7 ms·

When I was a young kid, I spoke with an agricultural engineer once that came to our school and he gave a talk about his career and what he did and the things he

When I was a young kid, I spoke with an agricultural engineer once that came to our school and he gave a talk about his career and what he did and the things he was finding (this was in say 2007/2008) The part I remember the most and what intrigued me is when he was talking about ground water supply. He said that it would be unwise to keep digging into ground water supply for fresh water, for agriculture or otherwise, and what we really needed desperately was a nation-wide grid (I live in the USA, for reference) of pipes similar to how oil gets pumped for hundreds or in some cases thousands of miles, to supply desalinated water from the coasts to every part of america and to use properly use desalinated water to re-hydrate American rivers and wells, otherwise we will find ourselves in a situation of hastening a cycle of pumping ground water at an unfeasible pace, which to me is suggested in this article. Seems relevant now, and I imagine the long term sustainability of such a thing would be much higher (and less depleting). Looks like that guy was right. I wonder how many people have been sounding this alarm over the last decade.

adamwong246 7y ago
Im interested to know the scale of a "water grid". Is there any idea how much water we'd need to move to satisfy all our demands with desalinated water? Also, what sort of energy is needed to raise all water up from sea-level?
- dsfyu404ed 7y ago
  The average person uses 80-100gal per day. We'd need a grid that's about an order of magnitude larger than our current petroleum fuel distribution system (the average person probably uses less then 8-10gal of liquid petroleum fuel/day).
  - Scoundreller 7y ago
    Should be trivial to reduce that by 50% or more. But if water is artificially cheap, there will be no incentive. But will we learn to tax water and write everyone a cheque to cover the cost of a basic user? Just start with gray water re-use: nothing fancy: just a 55gal drum that collects the good gray water and discards anything looking spoiled. Pumps to toilet bowl with cheap pump.
    - coryrc 7y ago
      You can't keep greywater for much time (~<24 hours) without it turning to a stinking, fetid mess. It has to either be used immediately or filtered then kept sanitized (chlorinated typically).
      - Scoundreller 7y ago
        Mostly my comment was because I saw an expensive and complicated home gray-water contraption that seemed to aim for 100% recycling of gray-water. I figured there was cost-savings to be had by aiming for a lower recovery rate. Yes, probably needs some disinfection, but should vastly reduce the filtration load.
    - basementcat 7y ago
      "If it’s yellow, let it mellow; if it’s brown flush it down!"
    - api 7y ago
      Isn't like 90% of water use in CA agricultural?
- rebuilder 7y ago
  Nevermind the energy cost of pumping the water - what about what it would take to desalinate that much water?!
  - avip 7y ago
    The "commonly used" figure is 5 [kWh/m^3] (you'll find higher and lower).
mr_overalls 7y ago
Large swaths of the country currently receive sufficient rainfall to meet agricultural, industrial, and municipal needs. Desalinating and pumping water from the coasts as a complete replacement solution is madness. Any realistic solution to water scarcity will be a multi-pronged approach: improvements in water infrastructure, groundwater recharge, pollution control, water conservation, rainwater harvesting, and technology-driven gains in purification/distribution efficiency.
- jdavis703 7y ago
  How can we make this argument when rivers like the Colorado are barely a trickle by the time they reach the ocean? Even arid areas that seem fertile like the Southwest and the Central Valley are only fertile because we're diverting and pumping water unsustainably.
  - joe_the_user 7y ago
    A "water grid" sounds appealing, especially given the uncertainty of climate change. But you have to consider that water is used so much by human that you need pipes on much larger scale than you need with petroleum (the water needed for agriculture dwarfs that needed for cities - it can be easier to move the farms to the water than the water to farms). And water is quite heavy given the amount being moved, so you much more energy than you need for petroleum. Just remember that to move a river across a mountain you need the more than energy of a vast series of dams on the other side - since a some proportion is lost to friction.
    - maxander 7y ago
      Nee gig for Musk’s Boring Company? Drilling water pipelines right through the mountains.
  - labster 7y ago
    On the Colorado we’re not even taking the easy wins like “store all the water in one big reservoir during drought to prevent evaporation”.
nradov 7y ago
A nationwide water grid wouldn't be economically viable unless electric power gets a lot cheaper. Pumping water uphill is just too expensive. And we don't really have a unified grid of oil pipelines either.
planteen 7y ago
There's already a big "grid" in place in the western US: the Colorado River. A first pass solution could be to desalinate on the coast and then pump up to Lake Meade to meet all of California's use. Then upper basin states could remove more water, no longer being required to give California their 4 million acre-feet. But the amounts of energy required to do that would be insane.
- niftich 7y ago
