveyed from those pictures. It took a good 3-5 minutes of
walking down stairs just to reach the bottom of the tank floor, and once
you're down there it takes some more to appreciate the expansiveness of it
all. Definitely recommended if you're in the area.

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pdx_flyer
Looks similar to the old Houston cistern -
[https://www.houstonpublicmedia.org/articles/news/2016/05/13/...](https://www.houstonpublicmedia.org/articles/news/2016/05/13/150402/buffalo-
bayou-cistern-opens-to-public/)

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k_sze
Is intake into that discharge channel controlled?

Flash flooding is a thing. In Hong Kong, the Drainage Services Department puts
up warnings and runs TV ads to tell people to stay clear of discharge
channels, lest they get swept away by flash flooding during heavy rains.

So if intake into the discharge channel is not controlled, isn't it kinda
dangerous to film there?

~~~
thaeli
The "temple" where filming is done is a secondary reservoir, it only receives
water after the primary detention silos are full. So there is plenty of
warning.

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HankB99
The picture "Metropolitan Area Outer Underground Discharge Channel" is
startlingly similar to one of the scenes in the Mines of Moria (Lord of the
Rings - Peter Jackson's movie.)

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Theodores
Tokyo was a city of canals before the Allies firebombed the city. Apparently
the canals boiled due to the incendiaries used, so there was no escape from
the fire during that tragic phase of life in the city. 100,000 deaths in one
night is a statistic that few people think about, the Nazi death camps worked
at a glacial pace in comparison, the craziness of WW1 campaigns gains a new
perspective too, the bombing of Tokyo, with the loss of those canals, was
something else. Hard to imagine. So we don't talk about it.

Tokyo was built on an estuary so the canals came from the management of the
water that was already there. The final evolution being the water being pushed
completely underground is pretty predictable. Other cities have dealt a
similar fate to their rivers, London being a prime example where only the
Thames is really 'welcomed' as a river, everything else is kind of banished
underground.

~~~
ekianjo
Dresden was also completely destroyed by Allies (for no good reason) and its
firebombing caused between 200 000 and 300 000 victims (largely women,
children and elderly). We don't talk about it much even though it was a crime
against humanity as well.

[https://en.wikipedia.org/wiki/Bombing_of_Dresden_in_World_Wa...](https://en.wikipedia.org/wiki/Bombing_of_Dresden_in_World_War_II)

~~~
bamboozled
From the Wikipedia article supplied:

“Large variations in the claimed death toll have fuelled the controversy. In
March 1945, the German government ordered its press to publish a falsified
casualty figure of 200,000 for the Dresden raids, and death toll estimates as
high as 500,000 have been given.[15][16][17] The city authorities at the time
estimated up to 25,000 victims, a figure that subsequent investigations
supported, including a 2010 study commissioned by the city council.[18]”

It’s a tragedy none the less but that figure doesn’t seem actuate ?

~~~
ekianjo
Nobody actually knows the real number of victims since it was not just the
population of Dresden but also refugees from all over the place who had taken
to live in Dresden. These are not accounted for by the city statistics, so 25
000 people killed is probably on the low end of actual numbers.

You want a different source? [https://www.britannica.com/event/bombing-of-
Dresden](https://www.britannica.com/event/bombing-of-Dresden)

> The U.S. Eighth Air Force followed the next day with another 400 tons of
> bombs and carried out yet another raid by 210 bombers on February 15. It is
> thought that some 25,000–35,000 civilians died in Dresden in the air
> attacks, though some estimates are as high as 250,000, given the influx of
> undocumented refugees that had fled to Dresden from the Eastern Front. Most
> of the victims were women, children, and the elderly.

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howard941
Related previous discussion
[https://news.ycombinator.com/item?id=15436943](https://news.ycombinator.com/item?id=15436943)

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zuypaweu
looks like a mirror's edge scene.. :)

~~~
lmm
Well yeah, the article says the location is used in mirror's edge.

