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| Titel |
Where does streamwater come from in low-relief forested watersheds? A dual-isotope approach |
| VerfasserIn |
J. Klaus, J. J. McDonnell, C. R. Jackson, E. Du, N. A. Griffiths |
| 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. 1 ; Nr. 19, no. 1 (2015-01-08), S.125-135 |
| Datensatznummer |
250120584
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| Publikation (Nr.) |
 copernicus.org/hess-19-125-2015.pdf |
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| Zusammenfassung |
| The time and geographic sources of streamwater in low-relief watersheds are
poorly understood. This is partly due to the difficult combination of low
runoff coefficients and often damped streamwater isotopic signals precluding
traditional hydrograph separation and convolution integral approaches. Here
we present a dual-isotope approach involving 18O and 2H of water
in a low-angle forested watershed to determine streamwater source components
and then build a conceptual model of streamflow generation. We focus on
three headwater lowland sub-catchments draining the Savannah River Site in
South Carolina, USA. Our results for a 3-year sampling period show that the
slopes of the meteoric water lines/evaporation water lines (MWLs/EWLs) of the
catchment water sources can be used to extract information on runoff sources
in ways not considered before. Our dual-isotope approach was able to
identify unique hillslope, riparian and deep groundwater, and streamflow
compositions. The streams showed strong evaporative enrichment compared to
the local meteoric water line (δ2H = 7.15 · δ18O
+9.28‰) with slopes of 2.52, 2.84, and 2.86. Based on
the unique and unambiguous slopes of the EWLs of the different water cycle
components and the isotopic time series of the individual components, we
were able to show how the riparian zone controls baseflow in this system and
how the riparian zone "resets" the stable isotope composition of the
observed streams in our low-angle, forested watersheds. Although this
approach is limited in terms of quantifying mixing percentages between
different end-members, our dual-isotope approach enabled the extraction of
hydrologically useful information in a region with little change in
individual isotope time series. |
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