How much runoff originates as snow in the western United States, and how will that change in the future?

Abstract In the western United States, the seasonal phase of snow storage bridges between winter‐dominant precipitation and summer‐dominant water demand. The critical role of snow in water supply has been frequently quantified using the ratio of snowmelt‐derived runoff to total runoff. However, curr...

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Bibliographic Details
Published inGeophysical research letters Vol. 44; no. 12; pp. 6163 - 6172
Main Authors Li, Dongyue, Wrzesien, Melissa L., Durand, Michael, Adam, Jennifer, Lettenmaier, Dennis P.
Format Journal Article
LanguageEnglish
Published Washington John Wiley & Sons, Inc 28.06.2017
Subjects
Annual runoff
Atmospheric precipitations
Bridges
Climate
Climate change
Computer simulation
Falling
Hydrologic models
Hydrology
Inflow
Intergovernmental Panel on Climate Change
Mathematical models
Mountain regions
Mountainous areas
Phase transitions
Precipitation
Reservoirs
Runoff
Snow
Snow storage
Snowmelt
Summer
Water demand
Water inflow
Water supply
Winter
United States > US
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Summary:Abstract In the western United States, the seasonal phase of snow storage bridges between winter‐dominant precipitation and summer‐dominant water demand. The critical role of snow in water supply has been frequently quantified using the ratio of snowmelt‐derived runoff to total runoff. However, current estimates of the fraction of annual runoff generated by snowmelt are not based on systematic analyses. Here based on hydrological model simulations and a new snowmelt tracking algorithm, we show that 53% of the total runoff in the western United States originates as snowmelt, despite only 37% of the precipitation falling as snow. In mountainous areas, snowmelt is responsible for 70% of the total runoff. By 2100, the contribution of snowmelt to runoff will decrease by one third for the western U.S. in the Intergovernmental Panel on Climate Change Representative Concentration Pathway 8.5 scenario. Snowmelt‐derived runoff currently makes up two thirds of the inflow to the region's major reservoirs. We argue that substantial impacts on water supply are likely in a warmer climate. Key Points We estimate that 53% of the total runoff in the western U.S. originates as snow, despite only 37% of the precipitation falling as snow Snowmelt produces 70% of the total runoff in mountainous areas in the West The ratio of snow‐derived runoff to the total runoff will reduce by one third by 2100 in a business‐as‐usual climate scenario
ISSN:0094-8276
1944-8007
DOI:10.1002/2017GL073551