Snowpack Sublimation: Measurements and Modeling in the Colorado River Basin

Introduction

Lochvale blowing snow

Sublimation losses can amount to 10 - 30% of annual snowfall.

Snow is an essential resource in the western United States (U.S.), providing water for drinking, irrigation, industry, energy production, and ecosystems across much of the region.  In the mountains of the western U.S., most precipitation falls as snow, which accumulates in seasonal snowpacks that serve as a large natural reservoir.

Snowpack sublimation, which is analogous to evaporation from land or water bodies, represents an important, but poorly quantified, loss of water from the snowpack. Sublimation is one the major uncertainties in runoff forecast models, and is thought to be particularly important during drought years, when water is scarce.


Colorado River Basin Map

Lochvale blowing snow

Colorado River Basin

The map on the left shows the Colorado River Basin (CRB). On average, 70 to 85% of annual runoff in the Colorado River Basin originates as mountain snowmelt, which is a critical water supply for Denver, Las Vegas, Phoenix, Tucson, Los Angeles, and San Diego.

The U.S. Geological Survey (USGS) is conducting a study of snowpack sublimation in the CRB as part of the USGS National Water Census program.

The primary goal is to develop sublimation estimates for the CRB using ground-based measurements and moderate-resolution and high-resolution gridded models to inform hydrologic modeling studies, water availability studies, and water use assessments.