New research from the University of Colorado Boulder has found that the amount of water supplied by snowmelt in the western United States is influenced by a combination of factors, including temperature, precipitation, and the amount of snow that falls.

The study, published in the journal Water Resources Research, is the first to examine how these factors interact to affect snowmelt-derived water supply. The findings have implications for water management in the western United States, where snowmelt is a critical source of water for drinking, irrigation, and hydropower.

"Our study found that temperature is the most important factor controlling snowmelt-derived water supply, but that precipitation and snow water equivalent also play a role," said lead author Katharine Niswonger, a graduate student in CU Boulder's Department of Civil, Environmental and Architectural Engineering.

The study used a statistical model to analyze data from 114 snowmelt-dominated watersheds in the western United States. The model found that a 1 degree Celsius increase in temperature resulted in a 5% decrease in snowmelt-derived water supply. A 10% increase in precipitation resulted in a 7% increase in snowmelt-derived water supply. And a 10% increase in snow water equivalent resulted in a 6% increase in snowmelt-derived water supply.

The study also found that the effects of temperature, precipitation, and snow water equivalent on snowmelt-derived water supply varied depending on the region. In the northern Rockies, for example, temperature was the most important factor controlling snowmelt-derived water supply. In the southern Rockies, precipitation was the most important factor. And in the Sierra Nevada, snow water equivalent was the most important factor.

The findings of this study can help water managers better understand how climate change will affect snowmelt-derived water supply in the western United States. Climate change is expected to cause temperatures to rise and precipitation to become more variable in the western United States. These changes will likely lead to a decrease in snowmelt-derived water supply, which could have significant implications for water users in the region.

"Our study provides new insights into the factors that control snowmelt-derived water supply in the western United States," said Niswonger. "This information can help water managers develop strategies to adapt to climate change and ensure that there is enough water to meet the needs of people and the environment."