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.

Systems for management of water throughout the developed world have been designed and operated under the assumption of stationarity. Stationarity-the idea that natural systems fluctuate within an unchanging envelope of variability-is a foundat