Increasing influence of air temperature on upper Colorado River streamflow

• Published in: Geophysical research letters Vol. 43; no. 5; pp. 2174 - 2181
• Main Authors: Woodhouse, Connie A., Pederson, Gregory T., Morino, Kiyomi, McAfee, Stephanie A., McCabe, Gregory J.
• Format: Journal Article
• Language: English
• Published: Washington John Wiley & Sons, Inc 16.03.2016
• Subjects: Air temperature; Amplification; Annual precipitation; Atmospheric precipitations; Basins; Colorado River Basin; Cool season; Drought; Droughts; Drying; Geophysics; Moisture; Precipitation; River basins; Soil; Soil moisture; Soil temperature; Soils; Stream discharge; Stream flow; Temperature; Temperature effects; Variability; warming temperatures; Water runoff; Water supplies; Water supply; water year streamflow; Winter; Colorado River; USA, Arizona, Colorado R. basin; USA, Colorado R
• ISSN: 0094-8276; 1944-8007
• DOI: 10.1002/2015GL067613

This empirical study examines the influence of precipitation, temperature, and antecedent soil moisture on upper Colorado River basin (UCRB) water year streamflow over the past century. While cool season precipitation explains most of the variability in annual flows, temperature appears to be highly influential under certain conditions, with the role of antecedent fall soil moisture less clear. In both wet and dry years, when flow is substantially different than expected given precipitation, these factors can modulate the dominant precipitation influence on streamflow. Different combinations of temperature, precipitation, and soil moisture can result in flow deficits of similar magnitude, but recent droughts have been amplified by warmer temperatures that exacerbate the effects of relatively modest precipitation deficits. Since 1988, a marked increase in the frequency of warm years with lower flows than expected, given precipitation, suggests continued warming temperatures will be an increasingly important influence in reducing future UCRB water supplies. Key Points When UCRB flow departs from precipitation, temperature is a major forcing Since 1988, flows have often been less than expected given winter precipitation Warm temperatures exacerbated modest precipitation deficits in the 2000s drought