[HN Gopher] Peru is reviving a pre-Incan technology for water
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Peru is reviving a pre-Incan technology for water
Author : midnightcity
Score : 152 points
Date : 2021-08-20 12:08 UTC (10 hours ago)
(HTM) web link (www.bbc.com)
(TXT) w3m dump (www.bbc.com)
| menrris wrote:
| They should probably make a sustainable method other than an old
| tradition as our planet will inevitably go hotter.
| jazzyjackson wrote:
| 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.
| wolverine876 wrote:
| The _amunas_ are channels that slow the movement of water from
| mountain streams to farmers; "the diverted water spends between
| two weeks to eight months underground, with an average delay of
| 45 days".
|
| As far as I can tell, they are used to retain water from the wet
| season into the dry season. How is that advantageous over using
| water storage at or near the endpoints? Perhaps ancient farmers
| didn't the ability to create underground storage, but how are
| amunas preferable now?
|
| I imagine there's a good answer, but if it's in the article I
| overlooked it.
| tharkun__ wrote:
| Storing water in ponds has to deal with evaporation, algae
| growth etc. Also expensive to build.
|
| Storing water in tanks means buying and maintaining something
| as well.
|
| I think the point here is the "low tech, thousands of years old
| and it works" part. Underground water doesn't evaporate or grow
| nasty stuff. You do have to have the right terrain I suppose
| but where you do this sounds awesome. The ground will actually
| even help with filtering out many nasties.
| appleflaxen wrote:
| It's a capacity issue. The bandwidth of the amunas is enormous
| compared to a reservoir.
| themanmaran wrote:
| 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."
| hinkley wrote:
| Ground storage of fresh water is a simple technique that people
| seem to resist. 'Controversial' is not the right word but in
| the permaculture community there is a definite divide between
| people who embrace it and those who resist. The interactions
| are... frustrating.
|
| There's also a relationship between water, soil health and
| climate change. The rule of thumb is that an acre of land can
| store an additional 20k gallons of water by increasing the soil
| carbon by 1% (of overall fraction, not relative to previous
| carbon levels, so in most real world cases that may involve
| increasing carbon by 10-25%).
| markdown wrote:
| Interesting. I thought the use of swales was pretty well
| accepted. Surprised to hear that there's a faction that's
| opposed to that.
| Cerium wrote:
| I didn't know it was controversial. In San Jose we have many
| (currently dry) ground water recharge ponds where water is
| let in for the purposes of seeping into the water table. Much
| of the city uses ground water, the resulting water is quite
| hard but has a decent flavor profile.
| naravara wrote:
| What arguments do people have for resisting it?
| hinkley wrote:
| Some people think 'store water' and immediately jump to
| cisterns, or above-ground storage tanks. You simply cannot
| store a useful amount of water above ground, and exposing
| it to light and air (and thus mosquitoes) is a whole other
| set of problems.
|
| Some people do it anyway, others get very upset about what
| they see as wasted time and resources.
|
| Storing water [this way] is fundamentally about reserving
| the right to be wrong about where water 'needs to be' on
| your property, and I think without a way to correct it they
| feel like their hands are tied. The person I know who is
| loudest against this strategy is also very philosophical
| about not fighting nature. If a tree is happy, great. If
| it's not happy, then it wasn't meant to be. Let it go, get
| over the sunk cost, and try something else. To his
| thinking, trying things is cheap, forcing things is
| expensive (and arrogant).
| [deleted]
| baxtr wrote:
| What is the right way to do it then? Can share any
| resources on this topic? I think it's very interesting.
| AareyBaba wrote:
| You might find this project in India informative
| https://youtu.be/-8nqnOcoLqE?t=60
| nanomonkey wrote:
| Basically you want to slow the flow of water and increase
| the soil's permeability and retention capabilities.
| Beaver dams are a good way to start, but things like
| Hugelkultur burms, terracing and swales are all methods
| of capturing water run off and directing them into the
| ground where they can enter aquafers or be absorbed by
| the immediate soil.
| secondcoming wrote:
| That technique has led to conflict for over 4000 years
| though [0]
|
| [0] http://www.worldwater.org/conflict/list/
| hinkley wrote:
| Stopping is different from slowing. Slow water keeps
| streams from drying up in the summer. Lots of stories of
| seeps and seasonal streams coming back after years of
| having dried up.
