4 ms·
Something like that. Aquifers are different from reservoirs -- reservoirs are our above-ground water stores, aquifers are our below ground water stores. The p
by floatrock 10y ago
Something like that. Aquifers are different from reservoirs -- reservoirs are our above-ground water stores, aquifers are our below ground water stores.
The problem is that while reservoirs can be refilled from the surface watershed with a good rainy season or two, aquifers take decades of water slowly percolating down through the soil to replenish. If your rate of consumption exceeds the refill rate, well, you're in a bit of an unsustainable situation and the clock starts ticking.
As the drought progressed and surface water became scarce, agriculture started drilling deeper and deeper wells to access the aquifer reserves. The aquifers got so drained that there were stories of fracking companies being hired to drill wells which had depths beyond the capabilities of most traditional well-drilling machines.
Worse, there's also positive feedback loops at play -- as an aquifer gets depleted, the ground above it can settle in a way that slows the refill rate (I've heard it described as the volume occupied by the water goes away so dirt fills in the small gaps creating more compacted/sealed off soil). If the refill rate slows down and your consumption rate stays steady or increases (development!), well, the aquifer's rate of depletion accelerates. Feedback is a bitch.
The anecdote about fracking companies being called in to drill super-deep water wells tells you all you need to know about how market forces price the sustainable consumption of our water reserves.
- elihu 10y agoAnother interesting thing that can happen (I don't know if this is a concern in California, but I've heard that it's a major problem in Jakarta, Indonesia) is that if you're close to the ocean, pulling fresh water from the ground can result in the fresh water being displaced by salt water which makes the aquifer useless.
- dubyah 10y agoIt's a problem in SoCal. They mitigate it by using injection wells in coastal areas as a seawater barrier. Orange County's initial efforts of using RO treated wastewater were for seawater barrier injection wells.
- khuey 10y agoThis is a big concern in South Florida. A number of wells had to be moved inland due to salt water intrusion in the aquifer near the coast.
- floatrock 10y agoWe do have this in California, and it's not just aquifers that suffer salt water intrusion. Most people know that LA wouldn't exist if we didn't pump a good chunk of the Colorado to satisfy its thirst. But we also pump a lot of northern california water down there with a massive state aqueduct project. Currently in the delta between SF and Sacramento, there's a huge infrastructure project going on called the Bay Tunnels. It wants to install a pair of water tunnels upstream of the delta to pump water to these state aqueducts that eventually send it down to LA. One reason it's controversial is because pumping out that much water upstream of the delta would cause salt water to encroach up the delta, quite literally salting the fields and causing other watershed environmental issues. More reasons include who's going to pay for it: http://www.latimes.com/opinion/op-ed/la-oe-leslie-costs-and-benefits-delta-tunnel-20161120-story.html http://www.latimes.com/opinion/op-ed/la-oe-leslie-costs-and-...