New study of snow, ice, and rain aims to improve Colorado River flow forecasts

In a historic first, the U.S. Bureau of Reclamation earlier this month declared a water shortage on the Colorado River, triggering emergency measures that will require farmers in Arizona to cut their use of irrigation water by 20% next year. The immediate cause of the declaration is record low water levels in Lake Mead, the largest reservoir fed by the river. But scientists say the crisis has been years in the making—and could soon get worse. For reasons they don’t completely understand, but that are related to the West’s changing climate, snow that falls in the Rocky Mountains—the source of about 80% of the Colorado—has been providing the river with less and less water. “This is an existential water crisis for the Southwest,” says Jonathan Overpeck, a climate scientist at the University of Michigan, Ann Arbor.

Next week, researchers will begin an innovative campaign to better understand the fundamental processes—from the behavior of tiny particles that become snowflakes to weather patterns that influence how snow vanishes into thin air—that determine how mountain precipitation becomes surface water for 40 million people. “What gets us going in the morning is the large number of people that really rely on this resource,” says atmospheric scientist Daniel Feldman of the Department of Energy’s (DOE’s) Lawrence Berkeley National Laboratory (LBNL), who leads the effort.

For the more than $8 million project, called the Surface Atmosphere Integrated Field Laboratory (SAIL), researchers are deploying dozens of instruments that will measure wind, rain, snow, solar radiation, and atmospheric particles in a high-elevation Colorado watershed. Hydrologists have already been studying the streams and bedrock there for years. But the additional equipment will collect data intended to sharpen models that produce a variety of critical forecasts, including short-term predictions of seasonal stream flows and long-term scenarios of how climate change might alter regional water supplies. SAIL is “going to make advances in mountain precipitation and snow studies that would just be impossible without this level of instrumentation,” says Jessica Lundquist, a mountain hydrologist at the University of Washington, Seattle. “It’s really exciting.”

To read more of this article by Erik Stokstad on science.org, click here.