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| Titel |
Using stable isotope tracers to assess hydrological flow paths, residence times and landscape influences in a nested mesoscale catchment |
| VerfasserIn |
P. Rodgers, C. Soulsby, S. Waldron, D. Tetzlaff |
| 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 ; 9, no. 3 ; Nr. 9, no. 3 (2005-07-22), S.139-155 |
| Datensatznummer |
250006861
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| Publikation (Nr.) |
 copernicus.org/hess-9-139-2005.pdf |
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| Zusammenfassung |
| δ18O measurements in precipitation and stream waters were used to
investigate hydrological flow paths and residence times at nested spatial
scales in the mesoscale (233 km2) River Feugh catchment in the northeast
of Scotland over the 2001-2002 hydrological year. Precipitation δ18O exhibited strong seasonal variation, which although significantly
damped within the catchment, was reflected in stream water at six sampling
sites. This allowed δ18O variations to be used to infer the
relative influence of soil-derived storm flows with a seasonally variable
isotopic signature, and groundwater of apparently more constant isotopic
composition. Periodic regression analysis was then used to examine the
sub-catchment difference using an exponential flow model to provide
indicative estimates of mean stream water residence times, which varied
between approximately 3 and 14 months. This showed that the effects of
increasing scale on estimated mean stream water residence time was minimal
beyond that of the smallest (ca. 1 km2) headwater catchment scale.
Instead, the interaction of catchment soil cover and topography appeared to
be the dominant controlling influence. Where sub-catchments had extensive
peat coverage, responsive hydrological pathways produced seasonally variable
δ18O signatures in runoff with short mean residence times (ca.
3 months). In contrast, areas dominated by steeper slopes, more freely
draining soils and larger groundwater storage in shallow valley-bottom
aquifers, deeper flow paths allow for more effective mixing and damping of
δ18O indicating longer residence times (>12 months). These
insights from δ18O measurements extend the hydrological
understanding of the Feugh catchment gained from previous geochemical tracer
studies, and demonstrate the utility of isotope tracers in investigating the
interaction of hydrological processes and catchment characteristics at
larger spatial scales. |
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