
How to Build a City That Doesn’t Flood? Turn It into a Sponge - fern12
https://daily.jstor.org/build-a-city-that-doesnt-flood/
======
Spooky23
I think a great example of a good outcome when people give a hoot about
stormwater (and other water removal options since it is an low lying coastal
island!) and the environment is Hilton Head Island, SC. The town is aggressive
or even militant about unnecessary tree removal.

The result is really interesting suburban infrastructure that reducing demand
on the storm sewer. The Walmart parking lot isn't 5 acres of asphalt -- they
left trees in place and have soil buffers with grass or other landscaping.
Curbs are designed to direct water flow to those buffers.

I live in upstate NY, and even in that very different environment, those types
of techniques as well as things like retaining pounds can really improve the
situation with respect to flooding. Otherwise, the only way to remediate the
impact of the increasing number of high volume thunderstorms is to dig up
streets and build cisterns to sudden inflows.

~~~
galobtter
While I think having more trees is good, I wonder if those trees and grass
could lead to problems in the concrete and asphalt.

~~~
robotresearcher
Won't somebody think of the concrete and asphalt!?

~~~
jliptzin
One of the rare comments that actually made me LOL

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geebee
San Francisco has a similar problem to the one described in Pittsburg. We use
an old, single pipe, gravity based system that carries both storm water and
sewage. When it rains heavily, the system backs up at various bottlenecks.
Unfortunately, some of these are in heavily populated and residential areas,
which get flooded with human waste. Even areas not at the bottlenecks may see
more mild drainage backups.

Sadly, SF has done a pretty bad job managing this:

[http://www.sfweekly.com/news/shit-storm-why-wont-sf-stop-
flo...](http://www.sfweekly.com/news/shit-storm-why-wont-sf-stop-flooding-
homes-with-sewage/)

SF's esponse to this problem has shaken my confidence in the city's
governance. SF is going in the opposite direction from what is suggested in
this article - we are paving over (with non-permeable surfacing) more than
ever. The common practice of paving over your front year for extra parking is
generally illegal, but like most quality of life issues in SF, enforcement is
so rare that the city created an entitlement - and it has become the norm in
some neighborhoods.

I know some people my chuckle that this particular issue would cause me to
question SF's government, considering what is going on. But I think it's the
straightforward nature of this - the clear engineering failure, the cause and
effect between excessive paving and storm system overflow, the unenforced
legislation to curtail it, the massive city budget and projects without
adequate funding for critical infrastructure... it's the mundane failures that
really drive home how badly SF's government is handling serious problems.

~~~
closeparen
What’s wrong with parking on grass? Why do people feel a need to pave?

~~~
lojack
Parking on the grass kills the grass, and dead grass eventually turns into mud
when it rains, and mud eventually gets your car stuck. People often use gravel
to prevent this, which is permeable, but you need to add fresh gravel every
year or so.

~~~
sharpercoder
Gravel is only permeable with permeable undersurface. This is usually not the
case, because non-permeable plastics are used to prevent weed from growing in
gravel area.

~~~
abritinthebay
There are water permeable barriers that resist weeds too. It’s solvable.

~~~
TheCoelacanth
Those surfaces are quite a bit more expensive than asphalt, so most companies
won't put them in unless they are incentivized through something like a non-
permeable surface tax.

~~~
abritinthebay
True, it's up to the people involved. My point was more that it's _possible_

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gipp
The last time I saw something about these highly porous pavement alternatives,
it was pointed out they tend to be very vulnerable to freeze-thaw damage and
that this damage also lowers the porosity dramatically. Basically making these
kinds of materials unsuitable for urban use outside of tropical- or near-
tropical areas. Has this changed?

~~~
galobtter
[http://www.cement.org/cement-concrete-
applications/paving/pe...](http://www.cement.org/cement-concrete-
applications/paving/pervious-concrete/pervious-concrete-and-freeze-thaw)
"However, in climates prone to severe freeze-thaw cycles, some are hesitant to
use pervious concrete pavements until it has been proven that pervious
concrete can be made to resist freeze-thaw damage." Pittsburgh does go through
freeze thaw cycle, so I assume there aren't much problems

[https://www.unh.edu/unhsc/sites/unh.edu.unhsc/files/pubs_spe...](https://www.unh.edu/unhsc/sites/unh.edu.unhsc/files/pubs_specs_info/unhsc_houle_thesis_9_08.pdf)

According to this, it also reduces the amount of salt needed 75% for deicing
and the pavement doesn't seem to have been damaged from reading the abstract.

~~~
mcgrath_sh
Well, if Pittsburgh is using it, it is terrible. We have so many potholes (and
huge ones). It has become much worse over the last ~5 years. For several
months we had a multi-foot hole blocked off by cones until the city could fix
it. It essentially was in the middle of a two way road. It was _terrible._ I
see more and more each winter.

