At the end of August and the beginning of October 2020, southern Switzerland and neighbouring mountain cantons were affected by two storms, some of which resulted in considerable runoff, but relatively little damage. In the sense of an assessment of the situation, the two storm events were taken as an opportunity to review the functioning of the warning network at the interface between the federal agencies and the cantons. For this purpose, the hydrometeorological forecasts before and during the two storms as well as the warnings derived from them were analysed for their quality and mutual coordination. Furthermore, interviews were conducted with those responsible in the affected cantons to find out how they dealt with the warnings and their assessment of the functioning of the warning network. Finally, potential optimization measures were developed in a joint workshop.
The analyses and feedback have shown that the warning chain basically functioned well during the two severe weather events. In both cases, the procedure of the individual cantons with regard to the receipt of information, internal assessment, and decisions on measures, as well as contact with the federal authorities, was very different. Overall, the flow of information from the Confederation during the two events was assessed by the cantons as purposeful. However, the analysis of the severe weather events in August and October 2020 also revealed selective optimization possibilities and raised questions, for example, regarding the communicative interaction of heavy precipitation and flood warnings.
I organized and moderated a workshop with cantonal experts and managers and representatives of the Swiss Confederation on 11 June 2021 (Photo: Christophe Lienert)
Publications (in German)
Steeb, Nicolas; Badoux, Alexandre; Bialek, Roland; Bogner, Konrad; Hug Peter, Dorothea; Kellner, Elke Lienert, Christophe; Willemse, Saskia; Zappa, Massimiliano; Stähli, Manfred (2022): Vorhersage und Warnung von Unwettern in der Schweiz: Das Zusammenwirken von Bund und Kantonen anhand von zwei Fallbeispielen im Jahr 2020. In Wasser Energie Luft 114 (2), pp. 98–104.
Steeb, Nicolas; Badoux, Alexandre; Kellner, Elke; Bogner, Konrad; Hug Peter, Dorothea; Zappa, Massimiliano; Stähli, Manfred (2021): Analyse der Vorhersage und Warnkette anhand von zwei Unwetterereignissen im Jahr 2020. Starkniederschlagsereignisse vom 28. – 31. August und 1.-3. Oktober 2020. Edited by Eidgenössische Forschungsanstalt für Wald, Schnee, und Landschaft WSL. Birmensdorf, Schweiz, pp 51.