  Top users of California's allocation of Colorado River water are [1]: ~61% Imperial Irrigation District; ~20% Metropolitan Water District of Southern California; ~8% Palo Verde Irrigation District; ~8% Coachella Valley Water District; Out of these, only the Palo Verde Irrigation District is inside the Colorado River basin. The Metropolitan Water District of Southern California has access to the coastline, so it can mix in desalinated water directly. It currently mixes in local water sources and water delivered from Northern California [2]. The Imperial and Coachella valleys require an interbasin transfer in either case, but despite the presence of canals and pipelines from the lower Colorado River to these sites, supplying them with additional water from the coast would require significantly less infrastructure than pumping said coastal water all the way up to Lake Mead. [1] https://www.usbr.gov/lc/region/g4000/4200Rpts/DecreeRpt/2018/2018.pdf https://www.usbr.gov/lc/region/g4000/4200Rpts/DecreeRpt/2018... [2] http://www.mwdh2o.com/AboutYourWater/Sources%20Of%20Supply/Pages/default.aspx http://www.mwdh2o.com/AboutYourWater/Sources%20Of%20Supply/P...
- AnimalMuppet 7y ago
  Desalination usually happens on the coast. Pumping water from their to Lake Mead, to let it run down the Colorado to be pumped to LA seems really inefficient. Why not just pump it from the desalination plant to LA? But as an overall plan, it's not so nuts (except for the energy cost, and the hundreds of miles of aqueducts that need to be built). The point about the upper states getting water out of this is a valid one, and Lake Mead supplies Arizona as well as California. One downside to this plan: You'd kill the Grand Canyon.
bufferoverflow 7y ago
Water is freaking heavy and turbulent. You will be spending ridiculous amounts of energy pumping water on just that turbulence which is basically heat. It's much better to have mandatory water-conserving farming practices, like covering the soil to prevent evaporation. Or even better, underground water-dripping systems, like they do in Israel and other desert-like places. Or even even better, start switching to airponics.
deleted 7y ago
[deleted]
vhold 7y ago
People have been trying to sound the alarm for decades. Here's a picture from 1977 demonstrating how far the land in the California central valley had fallen in ~50 years. https://mavensnotebook.com/wp-content/uploads/2015/03/Graham-Fogg-PPT_Page_43.jpg https://mavensnotebook.com/wp-content/uploads/2015/03/Graham...
- benj111 7y ago
  How did they measure that, out of interest? Theodolite to measure the surrounding hills?, how can you be sure those hills aren't subsiding? Compare to other hills?
  - vhold 7y ago
    I'm not sure, I did some searching. Here is an article that contains some technical detail. https://www.xyht.com/surveying/subsidence/ https://www.xyht.com/surveying/subsidence/ "As a point of clarification, the sign Dr. Poland is holding says this is the change detected in BM S661. However, according to the NGS datasheet for that bench mark (PID GU0103), it was not set until 1942. I have been told by reliable sources at the USGS that the pre-1942 subsidence, back to 1925, was a linear estimate. " This appears to be the data sheet for the bench mark used. https://www.ngs.noaa.gov/cgi-bin/ds_mark.prl?PidBox=GU0103 https://www.ngs.noaa.gov/cgi-bin/ds_mark.prl?PidBox=GU0103 Here is a recent analysis from 2018 regarding that area, the photo, and the data used. http://www.itrc.org/papers/pdf/subsidence.pdf http://www.itrc.org/papers/pdf/subsidence.pdf Which seems to conclude that the photo is possibly very wrong, they include a new updated photo at the bottom that only goes back as far as there is reliable data.
    - benj111 7y ago
      Great thanks. I had a look and couldn't really find anything either, you did better than me!
WalterBright 7y ago
A far more pragmatic solution is to move the farms to where the water is. The eastern US seems to always be in the news being flooded. It's also hella cheaper to move the produced food than the water needed to grow them.
cjensen 7y ago
Desalinated water is expensive compared to "free" water. At current prices for desalinated water and for produce, you cannot profitably run a farm using desalinated water. Currently, desalinated water is used in the US only in urban/suburban areas where homeowners are willing and able to pay a bit more than usual for their existing water use.
- benj111 7y ago
  >"free" water Maybe they (we) should be paying for the externalities of their 'free' water?
  - cjensen 7y ago
    Perhaps. There's two problems: (1) The current system in the West is rights based. First person to make productive use of water gets the right to use that water forever. It's an odd system, but it's basically land-ownership for water resources. It's easy to see the flaws in the system. (2) You have to invent a new system. It's a fun thought exercise, but there are a lot of things to consider. The environment needs water. Should a farm making productive use of water have to pay as much per unit as an urban household using it to water a lawn? Lot's of considerations. Now that you've done that, you have to get the law changes across the entire West. The entrenched interests will lobby energetically against the change. The people who would benefit probably aren't paying enough attention to care. So the change loses.
    - benj111 7y ago
      Id leave households out of such a system, they need water to drink, and pay more than 'free' + externalities anyway. I don't think you need to change ownership of the water, a tax to cover the externalities would suffice. But I agree, it would probably never happen.

