Moderate damage, but five deaths in severe weather events 2012


Felssturz Gurtnellen 2012

The tracks of the Gotthard railway line in Gurtnellen (Canton Uri) were buried on several occasions during 2012 (click for large version).
Photo: Marc Hauser, SBB
 
Felssturz Gurtnellen 2012
Photo: Marc Hauser, SBB

The tracks of the Gotthard railway line in Gurtnellen (Canton Uri) were buried on several occasions during 2012 (click for large version).
 
Unwetterschäden 2012

Location and magnitude of significant losses in 2012. The symbols also indicate the type of process (map courtesy of BFS GEOSTAT / Federal Office of Topography; click for large version).
Artwork: WSL
 
Unwetterschäden 1972-2012

Change in total annual losses arising from natural events from 1972 to 2012 (adjusted for inflation, basis 2011; click for large version).
Chart: WSL
 
Unwetterschäden nach Ursachen
Portions of total costs attributable to individual causes of damage in 2012. (click for large version).
Chart: WSL
 
Unwetterschäden nach Prozessen
Portions of total costs attributable to individual damage processes in 2012. (click for lartge version).
Chart: WSL
 
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Landslides, debris flows, floods and rockfalls gave rise to property damage in Switzerland of almost 40 million Swiss Francs in 2012 – much less than the long-term average figure for the period 1972-2011. The greatest losses were caused by floods and debris flows and the three rockfall events that buried the railway line in Gurtnellen (Canton Uri). Each of the five deaths in 2012 is attributable to rockfall. These findings are revealed by an analysis of the national storm damage database that is maintained by the Swiss Federal Institute for Forest, Snow and Landscape Research WSL.

Floods and debris flows, which gave rise to estimated losses of 28 million Francs, were the most costly storm damage events in 2012. The largest portion of these costs is attributable to the floods in the second half of the year. The relatively high proportion of losses (estimated at 10 million Francs) compared with other years, due to rockfall events, is primarily attributable to the events in Gurtnellen (Canton Uri). Rock and soil masses buried the tracks of the Gotthard railway line on several occasions during the year (on March 7, June 5 and November 14). The event in June, which occurred while slope stabilisation works were being performed there, resulted in the death of one construction worker and serious injuries to two others. An event in the same district in 2006 had caused losses on a similar scale when several rocks crashed onto the autobahn and buried two people.

Gurtnellen was not the only place to be affected rockfall events in 2012. On May 15 a massive rockfall in Preonzo (Canton Ticino) caused relatively little damage, measured against its size. In Tschlin (Canton Grisons), rocks buried a coach (not carrying any passengers) and a car on March 30. Regrettably, the accident cost the coach driver his life. And three people were killed by rockfalls in St Gingolph (Valais) and below the Säntis (Hundwil in Canton Appenzell Ausserrhoden). "Although this figure is higher than the annual average number of deaths arising from rockfall, which we have been recording since 2002, it does not indicate a trend. The elevated total simply reflects the occurrence of several natural events with tragic consequences," comments Norina Andres of the Swiss Federal Research Institute WSL.

Basements and roads flooded by precipitation

Around 40% of all property damage arising in 2012 was triggered by heavy thunderstorms. On July 28, for example, torrential rainfall flooded basements and roads in Frenkendorf, Füllinsdorf and Giebenach (Canton Basel-Landschaft). Strong thunder showers damaged more than 100 buildings in Bomatt and Zollbrück (Canton Bern) on August 20. Around 30% of the total losses were prompted by continuous rain. On October 9 and 10, for instance, flooding in Cantons Aargau, Basel-Landschaft, Lucerne, Schwyz and Zurich inundated hundreds of basements and numerous roads. On November 10, large quantities of rain fell in Canton Waadt in particular and caused property damage in the amount of more than four million Francs.

With regards to property damage, in the amount of around 40 million Francs, 2012 can be considered a low-loss year; the long-term average (1972-2011), adjusted for inflation, stands at about 329 million Swiss Francs. The events in 2012 gave rise to just one-eightieth of the losses incurred in 2005, when the Bernese Oberland, Central Switzerland and Prättigau were affected by serious flooding.

Original article

Andres, N., Badoux, A., Hegg, C. (2013): Unwetterschäden in der Schweiz im Jahre 2012. Rutschungen, Murgänge, Hochwasser und Sturzereignisse. Wasser Energie Luft, 105. Jg., Heft 1: 55-61. (PDF, 1.1 MB)

The Swiss Federal Research Institute WSL has been systematically recording storm damage data since 1972. Created in collaboration with the National Environmental Agency (BAFU), the database contains information on the losses caused by flooding, debris flows and landslides and, since 2002, rockfalls. The analyses disregard losses arising from avalanches, snow pressure, earthquakes, lightning strikes, hail and storm force winds. Deaths occurring in connection with high-risk sports (such as canyoning) are likewise omitted from the database. The losses are estimated primarily on the basis of media reports. The data are made available to experts on request and play a fundamental role in risk assessment.

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