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| Titel |
Is there a trend in extremely high river temperature for the next decades? A case study for France |
| VerfasserIn |
F. Huguet, S. Parey, D. Dacunha-Castelle, F. Malek |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1561-8633
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| Digitales Dokument |
URL |
| Erschienen |
In: Natural Hazards and Earth System Science ; 8, no. 1 ; Nr. 8, no. 1 (2008-02-13), S.67-79 |
| Datensatznummer |
250005322
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| Publikation (Nr.) |
 copernicus.org/nhess-8-67-2008.pdf |
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| Zusammenfassung |
| After 2003's summer heat wave, Electricité de France created a global
plan called "heat wave-dryness". In this context, the present study tries
to estimate high river temperatures for the next decades, taking into
account climatic and anthropogenic evolutions. To do it, a specific
methodology based on Extreme Value Theory (EVT) is applied. In particular, a
trend analysis of water temperature data is done and included in EVT used.
The studied river temperatures consist of mean daily temperatures for 27
years measured near the French power plants (between 1977 and 2003), with
four series for the Rhône river, four for the Loire river and a few for
other rivers. There are also three series of mean daily temperatures
computed by a numerical model. For each series, we have applied statistical
extreme value modelling. Because of thermal inertia, the Generalized Extreme
Value (GEV) distribution is corrected by the medium cluster length, which
represents thermal inertia of water during extremely hot events. The μ
and σ parameters of the GEV distributions are taken as polynomial or
continuous piecewise linear functions of time. The best functions for μ
and σ parameters are chosen using Akaike criterion based on
likelihood and some physical checking. For all series, the trend is positive
for μ and not significant for σ, over the last 27 years.
However, we cannot assign this evolution only to the climatic change for the
Rhône river because the river temperature is the resultant of several
causes: hydraulic or atmospheric, natural or related to the human activity.
For the other rivers, the trend for μ could be assigned to the climatic
change more clearly. Furthermore, the sample is too short to provide
reliable return levels estimations for return periods exceeding thirty
years. Still, quantitative return levels could be compared with physical
models for example. |
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