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Flood Debris flow Landslide |
The extensive rainfall on 7 and 8 August 1987 caused great damage in the canton Ticino and in the catchment of the river Thur. In the canton of Ticino nine casualties and several injuries have been recorded. Great damage occurred in settlements, along traffic infrastructure and in agricultural and forested areas. The municipalities of Ascona and Losone were especially affected due to outbreaks of the streams Melezza and Maggia that led to flood devastation (Zeller et al. 1979).
On the 18 and 19 July 1987, intensive rainfall with a duration of over 30 hours led to river and stream outbursts, debris flows, inundations and landslides in the cantons of Graubünden and Ticino. Settlements were cut off from the outside world and traffic infrastructure was blocked. Four persons lost their lives and hundreds had to be evacuated. In Poschiavo the center of the village was totally destroyed by a debris flow. In the valley Blenio high damage was caused by the outburst of the Brenno river and its lateral torrents (Zeller et al. 1988).
On 24 and 25 August of 1987, roughly one month after the devastating events in Graubünden and Ticino, especially the Alpine region was badly affected. Erosion along the river Reuss caused the bursting of dams and the undercutting of roads. Large areas in the lower flatland of the Reuss remained inundated. Debris flows caused high damage e.g. in the village Münster in the canton Valais. In the canton Ticino especially traffic infrastructure was affected (Zeller et al. 1988).
Long lasting rainfall over the cantons of Valais and Ticino caused floods on the 24 September. In Brig, bedload clogged a bridge over the Saltina river, whereupon parts of the town with a lot of buildings were covered with material several meters high. Two persons died in Brig during this flood event (Röthlisberger 1994).
Extensive rainfall in May 1999 combine with snowmelt caused two consecutive flood events (11-15 and 20-22 May), which especially affected areas along lakes and large rivers in the Swiss Plateau, like e.g. Bern and Thun (both canton of Berne). Flooding occurred in almost all large lakes of Switzerland situated north of the Alps, and the rivers exiting the lakes were proportionally more effected (General Hegg et al. 2000).
Especially the southern side of the Alps was affected by the long lasting rainfall of 13-15 October 2000. The extreme high water-level of Lago Maggiore in the canton of Ticino caused substantial damage especially in the city of Locarno. Erosion, landslides and debris flows caused very large damage in the entire canton Valais. During this event 16 persons lost their lives, 13 thereof in the village Gondo in the canton of Valais (Hegg et al. 2001).
The flood event of 21-22 August 2005 was the most costly event since the beginning of the systematic data collection in 1972. Damage was caused along the large rivers in the Swiss Plateau, in the Prealps and in central Switzerland. The heavy rainfall that caused six fatalities and led to large-scale inundations, debris flows, landslides, hillslope debris flows (Hilker et al. 2007).
Long lasting rainfall caused the exceedance of the capacity of the Jura lakes and the river Aare on 8 and 9 August. Overflowing streams severely damaged villages in the cantons Aargau, Solothurn, Basel-Landschaft, Bern and Vaud (Hilker et al. 2008).
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