10 years after 2005: “We have made major gains in terms of safety”

Around ten years ago, torrential rain fell over the Alpine region. Torrents and lakes breached their banks and entire mountain slopes slid. It was by far the most expensive storm of the last 100 years. Would we be better equipped to deal with such an event today? environment asked Hans Peter Willi, head of the Hazard Prevention Division at the FOEN, this very question.

Hans Peter Willi
Hans Peter Willi is a hydraulic engineer. Following his studies at the ETH Zurich, he initially worked in the private sector. In 1982 he became a project manager at the Office for Water Protection and Hydraulic Engineering of the Canton of Zurich. He then held the position of Director of the Water Risks Section of the Federal Office for Water and Geology (BWG) for 18 years. He has been head of the Hazard Prevention Division at the FOEN since 2006.
© Christine Baerlocher, Ex-press/FOEN

Interview: Hansjakob Baumgartner

environment: Mr Willi, the storm of August 2005 claimed six lives in Switzerland and the damage caused totalled around 2.9 billion euro. What are the insights that emerged from the event analysis that was subsequently carried out?

Hans Peter Willi: It confirmed what we had already learned from the floods of 1987: extreme weather events that exceed the capacity of our protective structures will always happen. The hazard statistics show that most of the damage arising from natural hazards is caused by events like this which exceed the overload capacity of the hazard protection structures. To manage such events, we need the integrated risk management of natural hazards, which incorporates all action options in addition to structural measures. These options have not been availed of sufficiently up to now for the simple reason that the necessary hazard information and organisational structures were lacking.

What kind of action options are available to us?

We can improve our emergency planning. Major progress has been made in this area in recent years. In some cantons every commune has its own emergency plan that builds on the hazard maps.

Together with the cantons, the federal authorities provide support for the training of local natural hazard consultants. They can correctly assess the local hazard situation and support management and emergency staff with their knowledge in the case of a hazard event.

With regard to existing buildings, owners can invest in protective measures, adapt the way they use their buildings or even give them up if the risks are too high. With new buildings, construction in areas at risk from natural hazards should be avoided or should be carried out in such a way that unacceptable risks do not arise. We can also ensure that the flow of water is controlled if overload capacity is exceeded.

How is that done?

During extreme flood events, areas in which the flowing water and bedload would cause least damage, are flooded using integrated safety relief valves. On the river Engelberger Aa, the airfield, sport fields and lake bathing area form a flood relief corridor before the river enters Lake Lucerne. This mechanism worked very well in 2005 and the inhabited area of Buochs was protected from the flood.

Reliable hazard information is essential for all of this, however. In this regard too, we have made great progress today as compared with 2005.

To what extent?

Hazard maps for floods, avalanches, rockfall and landslides are now available for almost all built-up areas in Switzerland. So we are much better informed about what can happen where.

The event analysis report of 2005 also states that: “Far from all of those affected by the floods were sufficiently informed to be able to act in good time under their own initiative and within the scope of the possible measures.” Would this be different today?

Yes, efforts have been made since then to improve warning and alerting –for both the emergency services and the population. A large number of actors co-operated intensively on this with the FOEN: Federal Office for Meteorology and Climatology MeteoSwiss, the Federal Office for Civil Protection’s (FOCP) National Emergency Operations Centre (NEOC), the Swiss Federal Institute for Forest Snow and Landscape Research (WSL) and its affiliated WSL Institute for Snow and Avalanche Research (SLF), and the Swiss Seismological Service (SED). Thanks to the considerable efforts on the part of all stakeholders, we are far more quickly informed than we were ten years ago.

For example, experts on all levels have online access to weather and precipitation forecasts and all measurement stations through the Common Information Platform for Natural Hazards (GIN). Thanks to the website www.naturgefahren.ch, the public can also obtain information about current hazard situations at all times.

We are well on the way. However, we must ensure that the financial resources required for these structures and services, are also available in the future.

Extreme weather events had to be managed again in 2014. What did the rainy summer that year teach us?

It simply showed that storms are part of nature. Nature has its sunny and dark sides and we have to live with them. During the rainy summer of 2014, very long periods of rain gave rise to numerous landslides. These processes still present a challenge for us. We need to be able to identify the point at which landslides become really critical. On the other hand, some of the measures implemented since 2005 proved their worth. We have made clear gains in terms of safety but there is still room for improvement.

What do you have in mind here?

For example, the optimum management of the reservoir lakes in the Alpine region. Instead of continuing to operate the turbines when the flood wave comes, volume should be made available by lowering the water level in advance. This measure is already implemented today on the Mattmark reservoir lake in Valais. A permanently available storage volume reduces the flood risk for the river Visp. On Lake Sihl, upstream of Zurich, the volume is increased through advanced lowering to provide better protection for the city of Zurich.

Based on a parliamentary dispatch, the FOEN was commissioned to compile a report on natural hazards in Switzerland. What are its main findings?

The report shows where we stand today and where action is required for the implementation of integrated risk management. One task that lies ahead is the completion of the hazard information documents. For example, the comprehensive data for surface runoff, which accounts for a major proportion of the damage caused, are lacking. With respect to climate change, we must monitor the different processes in greater detail: the thawing of the permafrost in the Alps, the bedload being released as a result and the corresponding ground motion. What we need to do here is to identify problem areas in good time through systematic monitoring.