~~~
sonar_un
That's not because of the cement but the geology of Pittsburgh itself.
Limestone bedrock and the "underground river" contributes to potholes and
other geologic anomalies. If anything, adding bioswales and having a way to
put the water back into the ground would stop the potholes from happening in
the first place.

~~~
vwcx
Yes, but that still doesn't mitigate the rapid freeze/thaw effects on the
concrete/asphalt that the City of Pittsburgh uses.

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Dowwie
Or you can build a ginormous cistern beneath the city, as Tokyo did:
[https://gizmodo.com/tokyo-has-the-largest-underground-
water-...](https://gizmodo.com/tokyo-has-the-largest-underground-water-tank-
in-the-wor-1696967098)

~~~
jbeales
Which may not be large enough: [http://www.todayonline.com/world/tokyo-
preparing-floods-beyo...](http://www.todayonline.com/world/tokyo-preparing-
floods-beyond-anything-weve-seen)

------
AhtiK
There's a related story on Berlin being built into a sponge city.
[https://www.bloomberg.com/news/videos/2017-08-18/sponge-
city...](https://www.bloomberg.com/news/videos/2017-08-18/sponge-city-making-
berlin-cooler-video)

~~~
baldfat
I think Berlin's approach is better for colder climates. It just makes sure
the water lands in soil and stays there. Each new construction site must do
the same. So the roofs are green with soil and the road's water goes into the
soil and the buildings have a layer of soil on top of underground garages.

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emersonrsantos
In Brazil, there’s a capital called Curitiba that use rivers and parks with
artificial lakes to control flooding with great success.

[http://i2ud.org/2013/08/flood-management-in-curitiba-
metorop...](http://i2ud.org/2013/08/flood-management-in-curitiba-
metoropolitan-area-brazil/)

------
n0us
anyone who hasn't watched a clip on Tokyo's massive drainage system should
check this out
[https://www.youtube.com/watch?v=o85teh1vU_0](https://www.youtube.com/watch?v=o85teh1vU_0)

~~~
bob_theslob646
Super interesting. Essentially, they built an underground river which is
connected to many of Tokyo's rivers (many kilometer underground tunnel) that
diverts overflow water from the rivers to prevent catastrophic flooding.

It cost 3 billion dollars and took 13 years to build.

I would like to see how these held up during the tsunami.

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dogprez
Michigan has be fighting a similar fight for the past couple decades. Wetlands
were disappearing quickly from development and they realized how important
they were to environmental health, essentially turning the state into a
sponge/filter. There is a law there now that removal of wetlands requires
developers to build a new wetlands elsewhere. They still have 40% less
wetlands than pre-european times.

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dsego
Solutions mentioned are I think referred to as BMPs - best management
practices [1]. Regulations exists and there are scientific software tools for
tracking and planning [2].

[1]
[https://en.wikipedia.org/wiki/Best_management_practice_for_w...](https://en.wikipedia.org/wiki/Best_management_practice_for_water_pollution)

[2] [http://www.2nform.com/tools/](http://www.2nform.com/tools/)

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peterwwillis
Dig up all the paved streets and replace with soil, with train tracks on top.
Adapt vehicle wheels to train wheels and provide platforms on train wheels for
the ones you don't adapt. Provide overhead lines to power vehicles adapted to
use them.

You get 1. drainage, 2. reduction of heated urban micro-climates, 3.
elimination of emissions, 4. "driving automation" in the sense that you don't
really need to steer something on rails.

~~~
heartbreak
Are we planning to use manual labor to dig up the streets? Otherwise that
sounds like a significant emissions problem in itself.

~~~
swimfar
Depending on where you live, they may already be doing that every 2-3 years
anyways.

~~~
heartbreak
I’m aware of resurfacing projects, but I’m not aware of total replacement
projects.

------
WillReplyfFood
How to build a City that doesent swarm with mosquitos? Design the sponge to
kill live near the surface

~~~
chmod775
Birds?

