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Comparison of instantaneous and constant‐rate stream tracer experiments through non‐parametric analysis of residence time distributions
Author(s) -
Payn Robert A.,
Gooseff Michael N.,
Benson David A.,
Cirpka Olaf A.,
Zarnetske Jay P.,
Bowden W. Breck,
McNamara James P.,
Bradford John H.
Publication year - 2008
Publication title -
water resources research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.863
H-Index - 217
eISSN - 1944-7973
pISSN - 0043-1397
DOI - 10.1029/2007wr006274
Subject(s) - tracer , residence time distribution , residence time (fluid dynamics) , parametric statistics , constant (computer programming) , environmental science , mathematics , statistics , flow (mathematics) , computer science , geology , physics , geometry , geotechnical engineering , nuclear physics , programming language
Artificial tracers are frequently employed to characterize solute residence times in stream systems and infer the nature of water retention. When the duration of tracer application is different between experiments, tracer breakthrough curves at downstream locations are difficult to compare directly. We explore methods for deriving stream solute residence time distributions (RTD) from tracer test data, allowing direct, non‐parametric comparison of results from experiments of different durations. Paired short‐ and long‐duration field experiments were performed using instantaneous and constant‐rate tracer releases, respectively. The experiments were conducted in two study reaches that were morphologically distinct in channel structure and substrate size. Frequency‐ and time domain deconvolution techniques were used to derive RTDs from the resulting tracer concentrations. Comparisons of results between experiments of different duration demonstrated few differences in hydrologic retention characteristics inferred from short‐ and long‐term tracer tests. Because non‐parametric RTD analysis does not presume any shape of the distribution, it is useful for comparisons across tracer experiments with variable inputs and for validations of fundamental transport model assumptions.