adamwong246 7y ago

Im interested to know the scale of a "water grid". Is there any idea how much water we'd need to move to satisfy all our demands with desalinated water? Also, what sort of energy is needed to raise all water up from sea-level?

dsfyu404ed 7y ago
The average person uses 80-100gal per day. We'd need a grid that's about an order of magnitude larger than our current petroleum fuel distribution system (the average person probably uses less then 8-10gal of liquid petroleum fuel/day).
- Scoundreller 7y ago
  Should be trivial to reduce that by 50% or more. But if water is artificially cheap, there will be no incentive. But will we learn to tax water and write everyone a cheque to cover the cost of a basic user? Just start with gray water re-use: nothing fancy: just a 55gal drum that collects the good gray water and discards anything looking spoiled. Pumps to toilet bowl with cheap pump.
  - coryrc 7y ago
    You can't keep greywater for much time (~<24 hours) without it turning to a stinking, fetid mess. It has to either be used immediately or filtered then kept sanitized (chlorinated typically).
    - Scoundreller 7y ago
      Mostly my comment was because I saw an expensive and complicated home gray-water contraption that seemed to aim for 100% recycling of gray-water. I figured there was cost-savings to be had by aiming for a lower recovery rate. Yes, probably needs some disinfection, but should vastly reduce the filtration load.
  - basementcat 7y ago
    "If it’s yellow, let it mellow; if it’s brown flush it down!"
  - api 7y ago
    Isn't like 90% of water use in CA agricultural?
rebuilder 7y ago
Nevermind the energy cost of pumping the water - what about what it would take to desalinate that much water?!
- avip 7y ago
  The "commonly used" figure is 5 [kWh/m^3] (you'll find higher and lower).

mr_overalls 7y ago

Large swaths of the country currently receive sufficient rainfall to meet agricultural, industrial, and municipal needs. Desalinating and pumping water from the coasts as a complete replacement solution is madness. Any realistic solution to water scarcity will be a multi-pronged approach: improvements in water infrastructure, groundwater recharge, pollution control, water conservation, rainwater harvesting, and technology-driven gains in purification/distribution efficiency.

jdavis703 7y ago
How can we make this argument when rivers like the Colorado are barely a trickle by the time they reach the ocean? Even arid areas that seem fertile like the Southwest and the Central Valley are only fertile because we're diverting and pumping water unsustainably.
- joe_the_user 7y ago
  A "water grid" sounds appealing, especially given the uncertainty of climate change. But you have to consider that water is used so much by human that you need pipes on much larger scale than you need with petroleum (the water needed for agriculture dwarfs that needed for cities - it can be easier to move the farms to the water than the water to farms). And water is quite heavy given the amount being moved, so you much more energy than you need for petroleum. Just remember that to move a river across a mountain you need the more than energy of a vast series of dams on the other side - since a some proportion is lost to friction.
  - maxander 7y ago
    Nee gig for Musk’s Boring Company? Drilling water pipelines right through the mountains.
- labster 7y ago
  On the Colorado we’re not even taking the easy wins like “store all the water in one big reservoir during drought to prevent evaporation”.

nradov 7y ago

A nationwide water grid wouldn't be economically viable unless electric power gets a lot cheaper. Pumping water uphill is just too expensive. And we don't really have a unified grid of oil pipelines either.

planteen 7y ago

There's already a big "grid" in place in the western US: the Colorado River. A first pass solution could be to desalinate on the coast and then pump up to Lake Meade to meet all of California's use. Then upper basin states could remove more water, no longer being required to give California their 4 million acre-feet. But the amounts of energy required to do that would be insane.

