Abstract
Comparison of instantaneous and constant-rate stream tracer experiments through non-parametric analysis of residence time distributions
Hydrologic Science and Engineering Program/Department of Geology and Geological Engineering, Colorado School of Mines, Golden, Colorado, USA
Department of Civil and Environmental Engineering, Pennsylvania State University, University Park, Pennsylvania, USA
Hydrologic Science and Engineering Program/Department of Geology and Geological Engineering, Colorado School of Mines, Golden, Colorado, USA
Swiss Federal Institute of Aquatic Science and Technology (EAWAG), Dübendorf, Switzerland
Department of Geosciences, Oregon State University, Corvallis, Oregon, USA
Rubenstein School of the Environment and Natural Resources, University of Vermont, Burlington, Vermont, USA
Department of Geosciences, Boise State University, Boise, Idaho, USA
Department of Geosciences, Boise State University, Boise, Idaho, USA
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.
Received 16 June 2007; accepted 5 February 2008; published 4 June 2008.
Citation: (2008), Comparison of instantaneous and constant-rate stream tracer experiments through non-parametric analysis of residence time distributions, Water Resour. Res., 44, W06404, doi:10.1029/2007WR006274.
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