La politique suisse de protection contre les crues forgée par les crues historiques

Flood management policies in Switzerland determined by historical events

Office Fédéral de l’Environnement, Section risques liés à l’eau Suisse

Abstract

Prevention policies against natural hazards are often the result of a learning process gained under the pressure of coping with the consequences of natural disasters. Disasters did not only have adverse effects on society but were also the source of innovations. In Switzerland, the process of fund raising after natural disasters in the 19th century significantly helped the process of national integration. Then, the shock provoked by the floods in the central part of the Alps in 1868 strongly contributed to the introduction of an article on embankments and forests in the revision of the federal constitution in 1874, which boosted the domain of protection against floods. More recently, the analysis of the 1987 floods showed that the protective measures could not solely by themselves guarantee the protection against floods, and that this hazard had to be taken into consideration in land use planning. The federal law of 1991, that followed as a consequence, focuses strongly on preventive measures. The positive effects of this change of paradigm could be seen in major events after the law was passed, in particular in 2000 in the canton of Valais and more recently in august 2005. The record damage caused by this last episode shows that there is still a lot to do. Nevertheless, it is too early to judge if the expected return of experience will lead to an adaptation of the actual approach.