Precipitation, moderated by spring temperature and vegetation, drives runoff efficiency in the Upper Colorado River Basin, USA
Abstract
Streamflow in the Upper Colorado River Basin, USA has decreased proportionally more than precipitation in the recent multi-decadal drought. The causes are debated. Understanding how precipitation, and seasonal temperature, vegetation, and evapotranspiration dynamics affect streamflow is essential. Here we use causal inference with historical data to identify surface runoff efficiency drivers. Runoff efficiency increases in years with higher precipitation and snow accumulation accompanied by cooler spring temperatures and delayed vegetation phenology, which generally attenuates biomass accumulation. Conversely, runoff efficiency decreases in years with lower precipitation and snow accumulation, or warmer springs, when vegetation activity and productivity are accelerated or amplified. Summer temperature, often identified as a driver of higher evaporation and aridity, does not emerge as statistically significant. Years with extreme phases of winter-spring precipitation have distinct atmospheric circulation patterns and associated sea surface temperatures, indicating the influence of larger-scale climate drivers on the Basin’s precipitation and runoff efficiency dynamics.
Data availability
All processed hydroclimatic datasets supporting the analyses in this study are available at Zenodo (https://doi.org/10.5281/zenodo.17843029)79. These processed files were derived from publicly accessible datasets obtained from the sources referenced throughout the manuscript.
Code availability
All analyses were conducted using exiting R packages referenced throughout the manuscript.
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Acknowledgements
This research was partially funded by the Bureau of Reclamation. The views expressed in this paper are those of the authors and do not reflect the views or endorsements by the Bureau of Reclamation. Any use of trade, firm, or product names is for descriptive purposes only and does not imply endorsement by the U.S. Government. We thank reviewers Gregory Pederson and Olivier Champagne, the anonymous reviewer(s), and the editors for their constructive comments and suggestions, which improved the clarity and quality of this manuscript.
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David Palumbo conceived and refined the study hypothesis, designed and conducted the research, performed the analyses, and prepared the manuscript. Subhrendu Gangopadhyay refined the study hypothesis, designed and conducted the research, performed the analyses, and prepared the manuscript. Upmanu Lall refined the study hypothesis, designed and conducted the research, performed the analyses, and prepared the manuscript.
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Communications Earth and Environment thanks Gregory Pederson, Olivier Champagne and the other, anonymous, reviewer(s) for their contribution to the peer review of this work. Primary Handling Editors: Rahim Barzegar, Somaparna Ghosh, and Aliénor Lavergne [A peer review file is available].
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Palumbo, D., Gangopadhyay, S. & Lall, U. Precipitation, moderated by spring temperature and vegetation, drives runoff efficiency in the Upper Colorado River Basin, USA. Commun Earth Environ (2025). https://doi.org/10.1038/s43247-025-03136-w
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DOI: https://doi.org/10.1038/s43247-025-03136-w