We’re learning about water resource management
here In the Field in Abernathy, Texas! [♫ intro music ♫] Water. It’s becoming an increasingly more valuable resource all over the world. But that especially holds true here on the South Plains. Below us is the Ogallala Aquifer, and we depend on that for agriculture production, municipalities, and also for our energy production. The problem is we’re taking the water out of the Ogallala Aquifer faster than it’s replenishing itself. I’m here today with Dr. Venki Uddameri, who is the director of the Water Resources Center here at Texas Tech University. How are you today?
I’m doing good. How are you?
I’m doing fine. So tell me a little bit about the Ogallala Aquifer and how we’re using it today. The Ogallala Aquifer is the largest aquifer in the United States. It spans over eight different states.
Texas has about 20% of the Ogallala. But we are the second largest user after Nebraska. We use about 6 million acre-feet of water. So most of that water we use is for irrigated agriculture. Some of it is used for municipal uses, energy uses, livestock. We’ve made progress towards reducing our use of Ogallala water without really hurting the productivity of the agricultural economy of this region. But still, we are pulling out a lot more water than we are actually putting in, which means the aquifer will deplete over time. So if we’re taking out faster than we’re putting it in, or nature is putting it in, what do we do? Well, there are a couple of things we can do. There’s really no one magic bullet to solve this problem. But, one: we need to be more efficient in the way we use water and we also have to look at alternative sources for water, like there are aquifers below the Ogallala that contain water. Really?
Yes, and there has been a growing interest to start looking and exploring these aquifers and their potential for serving as an alternative source. But cities are very much interested in using these waters as a supplemental source because if we can move some of the users off to this poor quality deeper aquifers, that means we have more fresh water left for agriculture and other activities that need fresher sources of water. So that’s why we’re here in Abernathy, I take it.
That’s right, you know. The City of Abernathy, along with the High Plains Water District here, set up a test well in the Dockum Aquifer. So one of the reasons, one of the times we want to look at an aquifer, we need to drill a well, which kind of provides us with a window to see what’s happening in the aquifer. Right. Because you can’t actually view it.
Right. Exactly. And that’s a problem with groundwater, because we can’t see it. So how am I helping you with your research today?
So what we’re going to do today is walk over to the Abernathy test well. We’re going to have, students of mine are looking at the quality of the water. So we’ll be doing some water quality measurements, seeing how that quality changes across the well. Then we’ll be doing a small test called a slug test to look at how does the aquifer respond, you know, how does the water levels in the aquifer respond if we increase or decrease water in that well. All right. Well, lead the way. Let’s take a look.
All right. Great. All right. So what are we doing?
So we’re at the Dockum well. This is a test well that was drilled by the City of Abernathy and the High Plains Water District. So I have here one of my PhD students, Jorge Ruiz.
Jorge, good to meet you. I’m John. Nice to meet you. So Jorge’s been working on looking at the salinity characterization of the Dockum Aquifer. So how much salt’s in the water?
Exactly. And, you know, so what happens is the older waters have been sitting there for a much longer period of time. So they’ve had a chance to interact with much more with the salts, with the minerals, that are there in the aquifer. So they tend to be more saltier, whereas the fresher waters tend to be on the top. So we’re trying to map you know, where is the transition zone between fresher and saltier water? Because for some applications where we don’t need a lot of water, we might just be able to skim off the top. So this is your window into the groundwater?
Into the Dockum water. This is what takes us back in time from now to the late Triassic age, you know, before the dinosaurs. And we get to see what has happened to the water all that time. OK. So tell me a little bit about this experiment, Jorge.
Well, as Dr. Uddameri was explaining, we’re measuring the salinity profile of the aquifer. And so we’re going to do is we’re going to use this instrument This is a TLC meter. It’s going to measure the depth of the well, the aquifer, where the water is. We’re also gonna be measuring the temperature of the water, and most importantly we’re going to measure the salinity. But we don’t measure the salinity directly. What we do is we measure the conductivity of the water. That’s what this instrument does, and after that we can we can do a calculation to see what the salinity is And this is your little probe right there?
Yeah, this is the probe that measure this here. And we get the measurements here and on this little screen here. OK. Do you want me to wind ‘er down?
Sure, if you want to.
All right. The well is over 1200 feet deep. When it beeps, do I need to stop?
Yeah. It’s getting heavy. [meter beeps]
Oh, there it is! OK. Pull ‘er back up? Yeah. So we can get a exact number. You see? Right there. So, 454, minus the 7 that we have here So we have 447.
