5 ms·

In Southern Utah, which is part of the Mojave Desert, the farmers still doing plain old flood irrigation. It's so staggeringly wasteful it's hard to understand

by fooey 5y ago

User23 5y ago
Are there good figures on how much of that water is “wasted” and how much ends up replenishing groundwater reservoirs? Utah isn’t that close to the Pacific so that water has a lot of opportunities to do something other than flow into the ocean.
- fooey 5y ago
  I don't know any numbers, but we're over 100 all summer, so I imagine it mostly evaporates. Flood irrigation here is just as bad as if they were doing it in Phoenix or Las Vegas
  - brewdad 5y ago
    Many of the old neighborhoods and a few remaining urban farms are flood irrigated in Phoenix. The small city park in my old neighborhood was also flooded once a week to keep the grass green all summer.
- ajross 5y ago
  Virtually all agricultural irrigation evaporates. It doesn't even run off into local streams (which you can verify by, heh, the lack of local streams in the Utah desert), much less seep into the ground. Underground aquifers fill over decades and centuries, and in this environment, almost always laterally, not from seepage from rainfall. I think the demand for proof needs to go the other way, honestly. Presumptively this water is pretty clearly "wasted".
  - D13Fd 5y ago
    I think the question is how much less water would be used with a modern irrigation system rather than flood irrigation.
    - tfigment 5y ago
      Ostensibly you could grow hydroponically and have very little waste but order of magnitude cost increase in power needs. Every other solution falls in between I guess.
      - ashtonkem 5y ago
        Electricity is orders of magnitude easier to move than water, and its price is dropping too.
  - User23 5y ago
    > Virtually all agricultural irrigation evaporates. It doesn't even run off into local streams (which you can verify by, heh, the lack of local streams in the Utah desert), much less seep into the ground. The evaporation figures I can find range from 30% to 50%, which is hardly virtually all. I've never been to the Utah desert, but in the California desert I've dumped out water and watched it disappear into the ground. The absence of streams only indicates that seepage and evaporation together get all of the water that would otherwise flow in them. > Underground aquifers fill over decades and centuries, and in this environment, almost always laterally, not from seepage from rainfall. I think the demand for proof needs to go the other way, honestly. Presumptively this water is pretty clearly "wasted". Unconfined aquifers will fill as fast as rainfall can seep in, which depending on the area can be a lot less than decades. How is letting the Colorado flow into the Pacific more of a "waste" than using that water to grow food and letting the excess seep into the water table and fall as rain on the other side of the Rockies?
    - ajross 5y ago
      Those figures are for water that doesn't enter the plants, though. All that water, except for a tiny fraction represented in the shipped output (nuts, whatever) still ends up locally in the air. And "disappearing into the ground" is absolutely not water entering an aquifer! All you get is wet dirt. Which then... dries out. Again, this isn't how aquifers work. There's no free lunch here. Growing plants in a desert under the open sky requires a staggering amount of water. It just does. If you want to push efficiency measures look at greenhouses.
      - User23 5y ago
        > Again, this isn't how aquifers work. Are you confusing confined aquifers and unconfined aquifers? That's exactly how unconfined aquifers work. Where I live the wells never go dry because every time it rains they are replenished. Maybe the desert doesn't have unconfined aquifers and that's why you're so strident on this? I really don't know, but I'm curious so please elucidate if you can.
- deleted 5y ago
  [deleted]
woolcap 5y ago
nit-pick, but only a tiny portion of Utah is in the Mojave desert. https://en.wikipedia.org/wiki/Mojave_Desert https://en.wikipedia.org/wiki/Mojave_Desert
- dylan604 5y ago
  While that may be accurate, it's still a lot of acerage that is specifically Mojave. At the same time, if I stand on the border of the Mojave in Utah, I'm still in a desert anywhere I go.
  - LeifCarrotson 5y ago
    Humans love taxonomy, nature does not. If you stand on the border of the Mojave, you probably have one foot in the Great Basin desert that covers the west half of the state. The parent probably simply described or generalized to the wrong desert. A climate map [1] shows that the only parts of the state which aren't desert are arid mountains; the Salt Lake area has a bit of lake effect snow but that's not in the Colorado River watershed. [1] https://upload.wikimedia.org/wikipedia/commons/9/95/Utah_K%C3%B6ppen.svg https://upload.wikimedia.org/wikipedia/commons/9/95/Utah_K%C...

