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| Titel |
Assessing residence times of hyporheic ground water in two alluvial flood plains of the Southern Alps using water temperature and tracers |
| VerfasserIn |
E. Hoehn, O. A. Cirpka |
| 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 ; 10, no. 4 ; Nr. 10, no. 4 (2006-07-27), S.553-563 |
| Datensatznummer |
250008141
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| Publikation (Nr.) |
 copernicus.org/hess-10-553-2006.pdf |
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| Zusammenfassung |
| Water temperature can be used as a tracer for the interaction between river
water and groundwater, interpreting time shifts in temperature signals as
retarded travel times. The water temperature fluctuates on different time
scales, the most pronounced of which are the seasonal and diurnal ones.
While seasonal fluctuations can be found in any type of shallow groundwater,
high-frequency components are more typical for freshly infiltrated river
water, or hyporheic groundwater, and are thus better suited for evaluating
the travel time of the youngest groundwater component in alluvial aquifer
systems. We present temperature time series collected at two sites in the
alpine floodplain aquifers of the Brenno river in Southern Switzerland. At
the first site, we determine apparent travel times of temperature for both
the seasonal and high-frequency components of the temperature signals in
several wells. The seasonal signal appears to travel more slowly, indicating
a mixture of older and younger groundwater components, which is confirmed by
sulphate measurements. The travel times of the high-frequency component
qualitatively agree with the groundwater age derived from radon
concentrations, which exclusively reflects young water components. Directly
after minor floods, the amplitude of temperature fluctuations in an
observation well nearby the river is the highest. Within a week, the
riverbed is being clogged, leading to stronger attenuation of the
temperature fluctuations in the observation well. At the second site, very
fast infiltration to depths of 1.9 m under the riverbed could be inferred
from the time shift of the diurnal temperature signal. |
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