| john579 wrote:
| Peru is also reviving other ancient practices to obtain water,
| such as the rain dance.
| vanderZwan wrote:
| I can't speak for Peru specifically, but natural ecosystems play
| a huge role in absorbing and holding on to rain water, ensuring
| it doesn't all just flow back into the sea. This has been known
| for ages - I remember a friend who did environmental sciences
| telling me stories of cities in developing countries that cut all
| the nearby forests and as a side-effect also ruined their water
| supply.
|
| So with that in mind I'm a bit surprised at the skepticism on
| display here.
| beambot wrote:
| Too true. For example, compare the 2-meter long root ecosystem
| of prairie grass that holds water exceptionally well to that of
| wheat:
|
| https://images.app.goo.gl/PHmVUNRwwBg8oUKv7
| jhayward wrote:
| There is a really interesting example of the role of the
| surface vegetation for groundwater in Bamberger Ranch[1] in
| Central Texas.
|
| Central Texas was massively overgrazed by cattle in the 1800's
| and 1900's, and the ecosystem was completely transformed from
| prairie grass dominant to cedar and mesquite dominant
| vegetation. This resulted in a drastic loss of groundwater and
| utterly transformed the ecosystem.
|
| David Bamberger restored 5,500 acres to close to original
| condition and the results are amazing.
|
| [1] https://bambergerranch.org/
| droopyEyelids wrote:
| I saw an interesting farmer presentation on YouTube[1] the
| other day where he eventually starts talking about how cover
| crops have improved his land's ability to absorb and retain
| water. He even includes photos contrasting his neighbor's
| monoculture fields with his during rain storms.
|
| https://www.youtube.com/watch?v=9yPjoh9YJMk
| wolverine876 wrote:
| For a more scientific, technical discussion, see this paper,
| linked in the article:
|
| https://www.nature.com/articles/s41893-019-0307-1
|
| Available here:
|
| http://mural.maynoothuniversity.ie/13800/1/SG_geog_potential...
|
| (Thanks abdullahkhalids for finding the latter link; I'm just
| posting it here for more visibility.)
| slownews45 wrote:
| What's interesting is water management historically was a huge
| area of research and work for cultures.
|
| But if you look at a place like CA, despite supposed water
| shortages - there are very very few water projects to increase
| for example storage capacity. I'd be curious in last 10 years how
| much capacity has come online vs population growth. I mention
| supposed shortages because it's really a shortage of free or near
| free water.
|
| We have passed a lot of bonds for water projects - with little to
| show for some reason. Not at all close to the details, but would
| be curious to know what is going on.
| vidanay wrote:
| I think this is derivative of humans inability to comprehend
| large numbers.
|
| Do I have enough water for me and my family? Yes, I'm not
| thirsty and my crops look fine.
|
| Do we have enough water for 10 billion people for the next 150
| years? We have no clue.
| slownews45 wrote:
| What's funny though is that folks are paying $5 for a tiny
| water bottle in an airport. They are rationing URBAN water
| use (where water is relatively insanely expensive already).
|
| Even in CA where we have droughts - the amount of water used
| in ag / industrial is measured in ACRE FEET. And the cost is
| in pennies to dollars per ACRE FOOT. The scale is just
| totally different than your bottle of water or glass of
| water. You go to a restaurant "due to water shortage we
| aren't serving water"??
|
| We've had insane population growth here. Last damns were in
| like 71 and maybe 79? So it's been 40+ years with no new
| reservoirs?
|
| https://www.mercurynews.com/wp-
| content/uploads/2016/08/20140...
|
| You'd better be working on desalination or maybe a small tax
| on water for all users (could be TINY) or something because
| otherwise yeah, you are going to have serious water problems.
|
| We've doubled population since 71. You can't do that without
| doing something around reservoirs, water use in ag /
| industrial or supply improvements.
| foxhop wrote:
| I'm not sure why it's only happening in Peru, we should be doing
| this work world wide. I have similar water capturing techniques
| at my house where I redirect road runoff into a gentle stream and
| allow it to infiltrate my landscape, watering Maple, Apple, Plums
| trees, hydrating the landscape to reduce effects of multi-month
| droughts:
|
| Reference: https://www.youtube.com/watch?v=lAQS4CN_4OY
| kjkjadksj wrote:
| Road runoff is usually pretty polluted in cities and some
| places have laws against capturing rainwater to protect
| downstream resources.
