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| Titel |
The influence of decadal-scale variability on trends in long European streamflow records |
| VerfasserIn |
J. Hannaford, G. Buys, K. Stahl, L. M. Tallaksen |
| 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 ; 17, no. 7 ; Nr. 17, no. 7 (2013-07-15), S.2717-2733 |
| Datensatznummer |
250018933
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| Publikation (Nr.) |
 copernicus.org/hess-17-2717-2013.pdf |
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| Zusammenfassung |
| This study seeks to provide a long-term context for the growing number of
trend analyses which have been applied to river flows in Europe. Most
studies apply trend tests to fixed periods, in relatively short (generally
1960s–present) records. This study adopts an alternative
"multi-temporal" approach, whereby trends are fitted to every possible
combination of start and end years in a record. The method is applied to 132
catchments with long (1932–2004) hydrometric records from northern and
central Europe, which were chosen as they are minimally anthropogenically
influenced and have good quality data. The catchments are first clustered
into five regions, which are broadly homogenous in terms of interdecadal
variability of annual mean flow. The multi-temporal trend approach was then
applied to regional time series of different hydrological indicators
(annual, monthly and high and low flows). The results reveal that the
magnitude and even direction of short-term trends are heavily influenced by
interdecadal variability. Some short-term trends revealed in previous
studies are shown to be unrepresentative of long-term change. For example,
previous studies have identified post-1960 river flow decreases in southern
and eastern Europe: in parts of eastern Europe, these trends are resilient
to study period, extending back to the 1930s; in southern France, longer
records show evidence of positive trends which reverse from the 1960s.
Recent (post-1960) positive trends in northern Europe are also not present
in longer records, due to decadal variations influenced by the North
Atlantic Oscillation. The results provide a long-term reference for
comparison with published and future studies. The multi-temporal approach
advocated here is recommended for use in future trend assessments, to help
contextualise short-term trends. Future work should also attempt to explain
the decadal-scale variations that drive short-term trends, and thus develop
more sophisticated methods for trend detection that take account of
interdecadal variability and its drivers. |
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