Naturgefahrenereignisse betreffen die mit dem Vollzug der Gefahrenprävention beauftragten Organisationen unmittelbar. Sie sind einerseits in die Bewältigung der Ereignisse involviert und andererseits zeigen die Ereignisse auf, ob die bisherigen Vorstellungen, Beurteilungen und Massnahmen adäquat und hinreichend sind. Die Vollzugsorganisationen von Bund und Kanton haben unterschiedliche Rollen und Aufgaben. Im Beitrag werden wichtige Ereignisse der letzten Jahrzehnte und daraus erfolgte Lehren sowie Anpassungen und Entwicklungen aus der Sicht des Kanton Nidwalden und des Bundes aufgezeigt. Im Weiteren werden die gegenseitigen Beeinflussungen zwischen Kanton und Bund, sowie die Verbreitung der Erfahrungen betrachtet. Schliesslich werden Erfolgsfaktoren und Grenzen sowie Verbesserungsmöglichkeiten und Herausforderungen erörtert.

Dealing with flooding: lessons learned by cantons and the federal government
The organisations responsible for implementing preventive measures are directly affected by the events associated with natural hazards. On the one hand, they are involved in managing the impact of such events, whose consequences simultaneously indicate whether previous ideas, assessments and measures were adequate and sufficient. The federal and cantonal organisations implementing preventive measures perform different roles and duties. The article presents major events in recent decades and lessons learned as well as adaptations and developments from the point of view of the Canton of Nidwalden and Switzerland’s federal authorities. It also considers the mutual influences between the canton and federal authorities and how experience is shared, and then concludes by discussing success factors, limits, challenges and potential for improvements.
Storms that hit the Canton of Nidwalden between 1997 and 1984 prompted a number of adjustments and developments. The weaknesses in the roughly century-old defences dating from the19th century were recognised and eliminated. The previous practice of using barriers to reduce bed loads was replaced by a comprehensive, systematic approach.
At the federal level, after a roughly 70-year breather, the first major loss event in 1987 triggered a paradigm shift in how Switzerland deals with natural hazards. The event in 2005, in particular, led to the optimisation of warnings and alerts between the federal authorities and the cantons and to the establishment of a nationwide Swiss natural hazard warning and alert system.
Many lessons from past events have already been learned and implemented both in the Canton of Nidwalden and by the federal authorities. However, in future there will be further challenges to face with regard to changing framework conditions, such as technological advances, socioeconomic developments and climate change. On the other hand, established structures need to be maintained and constantly adapted to these new framework conditions. At the same time, education and training must pass on the experience gained from such events to the next generation, which did not live through them.