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| Titel |
On the use of spring baseflow recession for a more accurate parameterization of aquifer transit time distribution functions |
| VerfasserIn |
J. Farlin, P. Maloszewski |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1027-5606
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| Digitales Dokument |
URL |
| Erschienen |
In: Hydrology and Earth System Sciences ; 17, no. 5 ; Nr. 17, no. 5 (2013-05-13), S.1825-1831 |
| Datensatznummer |
250018874
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| Publikation (Nr.) |
 copernicus.org/hess-17-1825-2013.pdf |
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| Zusammenfassung |
| Baseflow recession analysis and groundwater dating have up to now developed
as two distinct branches of hydrogeology and have been used to solve entirely
different problems. We show that by combining two classical models, namely
the Boussinesq equation describing spring baseflow recession, and the
exponential piston-flow model used in groundwater dating studies, the
parameters describing the transit time distribution of an aquifer can be in
some cases estimated to a far more accurate degree than with the latter
alone. Under the assumption that the aquifer basis is sub-horizontal, the
mean transit time of water in the saturated zone can be estimated from
spring baseflow recession. This provides an independent estimate of
groundwater transit time that can refine those obtained from tritium
measurements. The approach is illustrated in a case study predicting
atrazine concentration trend in a series of springs draining the
fractured-rock aquifer known as the Luxembourg Sandstone. A transport model
calibrated on tritium measurements alone predicted different times to trend
reversal following the nationwide ban on atrazine in 2005 with different
rates of decrease. For some of the springs, the actual time of trend
reversal and the rate of change agreed extremely well with the model
calibrated using both tritium measurements and the recession of spring
discharge during the dry season. The agreement between predicted and
observed values was however poorer for the springs displaying the most
gentle recessions, possibly indicating a stronger influence of continuous
groundwater recharge during the summer months. |
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