Groundwater recharge and your checkbook

“Atmospheric Rivers” (a.k.a. the Pineapple Express) are all the rage these days, and those of us west of the Rockies are hoping that the current weather patterns will help put an end to the recent drought, as well as fill the many reservoirs that have been severely depleted over the past several years.

And fix the groundwater depletion issue! Some — but surely not all — of the news reports from those who claim to be informed on these atmospheric wonders finally get to this as the primary need.

I have to agree that while surface waters are important, the use and abuse of our groundwater resources over the past hundred years or so borders on being criminal. The good news is that — like the changing climatic patterns — the doodoo hasn’t really hit the fan… yet. But, again like climate change, it is our kids and grandkids (and their kids and grandkids) that are going to pay the price.

Why do I say that the water in the ground is the most important resource we have to slake the needs of a thirsty planet? Well, a couple numbers should help clarify the situation (we’ll put this in a simple table to make it easier for all of us):

Water Resources on Planet Earth, in percentage of the total

Oceans	97.2%
Glaciers	2.15%
Groundwater	0.625%
Lakes	0.017%
Atmosphere	0.001%
Streams	0.0001%
Total	99.9931%

“Where’s the remaining 0.0069%” I hear you ask. Well, it’s tied up in “minor reservoirs” like biologic organisms (you actually have a bit of it hiding in you), cans of Pepsi and Dinty Moore Beef Stew, beer and wine (we’ll choose to graciously accept these storage reservoirs as necessary to our survival as a species), and many, many others.

A careful observer will note immediately that the vast majority of earth’s water is in the ocean, and therefore saline and not usable for drinking or agriculture. With another 2.15% locked up in the polar ice caps (along with a couple drops in the alpine glaciers), we come to the realization that 99.35% of the water is unusable for our needs. Click here for an Introduction to Glaciers (Ice with an Attitude) from an earlier post.

You’ll also note that only 0.0181% is cycling through the atmosphere into lakes and rivers, both of which are, in many places around the globe, polluted beyond any and all rational use.

(Sidebar: While we’ll surely cover this in greater detail in a later post, it is important to note that we really don’t have to spend any time or energy cleaning the rivers. The water cleans itself, every time it goes through the evaporation and condensation steps of the hydrologic cycle. What we need to focus on is cleaning the atmosphere the precipitation falls through, and the surface it falls upon. So… keep your eyes on the main target, and put your efforts into de-detoxifying the air and the land!)

Anyway, so what’s left that we can use, and that has sufficient volume to do humanity any long-term good? You got it: the water in the ground (ingeniously called “groundwater“ by the clever folks at GeoSpeak).

But if groundwater is so important to humanity — and we have been pumping it out of the ground as fast as we possibly can to satisfy a growing need — it would seem to be of more than trivial importance that water is added back into the ground as fast as possible (this is called “recharge”).

This is obviously more of an issue in some areas than it is in others. Here in the United States, the arid southwest is especially vulnerable (due to population pressures as well as profligate usage), as is Sub-Sahara Africa (for pretty much the same reasons, without the golf courses and fountains). And there are many, many others…

Groundwater recharge is like your checkbook: if you add money into your account at a greater rate than you take it out, you’ll be fine. But… if your expenses exceed your income, the time will come when the account runs dry, so to speak.

Groundwater works exactly the same way. Unfortunately, we have, in many areas, been drawing down the water supply faster — much faster — than the earth is able to recharge the supply.

Another fun stat I saw once: For every 30 inches of rain that falls, 21 inches run off and rejoin the ocean, and another 9 inches are used by the trees and bushes (called “evapotranspiration”). I can’t be sure about my math, but it seems to me that 21 + 9 = 30, which — since that’s all we started with — doesn’t leave very much left over to recharge the groundwater.

The short version here is that water moves through the ground very slowly, and there is no way that the earth can recharge the groundwater fast enough to keep up with what we are pulling out.

This is especially true in arid regions. Fly over any of them and we see these weird circles on the ground. Ever wonder what they are? Well, in many cases they are watering systems that pivot on a deep well that is pumping from the groundwater to irrigate the crops — in many cases this is grass and hay that are used as feed for cattle that end up as hamburger.

So how can we decrease the drawdown of our groundwater resources and increase recharge? Well, it’s simple… although, like many other solutions to our currents woes, the cure is economically and/or socially painful, and therefore not likely to happen until absolutely necessary (and, in the case of groundwater, after it’s far too late to fix the problem).

First the obvious: pump less water, especially from deep wells in arid regions. Stop watering lawns and golf courses; again, especially in arid regions. Increase the percentage of natural, undeveloped land. This means less concrete, and more fields and forests (Joni Mitchel got it right back in the 60s when she warned us not to “pave paradise and put up a parking lot”). Get rid of levees and concrete channels. Let the water flood the land when it needs to, and then stay there until it soaks into the ground (apologies to the trailer parks and others living on the floodplains, but after all, these lands belong to the river in the first place).

Like I said: simple solutions, but so economically, socially, and politically abhorrent that they probably aren’t gonna happen anytime soon — at least at sufficient scale to do any good.

Enough for now. There is doubtless a lot more to say about groundwater, but I imagine we’ll circle back to the topic in later posts.