High water levels and flooding arising from water courses bursting their banks can be caused by lakes, streams and rivers carrying large quantities of water; runoff after heavy precipitation (rain or snow) and/or severe snow melt; or more groundwater than usual reaching the surface (e.g. springs).

High water levels in lakes usually persist for a long time, but generally have a less direct destructive effect than streams that burst their banks. These normally flow very fast and are thus capable of causing enormous damage in an extremely short time.

Meaning of danger level 1 (no or low danger)

The hazard is unlikely to disrupt traffic or cause damage.

Recommendations for action

• You can remain in the vicinity of lakes and rivers, but remain cautious at all times..

Additional information

• Rivers and streams: The discharge level remains below that of an event that occurs once every two years on average.
• Lakes: The water level is within the usual range.

Meaning of danger level 2 (moderate danger)

Localised flooding is unlikely, but may occur.

Recommendations for action

• It may be dangerous to be in the vicinity of lakes and rivers. As a precaution, maintain a safe distance.
• Keep an eye on the situation and take initial protective measures.
• Further information available at How to act during a flood.

Additional information

• It may be dangerous to be in the vicinity of lakes and rivers. As a precaution, maintain a safe distance.
• Keep an eye on the situation and take initial protective measures.

Meaning of danger level 3 (considerable danger)

Localised flooding may occur in exposed areas..

Recommendations for action

• It may be dangerous to be in the vicinity of lakes and rivers. As a precaution, maintain a safe distance.
• Keep an eye on the situation and take initial protective measures.
• Further information available at How to act during a flood.

Additional information

• Rivers and streams: The discharge level lies in the range of an event that occurs once every 10 to 30 years on average.
• Lakes: Water levels are very high, but still below the high water mark.

Meaning of danger level 4 (high danger)

Flooding may occur. Buildings and infrastructure (e.g. roads) may be affected. Traffic may be disrupted. The flooding is likely to cause damage.

Recommendations for action

• It is dangerous to be in the vicinity of rivers and streams. Keep your distance.
• Keep an eye on the situation and take initial protective measures.
• Further information available at How to act during a flood

Additional information

• Rivers and streams: The discharge level lies in the range of an event that occurs once every 30 to 100 years on average.
• Lakes: The water level is above the high water mark (less than 25cm above).

Meaning of danger level 5 (very high danger)

Widespread flooding is likely. Roads, railway lines, residential areas and industrial plants may be severely affected. Traffic is likely to be severely disrupted in some areas. The flooding is likely to cause major damage.

Recommendations for action

• It is very dangerous to be in the vicinity of rivers and streams. Keep your distance.
• Keep an eye on the situation and take initial protective measures.
• Further information available at How to act during a flood.

Additional information

• Rivers and streams: The discharge level reaches a value that occurs once every 100 years or even less frequently.
• Lakes: The water level is well above the high water mark (more than 25cm above).