In Southern Utah, which is part of the Mojave Desert, the farmers still doing plain old flood irrigation. It's so staggeringly wasteful it's hard to understand

by fooey 5y ago

In Southern Utah, which is part of the Mojave Desert, the farmers still doing plain old flood irrigation. It's so staggeringly wasteful it's hard to understand

User23 5y ago

Are there good figures on how much of that water is “wasted” and how much ends up replenishing groundwater reservoirs? Utah isn’t that close to the Pacific so that water has a lot of opportunities to do something other than flow into the ocean.

fooey 5y ago
I don't know any numbers, but we're over 100 all summer, so I imagine it mostly evaporates. Flood irrigation here is just as bad as if they were doing it in Phoenix or Las Vegas
- brewdad 5y ago
  Many of the old neighborhoods and a few remaining urban farms are flood irrigated in Phoenix. The small city park in my old neighborhood was also flooded once a week to keep the grass green all summer.
ajross 5y ago
Virtually all agricultural irrigation evaporates. It doesn't even run off into local streams (which you can verify by, heh, the lack of local streams in the Utah desert), much less seep into the ground. Underground aquifers fill over decades and centuries, and in this environment, almost always laterally, not from seepage from rainfall. I think the demand for proof needs to go the other way, honestly. Presumptively this water is pretty clearly "wasted".
- D13Fd 5y ago
  I think the question is how much less water would be used with a modern irrigation system rather than flood irrigation.
  - tfigment 5y ago
    Ostensibly you could grow hydroponically and have very little waste but order of magnitude cost increase in power needs. Every other solution falls in between I guess.
    - ashtonkem 5y ago
      Electricity is orders of magnitude easier to move than water, and its price is dropping too.
- User23 5y ago
  > Virtually all agricultural irrigation evaporates. It doesn't even run off into local streams (which you can verify by, heh, the lack of local streams in the Utah desert), much less seep into the ground. The evaporation figures I can find range from 30% to 50%, which is hardly virtually all. I've never been to the Utah desert, but in the California desert I've dumped out water and watched it disappear into the ground. The absence of streams only indicates that seepage and evaporation together get all of the water that would otherwise flow in them. > Underground aquifers fill over decades and centuries, and in this environment, almost always laterally, not from seepage from rainfall. I think the demand for proof needs to go the other way, honestly. Presumptively this water is pretty clearly "wasted". Unconfined aquifers will fill as fast as rainfall can seep in, which depending on the area can be a lot less than decades. How is letting the Colorado flow into the Pacific more of a "waste" than using that water to grow food and letting the excess seep into the water table and fall as rain on the other side of the Rockies?
  - ajross 5y ago
    Those figures are for water that doesn't enter the plants, though. All that water, except for a tiny fraction represented in the shipped output (nuts, whatever) still ends up locally in the air. And "disappearing into the ground" is absolutely not water entering an aquifer! All you get is wet dirt. Which then... dries out. Again, this isn't how aquifers work. There's no free lunch here. Growing plants in a desert under the open sky requires a staggering amount of water. It just does. If you want to push efficiency measures look at greenhouses.
    - User23 5y ago
      > Again, this isn't how aquifers work. Are you confusing confined aquifers and unconfined aquifers? That's exactly how unconfined aquifers work. Where I live the wells never go dry because every time it rains they are replenished. Maybe the desert doesn't have unconfined aquifers and that's why you're so strident on this? I really don't know, but I'm curious so please elucidate if you can.
deleted 5y ago
[deleted]

woolcap 5y ago

nit-pick, but only a tiny portion of Utah is in the Mojave desert. https://en.wikipedia.org/wiki/Mojave_Desert https://en.wikipedia.org/wiki/Mojave_Desert

dylan604 5y ago
While that may be accurate, it's still a lot of acerage that is specifically Mojave. At the same time, if I stand on the border of the Mojave in Utah, I'm still in a desert anywhere I go.
- LeifCarrotson 5y ago
  Humans love taxonomy, nature does not. If you stand on the border of the Mojave, you probably have one foot in the Great Basin desert that covers the west half of the state. The parent probably simply described or generalized to the wrong desert. A climate map [1] shows that the only parts of the state which aren't desert are arid mountains; the Salt Lake area has a bit of lake effect snow but that's not in the Colorado River watershed. [1] https://upload.wikimedia.org/wikipedia/commons/9/95/Utah_K%C3%B6ppen.svg https://upload.wikimedia.org/wikipedia/commons/9/95/Utah_K%C...