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How a Solar Revolution in Farming Is Depleting Groundwater

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Re: How a Solar Revolution in Farming Is Depleting Groundwater

#91

Post by fredrikholm »

westurner wrote: post #28
schneems wrote: post #13

I’m very naive in this space. What percent of water extracted makes its way back into the water table and how long does it take? I assume you lose some to the plant that is harvested and some to evaporation. But how much makes it back?

What are some solutions for water table depletion and how comparably sustainable are they? How much water is extracted from air by PV panels that output H2O, and what are the impacts? Do drilling and fracking consume lots of water and create holes through aquifers? Do holes in aquifers cause aquifers to drain out to lower chambers of the earth? Historically, people have moved to where the water is. Is there a subsurf…

> What are some solutions for water table depletion and how comparably sustainable are they?

Water harvesting has been successfully applied to thousands of villages in India and parts of northern Africa.

The Paani Foundation is especially amazing, as they annually lift hundreds of villages from dry wells and tanker dependence to tens of feet of water in wells and ponds in as little as one rain season using nothing but planning and cheap labour (the villagers).

Re: How a Solar Revolution in Farming Is Depleting Groundwater

#92

Post by _heimdall »

nonoesp wrote: post #83

> In theory, switching from diesel or electricity to PV pumping should eliminate greenhouse gas emissions. But in practice, farmers often use their solar pumps to supplement existing pumps, rather than replacing them. And, however it is pumped, the extra water available will also encourage farmers to adopt more intensive farming methods, using more fertilizer and machinery to grow thirstier cash crops, increasing the…

Farmers often don't have a choice on this. A vast majority of operations depend on debt and government subsidies just to get by, both come with strings attached related to both farming methods used and required yields.

I'd propose that the more sustainable solution here is to help get out of a farmers way (both financially and regulatorily) rather than trying to encourage get another round of changes. I'm assuming the encouragement would have to come similar to the current ones, as either legal requirements or strings attached to the money.

Farming is a nearly impossible business to be in today with depending entirely on debt and subsidies, at least in the US. Prices are insanely low relative to the cost and risk of raising animals and farming crops. Until that problem is fixed, farmers have little choice other than to look for expense optimizations anywhere they can (regardless of long term damage) and follow whatever rules are tied to the money they take.

Re: How a Solar Revolution in Farming Is Depleting Groundwater

#93

Post by MrVandemar »

no_wizard wrote: post #58
itsanaccount wrote: post #54

Earlier quoted context omitted.

Technocrats on this site are very fond of your argument, so fond that I stored the reply I saw years back when someone else said the same thing. There is no monitoring dashboard for the planet. News articles like this are your warnings. There is no innovation to be had that fixes global aquifer levels. >>> Original Mathusianism should be distinguished from neo-Malthusianism, in that the latter does at least have some…

What about the birth rate collapse[0] and how this affects things? It’s easy to project out with holding population levels but as the oldest among us die in the next 20-30 years there will be significant drops in population worldwide, before factoring other forms of population decline it’s already naturally going to happen. I wonder how this factors into all this. [0]: https://www.economist.com/leaders/2023/06/01/glo…

> What about the birth rate collapse

There are about 8 billion people (about 4 billion more than when I was born) in the world. The "birth rate collapse" isn't making much of a dent in that as far as I know.

Re: How a Solar Revolution in Farming Is Depleting Groundwater

#94

Post by _heimdall »

Jedd wrote: post #21

The margins are doubtless so narrow that it's not feasible, but pumping during the day into a storage tank, and irrigating at night (while evaporation is relatively low) would be a way to slightly improve soil (though not aquifer) recharge. Certainly it would require less water volume , but again, the infrastructure costs for panels + submersible + storage are probably untenable in precisely the places this is needed…

If one tries this approach I'd recommend pumping into a holding pond, ideally up hill from the land to be irrigated. Tanks would be absolutely massive for a crop on any meaningful scale, especially if its big enough to be putting a dent in the aquifer.

Re: How a Solar Revolution in Farming Is Depleting Groundwater

#95

Post by MichaelZuo »

nyokodo wrote: post #69
peterleiser wrote: post #43

Earlier quoted context omitted.

Drip is used quite a bit in Northern California for higher value crops like tomatoes, but it's too expensive for normal crops. It also seems like a non-starter for smaller scale and poorer farmers in developing nations; that's a lot of CapEx for generally lower value crops.

> that's a lot of CapEx for generally lower value crops. We’re not disagreeing. Those farming regions are not viable long term unless the economics change dramatically.

How are current farming regions without such systems not viable?

That’s the vast majority of current farm acreage in the world.

Re: How a Solar Revolution in Farming Is Depleting Groundwater

#96

Post by _heimdall »

fbdab103 wrote: post #57
peterleiser wrote: post #26

Earlier quoted context omitted.

