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Updated: Jul 7, 2026

Design and Construction of an Urban Runoff Research Facility
Published on: August 8, 2014
Human-induced changes in the hydrology of the western United States
Tim P Barnett1, David W Pierce, Hugo G Hidalgo
1Scripps Institution of Oceanography, University of California, San Diego, La Jolla, CA 92093, USA. tbarnett-ul@ucsd.edu
Abstract:
Observations have shown that the hydrological cycle of the western United States changed significantly over the last half of the 20th century. We present a regional, multivariable climate change detection and attribution study, using a high-resolution hydrologic model forced by global climate models, focusing on the changes that have already affected this primarily arid region with a large and growing population. The results show that up to 60% of the climate-related trends of river flow, winter air temperature, and snow pack between 1950 and 1999 are human-induced. These results are robust to perturbation of study variates and methods. They portend, in conjunction with previous work, a coming crisis in water supply for the western United States.
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