niftich 7y ago
Top users of California's allocation of Colorado River water are [1]: ~61% Imperial Irrigation District; ~20% Metropolitan Water District of Southern California; ~8% Palo Verde Irrigation District; ~8% Coachella Valley Water District; Out of these, only the Palo Verde Irrigation District is inside the Colorado River basin. The Metropolitan Water District of Southern California has access to the coastline, so it can mix in desalinated water directly. It currently mixes in local water sources and water delivered from Northern California [2]. The Imperial and Coachella valleys require an interbasin transfer in either case, but despite the presence of canals and pipelines from the lower Colorado River to these sites, supplying them with additional water from the coast would require significantly less infrastructure than pumping said coastal water all the way up to Lake Mead. [1] https://www.usbr.gov/lc/region/g4000/4200Rpts/DecreeRpt/2018/2018.pdf https://www.usbr.gov/lc/region/g4000/4200Rpts/DecreeRpt/2018... [2] http://www.mwdh2o.com/AboutYourWater/Sources%20Of%20Supply/Pages/default.aspx http://www.mwdh2o.com/AboutYourWater/Sources%20Of%20Supply/P...
AnimalMuppet 7y ago
Desalination usually happens on the coast. Pumping water from their to Lake Mead, to let it run down the Colorado to be pumped to LA seems really inefficient. Why not just pump it from the desalination plant to LA? But as an overall plan, it's not so nuts (except for the energy cost, and the hundreds of miles of aqueducts that need to be built). The point about the upper states getting water out of this is a valid one, and Lake Mead supplies Arizona as well as California. One downside to this plan: You'd kill the Grand Canyon.

bufferoverflow 7y ago

Water is freaking heavy and turbulent. You will be spending ridiculous amounts of energy pumping water on just that turbulence which is basically heat. It's much better to have mandatory water-conserving farming practices, like covering the soil to prevent evaporation. Or even better, underground water-dripping systems, like they do in Israel and other desert-like places. Or even even better, start switching to airponics.

deleted 7y ago

[deleted]

vhold 7y ago

People have been trying to sound the alarm for decades. Here's a picture from 1977 demonstrating how far the land in the California central valley had fallen in ~50 years. https://mavensnotebook.com/wp-content/uploads/2015/03/Graham-Fogg-PPT_Page_43.jpg https://mavensnotebook.com/wp-content/uploads/2015/03/Graham...

benj111 7y ago
How did they measure that, out of interest? Theodolite to measure the surrounding hills?, how can you be sure those hills aren't subsiding? Compare to other hills?
- vhold 7y ago
  I'm not sure, I did some searching. Here is an article that contains some technical detail. https://www.xyht.com/surveying/subsidence/ https://www.xyht.com/surveying/subsidence/ "As a point of clarification, the sign Dr. Poland is holding says this is the change detected in BM S661. However, according to the NGS datasheet for that bench mark (PID GU0103), it was not set until 1942. I have been told by reliable sources at the USGS that the pre-1942 subsidence, back to 1925, was a linear estimate. " This appears to be the data sheet for the bench mark used. https://www.ngs.noaa.gov/cgi-bin/ds_mark.prl?PidBox=GU0103 https://www.ngs.noaa.gov/cgi-bin/ds_mark.prl?PidBox=GU0103 Here is a recent analysis from 2018 regarding that area, the photo, and the data used. http://www.itrc.org/papers/pdf/subsidence.pdf http://www.itrc.org/papers/pdf/subsidence.pdf Which seems to conclude that the photo is possibly very wrong, they include a new updated photo at the bottom that only goes back as far as there is reliable data.
  - benj111 7y ago
    Great thanks. I had a look and couldn't really find anything either, you did better than me!

WalterBright 7y ago

A far more pragmatic solution is to move the farms to where the water is. The eastern US seems to always be in the news being flooded. It's also hella cheaper to move the produced food than the water needed to grow them.

cjensen 7y ago

Desalinated water is expensive compared to "free" water. At current prices for desalinated water and for produce, you cannot profitably run a farm using desalinated water. Currently, desalinated water is used in the US only in urban/suburban areas where homeowners are willing and able to pay a bit more than usual for their existing water use.

benj111 7y ago
>"free" water Maybe they (we) should be paying for the externalities of their 'free' water?
- cjensen 7y ago
  Perhaps. There's two problems: (1) The current system in the West is rights based. First person to make productive use of water gets the right to use that water forever. It's an odd system, but it's basically land-ownership for water resources. It's easy to see the flaws in the system. (2) You have to invent a new system. It's a fun thought exercise, but there are a lot of things to consider. The environment needs water. Should a farm making productive use of water have to pay as much per unit as an urban household using it to water a lawn? Lot's of considerations. Now that you've done that, you have to get the law changes across the entire West. The entrenched interests will lobby energetically against the change. The people who would benefit probably aren't paying enough attention to care. So the change loses.
  - benj111 7y ago
    Id leave households out of such a system, they need water to drink, and pay more than 'free' + externalities anyway. I don't think you need to change ownership of the water, a tax to cover the externalities would suffice. But I agree, it would probably never happen.