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| Titel |
On the trail of ‘hidden streamflow' in Luxembourgish catchments |
| VerfasserIn |
Michael Stewart, Laurent Pfister, Uwe Morgenstern, Núria Martínez-Carreras, Laurent Gourdol, Julian Klaus, Jeffrey McDonnell |
| Konferenz |
EGU General Assembly 2014
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 16 (2014) |
| Datensatznummer |
250099914
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| Publikation (Nr.) |
 EGU/EGU2014-15763.pdf |
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| Zusammenfassung |
| Tritium measurements are being carried out in well-studied catchments in the Attert
sub-basin of the Alzette River in Luxembourg to investigate transit times of baseflow from
the various lithologies in the area. Rock-types vary from sandstone with high permeability to
marl and schist with low permeabilities. In contrast to other methods, tritium reveals the full
spectrum of ages present in streams including ‘hidden streamflow’ (i.e. water older than that
measurable by stable isotope or conservative tracer methods) Stewart et al. (2012). In
principle, it can also provide ages for individual samples and therefore reveal variations in
age with flow if measurements are accurate enough. However, difficulties arise in determining
the tritium input function and from ambiguous age solutions due to the past input of
thermonuclear tritium. Previous and concurrent geochemical and stable isotope studies are
providing complementary information about the systems (e.g. geological controls on
catchment storage, mixing potential, isotopic signatures in streamflow) Pfister et al.
(2014).
Results to date are showing that old water with mean transit times of about 18 years flow
from catchments dominated by sandstone at medium to low flows. These streams also have
very homogeneous δD values at such flows showing large storages and mixing potentials. On
the other hand, catchments dominated by marl and schist show varying mean transit times
ranging from 2 to 20 years depending on flows, although data is limited. The δD
values of these streams are scattered and have a decreasing trend with streamflow
showing event and seasonal rainfall influence, and thus small storage capacities and
mixing potentials. It appears that ‘hidden streamflow’ is alive and well, and living in
Luxembourg!
Pfister L. et al. 2014: Catchment storage, baseflow isotope signatures and basin geology:
Is there a connection? In preparation.
Stewart, M.K., Morgenstern, U., McDonnell, J.J., Pfister, L. 2012: The ‘hidden’
streamflow challenge in catchment hydrology: A call to action for streamwater transit time
analysis. Hydrological Processes 26(13), 2061–2066. |
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