| tharkun__ wrote:
| He doesn't say where he lives. While I agree with you that if
| he indeed lives in a place where the "road runoff" is nasty
| he should be careful, I really can't see why capturing
| rainwater should be banned. Of course "some places" is very
| vague so there might be good reasons but you'd have to
| provide much more context for me to believe that it's a good
| idea to prevent it.
|
| If my house wasn't where it is, the ground on which it is
| built would absorb that water. Now I capture it and put it on
| my veggies or use it to flush the toilet which ends up going
| out to the septic drain field on the lwab and then it filters
| further down. I don't see any issues with that.
| aaron695 wrote:
| 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.
| seltzered_ wrote:
| Okay, the article references "Potential contributions of pre-Inca
| infiltration infrastructure to Andean water security"
| (https://www.nature.com/articles/s41893-019-0307-1 ,
| https://doi.org/10.1038/s41893-019-0307-1 )
|
| The problem is it could just be used just to extract more water
| rather than be part of a broader reforestation effort & cultural
| change around it's relationship to water. Joe Brewer criticized
| this a couple years ago:
| https://twitter.com/cognitivepolicy/status/12125332029649264...
| frankfrankfrank wrote:
| Water retention needs to be made a bigger issue globally. Others
| eluded to the fact that what is effectively the draining of the
| water cycle in CA is a main cause of CA's water/fire problems,
| but that is also the problem in places like central Europe where
| the straightening of the rivers during industrialization (19th
| C.) is and has essentially been "draining the swamp" of the
| central European water cycle.
|
| It's something I have had the hardest time getting people to
| understand. The various straightened rivers all throughout Europe
| that have far less retention capacity than in the past, are
| essentially drainage canals that are sucking the whole of the
| central European region dry of water, which will only compound
| problems.
|
| There are a couple things going on that are fooling people into
| an illusion that everything being fine, but it is happening and
| it is causing the low rainfalls, the low snow packs, and the low
| cloud cover that increases temperatures that are all perceived
| as/blamed on global warming.
|
| If Europeans don't stop the draining of the continent, the
| problems and heat will only accelerate. Just alone in order to
| prevent the necessity of using climate control systems that
| devour energy should be enough of an argument to try to restore
| the cloud cover and rainfalls that could lower temperatures to
| what they were like before the rivers were straightened and
| evaporation also caused more winds and breezes.
| rocqua wrote:
| Interesting. As a European (dutch even, so more water
| interested) I would love to learn more.
|
| I often felt that, in agriculture we (dutchies) have over
| engineered for short term profits. I wonder if the same holds
| for our water engineering.
| koheripbal wrote:
| 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.
| abdullahkhalids wrote:
| 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
| x 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 solutions for water security.
|
| https://www.nature.com/articles/s41893-019-0307-1
| gus_massa wrote:
| 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.
| abdullahkhalids wrote:
| I didn't have time to read the paper, but here is the pdf h
| ttp://mural.maynoothuniversity.ie/13800/1/SG_geog_potential
| ...
| qubidt wrote:
| FYI: https://unpaywall.org/
| ralfn wrote:
| Thank you so much. The article is just too polluted with pseudo
| intellectual nonsense, but water management is a very
| underappreciated discipline of engineering.
|
| Although it seems impossible to measure how much water is
| stored in the deep soil, it is often possible to notice if it
| runs out. We had that last summer in the Netherlands. I suppose
| knowing we reached zero, and knowing the influx (mm rain, and
| the flow of the Rhine), and then also knowing the outflow means
| you can make a some sound estimate.
|
| However, that requires a high density of weather stations and
| tooling at the influx and outputs.
|
| It's not something you can just do through some regulation
| targeted at the water company. You'll need a specific branch of
| the government, since messing with water affects everyone, from
| erosion to trade, to agriculture to climate (the presence of
| water makes the climate a more mild climate)
|
| In the Netherlands, this is all done by an independent water
| government, a democracy older than our democracy itself. It
| even predates notions of citizenship.
