Articles | Volume 21, issue 9
Hydrol. Earth Syst. Sci., 21, 4615–4627, 2017
Hydrol. Earth Syst. Sci., 21, 4615–4627, 2017

Research article 13 Sep 2017

Research article | 13 Sep 2017

Aggregation effects on tritium-based mean transit times and young water fractions in spatially heterogeneous catchments and groundwater systems

Michael K. Stewart et al.

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Cited articles

Bethke, C. M. and Johnson, T. M.: Groundwater age and groundwater age dating, Annu. Rev. Earth Pl. Sc., 36, 121–152,, 2008.
Blavoux, B., Lachassagne, P., Henriot, A., Ladouche, B., Marc, V., Beley, J.-J., Nicoud, G., and Olive, P.: A fifty-year chronicle of tritium data for characterising the functioning of the Evian and Thonon (France) glacial aquifers, J. Hydrol., 494, 116–133,, 2013.
Close, M., Stewart, M. K., Rosen, M., Morgenstern, U., and Nokes, C.: Investigation into secure groundwater supplies, ESR Client Report FW0034, for the Ministry of Health, Wellington, New Zealand, 30 pp., 2000.
Cook, P. G. and Böhlke, J.-K.: Determining Timescales for Groundwater Flow and Solute Transport, chap. 1, in: Environmental Tracers in Subsurface Hydrology, edited by: Cook, P. G. and Herczeg, A. L., Springer, New York, 1–30, 2012.
Gallart, F., Roig-Planasdemunt, M., Stewart, M. K., Llorens, P., Morgenstern, U., Stichler, W., Pfister, P., and Latron, J.: A GLUE-based uncertainty assessment framework for tritium-inferred transit time estimations under baseflow conditions, Hydrol. Process., 30, 4741–4760,, 2016.
Short summary
This paper presents for the first time the effects of aggregation errors on mean transit times and young fractions estimated using tritium concentrations. Such errors, due to heterogeneity in catchments, had previously been demonstrated for seasonal tracer cycles by Kirchner (2016a). We found that mean transit times derived from tritium are just as susceptible to aggregation bias as those from seasonal tracer cycles. Young fractions were found to be almost immune to aggregation bias.