Could aquifers be actively recharged?

Submitted by smontanaro t3_104we8o in askscience

I've seen a couple stories recently wondering if the atmospheric rivers hitting the West Coast will end the drought. While they might refill reservoirs, recharging the water tables will take more than a single season.

There are efforts to sequester CO2 underground. Fracking is successful, in part, because of the top secret toxic mixture they pump into the shale to fracture it and increasing oil/gas flow.

In a similar fashion, could aquifers be actively recharged, speeding up that process? If so, are there any feasibility studies underway to investigate this idea?

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atomfullerene t1_j38m61b wrote

California has a management strategy to recharge aquifers during flood events like this one. It's called ag-MAR or flood-MAR.

Basically, the idea is to intentionally flood areas like orchards or fields during the winter, allowing floodwaters to soak into the ground and down to the aquifer. There are things you have to be careful about when doing this (nitrate contamination of groundwater, for instance) but it's a promising approach.

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ExcelsiorStatistics t1_j399ykk wrote

An interesting accidental case study is the Thousand Springs area in south-central Idaho.

There were some naturally occurring springs there before farming and irrigation got going. The springs were substantially enhanced when a big network of surface canals were built in the late 19th century, and then substantially depleted as there was a transition to using well water and more efficient irrigation (edited to add: using sprinklers rather than flood irrigation). As butiwouldrathernot mentioned, the discharge and recharge happens on a timescale of decades.

When I lived in eastern Idaho a decade or so ago, there was a lively debate about whether we should deliberately run water through the canals all winter when the farmers were not using it, to recharge the aquifer and keep downstream wells from running dry.

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Butiwouldrathernot t1_j38af3e wrote

Deep groundwater takes decades to infiltrate. You can pump water underground, but the aquifers that have been depleted are porous formations and there's significant evidence in central California that aquifer depletion has resulted in sinkage, which means that space may no longer be available.

Fracking is the result of injecting liquid underground which fractures the porous formation and releases held oil or gas. These are different, and usually much deeper, formations than the formations that can hold potable aquifers.

Similarly, CO2 sequestration is done in very deep formations (typically around 2km below surface in my experience). This deep earth activity does not simulate subsurface potable water aquifers due to the difference in strata and pressure.

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2dog_photos t1_j396m54 wrote

Yeah, it you have subsidence from groundwater depletion, there's no place for the water to go back to. In the San Joaquin acquifer the ground has subsided by 10's of meters over the last century.

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davew_haverford_edu t1_j3a9t10 wrote

You might want to listen to the "Bengal Water Machine" segment of this podcast (or find the associated article):

Podcast/Article: Testing planetary defenses against asteroids, and building a giant ‘water machine’

URL: https://traffic.omny.fm/d/clips/e763ee7a-311f-4004-8c05-ad8a0018d51b/68fe80a5-856c-4341-9f13-ada1016db982/3ec14be4-bac0-4202-8a57-af1100fbc292/audio.mp3?utm_source=Podcast&in_playlist=dddf1674-4d7d-4aaf-a7f9-ada1016db98c

Description: <p>On this week’s show: NASA’s unprecedented asteroid-deflection mission, and making storage space for fresh water underground in Bangladesh</p>

URL: http://www.sciencemag.org/rss/podcast.xml

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