Groundwater dominates snowmelt runoff and controls streamflow efficiency in the western United States
Climate change in seasonally snow-covered mountain catchments is reducing water supply and decreasing streamflow predictability. Here, we use tritium age dating to show that contrary to the common assumption that snowmelt quickly contributes to runoff, streamflow during snowmelt in western US catchments is dominated by older groundwater. The average age of streamwater during snowmelt runoff (5.7 ± 4.3 years) was intermediate to the average age of groundwater (10.4 ± 4.5 years) and recent precipitation, indicating that 58% (±34%) of snowmelt runoff was derived from groundwater. Water ages, streamflow, and groundwater storage were mediated by bedrock geology: low-permeability hard rock/shale catchments exhibited younger ages, less storage, and more efficient streamflow generation than high-permeability sandstone/clastic catchments. Our results demonstrate that snowmelt runoff is the result of multiple prior years of climate mediated by groundwater storage. Including these interactions will be crucial for predicting water resources as climate and landscape changes accelerate. Snowmelt runoff in the western US is composed primarily of older groundwater, with precipitation taking 5.7 years on average to exit as streamflow, indicating that annual streamflow is a function of multiple years of climate-groundwater interactions, according to analysis of tritium age dating.
Authors
- Margaret Wolf (ORCID: https://orcid.org/0000-0003-4710-490X)
- Holly Barnard (ORCID: https://orcid.org/0000-0003-1965-8542)
- David M. Barnard (ORCID: https://orcid.org/0000-0003-1877-3151)
- Rosemary W. H. Carroll (ORCID: https://orcid.org/0000-0002-9302-8074)
- Kathleen A. Lohse (ORCID: https://orcid.org/0000-0003-1779-6773)
- A. A. Harpold (ORCID: https://orcid.org/0000-0002-2566-9574)
- Bethany T. Neilson (ORCID: https://orcid.org/0000-0001-8829-5082)
- Gregory T. Carling (ORCID: https://orcid.org/0000-0001-5820-125X)
- Megan Sears (ORCID: https://orcid.org/0000-0002-0568-3408)
- Carleton R. Bern (ORCID: https://orcid.org/0000-0002-8980-1781)
- Stephanie K. Kampf (ORCID: https://orcid.org/0000-0001-8991-2679)
- Francisco Meza (ORCID: https://orcid.org/0000-0002-9853-227X)
- D. Kip Solomon (ORCID: https://orcid.org/0000-0001-6370-7124)
- Sara R. Warix (ORCID: https://orcid.org/0000-0003-2509-6849)
- Jon Chorover (ORCID: https://orcid.org/0000-0001-9497-0195)
- P. D. Brooks (ORCID: https://orcid.org/0000-0001-9201-1062)
- Jennifer McIntosh
Institutions
- Brigham Young University (US)
- Idaho State University (US)
- Utah State University (US)
- University of Nevada, Reno (US)
- University of Arizona (US)
- Colorado Christian University (US)
- University of Colorado Boulder (US)
- University of Utah (US)
- North Idaho College (US)
- Louisiana Department of Natural Resources (US)
- Agricultural Research Service - Plains Area (US)
- Desert Research Institute (US)
- Colorado State University (US)
Publication Details
- Journal
- Communications Earth & Environment
- Published
- 2025-05-03
- DOI
- https://doi.org/10.1038/s43247-025-02303-3
- Citations
- 19
- Primary Topic
- Cryospheric studies and observations
- Type
- article
- Field-Weighted Citation Impact
- 24.71
Funders
- National Science Foundation
- Directorate for Geosciences