28 ms·

Can someone make a comment on the sustainability of our current water consumption, in terms of the US, other parts of the world, and the world itself? If we ar

by exacube 11y ago

Can someone make a comment on the sustainability of our current water consumption, in terms of the US, other parts of the world, and the world itself? If we are not living sustainably, should we expect more investment across the world on things like desalination plants (I understand that desalination is really energy-expensive currently, but will that change by much?)

mturmon 11y ago
Groundwater is the resource we are depleting, because everything else runs in a circle. Here is a good worldwide groundwater study, based partly on gravity inversions from the GRACE twin satellites: http://www.jpl.nasa.gov/news/news.php?feature=4626 http://www.jpl.nasa.gov/news/news.php?feature=4626 The conclusion is: Probably the most at-risk aquifer (based on people affected and severity) is in the Gangetic plain in northern India. There are also critically threatened aquifers in the Arabian peninsula, southeast China, and our own Sacramento Valley. This conclusion is supported by other hydrological modeling groups as well (e.g., the very highly-cited, but older, http://onlinelibrary.wiley.com/doi/10.1029/2010GL044571/full http://onlinelibrary.wiley.com/doi/10.1029/2010GL044571/full)
hugh4 11y ago
Depends what you mean by "sustainable". There's far more fresh water falling on the US than is being "used". Go look at any river. Gazillions of litres of fresh water per minute just flowing out to sea and getting salty. Then imagine the number of rivers doing that. Of course damming every river and diverting it to other uses is impractical and would have bad effects on various ecosystems, but there's a lot of spare fresh water just running out to sea. And then remember that the vast majority of the water that we "use" is not getting split into hydrogen and oxygen, it's staying molecular water and it's hanging around.
- jofer 11y ago
  The problem is spatial distribution, not amounts. Saying we have far more than is being used is true, but misses the forest for the trees. Some areas have lots of water resources, some don't. Unfortunately our water usage is almost inversely correlated to water resource availability. Arid soils are _incredibly_ productive when irrigated, so we grow a lot of crops in the desert (or semi-desert). Also, people like to live in dry, sunny places. Dry, sunny places usually don't have abundant water resources.
- deleted 11y ago
  [deleted]
Retric 11y ago
The best example is the Ogallala Aquifer. "At places, the water table was measured to drop more than five feet (1.5 m) per year at the time of maximum extraction." https://en.wikipedia.org/wiki/Ogallala_Aquifer https://en.wikipedia.org/wiki/Ogallala_Aquifer So it's a huge resource of fresh water that's being drained much faster than it's replacement rate. But, building deeper wells is cheap and there is little value in untapped water so it's reasonable for now. However, long term it's a finite resource. At the same time a lot of fresh water ends up in the ocean so desalination needs to compete with simply moving water around. Locally when transport is more expensive than desalination it may be useful, but long term it's a balancing act between moving water a thousand miles+, desalinating locally, or increasing efficiency. PS: In theory these Aquifers could be used as a cheap form of transport, but when any well get's to tap the water for 'free' who pays for it becomes a major issue.
- jofer 11y ago
  >In theory these Aquifers could be used as a cheap form of transport... For what it's worth, an aquifer isn't an underground river... It's solid rock. What would you be transporting?
  - Retric 11y ago
    Water, it's fine if it takes 10 years to move water from point A to point B as long as you don't need to build and maintain a pipe. Also, they are not solid rock or water, it's more like gravel with water in-between but the flow rate can get fairly high due to size even if the flow speed is very low. 1 mile per day is slow but * 365 days * 10 years that's a long way.
- krauthammer 11y ago
  People outside of Nebraska aren't going to get water from the Ogallala Aquifer. It's sacred. You should make other plans.
  - mturmon 11y ago
    This is a weird comment, because of course the Ogallala Aquifer extends through eight states, and has been extensively tapped in all of them for decades.

by exacube 11y ago

mturmon 11y ago

Groundwater is the resource we are depleting, because everything else runs in a circle. Here is a good worldwide groundwater study, based partly on gravity inversions from the GRACE twin satellites: http://www.jpl.nasa.gov/news/news.php?feature=4626 http://www.jpl.nasa.gov/news/news.php?feature=4626 The conclusion is: Probably the most at-risk aquifer (based on people affected and severity) is in the Gangetic plain in northern India. There are also critically threatened aquifers in the Arabian peninsula, southeast China, and our own Sacramento Valley. This conclusion is supported by other hydrological modeling groups as well (e.g., the very highly-cited, but older, http://onlinelibrary.wiley.com/doi/10.1029/2010GL044571/full http://onlinelibrary.wiley.com/doi/10.1029/2010GL044571/full)

hugh4 11y ago

Depends what you mean by "sustainable". There's far more fresh water falling on the US than is being "used". Go look at any river. Gazillions of litres of fresh water per minute just flowing out to sea and getting salty. Then imagine the number of rivers doing that. Of course damming every river and diverting it to other uses is impractical and would have bad effects on various ecosystems, but there's a lot of spare fresh water just running out to sea. And then remember that the vast majority of the water that we "use" is not getting split into hydrogen and oxygen, it's staying molecular water and it's hanging around.

jofer 11y ago
The problem is spatial distribution, not amounts. Saying we have far more than is being used is true, but misses the forest for the trees. Some areas have lots of water resources, some don't. Unfortunately our water usage is almost inversely correlated to water resource availability. Arid soils are _incredibly_ productive when irrigated, so we grow a lot of crops in the desert (or semi-desert). Also, people like to live in dry, sunny places. Dry, sunny places usually don't have abundant water resources.
deleted 11y ago
[deleted]

Retric 11y ago

The best example is the Ogallala Aquifer. "At places, the water table was measured to drop more than five feet (1.5 m) per year at the time of maximum extraction." https://en.wikipedia.org/wiki/Ogallala_Aquifer https://en.wikipedia.org/wiki/Ogallala_Aquifer So it's a huge resource of fresh water that's being drained much faster than it's replacement rate. But, building deeper wells is cheap and there is little value in untapped water so it's reasonable for now. However, long term it's a finite resource. At the same time a lot of fresh water ends up in the ocean so desalination needs to compete with simply moving water around. Locally when transport is more expensive than desalination it may be useful, but long term it's a balancing act between moving water a thousand miles+, desalinating locally, or increasing efficiency. PS: In theory these Aquifers could be used as a cheap form of transport, but when any well get's to tap the water for 'free' who pays for it becomes a major issue.

jofer 11y ago
>In theory these Aquifers could be used as a cheap form of transport... For what it's worth, an aquifer isn't an underground river... It's solid rock. What would you be transporting?
- Retric 11y ago
  Water, it's fine if it takes 10 years to move water from point A to point B as long as you don't need to build and maintain a pipe. Also, they are not solid rock or water, it's more like gravel with water in-between but the flow rate can get fairly high due to size even if the flow speed is very low. 1 mile per day is slow but * 365 days * 10 years that's a long way.
krauthammer 11y ago
People outside of Nebraska aren't going to get water from the Ogallala Aquifer. It's sacred. You should make other plans.
- mturmon 11y ago
  This is a weird comment, because of course the Ogallala Aquifer extends through eight states, and has been extensively tapped in all of them for decades.