A drone soared over a blazing hot cornfield in northeastern Colorado on a recent morning, snapping images with an infrared camera to help researchers decide how much water they would give the crops the next day.
After a brief, snaking flight above the field, the drone landed and the researchers removed a handful of memory cards. Back at their computers, they analyzed the images for signs the corn was stressed from a lack of water.
This U.S. Department of Agriculture station outside Greeley and other sites across the Southwest are experimenting with drones, specialized cameras and other technology to squeeze the most out of every drop of water in the Colorado River — a vital but beleaguered waterway that serves an estimated 40 million people.
Remote sensors measure soil moisture and relay the readings by Wi-Fi. Cellphone apps collect data from agricultural weather stations and calculate how much water different crops are consuming. Researchers deliberately cut back on water for some crops, trying to get the best harvest with the least amount of moisture — a practice called deficit irrigation.
In the future, tiny needles attached to plants could directly measure how much water they contain and signal irrigation systems to automatically switch on or off.
"It's like almost every month somebody's coming up with something here and there," said Don Ackley, water management supervisor for the Coachella Valley Water District in Southern California. "You almost can't keep up with it."
Researchers and farmers are running similar experiments in arid regions around the world. The need is especially pressing in seven U.S. states that rely on the Colorado River: Arizona, California, Colorado, Nevada, New Mexico, Utah and Wyoming.
The river has plenty of water this summer after an unusually snowy winter in the mountains of the U.S. West. But climatologists warn the river's long-term outlook is uncertain at best and dire at worst, and competition for water will only intensify as the population grows and the climate changes.
The World Resources Institute says the seven Colorado River states have some of the highest levels of water stress in the nation, based on the percentage of available supplies they use in a year. New Mexico was the only state in the nation under extremely high water stress.
The federal government will release a closely watched projection Thursday on whether the Colorado River system has enough water to meet all the demands of downstream states in future years.
The river supplies more than 7,000 square miles (18,000 square kilometres) of farmland and supports a $5 billion-a-year agricultural industry, including a significant share of the nation's winter vegetables, according to the U.S. Bureau of Reclamation, which manages most of the big dams and reservoirs in the Western states.
The Pacific Institute, an environmental group, says the river also irrigates about 700 square miles (1,820 square kilometres) in Mexico.
Agriculture uses 57% to 70% of the system's water in the U.S., researchers say. The problem facing policymakers is how to divert some of that to meet the needs of growing cities without drying up farms, ranches and the environment.
The researchers' goal is understanding crops, soil and weather so completely that farmers know exactly when and how much to irrigate.
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