1 LA HOUILLE BLANCHE/N° 1-2007 150 e anniversaire des crues de 1856 Extreme floods of the 19 th century in southwest Germany Crues Extrêmes du 19 ème siècle au sud-ouest de l’Allemagne KATRIN BURGER, JOCHEN SEIDEL, RÜDIGER GLASER, DIRK SUDHAUS Department of Physical Geography, University of Freiburg, Werderring 4, 79085 Freiburg, Germany Phone: +49(0)761 203 9120, Fax: +49(0)761 203 3596, e-mail: katrin.buerger@geographie.uni-freiburg.de PAUL DOSTAL, HELMUT MAYER Meteorological Institute, University of Freiburg I฀n INTRODUCTION Climate variability, floods and their impacts in Central Europe have received increasing attention in Germany in recent years. In particular, the floods in recent time demons- trated that changes in frequency and characteristics of floods may reflect climatic transitions [Benito et al., 2005; Bardossy & Filiz, 2005; Kliwa, 2006]. This led to an initiative by the German Federal Ministry of Education and Research (BMBF) for a “Risk Management of Extreme Flood Events” (RIMAX) to avoid or limit the adverse impact of floods in Germany [Merz & Didszun, 2005]. The research group Xfloods “Analysis of Historical Floods for a Preventive Risk Management of Extreme Floods” at the University of Freiburg is part of this initiative, focusing on historical extreme floods in southwest Germany [Bürger et al., 2006]. Historical floods receive increasing attention in flood research and in applied flood protection [Benito & Thorndycraft, 2004; Glaser & Stangl, 2004; Thorndycraft et al., 2003]. They have to be taken into account for the deve- lopment of floodplain mapping (e.g. flood hazard maps), the improvement of recent series of measurements, the statistical validation and the analysis of return period (fig. 1). This paper deals with the historical flood events of 1824, 1845 and 1882 and with the detailed reconstruction and analysis of the extreme flood of the Neckar River (southwest Germany) in October 1824 and its circumstances. The course of this flood event and the weather conditions which led to the flood were reconstructed by using the information from various historical sources. The evaluation of qualitative data, such as flood marks and documentary sources (e.g. official records and damage reports), has shown that the event of 1824 was the largest flood during the last 300 years in most parts of the Neckar catchment. Since this flood was caused solely by strong precipitation, the analysis of the 1824 event was of special interest for the regional authorities and deci- sion makers in the Neckar catchment. In co-operation with the Regional Council of Stuttgart and the State Institute for the Environment, Measurement and Nature Conservation of Baden-Württemberg, all information concerning the extreme flood of 1824 will be integrated into the contemporary flood risk management for the Neckar catchment. The method presented in this paper is the analysis of the flood triggering meteorological situation. This approach inte- grates the information from historical data, such as meteoro- logical and hydrological measurements, to quantify extreme flood events of the past 500 years. The aim is to determine the hydrometeorological conditions and circumstances that caused an extreme flood. The results can be used for flood risk management, modelling historical discharges and visua- lisation of the consequences of such an extreme meteorologi- cal event on today’s environmental conditions. L a variabilité de climat, les inondations et leurs impacts en Europe centrale ont retenu une attention crois- sante en Allemagne pendant les dernières années. Ainsi les crues historiques font l’objet de plus en plus d’attention dans la recherche scientifique et dans la protection contre les crues. Le projet « Xfloods » de l’Université de Freiburg (Allemagne) est intégré à l’initiative du Ministère Fédéral de Culture et de Recherche (BMBF) pour un « Gestion du Risque des Crues Extrêmes » (RIMAX). Les recherches sont particulièrement foca- lisées sur des crues historiques dans le sud-ouest de l’Allemagne. Le projet intègre les informations des données historiques pour identifier et mesurer des crues extrêmes comme base de la gestion du risque d’inondation. Les données seront extraites des sources historiques de 1500-1900 et complétées par des mesures instrumentales dis- ponibles depuis le milieu du 18 ème siècle. Le projet peut contribuer à établir une meilleure estimation des risques et à faire un traitement plus sûr des futures crues.Le site des recherche se trouve dans la région du sud-ouest de l’Allemagne et inclue la vallée supérieure du Rhin et ses affluents orientaux comme le Neckar. Cette région a été affectée par des crues extrêmes dans le passé comme celles des années 1824, 1845 et 1882. Sur l’exemple de l’évé- nement d’inondation d’octobre 1824 dans le bassin du Neckar, la reconstruction détaillée des crues historiques sera présentée. 10.1051/lhb:2007008