Evolution des extrêmes hydrométriques en France à partir de données observées

Observed changes in hydrological extremes in France

¹ CEMAGREF Lyon, 3 bis quai Chauveau, 69009 Lyon
² Laboratoire d’étude des Transferts en Hydrologie et Environnement, 1025 rue de la piscine, 38 400 Saint Martin d’Hères
³ EDF LNHE, 6 quai Watier, 78400 Chatou
⁴ Météo-France / ENM, 42 avenue Gaspard Coriolis, 31057 TOULOUSE Cedex 1
⁵ HydroSciences, 300 avenue du Professeur Emile Jeanbrau, 34090 Montpellier
⁶ EDF DTG, 21 avenue de l’Europe, 38040 Grenoble Cedex 9

Auteur de correspondance : renard@lyon.cemagref.fr

Abstract

Impact of climate change on hydrological extremes in France is still an open question. Results of a PNRH project about detecting trends or step-changes in the extreme hydrological regimes in France are here presented. A set of 192 hydrological series has been used, with at least 40 years of data and good quality rating curves. Statistical tests were applied on hydrological variables describing high flows (annual maxima, peak-over-threshold discharges and events frequency) and low flows (annual minima, duration and volume of droughts).Concerning high flows, no evidence of a consistent change has been found. The significant increase in the damages induced by floods thus arises from an increase in the vulnerability, caused by an unreasonable urbanization. Trends in annual minima may be stronger, but additional studies are needed in order to differentiate anthropogenic, metrological and climatic factors. Moreover, a Bayesian framework has been constructed in order to incorporate the hypothesis of stationarity as a new uncertainty in floods or droughts frequency analysis.