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| Titel |
Estimation of the spatial distribution of hydrological responsiveness based on solute series |
| VerfasserIn |
Christian Lehr, Gunnar Lischeid, Doerthe Tetzlaff |
| Konferenz |
EGU General Assembly 2015
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 17 (2015) |
| Datensatznummer |
250107548
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| Publikation (Nr.) |
 EGU/EGU2015-7252.pdf |
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| Zusammenfassung |
| Numerous studies have shown that time series of solute concentration in headwater streams
often reflect the dynamics of the hydrograph. The reverse has rarely been addressed: To what
degree do time series of solute concentration bear information about the hydrological
dynamics, and how can that information be extracted in an efficient way? Taking
water samples in remote areas is much less demanding compared to installing and
maintaining a set of gauging stations. Thus it would be worthwhile to study the reverse
approach.
The catchment of the River Dee (Central Scotland, UK) covers an area of 1849 km2,
ranging from the Cairngorm Mountains in the west towards the Northern Sea in the east.
Stream water had been sampled for one year at biweekly intervals at 59 sites along the main
stem of the river and in its tributaries and had been analysed for 11 solutes. In contrast,
discharge had been measured only at nine sites.
We followed two different approaches to infer spatial patterns of the hydrological
dynamics at the ungauged sites. In a “classic” Principal Component Analysis (PCA)
approach, a PCA was applied on a joint data set comprising concentration data of all
solutes at all sites and all dates. Assuming that the identified principal components
represented different processes or factors of influence, we aimed at identifying a
component that represented the effect of hydrological processes. To that end, time
series of the scores of the different components were compared to the hydrograph at
those sites where discharge data were available. In fact, the second component
exhibited close correlations with the discharge series at all gauged sites. Then the
time series of the scores of this component at all 59 sites were used as a proxy for
the hydrological dynamics. The resulting spatial pattern was analysed by a cluster
analysis.
The alternative approach assumed that part of the differences of time series of solute
concentration at different sites was due to hydrological processes. A PCA was applied to
identify different dimensions or axes of differences between time series of solute
concentration at different sites that would reflect different factors of influence. Separate PCA
were performed for each solute. Thus each site could be characterized by the respective
component scores. Based on correlation analysis of the resulting spatial patterns a set of nine
solutes and their respective components with very similar spatial patterns was identified.
Additional evidence confirmed that this spatial pattern in fact reflected the degree of
hydrological responsiveness at all sampled sites. Both approaches showed essentially the
same spatial pattern. We interpret this to be the spatial pattern of hydrological responsiveness. |
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