Trends in precipitation, runoff, and evapotranspiration for rivers draining to the Gulf of Maine in the United States

Journal of Hydrometeorology
By:  and 



Climate warming is projected to result in increases in total annual precipitation in northeastern North America. The response of runoff to increases in precipitation is likely to be more complex because increasing evapotranspiration (ET) could counteract increasing precipitation. This study was conducted to examine these competing trends in the historical record for 22 rivers having >70 yr of runoff data. Annual (water year) average precipitation increased in all basins, with increases ranging from 0.9 to 3.12 mm yr−1. Runoff increased in all basins with increases ranging from 0.67 to 2.58 mm yr−1. The ET was calculated by using a water balance approach in which changes in terrestrial water storage were considered negligible. ET increased in 16 basins and decreased in 6 basins. Temporal trends in temperature, precipitation, runoff, and ET were also calculated for each basin over their respective periods of record for runoff and for the consistent period (1927–2011) for the area-weighted average of the nine largest non-nested basins. From 1927 through 2011, precipitation and runoff increased at average rates of 1.6 and 1.7 mm yr−1, respectively, and ET increased slightly at a rate of 0.18 mm yr−1. For the more recent period (1970–2011), there was a positive trend in ET of 1.9 mm yr−1. The lack of a more consistent increase in ET, compared with the increases in precipitation and runoff, for the full periods of record, was unexpected, but may be explained by various factors including decreasing wind speed, increasing cloudiness, decreasing vapor pressure deficit, and patterns of forest growth.

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Additional publication details

Publication type Article
Publication Subtype Journal Article
Title Trends in precipitation, runoff, and evapotranspiration for rivers draining to the Gulf of Maine in the United States
Series title Journal of Hydrometeorology
DOI 10.1175/JHM-D-13-018.1
Volume 15
Issue 2
Year Published 2014
Language English
Publisher American Meteorological Society
Contributing office(s) Maine Water Science Center, New England Water Science Center
Description 18 p.
First page 726
Last page 743
Country United States
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