If you don't irrigate during the day in hot climates some crops will die, and the yields will be terrible for most.

Doesn't that mean we should stop growing crops in such regions?

It means that method of farming is a bad fit for that climate, yes.

Its a much more complex problem though. Most farms in the US depend on debt and subsidies to get by. That money comes with strings attached, from the yield required to cover expenses to subsidies that require mono-cropped fields that basically sit idle in the off season or when a crop fails.

There are different techniques that could be used, but none of them will match the sheer tonnage of yield from a mono-crop drenched in fertilizer, herbicides, and laid out in a way that allows for massive tractors and combines to be used. All of these methods cause huge damage to the land, but again I'd argue we've left those farmers with little to no choice in the matter given how our food system is designed.

Re: How a Solar Revolution in Farming Is Depleting Groundwater

#97

Post by _heimdall »

schneems wrote: post #13

I’m very naive in this space. What percent of water extracted makes its way back into the water table and how long does it take? I assume you lose some to the plant that is harvested and some to evaporation. But how much makes it back?

In the real world these systems are way too complex to have specific answers like this. We simply don't know, and have no way of knowing for sure.

The best, and my opinion only reasonable, answer to that kind of scenario is to just not intervene. We shouldn't be sucking water out of aquifers at such a scale that the water level drops when we have no idea of the long term impacts.

Re: How a Solar Revolution in Farming Is Depleting Groundwater

#98

Post by _heimdall »

WithinReason wrote: post #81
schneems wrote: post #13

I’m very naive in this space. What percent of water extracted makes its way back into the water table and how long does it take? I assume you lose some to the plant that is harvested and some to evaporation. But how much makes it back?

FTA: "Irrigation is responsible for around 70 percent of the global underground water withdrawals, which are estimated at more than 200 cubic miles per year. This exceeds recharge from rainfall by nearly 70 cubic miles per year." So 65% makes it back.

These numbers could be wildly innacurate. We have no good way of measuring this at scale and end up using modeling to answer these questions. Models are only as food as the inputs though, and we don't know what we don't know.

Re: How a Solar Revolution in Farming Is Depleting Groundwater

#99

Post by Jedd »

_heimdall wrote: post #94
Jedd wrote: post #21

The margins are doubtless so narrow that it's not feasible, but pumping during the day into a storage tank, and irrigating at night (while evaporation is relatively low) would be a way to slightly improve soil (though not aquifer) recharge. Certainly it would require less water volume , but again, the infrastructure costs for panels + submersible + storage are probably untenable in precisely the places this is needed…

If one tries this approach I'd recommend pumping into a holding pond, ideally up hill from the land to be irrigated. Tanks would be absolutely massive for a crop on any meaningful scale, especially if its big enough to be putting a dent in the aquifer.

> If one tries this approach I'd recommend pumping into a holding pond, ideally up hill from the land to be irrigated. Tanks would be absolutely massive for a crop on any meaningful scale, especially if its big enough to be putting a dent in the aquifer.

Sure, but almost all the countries TFA mentions are generally farmed by small landholders, so irrigation via stored water is not infeasible. The mammoth style broadacre tiny-return-per-hectare, heavily mechanised, fertiliser- and insecticide- reliant style agriculture popular in the USA isn't so common in these places.

The 'dent in the aquifer' you mention (and TFA dwells upon) is because there's thousands of people doing the same thing at the same time to the same aquifer for years on end.

Regrettably TFA doesn't talk volumes, other than three mentions of 'cubic miles'.

Apart from an exasperated 'why do they use anything but metric?' sigh, it's also obviously a heavily aggregated figure across large geo regions.

These small holdings with their panels + pump per field, pulling from an increasingly deep water table, are presumably extracting probably in the range of 10-20 kilolitres of water per day - the size of an average plastic water tank that has a one-off cost about the same as a submersible DC pump + panels. (Lined steel, concrete, etc, become more attractively priced at larger volumes.)

So, yes, absolutely, if your geography allows, then put in a megalitre+ sized hole in the ground up-hill, cover it to reduce evaporation & algae, fence it to prevent animal damage, etc. Happy days.

Re: How a Solar Revolution in Farming Is Depleting Groundwater

#100

Post by bee_rider »

throwup238 wrote: post #65
cameldrv wrote: post #64

Earlier quoted context omitted.

I remember reading about how in the Soviet Union, there were places they were irrigating with brackish water and how they were now infertile. The obvious conclusion was that the Soviet economic system was busted to permanently destroy land for some temporary gain.

The American equivalent is the dust bowl. The ancient equivalent is the desertification of Mesopotamia. Etc. etc. Humans are bad at long term thinking.

That’s different, it happened under capitalism, so it was an unforeseeable natural disaster that doesn’t reflect on the system in any way.
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