| hinkley wrote:
| I don't know what I was watching but someone mentioned and
| then drew a diagram showing that a well may be at a certain
| depth, to comfortably reach water, but the water level will
| drop as soon as you start pumping because the water has to
| move horizontally through the rock, and so you will get a
| gradient between 'water level' in the aquifer and water level
| at your well, and the faster you pump the higher the slope.
|
| I guess there are some ways to work out permeability and
| volume based on how the levels at one well are affected by
| activity at the next well.
| wolverine876 wrote:
| > The article is just too polluted with pseudo intellectual
| nonsense
|
| Always an ironic comment!
| hinkley wrote:
| Projection ain't just a river in Egypt.
|
| Wait... that doesn't sound right.
| dpierce9 wrote:
| Article woo aside, underground water is not impossible to
| measure. Min well depth (or depth of dry wells) is a
| straightforward way to measure the aquifer level for a small
| area. It doesn't tell you much but it tells you something.
| Combine with your neighbors taking the same measurement over
| time and you have a good data set. That is before you get to
| things like 'geology' which are known factors shaping
| underground water supplies.
|
| Further, if water goes into a pit, you can measure or estimate
| how much is going in. If you can measure the shape of the pit
| you know how much is there. If you know surface area at a given
| level and temp/environmental conditions you can estimate
| evaporation. So you can say: X vol went in, Y evaporated, and Z
| is how much we now think is ground water based on current depth
| and evaporation (excluding animals and humans drinking).
|
| It is much harder to associate the pit activity with a given
| well and obviously the scale here may be below the precision of
| any of the estimators.
| hinkley wrote:
| I learned that it's fairly routine in wetland restoration
| work to sink shallow 'wells' (stand pipes) a couple feet down
| to measure water table levels over the course of a year or
| so. Wetlands - and in particular the plants that are adapted
| to them - can be permanent or seasonal, and can change over a
| 20 foot distance, so knowing which you have and where can be
| the difference between a failed or successful restoration.
| IncRnd wrote:
| > 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.
| colochef wrote:
| If you are into this, you have to check all the different systems
| found in Lo Tek. Can't recommend this enough.
| https://lampoonmagazine.com/lo-tek-sustainable-resilient-inf...
|
| https://longnow.org/seminars/02020/sep/15/design-radical-ind...
| syntaxing wrote:
| The first link is NSFW as a headsup
| nikkinana wrote:
| 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.
| imagine99 wrote:
| 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?
| acdha wrote:
| 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.
| netr0ute wrote:
| Troll
| H8crilA wrote:
| 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
| acdha wrote:
| 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.
| KaiserPro wrote:
| 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.
| kjkjadksj wrote:
| The biggest issue with the west was that it was in a historic
| wet period 100 years ago when water rights laws were solidified
| with different groundwater levels. Its a drought only relative
| to this time, historically in Southern california it is usually
| dry like this. The issue with runoff water in LA and other
| cities is that its super polluted. You don't even want to swim
| in the ocean after a rain. If you wanted to be smart about it
| you would have to treat it, but it rains in earnest so few
| times that building that infrastructure would be too costly if
| its only going to be used when it deluges 6 times a year.
|
| What the city has been doing instead is honestly a better long
| term move imo. They treat sewage and turn it into grey water,
| which is used to water public grass spaces like parks and is
| starting to be used as well as recharge local aquifers since
| the state says the ground is the best filter for grey water.
| JuettnerDistrib wrote:
| > In LA, everything is done to make sure the water yeets into
| the sea as quick as possible.
|
| The infrastructure bill _may_ change that [0]:
|
| "Also, the money could fund stormwater capture and reuse
| projects, like the ones that filter rainwater into underground
| aquifers rather than let it flow into the ocean."
|
| Anyone know how likely this actually is?
|
| [0] https://laist.com/news/climate-environment/socal-could-
| get-b...
| kjkjadksj wrote:
| Unlikely since it rains so few times the cost to benefit
| ratio is terrible. Instead the city has been treating
| wastewater and using that constant source of greywater to
| irrigate public parks and recharge aquifers.
| hinkley wrote:
| Especially if you already use plants adapted to a dry season.
|
| There's a huge difference between surviving 50 days without
| rain and being able to survive 90 days without rain.
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(page generated 2021-08-20 23:01 UTC)