To help quantify how much water is lost as evapotranspiration -- the biggest unknown in estimating water use -- the Upper Colorado River Commission is installing EC towers across its basin.
For now, the eddy-covariance towers measure the water lost from soil and plants to the sky and carbon dioxide, a major component of global warming.
The towers take measurements 20 to 40 times every second, and each one costs a half- million dollars.
One is up and running now at the Southwestern Colorado Research Center in Yellow Jacket.
“Come next year, around this time, we will have 32 operating fully seamless, all of them communicating in the entire upper basin,” said Kaz Maitaria, Ph.D., a staff engineer at the Upper Colorado River Commission and a Fulbright Scholar.
As far as water goes, irrigated agriculture is the largest water-use sector.
Knowing how much water is lost to the sky could help people – especially farmers – be more prudent in how they use water, without really using less of it.
“We’re interested in counting water molecules, something that was nonexistent many decades ago because at that time, we thought water was just too much, but now all of a sudden, we have realized we need water. … Especially us, in the desert,” said Maitaria.
“We need to have better ways of measuring this water of ours.”
On the Colorado River, there’s about 800 reservoirs, created by the U.S. Bureau of Reclamation for some kind of water security. But how much of it is going up into the sky?
The answer tells the Upper Colorado River Commission how much water they can distribute, while still keeping some in the river and sending at least 75 million acre-feet to the lower basin every decade.
It also tells them how much water the upper basin uses: Are we using our share? If not, how much are we using?
“The problem has been, how do you measure crop consumption of the water? It’s so difficult to measure.” said Maitaria. “For a long time ... we just assumed, if you’re growing plant A, this is what it needs, and then we add in a fudge factor of losses, and there you go.”
“But now … it’ll be very easy. At the end of the year, we will tell them, look, Colorado has only used half a million-acre feet on irrigation, and here’s why. We can completely quantify, instead of assuming.”
Zooming in, farmers lose a revenue when they say they used more water than they did.
“Think of it like you’re a farmer,” said Maitaria. “Somebody says you’ve used 10 units, but the truth is that you’ve used eight. … If you’re given that other extra 2 units, you expand your farming land.”
By 2026, data will be available for everyone.
“We need to make sure the public gets data that is authentic, scientifically unbiased, so they can use it in whichever way they deem fit. We are not here to tell people, ‘This is how you should use the data,’” Maitaria said.
In the 250,000 square miles that make up Colorado’s Upper River Basin, an area equal to 15 European countries, the altitude fluctuates by nearly 8,000 feet.
“It’s a very unique problem,” said Kaz. “Think of the elevation change. You’re looking at 11- or 12,000-feet elevation in some of the headwater areas.”
In others, it drops to 2,500 feet.
Plus, for a long time, Indian nations haven’t been part of the storyline. They’ve operated as independent states, so they’re not very well instrumented, Maitaria said.
This year, the commission entered into a memorandum of understanding with them.
“From this moment onward, any time we talk water, Indian nations will be represented,” Maitaria said.
And so, there will be EC Towers on reservation land to benefit them and everyone else in the basin.
Technology before this couldn’t gauge fluxes on a farm because it looked at things on a straight line. EC Towers have instruments to measure wind in all directions, including vertical.
“When you have vertical component and you have fluxes coming in, it starts telling you a story,” Maitaria said.
When a farmer applies pesticides to their fields and UV is high, for example, the product is significantly less effective. EC Tower data would show this, so a farmer could choose to apply pesticides after 4 p.m., early in the morning or even days later when UV isn’t as strong.
“That makes them use lesser chemicals and still it’s effective,” said Maitaria. “Timing is everything.”
The towers also have barometers to measure when plants are photosynthesizing. At night, in the sun’s absence, plants are dormant, inactive. The towers will measure when plants are active and for how long each day.
Knowing this information, farmers could alter irrigation time, both in duration and time of day.
“Sometimes cutting consumption is saving, and it may not change our lifestyle,” he said.
Maitaria said he’s one year into a three-year study in Wyoming where they’re comparing two plots of land. One plot is irrigated 24 hours a day; the plot next to it is watered 8 hours a day, only at night.
“Year One has basically shown us, just irrigating at night alone, we are still getting the same (result). When you irrigate at night, the water has enough time to move down into the soils. But in daytime, when you water, the air is dry, so it also sucks in, so there’s quite a bit of water that you also lose to the sky,” Maitaria said.
In effect, by watering at night instead of day, they’re able to apply a fraction of the water – 30% – and get the same result.
“All these things, the EC Tower will be able to measure them,” said Maitaira. “Probably the work we are is doing will really make this be the most savvy instrumented area in the world, to be able to study all the dynamics within the semi-arid,” Maitaria said.
Eventually, the towers will measure more depending on what information people need.
On the Navajo Nation, for instance, they’re measuring methane because it feels like a “heat island” there. Scientists think it might be methane because of gas mining in the area many years ago, Maitaria said.
Ultimately, the goal with all of this is to better understand nature so we can live within its limits.
“Mother Nature is very, very forgiving. But you can stretch her up to only a certain limit,” said Maitaria. “After that, if you don’t change your ways to relieve the pressure, when Mother Nature reacts, anything can happen. We can be wiped out, but Mother Nature will still be around.”
And so, we must adapt and learn to live with what we have.
“We are not sitting down and crying that things are changing, (saying) ‘What are we going to do?’… Already, we have started acting. We are not on firefighting mode, no... we are just trying to make sure we live within the means of mother nature. We are trying to understand Mother Nature and disseminate that information to everybody,” Maitaria said.