------
brudgers
The techniques in the article will _mitigate_ the effects of storm water. As
was the case in Houston, urban flooding results from global weather events. No
matter how Houston had been planned, all the water had to go somewhere and it
was going to the low spots. The only counter-factual in which Houston would
not have had some flooding is if there was no Houston.

Ancient cities in Mesopotamia flooded. Ancient Rome flooded. Cities flood
because they are built on or near bodies of water and bodies of water flood.
The reason cities are built on or near bodies of water: water is a necessary
condition for any city. Water is also an economic engine: fisheries,
agriculture, waste removal, transport, trade. This makes flooding a price of
doing business.

It's not that mitigation is a bad idea. The bad idea is that a city will never
flood. Though it is theoretically possible, it is practically unlikely.

~~~
utexaspunk
One way to deal with flooding is to build highways in a manner where they
become channels in such events. Kuala Lumpur, for example, has their SMART
tunnel[1] which acts as a roadway normally but can be turned into a stormwater
drainage tunnels.

Houston had a prime opportunity in 1996 to do something similar[2] when I-10 W
was rebuilt- and engineers recommended building a conduit under I-10 to carry
flood water from the Barker and Addicks reservoirs to the ship channel. Alas,
that proposal was ignored so West Houston flooded during Harvey.

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

[https://www.dallasnews.com/news/harvey/2017/09/05/houston-
gr...](https://www.dallasnews.com/news/harvey/2017/09/05/houston-grew-
officials-ignored-lifetime-chance-spare-thousands-flooding)

~~~
brudgers
Re: Kuala Lumpur

October 30, 2017: [http://www.channelnewsasia.com/news/asiapacific/kuala-
lumpur...](http://www.channelnewsasia.com/news/asiapacific/kuala-lumpur-hit-
by-flash-floods-following-downpour-9358304)

September 2, 2017: [https://www.nst.com.my/news/nation/2017/09/275610/evening-
do...](https://www.nst.com.my/news/nation/2017/09/275610/evening-downpour-
brings-traffic-stop-flash-flood-hits-jalan-kuching)

2014: [http://www.themalaymailonline.com/malaysia/article/kl-
shop-o...](http://www.themalaymailonline.com/malaysia/article/kl-shop-owners-
surprised-by-flash-flood)

~~~
utexaspunk
One tunnel isn't going to solve all flooding problems in a huge city like KL.
It's a step in the right direction, though.

------
mlinksva
Some ideas along these lines (spongy waterfronts) for SF bay area cities at
[https://neighborland.com/resilientbay](https://neighborland.com/resilientbay)

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hsnewman
Broad statement for the subject. I suspect even a sponge can be saturated.

~~~
Arnt
Obviously, but that's not the test.

The test is whether the sponge can absorb rain as fast as it can fall for a
long-enough time that other consequences of the rain become serious problems
(e.g. deferred outdoor maintenance), while the sponge still isn't saturated.

~~~
galobtter
It's mostly I think the limit of how fast the ground can absorb water after it
has passed through the pavement. If the water rises through the pavement..

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lerie82
The problem isn't flooding, the problem is that people built the city in the
wrong place.

~~~
galobtter
I wouldn't say that. Cities were built next to rivers and seas because they
provided ways of transport, water, and places to dump waste etc. You can't
build a city inland without a lot of trouble. But rivers and oceans flood and
have hurricanes..

~~~
lerie82
Of course that's true but ships need water not buildings, I think we our
civilization is old enough to know about flooding, we just don't care to
address it until sometime happens. Can we not just transport the goods just a
bit farther and start moving away from the flooded areas without having to
waste money and manpower on sponges? Lol

~~~
Feniks
Not in my country, there are rivers every 50 kilometres and canals between
those.

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Retric
I suspect it's cheaper to simply build a large enough drainage system
initially. This is useful if you have already failed and are trying to cope
with failure.

Still, many people are pushing it because you get more plants not because it's
cost effective.

~~~
mnw21cam
It depends if you have somewhere benign to drain all the water into. If there
is a population downstream that might get annoyed if you dump lots of run-off
on them, then making your land more sponge-like can be really useful. If
"downstream" is the ocean a mile away, not so much.

~~~
wanderr
There is also potentially a lot of benefit to having the water enter the soil
and eventually make its way down into the aquifer instead of just shunting it
"away".

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nbrigmon
Hmmm... this invites some unintended consequences, no?

