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| Titel |
Mixing relationships of young-water fractions and solute concentrations in Swiss rivers -- a novel approach to describe catchment hydrological behavior |
| VerfasserIn |
Jana Von Freyberg, James Kirchner |
| Konferenz |
EGU General Assembly 2016
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| Medientyp |
Artikel
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| Sprache |
en
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 18 (2016) |
| Datensatznummer |
250124024
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| Publikation (Nr.) |
 EGU/EGU2016-3388.pdf |
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| Zusammenfassung |
| Fundamental catchment properties, such as storage, mixing and water flow pathways are
often described through mean transit times (MTT’s) or transit time distributions (TTD’s).
TTD’s are usually inferred from concentrations of conservative tracers in precipitation and
streamwater using lumped parameter models. Because of the simplifying assumptions of
these models, the meaning of a MTT as a descriptor for spatially heterogeneous catchments
is, however, highly uncertain. Instead the young water fraction (Fyw) – i.e., the fraction of
water that is younger than a specified threshold age – has recently been proposed
as a more reliable measure of water age in heterogeneous catchments (Kirchner,
2016a,b). This raises the question of whether the linkages previously found between
watersheds’ landscape characteristics (e.g., geomorphology, climate, soils, vegetation) and
their MTT’s or TTD’s still hold when Fyw is used instead to characterize water
age.
Using Kirchner’s (2016a,b) approach, we have calculated young-water fractions for a
series of Swiss catchments that represent a wide range of landscape characteristics and
hydro-climatic conditions. We then analyzed mixing relationships between Fyw and solute
concentrations in stream water for different flow regimes. For particular sites with wide
ranges of Fyw, we estimated the concentrations of solutes corresponding to idealized young
water (Fyw = 1) and old water (Fyw = 0) end-members, which we related to possible source
areas. This catchment comparison study tests the utility of water threshold ages for
quantifying catchment hydrological behavior and its linkages to site-specific landscape
characteristics.
References:
Kirchner, J.W. (2016a) Aggregation in environmental systems – Part 1: Seasonal tracer
cycles quantify young water fractions, but not mean transit times, in spatially heterogeneous
catchments, Hydrol. Earth Syst. Sci., in press.
Kirchner, J.W. (2016b) Aggregation in environmental systems – Part 2: Catchment mean
transit times and young water fractions under hydrologic nonstationarity, Hydrol. Earth Syst.
Sci., in press. |
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