These enormous underground projects are so interesting.<p>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.<p>So the city is building (and almost finished with) a set of <i>huge</i> 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]<p>I'd love to tour that construction. Not sure they offer public tours though. :)<p>[1] <a href="https://interestingengineering.com/chicagos-deep-tunnel-project-holds-17-5-billion-gallons-sewage-underground" rel="nofollow">https://interestingengineering.com/chicagos-deep-tunnel-proj...</a>
[2] <a href="https://www.mwrd.org/irj/portal/anonymous?NavigationTarget=navurl://9c5c7fe35c89b6ac5694df01de50b07c" rel="nofollow">https://www.mwrd.org/irj/portal/anonymous?NavigationTarget=n...</a>
Fun fact:<p>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].<p>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).<p>[0] <a href="https://en.wikipedia.org/wiki/Storm_Water_Management_Model#Hydrology_and_hydraulics_capabilities" rel="nofollow">https://en.wikipedia.org/wiki/Storm_Water_Management_Model#H...</a>
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!)<p>Note: it's about 1.5 hrs (each way) from Tokyo, and you need someone in your group who can speak Japanese.<p>Reservations here: <a href="https://reserva.be/guidetour" rel="nofollow">https://reserva.be/guidetour</a>
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!
Saw this BBC story on it last year:<p><a href="http://www.bbc.com/future/story/20181129-the-underground-cathedral-protecting-tokyo-from-floods" rel="nofollow">http://www.bbc.com/future/story/20181129-the-underground-cat...</a>
> 78 10 MW (13,000 hp) pumps that can pump up to 200 tons of water into the Edo River per second.[4]<p>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.
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.
Looks similar to the old Houston cistern - <a href="https://www.houstonpublicmedia.org/articles/news/2016/05/13/150402/buffalo-bayou-cistern-opens-to-public/" rel="nofollow">https://www.houstonpublicmedia.org/articles/news/2016/05/13/...</a>
Is intake into that discharge channel controlled?<p>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.<p>So if intake into the discharge channel is not controlled, isn't it kinda dangerous to film there?
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.)
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.<p>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.