Natural hazards: In brief

Switzerland has learned from past natural events. It exerts a great deal of effort to manage natural hazards. Nevertheless, maintenance and improvement remain ongoing tasks. New challenges are emerging as climate change and the increasing density of use are raising the risks. Costly protection structures alone cannot prevent damage. For this reason, spatial planning measures and cooperation between the public and private sectors are gaining in importance.

1. Hazard processes and how they are changing (drivers)

Switzerland is often affected by floods, debris flows, landslides, fall processes (rockfall and rock avalanches), avalanches and storms. Strong earthquakes are rare; yet, as history shows, they can arise in Switzerland, too, and pose a non-negligible risk. Forest fires can also occur in Switzerland.

The impacts of climate change are expected to lead to an increased danger due to natural events in Switzerland and to a rise in extreme events. More frequent flooding can be expected in winter and spring. Landslides, fall processes and debris flows will also become more common in the future. One reason for this is the thawing of the permafrost and the associated destabilisation of rock faces and slopes consisting of loose rocks. Natural hazards will also increase in areas and at times of the year that were previously spared such damaging events.

2. Land use and hazard situation (pressures)

To enable an adequate response to natural hazards, the danger they pose must be known. Different types of hazard documentation provide such information. A key example of such documentation, hazard maps indicate the locations in Switzerland where built-up areas and transport routes are threatened by natural hazards, the extent of the associated dangers, and their probability of occurrence. In early 2017, hazard maps were available for almost the entire country. However, only 73% have been implemented in communal land-use plans.

Natural drainage corridors for extreme events have been secured through spatial planning only in isolated cases. In 2018, the Confederation worked with insurance partners to develop the national "surface run-off hazard map", which enables hazards to be identified at an early stage, protective measures to be taken and damage reduced.

Natural events only become hazards if they affect people, buildings or infrastructure. Due to the intensification of land use and its expansion into potentially endangered areas, the possible damage is constantly increasing. Thus, information about land use is another important basis for integrated risk management for the protection of people and material assets against natural hazards.

3. Risks (state)

Risk is generally understood as the possibility that damage could arise as a result of a particular event. Risks can be identified and assessed and thus act as a yardstick for safety.

The risk resulting from natural hazards has increased in recent decades. The main reason for this is the greater potential for damage resulting from the growth of the population, the expansion of settlement areas into threatened regions and the increase in value of public infrastructures and private material assets. Approximately 20% of the Swiss population lives in areas that can be affected by floods. Moreover, around 30% of jobs and one-fourth of material assets, i.e. CHF 840 billion, are located in these areas. The percentage of the affected resident population varies greatly from canton to canton.

Great emphasis will be placed on the compilation of risk overviews in the years to come as it is only possible to reduce existing risks to an acceptable level, contain future risks and prioritise protective measures if these risks are known. The risk can be managed sustainably primarily through land use and spatial planning.

4. Damage and lessons to be learnt (impacts)

Switzerland has been the scene of natural disasters since time immemorial.

Natural events can also claim lives and cause extensive damage to the environment and material assets today. Despite the considerable improvement in the protection provided against natural hazards, the risk of natural hazards is constantly increasing due to the intensification of land use and the growing frequency of extreme events and will continue to increase unless the trend is monitored, evaluated and controlled in an aware and forward-thinking manner.

Between 1972 and 2017, the cost of the average damage caused by floods, debris flows and fall processes in Switzerland was around CHF 305 million per year. Flood-related damage was primarily the result of major events: for example, the flood of August 2005 alone caused damage totalling CHF 3 billion and claimed the lives of six people.

Extraordinary events provide an opportunity for studying their causes and impacts and to learn from them. Thus it is possible to identify gaps in the hazard documentation and test the effectiveness of existing protective measures. Event analyses provide new insights and indicate the lessons to be learnt for the future implementation of measures for dealing with natural hazards. Thus they provide an important basis for the optimisation of integrated risk management.

5. Dealing with natural hazards (responses)

Today, natural hazard protection is based on the principles of integrated risk management set out in the PLANAT strategy “Management of risks from natural hazards". Using an optimal combination of different protective measures, existing risks are reduced to an acceptable level, and unacceptable new risks are prevented. The “Adaptation to Climate Change” action plan also serves as a basis for natural hazard management. The federal report entitled “Management of Natural Hazards in Switzerland” also outlines the current situation in Switzerland and future action required in order to provide security.

The threat posed by natural hazards can best be counteracted through spatial planning measures or risk-based spatial planning. The insights from hazard mapping must be integrated into the cantonal structure plans and communal land-use plans as quickly as possible so that threatened areas can be used in a hazard-appropriate way or kept free from use.

In cases where this is not possible, technical, biological or organisational measures are implemented to avert the danger or reduce the damage. Minimising the vulnerability of buildings and facilities (protection of property) and robust adaptable protective measures that can withstand cases of overload are very important in this context. The existing protective effect should be guaranteed in the long term through proper maintenance and upkeep of water bodies, protective forests and protective structures.

The permanent monitoring of hazard processes must ensure that both imminent dangers and general changes in the hazard situation can be identified precociously. Damage can be reduced through timely warning, alerting and information in the case of a hazard event.

The protective measures implemented in recent years have proved effective in many locations. Projects for eliminating known priority protection deficits are co-financed by the federal authorities in the context of the programme agreements or through single projects.

Protection against natural hazards is a joint task, to which all participants must contribute:

  • In Switzerland, the communes and cantons are primarily responsible for protection against natural hazards.
  • The federal authorities adopt a strategic leadership role and provide financial and expert support to the cantons.
  • The population assumes its individual responsibility for the protection of personal property (property protection) and personal safety (adapted behaviour in the case of a hazard event)
  • The insurance companies provide insurance against potential damage by natural forces.

The only way to reduce damage during earthquakes is to build earthquake-resistant new buildings and to implement measures aimed specifically at improving the earthquake safety of existing buildings by ensuring consistent application of the relevant standards. Insurance against earthquake damage exists only on a voluntary basis. Since 2001, the federal government has coordinated its activities in the area of earthquake preparedness as part of a programme of measures.

Further information

Last modification 30.11.2018

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