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| Titel |
Filling the white space on maps of European runoff trends: estimates from a multi-model ensemble |
| VerfasserIn |
K. Stahl, L. M. Tallaksen, J. Hannaford, H. A. J. Lanen |
| 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 ; 16, no. 7 ; Nr. 16, no. 7 (2012-07-11), S.2035-2047 |
| Datensatznummer |
250013363
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| Publikation (Nr.) |
 copernicus.org/hess-16-2035-2012.pdf |
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| Zusammenfassung |
| An overall appraisal of runoff changes at the European scale has been
hindered by "white space" on maps of observed trends due to a paucity of
readily-available streamflow data. This study tested whether this white
space can be filled using estimates of trends derived from model simulations
of European runoff. The simulations stem from an ensemble of eight global
hydrological models that were forced with the same climate input for the
period 1963–2000. The derived trends were validated for 293 grid cells
across the European domain with observation-based trend estimates. The
ensemble mean overall provided the best representation of trends in the
observations. Maps of trends in annual runoff based on the ensemble mean
demonstrated a pronounced continental dipole pattern of positive trends in
western and northern Europe and negative trends in southern and parts of
eastern Europe, which has not previously been demonstrated and discussed in
comparable detail. Overall, positive trends in annual streamflow appear to
reflect the marked wetting trends of the winter months, whereas negative
annual trends result primarily from a widespread decrease in streamflow in
spring and summer months, consistent with a decrease in summer low flow in
large parts of Europe. High flow appears to have increased in rain-dominated
hydrological regimes, whereas an inconsistent or decreasing signal was found
in snow-dominated regimes. The different models agreed on the predominant
continental-scale pattern of trends, but in some areas disagreed on the
magnitude and even the direction of trends, particularly in transition zones
between regions with increasing and decreasing runoff trends, in complex
terrain with a high spatial variability, and in snow-dominated regimes.
Model estimates appeared most reliable in reproducing observed trends in
annual runoff, winter runoff, and 7-day high flow. Modelled trends in
runoff during the summer months, spring (for snow influenced regions) and
autumn, and trends in summer low flow were more variable – both among
models and in the spatial patterns of agreement between models and the
observations. The use of models to display changes in these hydrological
characteristics should therefore be viewed with caution due to higher
uncertainty. |
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