EC Tower at the Colorado State University Extension office in Yellow Jacket. (Photo by Kazungu Mainitalia)
The towers are being installed in areas including Colorado, Wyoming, Utah, New Mexico and Native American lands, and the data will be available by 2026.
To quantify the amount of water lost through evapotranspiration, the biggest unknown in estimating water use, the Upper Colorado River Commission is installing EC towers throughout the basin.
For now, the eddy correlation towers measure water lost from soil and plants to the atmosphere, as well as carbon dioxide, a key contributor to global warming.
The towers take 20 to 40 measurements per second, costing $500,000 each.
One of them is currently operating at Yellow Jacket's Southwest Colorado Research Center.
“By this time next year, we will have 32 units operating completely seamlessly throughout the entire Upper Basin, all communicating,” said Dr. Kaz Maitalia, staff engineer for the Upper Colorado River Commission and Fulbright scholar.
Kazungu “Kaz” Mainia wearing a yellow jacket next to the EC Tower. (Camerine Cass/The Journal)
In terms of water, irrigated agriculture is the largest water-using sector.
Knowing how much water is being lost to the sky can help people, especially farmers, become more careful in how they use water without actually using less.
“We're interested in counting water molecules, something that didn't exist decades ago, because then we thought we had too much water. But now, all of a sudden, we realize we need water… especially for us who live in the desert,” Maitalia said.
“We need better ways to measure our water.”
Sharing the Colorado River by the Numbers
There are about 800 reservoirs on the Colorado River that the U.S. Bureau of Reclamation built to provide some sort of water reserve, but how much of that water is leaking out into the sky?
The answer will help the Upper Colorado River Commission know how much water it can allocate, sending at least 75 million acre-feet of water downstream each decade while still leaving some water in the river.
It also tells us how much water is being used upstream. Are we using our share? If not, how much?
“The problem is, how do you measure the water consumption of a crop? It's very difficult to measure,” says Maitalia. “For a long time, we just assumed that if we were to grow plant A, this is what we needed, and then added in an imprecise component: losses.”
“But now … it becomes so much easier. We tell them, at the end of the year, Colorado is only using 500,000 acre-feet on irrigation, and here's why. It's not a guess, it's completely quantifiable.”
Looking more closely, farmers end up earning less if they claim to have used more water than they actually have.
“Think like a farmer,” says Maitalia, “when someone says they've used 10 units, they've only used eight. … If they could give us two more units, we could expand our farm.”
By 2026, data will be available to everyone.
Map of the Upper Colorado River Basin. Stars indicate current or future locations of EC towers. (Courtesy of Kaz Maitaria)
“The public needs to have reliable, scientifically unbiased data available to them and be able to use it however they see fit. We're not here to tell people, 'This is how you should use the data,'” Maitalia said.
Colorado's Upper River Basin covers an area of 250,000 square miles, an area the size of 15 European countries, and has an elevation range of nearly 8,000 feet.
“This is a very unique problem,” Kaz said. “Consider the elevation changes. In parts of the headwaters, the elevation is 11,000 to 12,000 feet.”
Elsewhere, the altitude drops to 2,500 feet.
Moreover, for a long time, Indian countries have not been part of the story. India has operated as an independent nation and therefore has been ill-equipped, Maiteria said.
This year, the committee signed a memorandum of understanding with them.
“From now on, whenever we talk about water, Indian countries will be represented,” Maiteria said.
So an EC tower will be built on the reservation for their benefit and that of all others in the basin.
From left: Radiation sensors measure the flow of radiant energy that fuels plant growth. Infrared temperature sensors record temperature. 3D sonic anemometers detect wind movement, and gas analyzers measure CO2 and water vapor. (Courtesy of Kaz Maitaria)
Previous technology didn't allow for wind speed measurements as you looked at things on the farm in a straight line – the EC tower has instruments that measure wind speed in all directions, including vertically.
“Once you have the vertical component and the flux comes in, it starts to tell a story,” Maitalia said.
For example, if UV rays are strong when a farmer sprays a field, the effectiveness of the pesticide will be greatly reduced. The EC Tower data will show this, so the farmer can choose to spray the pesticide when UV rays are not as strong, such as after 4pm, early in the morning, or a few days later.
“This way you can use less chemicals and still get the benefits,” Maitalia says. “Timing is everything.”
The tower also has a barometer that measures how long the plants are photosynthesizing. At night, without the sun, the plants go dormant and stop functioning. The tower measures how long the plants are active and how much they are active each day.
Knowing this information allows farmers to modify both the duration and timing of irrigation.
“Cutting back on consumption can save money, but it may not change our lifestyle,” he said.
On-site work
Maiteria said he is in the first year of a three-year study comparing two plots of land in Wyoming: one that is irrigated 24 hours a day and a plot next to it that is irrigated eight hours a day only at night.
“The first year proved that you can basically just irrigate at night and still get the same (results). When you irrigate at night, the water has enough time to soak into the soil. But when you irrigate during the day, because the air is dry, the water also gets sucked in and a significant amount of water is lost to the sky,” Maiteria said.
In fact, you can achieve the same results with a fraction of the amount of water (30%) by watering at night instead of during the day.
“The EC Tower can measure all of this,” Maitalia said. “The research we're doing will probably make this the most instrumented area in the world to study all the dynamics of a semi-arid area.”
Eventually, the towers will measure more and more information, depending on what information people need.
For example, methane is being measured on the Navajo Reservation because it feels like a “heat island,” and scientists think it could be from gas extraction that took place in the area years ago, Maitalia said.
Ultimately, the goal of all this is to better understand nature and be able to live within its limits.
“Mother Nature is very forgiving, but she can only withstand so much,” Maitalia says. “Once we exceed that limit, and we don't change the way we relieve the pressure, anything can happen when Mother Nature responds. We may go extinct, but Mother Nature will continue to exist.”
So we have to adapt and learn to live with what we have.
“We're not just sitting there and lamenting that things are changing and saying, 'What do we do?' We're already taking action. We're not in firefighting mode. We're just trying to live within the forces of Mother Nature. We're trying to understand Mother Nature and get that information out to everybody,” Mainitalia said.
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