Agriculture is one of the largest consumers of water in the world and in the US, about 70-80%. References here and here. It’s no wonder that there’s been a lot of media surrounding the California drought and over-pumping of the groundwater.
As you all might know, I LOVE podcasts. I love listening to them when I get ready, when I’m running, when I’m grocery shopping, when I’m driving. I love learning new tidbits of information. This week, I listened to Water Wars by NPR Reveal . It was educational, fascinating, and definitely worth the listen. The podcast starts with the water shortage in Yemen and then heads over to California and the land subsidence occurring a bit closer to home. I did find it biased and lacking from a scientific standpoint so I wanted to point out some things that I noticed. Give it a listen, check out the commentary below, and leave any questions in the comment box! 🙂
I was a bit interested in the quantity of water that is actually used for agriculture, so I found this image (below). There’s also some lovely irrigation water use maps at USGS, but be warned, the data looks to be from 2005.
The water level meter they use in the podcast looks like this. It’s a ubiquitous object in the groundwater world. Basically, a probe is attached to a measuring tape which rolls out to tell you how far down it is in the well. Inside the metal probe is an insulating gap between two electrodes. When the probe contacts water (a conductor) the gap is filled, completing the circuit. In the podcast, you hear the water level unwinding into the well, and the sound a water level meter makes when the probe reaches the water table. The water tape is usually used to measure in “feet below ground surface” (ft bgs) and then later converted to “feet above mean sea level” (ft amsl) once a survey has been completed.
One issue I took with the podcast was the referral of aquifers as “underground reservoirs” . Yes, they are reservoirs in the literal since of the word…but it’s not just an underground lake. Think of it as more of a sponge. The subsurface is a matrix of soil and rock with little voids in between the particles. It’s considered an aquifer when these voids have enough linkage that water has the ability to flow through the particles.
When the journalist referred to using satellites to see where the land is subsiding, he’s referring to remote sensing. In this picture, researchers at NASA’s Jet Propulsion Laboratory use InSAR (interferometric synthetic aperture radar) and aircraft platforms to measure how the ground changes in elevation over time. You can really see the two bowl shapes where the most over-pumping occurs!
I had a little bit of trouble wrapping my mind around the water needed for acres of almonds. It is interesting that 4 times the amount of water is used on almond acres than lettuce acres. How many more calories does that water produce? How many more pounds of food or meals? I need some easily…digestible… statistics. Haha–get it?
And that fake meat? *shudder* Not for this veggie.
Reading: The Girls by Emma Cline. v interesting writing style.
Listening: Hip-hop at my hip hop cardio dance class. Working on my dance moves…. 🙂
Working: Reviewing NPDES permits to quantify and qualify streamflow characteristics and water quality downstream of industrial discharge sites. The end goal is for the client to possibly pretreat and discharge their process water to a water(body) of the state. I’m missing being out on field work after listening to this podcast!