Why century floods in the Alps are happening more often

Contrary to the expectation that reduced snow and meltwater would lead to fewer flood events in mountainous regions, new research suggests the opposite may be true for the Alps. A recent study indicates that what was once considered a 100-year flood event could become significantly more intense and occur with greater frequency.

The findings propose that a 100-year flood event in the future might be 5 to 15 percent more intense and could happen every 45 to 80 years. This revised understanding challenges previous assumptions about the impact of changing climate conditions on alpine hydrology.

Recent summers have served as stark reminders of the destructive power of flash floods in alpine valleys. In late June two years ago, severe thunderstorms in the Swiss cantons of Valais and Ticino caused rivers to swell rapidly, reaching levels statistically expected only once every 100 to 300 years in some areas. This was followed by widespread flooding across Central Europe in September due to prolonged rainfall, causing extensive damage, including in Austria.