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Peru is reviving a pre-Incan technology for water

bbc.com

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Re: Peru is reviving a pre-Incan technology for water

#11

Post by gus_massa »

abdullahkhalids wrote: post #4
koheripbal wrote: post #3

TLDRV They divert the rainy season water to natural aquifers and hope it reappears down river in the dry season. The small scale of the effort currently makes me a little skeptical that it's achieving anything. Underground water is impossible to measure. What might be more effective and certainly more measurable would be to build a dam/reservoir.

The linked paper > Infiltrated water is retained for an average of 45 d before resurfacing, confirming the system’s ability to contribute to dry-season flows. We estimate that upscaling the system to the source-water areas of the city of Lima can potentially delay 99 × 106 m3 yr−1 of streamflow and increase dry-season flows by 7.5% on average, which may provide a critical complement to conventional engineering soluti…

I can't see the paper, but there is some interesting technical details in the supplementary data https://static-content.springer.com/esm/art%3A10.1038%2Fs418...

In page 15, table 2 they show that they put some Eosin https://en.wikipedia.org/wiki/Eosin upstream before the water entered the earth, and then they collected water from the springs downstream a few weeks later and measure how much Eosin was there, and used this to estimate how long the water was stored.

Re: Peru is reviving a pre-Incan technology for water

#12

Post by imagine99 »

nikkinana wrote: post #2

Fresh water is the new global warming scam. There's water everywhere, just nobody wants to route it properly. Instead just complain and wait for the leaders to leverage it to stay elected.

Have you considered, as a service to humanity or yourself, to teach and share how this could be done "properly"? You clearly appear to have some knowledge of techniques that, while you think them obvious, other people don't seem to understand (not even on HN, as the downvotes indicate).

At the same time, these techniques could solve a lot of issues including people losing their livelihoods, mass migration, devastation or even wars.

So don't you think sharing how to do it would be worth infinitely more than your one-liner comment?

Re: Peru is reviving a pre-Incan technology for water

#13

Post by themanmaran »

Very long winded. The actual technique is only described about 2/3s the way through. They're using canals to divert water into well draining soil.

"They use water canals called amunas – a Quechua word meaning "to retain" – to divert wet-season flows from mountain streams and route them to natural infiltration basins."

"Because the water moves more slowly underground as it travels through gravel and soil, it emerges downslope from springs months later, when the comuneros collect it to water their crops."

Re: Peru is reviving a pre-Incan technology for water

#16

Post by acdha »

H8crilA wrote: post #10
acdha wrote: post #6

Earlier quoted context omitted.

Can you explain where the article is wrong in saying that Peru has limited fresh water supplies? After that, explain “everywhere” including arid and desert regions. Please cite sources and your level of expertise.

The fact is that water is plentiful in some areas while insufficient in others (and the areas can change over time), but so fucking what - you cannot transport it efficiently enough. Well, sometimes you can: https://en.m.wikipedia.org/wiki/Great_Man-Made_River

Oh, as a native Southern Californian I completely understand this. It’s amazing to me that anyone can claim this is no big deal like there aren’t billions of dollars at stake in agriculture and industrial usage.

Re: Peru is reviving a pre-Incan technology for water

#17

Post by IncRnd »

koheripbal wrote: post #3

TLDRV They divert the rainy season water to natural aquifers and hope it reappears down river in the dry season. The small scale of the effort currently makes me a little skeptical that it's achieving anything. Underground water is impossible to measure. What might be more effective and certainly more measurable would be to build a dam/reservoir.

> TLDRV They divert the rainy season water to natural aquifers and hope it reappears down river in the dry season.

Simple diversion of water is not what was discussed. Thank you for the summation, but you summarized the non-relevant information.

> The small scale of the effort currently makes me a little skeptical that it's achieving anything. Underground water is impossible to measure.

Even if you are not familiar with how vegetation works, there is proof contained later in the article. They discuss how removing portions of peat land caused the surrounding plants to dry out and die.

Re: Peru is reviving a pre-Incan technology for water

#18

Post by aaron695 »

Africa has been using sand dams and India, Johad's for this.

You just slow the water down and save it in the ground. This is fine for small scale farmers and communities and seems to work.

On a larger scale -

Managed Aquifer Recharge (MAR) map (It includes a lot of models but also active sites)

https://ggis.un-igrac.org/view/marportal

This article is poor. Talking about Lima was silly and it as usual avoids the actual reason water is scarce, high populations with high use techniques. And where's the pictures, a big part of the amunas is they look awesome, like England and their stone walls lets not pretend it's the most efficient way of doing it. They look cool. That's a important part of communities.

Re: Peru is reviving a pre-Incan technology for water

#19

Post by KaiserPro »

tldr:

Diverting streams to go into different places increases the dwell time of the water by 45 days. when you have a rigid dry season, keeping the streams running for an extra 45 days is absolutely fucking huge. The clever part is that over the years the locals have managed to find the best place to divert water so it goes into springs that feed streams.

its a similar idea to a Johad, https://en.wikipedia.org/wiki/Johad which traps water for a number of days, increasing the dwell time and making the place wetter. The issue with Johads is that they can be a magnet for mosquitos. Johads differ in that they force the water into the soil rather than aquifers.

In LA, everything is done to make sure the water yeets into the sea as quick as possible. That water that would have hung around is replaced with the water from the LA aqueduct and the like. THe place gets drier, and hotter. I would wager, but can't assert that this water mismanagement is causing a large part of the drought in that area.

Re: Peru is reviving a pre-Incan technology for water

#20

Post by jazzyjackson »

menrris wrote: post #14

They should probably make a sustainable method other than an old tradition as our planet will inevitably go hotter.

Stashing water underground is a great strategy for a hotter earth. See also the great stepwells of India. Just because something is old doesn’t mean it’s not effective and sustainable.
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