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| Titel |
Quantifying groundwater dependence of a sub-polar lake cluster in Finland using an isotope mass balance approach |
| VerfasserIn |
E. Isokangas, K. Rozanski, P. M. Rossi, A.-K. Ronkanen, B. Kløve |
| 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 ; 19, no. 3 ; Nr. 19, no. 3 (2015-03-05), S.1247-1262 |
| Datensatznummer |
250120650
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| Publikation (Nr.) |
 copernicus.org/hess-19-1247-2015.pdf |
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| Zusammenfassung |
| A stable isotope study of 67 kettle lakes and ponds situated on an esker
aquifer (90 km2) in northern Finland was carried out to determine the
role and extent of groundwater inflow in groundwater-dependent lakes.
Distinct seasonal fluctuations in the δ18O and δ2H
values of lakes are the result of seasonal ice cover prohibiting evaporation
during the winter. An iterative isotope mass balance approach was used to
calculate the inflow-to-evaporation ratios (ITOT/E) of all 67 lakes
during the summer of 2013 when the isotopic compositions of the lakes were
approaching a steady-state. The balance calculations were carried out
independently for 2H and 18O data. Since evaporation rates were
derived independently of any mass balance considerations, it was possible to
determine the total inflow (ITOT) and mean turnover time (MTT) of the
lakes. Furthermore, the groundwater seepage rates to all studied lakes were
calculated. A quantitative measure was introduced for the dependence of a
lake on groundwater (G index) that is defined as the percentage contribution
of groundwater inflow to the total inflow of water to the given lake. The G index
values of the lakes studied ranged from ca. 39 to 98%,
revealing generally large groundwater dependency among the studied lakes.
This study shows the effectiveness of applying an isotope mass balance
approach to quantify the groundwater reliance of lakes situated in a
relatively small area with similar climatic conditions. |
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