1. Flooding of 2000

In October 2000, several days of persistent heavy rain in the cantons of Valais and Ticino not only caused landslips and mudslides but also created a precarious situation along mountain torrents, rivers and lakes.

The floods took a heavy toll, with 16 fatalities. A third of the village of Gondo (Valais) was devastated by water, earth and rocks. The Lago Maggiore exceeded the record levels of 1993 by 34 cm. The extent of the destruction was also immense, with losses of CHF 670 million. The damage was exacerbated by debris flows and landslides. The rainfall could have proved even more catastrophic, but a greater disaster was averted largely thanks to the measures initiated following the storms of 1993.

2. Flooding of 1999

In May 1999, Switzerland suffered a third episode of catastrophic flooding, not long after the floods of 1987 and 1993. After an exceptional winter marked by heavy snowfall, concerns were voiced at the end of February that 1999 could be a year of major floods, since "yesterday's" snow is "tomorrow's" runoff. These fears were realized in May, when heavy rainfall coincided with the main snowmelt period.

Increased flood risk situations may recur. In order to quantify the interaction between the precipitation event (predictable only a short time in advance) and the effects of snowmelt (known over a longer period), and to draw lessons for comparable situations that might arise in the future, what was then the Federal Office for Water and Geology studied and documented the floods of 1999 in detail. The results were published in two reports:

3. Flooding of 1993

Persistent heavy rain from 22 to 24 September 1993 in the southern side-valleys of the Upper Valais region and in Canton Ticino marked the beginning of a series of floods, some of which had devastating effects. The areas most seriously affected in Canton Valais were the town of Brig and the Saas valley. Further heavy rainfall continuing until mid-October led to the flooding of settlements around Lago Maggiore in the Ticino, with major damage in numerous side-valleys, especially in the Blenio valley.

4. Flooding of 1987

1987 was a year of natural disasters, with almost the whole of Switzerland being affected by storms. The spring already brought widespread flood damage, and persistent rainfall in June triggered landslides, with many rivers and streams in full flood. Following violent storms at the start of July, the year's worst natural disaster began on 18/19 of that month. Torrential rain wreaked havoc, particularly in the cantons of Ticino and Graubünden. On 24/25 August, a comparable weather situation led to extreme rainfall in the St. Gotthard region and caused devastation in the cantons of Uri, Valais, Ticino and Graubünden.