447 feet down? OK. And then we have here EC, and that’s the electroconductivity. So, is that good, or is that low conductivity?
That’s 7000. That’s high. Most municipal uses of water have to be under 1000.
So, we’re 7 times higher than…? Yeah, but the thing is we’re not looking to substitute freshwater. We’re just looking for another source of water that can be treated, mixed with fresher water. So for those purposes, it’s good enough. We continue to take measurements as we went 900 feet into the well. Once we got what we needed, it was time to move on to our next task . So what we’re doing here is we want to measure the water pressure in the water levels. So, in a well, we typically have the atmospheric pressure, or the pressure of the atmosphere, pushing on it there and then the water column. So this is a pressure transducer, and what we do is it’s programmed to take measurements every second.
OK. So we drop it in and we rest it. You know, we don’t go all the way down, but we rest it with some water column on top of it. OK.
And it measures if there’s a change in the water column. It measures, you know, what is that change? And it’s measuring it every second. And then we also have here another logger very similar to this which measures the barometric pressure. So we can subtract out what is the air pressure and then get what’s the pressure of the water. OK. So how we do this is just kind of drop it down that hole.
OK. But that’s not all we’re sending down the well. This is just nothing but what we call a bailer. So this is made out of PVC. It’s about 3 feet long. About an inch and a half in diameter. So it’s got an opening and when we lower it down, the water will start in from the well. And there is a ball in there, which you can probably see it floating. So as the water pushes the ball goes up and then once it’s filled with water, the ball will fall back due to gravity. And at that point, we’ve gotten about a liter of water. We don’t want the bailer going down into the well and not coming back up. [Laughs] Right. Right. Right. Well, Dockum is not Las Vegas, you know. Whatever goes into Dockum has to come out. It can’t stay there. [Laughs] How far are you going down?
We have to go at least 450 feet deep. The same as the water?
We have to get it under the water. Right. So we’ll probably go about 460 feet or so. Can I do this part?
Sure. All right. Just nice and slow?
It’s super light, so… It’s super light until it hits the water. Will I hear a splash?
You will feel it, you know. You will feel a pull on it, like, you know, because the water is coming in. [♫ awesome montage music ♫] Yep. 10 minutes or so and that will fill up the water and change our water level and all that good stuff. We’ll be right back after this. [♫ jammin’ music ♫] Here we go. Big reveal. It’s leaking, so get me a…
Get the bottle. Some dinosaur peed this out. Millions of years ago.
Not even a dinosaur! A prehistoric reptile. [Laughs] So this is the water that we pulled out of the well. What are you doing with it and what is this machine? This instrument is a wire sign multi-parameter water quality sonde. So what it does is, the sonde has different ports where you can fix multiple sensors, which will then measure whatever the sensors capabilities are. So what are your readings showing you right now? So right now it’s showing me all the readings and as a whole list. So if you notice you can see the temperature of the water. The water when it was in the ground, it was about 19 degrees. When we took it out and left it in the open air for some time, the temperature slowly went up. And at the same time, if you notice, the conductivity value that we got when we inserted the TLC was about 8000 thousand, in the ranges of 8000 and 9000, which is what even our YSI sonde is… So it’s matching up?
It is matching up. The moment it reads conductivity value, it converts and gives you the total dissolved solids value and if you notice, that is about 5600 milligrams per liter which is about 5 times more than the drinking water standards. 5 times more? OK. So it’s not quite what you want to slug right now? Right. So plus, since we have a dissolved oxygen sensor in it, it measures the dissolved oxygen in the water since the time we pulled out, which is about this 2.64 which is typically the value for dissolved oxygen in groundwater. So by looking at all this information, you’re able to tell municipalities like what kind of treatment they would have to perform to this water if they chose to use it as a drinking water source. Yes.
OK. So, what have we learned?
Well, as our water resources here on the South Plains continue to dwindle, researchers are trying to discover alternative sources of water to help meet the demands of municipalities, agriculture, and energy. And while their findings will definitely help us here in our region, they’ll also help other regions that are facing the same kinds of water issues in different parts of the world. For In the Field, I’m John Davis. Oh! Oh! Ah… Cup bass. Yeah, that’s not what you want to catch. Edit that out, OK? Dadgummit. [♫ funny fishin’ music ♫]

Author Since: Mar 11, 2019

Related Post