Natural Disaster Prevention: Surface Runoff Hazard Map Updated
Since its publication in 2018, the Surface Runoff Hazard Map (GOA) has become one of the most important tools for preventing natural hazards. It supports cantonal building insurance companies as well as the private insurance sector and also serves as a planning tool for flood protection projects and urban drainage systems. Based on new data sources and improved modeling capabilities, the map is currently undergoing a comprehensive update and will be released in a new version in early 2027.
Over the past few decades, property damage caused by natural hazards has more than doubled. Floods account for a significant portion of the total damage. Rising insurance coverage amounts, changing building vulnerability, and increasing soil sealing are major factors contributing to the rise in building damage. More than half of all flood damage is not caused by overflowing rivers, streams, and lakes, but rather by surface runoff.
To reduce or even prevent damage caused by flooding, buildings should be constructed and maintained to be as weather-resistant and damage-resistant as possible. However, it is first necessary to understand the risk posed by surface runoff in order to implement protective measures.
A Key Tool for Preventing Flood Damage
The GOA shows potential runoff paths and flood-prone areas throughout Switzerland in the event of heavy rainfall. Since its publication in 2018, it has become an indispensable tool for flood prevention. The hazard map thus fills an important gap in this area.
New data sources enable a comprehensive update
The surface runoff hazard map was created in 2018 based on the information and technologies available at that time. Since then, the data sources for precipitation, the terrain model, and land cover, as well as the methodology for modeling surface runoff, have improved—partly due to the steadily increasing computing power of computers. For this reason, the hazard map is being re-modeled and updated this year. It will be available free of charge in early 2027 and will replace the previous surface runoff hazard map. The project is once again being implemented as a collaboration between the Federal Office for the Environment (FOEN), the Swiss Insurance Association (SVV), and the Association of Cantonal Building Insurance Companies (VKG), and is funded by the SVV and the VKG.
When it comes to natural hazard prevention, raising public awareness is crucial. The update to the hazard map is therefore accompanied by a series of short videos. These videos explain surface runoff and the hazard map, and provide information about the risks to buildings. The videos will be released in stages and are available on a landing page created specifically for surface runoff on the «Protection Against Natural Hazards» information platform.
www.schutz-vor-naturgefahren.ch/goa
