
Pre-Inca canal system uses hillsides as sponges to store water - bryanrasmussen
https://eos.org/articles/pre-inca-canal-system-uses-hillsides-as-sponges-to-store-water
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vanderZwan
> _A team of hydrologists, engineers, and social scientists is hoping to
> strengthen the water security of Lima and other Peruvian cities through
> analysis of a 1,400-year-old nature-based system developed by pre-Inca
> mountain communities. The technique uses a canal system that diverts water
> from streams to small ponds or spreads it over rocky hillslopes that act as
> natural sponges. This slows the flow of water down the mountains, preserving
> it into the dry season._

Isn't that exactly what swales in permaculture practices intend to do as well?
Did the permaculture community copy this from indigenous techniques perhaps?

> _Like most modern cities, Lima relies on gray infrastructure like reservoirs
> and dams for water diversion and storage. Gray infrastructure alone,
> however, has its drawbacks. It is often expensive and challenging to
> implement. It also has a static threshold, unable to adapt to shifting
> environmental conditions._

> _Natural (green) infrastructure can be much more dynamic and cost-effective
> than gray infrastructure. Green infrastructure is a broad category that can
> include planting native grasses to prevent erosion and maintaining wetland
> health to hold and filter water. Crucially, communities can use it in
> addition to the dams and reservoirs already in place, amplifying their
> effectiveness and providing a buffer when their threshold is exceeded._

This reminds me of a few articles I've seen in the last years about a German
city that is trying to be better at coping with lots of rainfall by installing
lots of green areas specifically designed to hold a lot of water, while at the
same time reducing the heat island effect.

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cmrdporcupine
Keyline design predates Permaculture One. It was introduced by P A Yeomans as
a means of dryland farming in Australia. It's a somewhat similar concept to
the Inca system described here. Basically trenches are run horizontally with a
very slight slope from a 'keypoint' where water enters a topography. This
slowly distributes water throughout the land, producing fertile and moist
regions between the lines.

This in turn is predated by decades of contour plowing, and thousands of years
of terrace farming.

~~~
ptah
In the permaculture training i took he was extensively credited whenever his
ideas were discussed by lecturer

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KaiserPro
The paper is far more illuminating:
[https://agu.confex.com/agu/fm19/meetingapp.cgi/Paper/503994](https://agu.confex.com/agu/fm19/meetingapp.cgi/Paper/503994)

This similar to some of the things I've heard about in central india(I think)
where they create half moon dams (less than 2m(8ft) tall) that hold water back
creating mini-lakes.

This serves two purposes: one it slows down water, meaning that flash flooding
is reduced. Two is keeps water hanging around longer, meaning it makes the
area less arid.

However it means more mosquitoes, so its not all good.

~~~
CameronNemo
Dams also interfere with fish migration and reproduction. Even small ones are
not exempt from that without careful workarounds.

~~~
macewindu
Are there migrating fish in the area of Central India that OP talked about?

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CameronNemo
If there are fish in the river at all, the biological diversity could be
limited by the inability for those fish to wander beyond their side of the
dam. I am not sure if there are salmonid fish there, or other fish that
require swimming upstream to reproduce. I would doubt it that far inland.

~~~
soperj
You'd be surprised. They used to go as far inland as idaho.

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brianbreslin
If anyone ever has the chance to explore Peru and the Sacred Valley, I highly
recommend it. There are some fascinating ruins apart from Macchu Picchu like
Moray which they believe was a greenhouse where each steppe is a different
microclimate.

[http://www.andeantravelweb.com/peru/destinations/cusco/moray...](http://www.andeantravelweb.com/peru/destinations/cusco/moray-
inca-greenhouse.html)

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cbanek
This is really interesting! It's almost like the opposite of a qanat!
[https://en.wikipedia.org/wiki/Qanat](https://en.wikipedia.org/wiki/Qanat)

~~~
entwife
Such aquifer draining structures (quanat) would result in dry climate over
time, much like we see in Iran. Deep rooted plants - trees, perennial grasses
- would no longer get water from the drier aquifer.

In contrast, aquifer recharging systems (amunas, swales) tens to create a
wetter climate over time. In addition to the plants using water themselves,
some trees also create aerosols that cause more rain. Very special trees -
such as redwoods [0] - can directly capture moisture from fog, that would
otherwise never fall as rain. .

[0] e.g. "Foliar water uptake: a common water acquisition strategy for plants
of the redwood forest" Limm et al., 2009
[https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2727584/](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2727584/)

~~~
cbanek
Yeah, it seems like you would of course want to balance the amount of water
taken out and how much is replenished by rain/snow/underground movement.

I just find it fascinating how smart ancient people were!

Also, it's nice to meet you, and I think someone has been looking for you. (I
love your name :) )

