Aquifer systems extending far offshore on the U.S. Atlantic margin | Hacker News Reader

Aquifer systems extending far offshore on the U.S. Atlantic margin

nature.com

28 pointsbookofjoe19 comments

> Our data suggest a continuous submarine aquifer system spans at least 350 km of the U.S. Atlantic coast and contains about 2800 km3 of low-salinity groundwater.

That’s a lot of water.

That is certainly a lot of water. To put it in perspective that's something like 10% of what's in the Great Lakes

Not really. The Ogallala aquifer is bigger than that (3,600 km^3), and we've already drawn it down 312 km^3 since 1950.

We've only used up a tenth of the Ogallala aquifer in 70 years? That's far better than I thought. (Still not good...)

It's worse, effectively, than the raw numbers, though. It's not like the aquifer is a swimming pool that you can pump out entirely from a single low point.

It's water in a porous rock formation. The more we deplete it, the deeper we have to drill wells and the less water comes out of any given well before it goes dry. And it's not like we can recover anywhere near 100% of the water for any amount of effort.

This report cites the same 3.6E3 km^3 figure (2.91 billion acre-feet) as the amount of "recoverable water" in the aquifer. Do you know if that accounts for the effects you described?

https://ne.water.usgs.gov/projects/HPA/index.html

edit: from the report

Recoverable water in storage is the fraction of water in the aquifer that will drain by gravity and can be withdrawn by wells. The remaining water in the aquifer is held to the aquifer material and generally cannot be withdrawn by wells (Meinzer, 1923).

It’d be interesting to find out if similar systems exist off shore from Australia, South Africa and India among others where they could exploit this to complement desal plants for household consumption in regions where there is little groundwater but are near the coast.

In Africa it could maybe be used to reverse desertification in the Sahara. There have already been ideas touted using desalination plants which are within the bounds of reality. If you can just pump the water then the project begins to look like something not just realistic but also worth while attempting.

While not offshore, the Great Man-Made River project [1] in Libya exploits the Nubian Sandstone Aquifer [2] which may have 150,000 km3 of groundwater (7x the volume of The Great Lakes), or if you’re in the UK enough to fill Wembley Stadium 131,682,907 times.

It’s a significant amount of water.

[1] https://en.m.wikipedia.org/wiki/Great_Man-Made_River

[2] https://en.m.wikipedia.org/wiki/Nubian_Sandstone_Aquifer_Sys...

Interesting. That’s a lot of water, depending on drought it could also be depleted fairly quickly.

Aside. Wonder why they call percolated rainwater “meteoric” rather than pluvial. Obviously some relation to meteorology, big seems a bit of an odd choice.

The cost of desalination (thermal & reverse osmosis) remains quite prohibitive for most nations due to its high capital and operating cost [1]. Unless the world finds a scientific rationale for doing something of that magnitude (E.g. Pour water in the Sahara to slow down world temperature from rising) or a major resource discovery, it would seem counter-intuitive to desertify it on behalf of 2.5m people [2]. That is not even accounting the unintended consequence such as the Saharan desert feeding the Amazon [3], a place considered the lung of the earth. It would likely be more manageable to have that population become climate refugees.

[1] https://www.advisian.com/en-us/global-perspectives/the-cost-... [2] https://www.britannica.com/place/Sahara-desert-Africa/People [3] https://www.nasa.gov/content/goddard/nasa-satellite-reveals-...

These "lungs of the Earth" consume almost the entirety of the oxygen they produce directly. The oxygen that they do produce, indirectly, that we are able to consume comes from 'run-off' from the forest floor producing plankton blooms, which produce oxygen and sequester carbon as they fall to the ocean floor. What this would instead do is stop redistributing resources from a water-starved but resource-rich Africa to a water-rich but relatively resource-starved South America. Whether that's a good thing or not seems more like something to leave them to figure out amongst themselves, but I imagine it will be hard for hundreds of millions of Africans to turn down if it was possible to cheaply bring water there.

Some of the water is believed to be deposited by glaciers in the Last Glacial Maximum, which didn't include any of these areas. But some of it is connected to onshore aquifers. It still has to be desalinated to drink, but it would be cheaper as it's less salty than ocean water.

Cheaper to desalinate, but you have to drill and pump it to the desalination plant. Compare that to the instant availability of unlimited amounts of sea water and it might not be such a good deal.

Pipeline transport is cheap. Should more than compensate with the difference in salinity and thus ease of low level desal.

> Pipeline transport is cheap.

Seawater is salty, corrodes the pipes pretty fast.

Sure, but pipes can be made from more than oxidizing metals.

Australia is probably covered, if push comes to shove: https://en.wikipedia.org/wiki/Great_Artesian_Basin

Once in a lifetime discovery.

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