Pre-Inca canal system uses hillsides as sponges to store water

https://eos.org/articles/pre-inca-canal-system-uses-hillsides-as-sponges-to-store-water

118 20 7 years ago

vanderZwan• 7 years ago

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.

agumonkey• 7 years ago

I'm gonna say this century will about revisiting our 'mastering of nature'. we have the means and the need.

cmrdporcupine• 7 years ago

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.

ptah2• 7 years ago

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

rapnie• 7 years ago

In a lot of Dutch towns and cities new neighborhoods are designed to have a system of Wadi's [0] where rooftop rainwater is directed to instead of to the sewer system. These are usually dry, but fill up when it rains. They provide attractive green spaces between the buildings and road network where plants, flowers and other fauna can thrive.

Other cities, like Apeldoorn, are providing subsidies to decouple the rainwater drain from the sewer to let the water infiltrate in your own garden instead.

[0] https://en.wikipedia.org/wiki/Wadi

technothrasher• 7 years ago

where plants, flowers and other fauna can thrive.

Calling plants and flowers "fauna" makes me think of Seymour from Little Shop of Horrors. Not sure a bunch of man eating plants between the buildings would be optimal civil engineering.

ptah2• 7 years ago

yes, this is extensively taught in permaculture. it is based on pa yeoman's keyline design. not sure why this article thinks it's new

KaiserPro3• 7 years ago

The paper is far more illuminating: 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.

CameronNemo2• 7 years ago

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

macewindu• 7 years ago

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

KaiserPro3• 7 years ago

The term I was looking for is "Johads"

https://www.notechmagazine.com/2015/06/water-johads-a-low-te...

They expressly do not dam a stream, they collect runoff. You put them in low lying areas that normally form puddles in monsoon.

The idea is to prevent runoff, just like the ones in peru.

dredds• 7 years ago

Australian example - "For more than a decade, two farmers have shown that parched landscapes can be revived. And finally Canberra [is] listening."

https://www.youtube.com/watch?v=-4OBcRHX1Bc

KaiserPro3• 7 years ago

Ahh smashing, Its interesting to note that the aussie version involves leaky weirs.

I suspect thats because the rain pattern in the indian example is different.

brianbreslin• 7 years ago

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...

cbanek2• 7 years ago

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

entwife• 7 years ago

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/

cbanek2• 7 years ago

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 :) )

carapace• 7 years ago

some trees also create aerosols that cause more rain

I was up in Boonville on the coast of California for a bit and on certain days you could actually see the trees breathing out clouds!

Pre-Inca canal system uses hillsides as sponges to store water

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