Surface Runoff Hazard Map
The map shows where there is potential risk from surface runoff. It covers the whole of Switzerland, including both populated and unpopulated regions, and is publicly available online.
Surface Runoff Flood Areas
FOEN Web GIS Full-screen version of the map and additional layers on natural hazards
The flood-prone areas shown on the surface runoff hazard map have been mapped across the whole of Switzerland using a uniform methodology. They are based on scientifically sound modelling without on-site plausibility check. The surface runoff hazard map provides a general overview and identifies areas that may potentially be affected during rare to very rare events. The estimated return period is greater than 100 years, meaning that, over the long term, such an event occurs, on average, less frequently than once every 100 years. It cannot be ruled out that surface runoff may also occur in areas that appear unaffected on the map. An on-site plausibility check is required when planning specific protection measures.
Areas affected by flooding from rivers and lakes are not shown on the map. Furthermore, protection structures, road underpasses and, for example, culverts through railway embankments are ignored. The map has no legal binding force.
Publication Rainwater in Urban Areas
As a result of climate change, heavy rainfall events are becoming more intense and frequent. In urban areas, where infill development often leads to additional impervious surfaces, the risk of flooding caused by surface runoff following heavy rainfall is therefore increasing. In climate-adapted and risk-based urban development, the sustainable management of rainwater as a resource is becoming increasingly important.
The following publication (only in german, french and italian) is available on rainwater in urban areas: