Dating base flow in streams using dissolved gases and diurnal temperature changes

Water Resources Research
By: , and 

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Abstract

A method is presented for using dissolved CFCs or SF6 to estimate the apparent age of stream base flow by indirectly estimating the mean concentration of the tracer in the inflowing groundwater. The mean value is estimated simultaneously with the mean residence times of the gas and water in the stream by sampling the stream for one or both age tracers, along with dissolved nitrogen and argon at a single location over a period of approximately 12–14 h. The data are fitted to an equation representing the temporal in-stream gas exchange as it responds to the diurnal temperature fluctuation. The efficacy of the method is demonstrated by collecting and analyzing samples at six different stream locations across parts of northern Virginia, USA. The studied streams drain watersheds with areas of between 2 and 122 km2 during periods when the diurnal stream temperature ranged between 2 and 5°C. The method has the advantage of estimating the mean groundwater residence time of discharge from the watershed to the stream without the need for the collection of groundwater infiltrating to streambeds or local groundwater sampled from shallow observation wells near the stream.

Additional publication details

Publication type Article
Publication Subtype Journal Article
Title Dating base flow in streams using dissolved gases and diurnal temperature changes
Series title Water Resources Research
DOI 10.1002/2014WR016796
Volume 51
Issue 12
Year Published 2015
Language English
Publisher Wiley
Contributing office(s) National Research Program - Eastern Branch
Description 14 p.
First page 9790
Last page 9803
Country United States
State Virginia