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Groundwater and surface water studies are leading to better water supply planning Posted on December 12, 2023


Natalie Ballew – Groundwater Division Director, Texas Water Development Board

The Texas Water Development Board does planning for our future water supplies. To do effective planning, we need to know exactly how much water you have. One piece of the kind of hydrologic cycle that we don't have a full understanding of is how groundwater and surface water interacts with one another. What's the flow of volume going from groundwater to surface water and vice versa?

And we know that this kind of interaction happens because we've seen springs bubbling up, you see rivers that lose water and then suddenly gain water again. So we know it happens, but we don't have a good idea of what volume of water that is.

Andrew Weinberg – Geoscientist, Texas Water Development Board

The bottom line question is, can we predict what that stream flow is going to be six months out? Mostly, we're in contact with entities like groundwater conservation districts, but we get inquiries from just private citizens who want to know about wells, and river authorities, all sorts of folks who have an interest in water resources, and they'll reach out and want to know what's going on with the groundwater here.

Natalie Ballew – Groundwater Division Director, Texas Water Development Board 

Field staff at the Texas Water Development Board, they go out into the field and collect data. They use, kind of, the old-school methods of collecting information to understand groundwater and surface water flows, which is essentially just taking the flow in a stretch of river, upstream and downstream, and comparing those flows to one another and see how they’ve changed.

Cody Bjornson – Hydrologist, Texas Water Development Board

And, over time, as we visit these sites and download the data, we'll be measuring flow under different conditions, such as during a drought or average flow conditions or even after a rainfall event. So, over time, you'll create this relationship of this curve between varying flow measurements and the height of the water above the transducer. So then, you kind of have this correlation, and you can actually look at how that flow changes over time.

Natalie Ballew – Groundwater Division Director, Texas Water Development Board

And there are some newer technologies to help us pinpoint where we might want to collect a little bit more field data. And one example of that is a thermal sensor. And these are devices that you can attach to a little camera stand and point at the water, or you can fly a drone with the sensor attached to it over a river, and it picks up changes in temperature in the water. And so, if you are, you know, looking at a stretch of river, they’re pretty cool, colorful maps that show where it’s colder and warmer. And if you see, kind of, an anomaly, something that’s different, you can pinpoint, there’s something different happening here, let’s go investigate that a little bit more.

And another new technology, a suite of methods really, is remote sensing techniques. And remote sensing is essentially a way that you can observe what’s happening on the land surface or even underneath the ocean surface from really far away. And so, it’s a lot of satellite data or a high-flying aircraft data. And some examples of that are Lidar, evapotranspiration data, and thermal imagery is also an example of remote sensing. And so, whenever you pair the field data with data collected from remote sensing techniques, you can kind of make assumptions about different stretches of the river in different areas.

So you can then kind of extrapolate so you don't have to do individual studies at each individual stream segment. And after we figure out the numbers, we can apply that to many different uses. It can be used to just understand exactly when springs are discharging, when your spring might stop flowing if it's a drought period, when it'll start appearing again if it's wet. It can be used to determine how much water is going to end up in reservoirs and down into our bays and estuaries.

And here in the groundwater division, we develop groundwater availability models that are used in that future planning process. Having the best data to build those models and most accurately represent the system is really important for future water planning.


This article is posted in Springs / Water Planning / Technology / Water Supply / Groundwater .