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| Titel |
Temporal and spatial analysis of groundwater inflow into lakes by ²²²Rn |
| VerfasserIn |
T. Kluge, C. von Rohden, P. Sonntag, S. Lorenz, M. Wieser, W. Aeschbach-Hertig, J. Ilmberger |
| Konferenz |
EGU General Assembly 2012
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 14 (2012) |
| Datensatznummer |
250060180
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| Zusammenfassung |
| For the investigation of the groundwater - surface water interaction 222Rn is increasingly used
as an important tracer due to its unique properties. It is especially suitable as its concentration
in surface waters is about three orders of magnitude lower compared to groundwater and,
therefore, enables the tracing of even small amounts of groundwater seeping into surface
waters such as lakes.
So far, simple one or two box models have been used to determine a general estimate of the
groundwater inflow in lakes with 222Rn. We introduce and discuss a multi-box model for the
vertical radon distribution in a lake which accounts for inhomogeneities in the groundwater
inflow and transport between the boxes. Measurements of precise profiles during different
states of stratification from 2005 to 2009 enabled the depth-resolved calculation of the
groundwater inflow and the validation of previous mass balance calculations. Furthermore,
the multi-box model yields the possibility to detect depth levels of enhanced or suppressed
groundwater input and to trace seasonal changes in the interstratification of groundwater in
the lake. Additionally, the depth-dependent calculation helps to constrain several parameters
in the Rn mass balance (e.g. the diffusive radon sediment flux and the gas exchange with the
atmosphere).
Exemplary data from the studied lake (Lake Willersinnweiher, Germany) show the
groundwater inflow to be restricted to a limited layer (upper 5 m) whereas the groundwater
interstratification signal and depth varies with the stratification pattern in the water column.
The average inflow rate determined from the multi-box model (440 ± 140 m3/d) agrees with
previous one-box model calculations (400 ± 410 m3/d) and a simple estimate based on
Darcy’s law, however, the new approach is more precise and yields substantially more
information about the system.
References:
Kluge, T., Ilmberger, J., von Rohden, C., Aeschbach-Hertig, W., 2007. Tracing and
quantifying groundwater inflow into lakes using radon-222. Hydrol. Earth Sys. Sci. 11,
1621–1631. |
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