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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

#121

Post by hinkley »

TrainedMonkey wrote: post #56
hinkley wrote: post #52

Earlier quoted context omitted.

I did the math once and the amount of water we’ve pumped out of the aquifers worldwide and not replaced is worth more than a mm of sea level rise.

Please show the math and sources, I would love to see the sauce.

OK, I am finding that my memory was faulty here. Global aquifer depletion isn’t equivalent to 1 mm of ocean volume. It’s equivalent to 3 mm of ocean volume per year (2010: https://www.ngwa.org/what-is-groundwater/About-groundwater/f...)

    Groundwater is the world’s most extracted raw material with withdrawal rates currently in the estimated range of 982 km3 /yea
Surface area of the ocean:

361,000,000 km²

1,000,000 mm per kilometer means 361 km³ per millimeter of sea level, ignoring inundation.

The USGS estimates that just the US has lost 1000 km³ from 1900-2008, most recently (2008) at rate of 25 km³ per year which is at least another 400, so let’s call it 1400 km³ which is almost 4 mm. Just for the United States.

I can no longer find the studies that estimated global depletion of aquifers. I don’t know if my queries changed or SEO rotted the search engines. But if it’s anything like the US, (2.5% a year) then we are over 40,000 km³ globally. Which is about 10 centimeters of sea level rise we could mitigate if we could refill all of the world’s aquifers.

I know California has been experimenting with this, but we know with boil orders that untreated water made it into the water supply. What happens when the same thing happens with groundwater injection wells?

Re: How a Solar Revolution in Farming Is Depleting Groundwater

#122

Post by hinkley »

hinkley wrote: post #52
leros wrote: post #36

I know some farmers in North Texas where they are pulling water out of a depleted aquifer. The water is starting to get salty so they're adjusting to salt tolerant variants of their crops. The ground is also starting to drop due to the aquifer draining. It's crazy to see

I did the math once and the amount of water we’ve pumped out of the aquifers worldwide and not replaced is worth more than a mm of sea level rise.

Correction: 10 cm

https://news.ycombinator.com/item?id=39736050

Re: How a Solar Revolution in Farming Is Depleting Groundwater

#123

Post by kwere »

tuatoru wrote: post #71
itsanaccount wrote: post #59

Earlier quoted context omitted.

population is still rising into 2050 by conservative estimates, and it's not counting the energy requirements per person that's exploding. on a century scale, we will fix this by either getting to space or having a lower population. but the pressure is going to crack our systems long before that. I'm still hoping we get better as pressure increases, but there's nothing in nature that says that has to be true. the sys…

Getting to space is not going to happen. We don't have the ability to live sustainably on Antarctica, which is several orders of magnitude easier logistically and technologically.

there is no economy in Antartica besides resource extraction, which is banned. Instead a space economy (logistics, tourism, manufacturing, research) its on the rise. No selfsufficient space colonies in the next 50 years for sure

Re: How a Solar Revolution in Farming Is Depleting Groundwater

#124

Post by CatWChainsaw »

BurningFrog wrote: post #112
throwup238 wrote: post #65

Earlier quoted context omitted.

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

We've been farming for 10,000 years, and the vast majority of farm land is still fertile.

And thanks to fossil fuel fertilizers and land degradation a lot of topsoil is less than 60 harvests from being degraded completely.

Re: How a Solar Revolution in Farming Is Depleting Groundwater

#125

Post by owyn »

lifeisstillgood wrote: post #78
dreamcompiler wrote: post #49

Earlier quoted context omitted.

The water in most of the big US aquifers is at least 10,000 years old. There are some exceptions like the Edwards Aquifer in Texas but for most, rainwater is irrelevant. The water was put there by glaciers during the last ice age and once it's gone, it's gone forever. This is why most groundwater pumping is properly called water mining.

I simply assumed it was refilled by rain … darn half remembered geography lessons! Amazing - if it was a mineral or metal then there would be a mining company charging market rates for the mining … what is happening in this case?

It's a pretty great deal if you are a farmer. In California, you have unlimited rights to pump water from your own land, which extends to the ground underneath. So they just keep drilling deeper. Such a great system for the people who own land, I have no idea why anyone would complain about it...

Re: How a Solar Revolution in Farming Is Depleting Groundwater

#126

Post by CatWChainsaw »

lettergram wrote: post #50
Voultapher wrote: post #48

Earlier quoted context omitted.

Picture a roller coaster where the carts have little steering wheels .. that do nothing. We like to imagine we are in control, but zoomed out we behave quite predictably, chasing that unsustainable growth. I feel you, and I'm not sure how to explain this to children. How honest should we be? I believe there is no version of this that ends well, we are left with outcomes to our decisions on the spectrum of awful to re…

I actually argue the opposite zooming out. Zooming out our trajectory is up and to the right, like a hockey stick. Almost on every level. We’ve done that with all these disasters that have always happened. Almost like we can innovate or something

Want to know where you can shove your hockey stick?

Re: How a Solar Revolution in Farming Is Depleting Groundwater

#127

Post by CatWChainsaw »

lettergram wrote: post #113
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…

Bacteria cannot produce new ways to obtain resources, we can. Quite literally we’ve developed ways to grow food in space. We will be fine.

Lenski.

Re: How a Solar Revolution in Farming Is Depleting Groundwater

#128

Post by blendo »

I don’t think solar powered irrigation is practical.

To water 10 acres of orchard in northern California, where our water levels are “good” (wells are 100-150 ft deep), we need about a 25 hp (20 kW) well pump. That’s ~2 kW per acre.

A typical irrigation cycle is on the order of 10-20 hours. So budget about 20-40 kWh/acre for a cycle, and repeat every 10 days or so (crops need to dry out between waterings else disease spreads.)

In theory, a kW of solar panels charging a 20 kWh battery for 10 days should work to water 1 acre for an entire summer season, at a capital cost of a wildly uneconomic cost of perhaps $20,000 per acre.

These are my wild guesstimates informed by some orchard experience, but please correct me if my numbers seem badly amiss.

ps: With PG&E power, we currently pay about $400/acre, per year.

Re: How a Solar Revolution in Farming Is Depleting Groundwater

#129

Post by blendo »

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?

No, groundwater is renewable in a lot of places, like in much if the Sacramento Valley, where it rain 20-30” a year.

But in the Fresno/Bakersfield area of California, with only 5-10” if rain per year, over pumping is making farming uneconomic. See SGMA https://en.wikipedia.org/wiki/Sustainable_Groundwater_Manage...

Re: How a Solar Revolution in Farming Is Depleting Groundwater

#130

Post by yencabulator »

contravariant wrote: post #111
cutemonster wrote: post #101

Earlier quoted context omitted.

Apparently pumping up, yes, managing, less. See this comment here: https://news.ycombinator.com/item?id=39732506 > ... ground water shortages. Reason: farmers like irrigating their land (much of it below sea level) with ground water because it is cheap ...

It should be noted however that this shortage is happening because the water suppliers are refusing to pump up more water than is sustainable. This is rather different from the free-for-all depicted in this article, and is in fact what I mean by managing the ground water.

They are refusing because of the previous over-pumping.
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