Réf. Benito 2003 - P

Référence bibliographique complète
BENITO, G. Palaeflood hydrology in Europe. In: V.R.Thorndycraft, G. Benito, M. Barriendos and M.C. Llasat (Eds). Palaeofloods, Historical Floods and Climatic Variability: Applications in Flood Risk Assessment, Proceedings of the PHEFRA Workshop, Barcelona, 16-19th October, 2002, p. 19-24.

Mots-clés
Floods reconstruction, Europe.

Organismes / Contact
CSIC-Centro de Ciencias Medioambientales, Serrano 115 bis, 28006 Madrid, Spain
benito@ccma.csic.es

(1) - Paramètre(s) atmosphérique(s) modifié(s)
(2) - Elément(s) du milieu impacté(s)
(3) - Type(s) d'aléa impacté(s)
(3) - Sous-type(s) d'aléa
    Floods  

Pays / Zone
Massif / Secteur
Site(s) d'étude
Exposition
Altitude
Période(s) d'observation
Europe / Southern France          

(1) - Modifications des paramètres atmosphériques
Reconstructions
 
Observations
 
Modélisations
 
Hypothèses
 

Informations complémentaires (données utilisées, méthode, scénarios, etc.)
 

(2) - Effets du changement climatique sur le milieu naturel
Reconstructions
 
Observations
 
Modélisations
 
Hypothèses
 

Sensibilité du milieu à des paramètres climatiques
Informations complémentaires (données utilisées, méthode, scénarios, etc.)

 

(3) - Effets du changement climatique sur l'aléa
Reconstructions
The magnitude of the Gard River (Southern France) flood on the 8-9 of September 2002 is larger than any historical flood on record. Palaeoflood studies within the SPHERE Project in that area (Sheffer et al., 2003) reveals the occurrence of several past extreme floods of even greater magnitude than that of the 2002 flood, and therefore larger than any observed flood that has occurred in the recent past.
Observations
 
Modélisations
 
Hypothèses
 

Paramètres de l'aléa
Sensibilité du paramètre de l'aléa à des paramètres climatiques et du milieu
Informations complémentaires (données utilisées, méthode, scénarios, etc.)
 
 

(4) - Remarques générales
 

(5) - Préconisations et recomandations
In terms of the hydrological effects of climate change, future global circulation model projections incorporate too much uncertainty to accurately specify expected patterns of precipitation change, and even less the frequency and magnitude of extreme storm and flood events. Predictions can be improved by incorporating long-term flood records (several millennia) in climatic modelling and statistical analysis. The study of temporal variability of past climate-flood links can establish short-and long-term relationships at regional levels and in areas within different climatic zones (Benito et al., in press). Regional studies of long-term climate-flood links involve calibrating the relationships, detecting trends (where they exist) and revising estimates of return periods. This integration will greatly advance our understanding of flood frequency and magnitude in the context of changing climates where the assumption of stationarity (implicit in most current flood risk models) is being questioned.

European palaeoflood studies can take advantage from long documentary records (last 1000 years) which describe extreme flood occurrence (exact dates) and produced damages. The best scenario combines palaeoflood discharge estimates from bedrock canyons with documentary description and quantification of flood impacts on past socities, including economic losses, recovery strategies and flood management at different periods. The history of past floods [...] provide a unique opportunity to understand the flood hydrology and the social impact of “catastrophic floods” with magnitudes far beyond the ones recorded at gauge stations. This, in turn, means gaining an understanding of individual extreme events not available and perhaps not predicted by the instrumental record, as well as to gain a new dimension on socio-economic impacts and perception of extreme events, which needs to be evaluated according to different historical contexts. Flood damage exerted on riverside societies during centuries is very valuable information to be used in risk education tasks directed to Civil Protection technicians, volunteer bodies and in schools.

In the investigation of the environmental effects and risks associated with fluvial systems in natural and anthropogenic disasters, the participation of multidisciplinary groups made up of geomorphologists, sedimentologists and hydrologists, mathematicians and environmental mangers is increasingly called for. The appropriate analysis of hydrological risks is dependent upon the development of new methods in the field of palaeoflood hydrology as a complement and/or alternative to instrumental hydrology.  These should allow the standardization of discharge estimation procedures and flood risk assessment using non-systematic data for small watersheds devoid of gauging stations, and also improve the estimation of peak discharges for floods of long return periods (500 and 1000 years) aimed at increasing the safety of dams.