What is the role of the protection forest?

The protection forest is very important in Switzerland and, as a part of the infrastructure, it is a component of integrated risk management. Almost half of Swiss forests protect built-up areas and infrastructure and roads and railways. It is far cheaper to maintain protection forests than to build protective structures.

And what needs to be done for the rest of the protective infrastructure?

Maintaining and guaranteeing the functionality of our hazard protection structures is a permanent task. We must think and act in terms of life cycles today and a backlog already exists. The structures themselves must be robust enough to withstand events that exceed their maximum load. Experience shows that, otherwise, major damage may be expected. We must check the design of the protective structures and, if necessary, adapt, supplement and update them. An inventory of the relevant protective structures is currently being compiled.

New protective structures should be constructed in such a way that they are adaptable. This is a key concern. Nothing is more stupid than building structures that have to be demolished and replaced when the requirements change. Today’s solutions must not become tomorrow’s problem. Future generations must also have options open to them. This also necessitates a degree of generosity in terms of the space provided for water bodies.

You have hit on a controversial topic here. Opposition to the legally prescribed minimum space for water bodies exists among farmers who have to give up their already scarce arable land for it.

The additional space is needed not only in the context of flood protection. Water bodies must also be able to fulfil their functions as habitats, connective elements and recreational areas. Providing the necessary space for this is clearly a challenge, but I am convinced that win-win solutions with agriculture can even be found here.


Farmers themselves need the water bodies both to take up water from drained areas and to irrigate their crops. And in many cases it is they who ensure their maintenance. In doing this they provide a service in the interest of all of society. Rehabilitated water bodies also require care and maintenance. This work should be fairly remunerated so that the loss of land does not involve any loss of income. We also provide financial support for protection forest maintenance.

We must not forget that our ancestors reclaimed huge areas from the water bodies in the valley plains. Between two and three percent of this land should now be returned to the water bodies. This answers the question regarding proportionality. It is important that cases of hardship are alleviated using appropriate measures.

Another field of action is, of course, the consideration of hazard information in spatial planning. What happens with the people who already live in red zones where there is a fundamental ban on construction?

A red zone merely indicates: ‘Attention, people in buildings risk losing their lives due to natural events’. It is necessary to check whether it is still acceptable to allow people to live there. There may be options for keeping the risk at an acceptable level. However, there will be cases, in which we must decide that demolition is the only option.

An example of this is the commune of Weggis on Lake Lucerne. Due to the rockfall potential which cannot be controlled at a reasonable cost, five regular homes and holiday homes were demolished. The owners were compensated for the value of the houses but not for the loss of the land. Other cases, for which fair solutions will have to be found, will also arise.

And what can people, who live in a blue zone where building is only allowed in future under certain conditions, do to ensure the safety of their belongings?

The owners of existing buildings have the option of providing better protection with the help of structural measures. Some cantonal buildings insurance companies already offer to co-finance such property protection measures. More could be done here. For example, a natural hazards renovation programme similar to the energy-related buildings renovation programme could be developed. However, financing such a programme would be a major challenge.

And for new buildings?

With regard to new buildings, we have to reach a stage whereby the natural hazard situation is taken into account in all building and planning processes. All building projects should be hazard-appropriate – irrespective of the hazard zone category in which they are constructed. This is also applicable, not least, to earthquake safety.

Overall, managing natural hazards is a joint task, for which many actors bear responsibility: from the cantons, communes and business sector to the potential victims. They all have their tasks and responsibilities. The state monitors weather developments constantly, makes hazard documentation available, provides information, issues warnings – where possible in good time – and also guarantees a certain level of area protection. However, individual citizens must also take responsibility on a personal level. We are working at all levels to make society less vulnerable to natural hazards and to improve the knowledge available about the associated risks.

Integrated risk management

Integrated risk management takes all natural hazards into account, involves all actors and includes all three dimensions of sustainability – ecology, economy, society. It combines measures for preparedness for natural hazard events, the response to them and recovery from them. Comprehensive hazard and risk information and documentation is at the heart of this process.

The targeted level of safety is the product of an ongoing risk dialogue with all stakeholders. Difficult questions must not be excluded from this process: What level of safety can be attained at what price? What level of residual risk must be accepted? How much are we willing to invest to avoid a fatality within a certain period of time?

The price of safety

Approximately 2.8 billion euro is spent on natural hazard risk management in Switzerland every year. Of this, 1.6 billion euro is raised by private individuals, of which 830 million is covered by insurance companies. These costs are counterbalanced by enormous benefits. These are generally difficult to quantify as avoided costs do not show up on any balance sheet. However, they can be estimated in some cases. For example, 25 million euro was invested in the structural measures for the protection of the commune of Buochs on Lake Lucerne against flooding of the river Engelberger Aa. During the first subsequent flood event of 2005, this investment prevented damage to the tune of 150 million euro.

It is impossible for us to imagine how Switzerland would look without natural hazard prevention. Large parts of the country located in the mountain region and river valleys, would be uninhabitable due to the lack of safety.

Further information

Last modification 20.05.2015

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