Colorado River’s Snowpack Decline Due to Lack of Spring Precipitation

The Science

The Colorado River relies on melting mountain snow for much of its water. Since 2000, the river’s flow has decreased and often has been less than expected. Researchers found the main cause is less spring rain. The combination of drier conditions and sunnier, warmer springs delivers a dual strike to water resources in the Colorado River. With less rain over the springtime growing season, mountain plants are forced to use more snowmelt to grow. As a result, the lack of rain and increased plant water use leave less water flowing into the river.

The Impact

Experts struggle to predict how much water will be available each year. This study identifies key reasons why the Colorado River has been getting less water than expected, which is important because millions of people and sensitive ecosystems rely on the river. By showing less spring rain and warmer, sunnier days are causing plants to use more snowmelt, researchers can help water managers make better predictions. The findings suggest that researchers need to focus more on what happens in the spring to better manage water resources.

Summary

With over 40 million people dependent on the Colorado River, the 19% streamflow decrease since 2000 has been worrying, especially because its cause is not well understood. To explain this decrease, a team of researchers focused on changes to spring weather in snow-dominated basins, which contribute over 80% of the river’s water. Results showed spring precipitation decreases since 2000 not only reduced streamflow but also correlated with higher temperatures and evaporation rates and less cloudiness. These impacts combined to intensify streamflow declines in basins with earlier snowmelt. The importance of spring precipitation to Colorado River streamflow underscores the need to improve seasonal precipitation forecasts.

Principal Investigator

Jessica Lundquist
University of Washington
[email protected]

Program Manager

Paul Bayer
U.S. Department of Energy, Biological and Environmental Research (SC-33)
Environmental System Science
[email protected]

Funding

Funding was provided by the National Science Foundation under Grant Number 2139836 and the U.S. Department of Energy under Grant Number DE-SC0024075: Seasonal Cycles Unravel Mysteries of Missing Mountain Water.

References