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Natural Hazards and Earth System Sciences An interactive open-access journal of the European Geosciences Union
https://doi.org/10.5194/nhess-2018-134
© Author(s) 2018. This work is distributed under
the Creative Commons Attribution 4.0 License.
Research article
22 May 2018
Review status
This discussion paper is a preprint. It is a manuscript under review for the journal Natural Hazards and Earth System Sciences (NHESS).
Reconstruction and simulation of an extreme flood event in the Lago Maggiore catchment in 1868
Peter Stucki1,2, Moritz Bandhauer1,2,a, Ulla Heikkilä3,b, Ole Rössler1,2, Massimiliano Zappa4, Lucas Pfister2, Melanie Salvisberg1,5, Paul Froidevaux2,3, Olivia Martius1,2, Luca Panziera1,2,6, and Stefan Brönnimann1,2 1Oeschger Centre for Climate Change Research, University of Bern, Bern, 3012, Switzerland
2Institute of Geography, University of Bern, Bern, 3012, Switzerland
3Meteotest, Bern, 3012, Switzerland
4Eidg. Forschungsanstalt WSL, Birmensdorf, 8903, Switzerland
5Institute of History, University of Bern, Bern, 3012, Switzerland
6MeteoSvizzera, Locarno Monti, 6605, Switzerland
anow at: Schweizerische Energie-Stiftung SES, Zurich, 8005, Switzerland
bnow at: LogObject, Zurich, 8048, Switzerland
Abstract. Heavy precipitation on the south side of the central Alps produced a catastrophic flood in October 1868. We assess the damage and societal impacts, as well as the atmospheric and hydrological drivers using documentary evidence, observations, and novel numerical weather and runoff simulations.

The greatest damage was concentrated close to the Alpine divide and Lago Maggiore. An atmospheric reanalysis emphasizes the repeated occurrence of streamers of high potential vorticity as precursors of heavy precipitation. Dynamical downscaling indicates high freezing levels (4000 m a.s.l.), extreme precipitation rates (max. 270 mm/24 h), and weather dynamics that agree well with observed precipitation and damage, and with existing concepts of forced low-level convergence, mid-level uplift and iterative northeastward propagation of convective cells. Simulated and observed peak levels of Lago Maggiore differ by 2 m, possibly because the exact cross-section of the lake outflow is unknown. The extreme response of Lago Maggiore cannot be attributed to low forest cover. Nevertheless, such a paradigm was adopted by policy makers following the 1868 flood, and used to implement nationwide afforestation policies and hydraulic structures.

These findings illustrate the potential of high-resolution, hydro-meteorological models – strongly supported by historical methods – to shed new light on weather events and their socio-economic implications in the 19th century.

Citation: Stucki, P., Bandhauer, M., Heikkilä, U., Rössler, O., Zappa, M., Pfister, L., Salvisberg, M., Froidevaux, P., Martius, O., Panziera, L., and Brönnimann, S.: Reconstruction and simulation of an extreme flood event in the Lago Maggiore catchment in 1868, Nat. Hazards Earth Syst. Sci. Discuss., https://doi.org/10.5194/nhess-2018-134, in review, 2018.
Peter Stucki et al.
Peter Stucki et al.
Peter Stucki et al.

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Short summary
A catastrophic flood south of the Alps in 1868 is assessed using documentaries, a reanalysis, and the earliest high-resolution weather simulation so far. Simulated weather dynamics agree well with observations and damage reports, while simulated peak water levels are biased. No flood-causing effect by low forest cover is found, but such a paradigm was used to implement afforestation. The simulations – supported by historical methods – have potential to shed new light on long past weather events.
A catastrophic flood south of the Alps in 1868 is assessed using documentaries, a reanalysis,...
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