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Article
Effects of Runoff Sensitivity and Catchment Characteristics on Regional Actual Evapotranspiration Trends in the Conterminous US
Environmental Research Letters
  • Il-Won Jung, APEC Climate Center
  • Heejun Chang, Portland State University
  • John Risley, Oregon Water Science Center
Document Type
Article
Publication Date
10-4-2013
Subjects
  • Evapotranspiration,
  • Runoff -- Environmental aspects -- United States
Abstract

An understanding of the role of hydro-climatic and geographic regimes on regional actual evapotranspiration (AET) change is essential to improving our knowledge on predicting water availability in a changing climate. This study investigates the relationship between AET change for a 60 year period (1951–2010) and the runoff sensitivity in 255 undisturbed catchments over the US. The runoff sensitivity to climate change is simply defined as the relative magnitude between runoff and precipitation changes with time. Runoff sensitivity can readily explain the conflicting directions of AET changes under similar precipitation change. Under increasing precipitation, AET decreases when runoff is increasing more rapidly than precipitation based on the water balance. Conversely, AET increases when runoff is decreasing more rapidly than precipitation. This result indicates that runoff sensitivity to climate change is a key factor for understanding regional water availability change at the catchment scale. In addition, a stepwise multiple regression analysis and a geographically weighted regression analysis show that the portion of evergreen forest and the mean elevation of a catchment may play a secondary role in the spatial pattern of the AET change, and the relative importance of such explanatory variables may change over space.

Description

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DOI
10.1088/1748-9326/8/4/044002
Persistent Identifier
http://archives.pdx.edu/ds/psu/12228
Citation Information
Jung, I. W., Chang, H., & Risley, J. (2013). Effects of runoff sensitivity and catchment characteristics on regional actual evapotranspiration trends in the conterminous US. Environmental Research Letters, 8(4), 044002