Warning and alerting: When the Heavy Rains Fall

Time is money. This principle also applies to the management of storm events: the damage they cause can be reduced considerably if everyone receives timely warnings. Some aspects of this task were poorly managed during the storms of 2005. Thanks to the measures that have been taken since then through the OWARNA project, the warning and alerting system works considerably better today.

Beaver tubes
Mobile flood barriers – Beaver tubes – along the river Reuss in Lucerne.
© Beaver Schutzsysteme AG, Grosswangen

Text: Elsbeth Flüeler

2014 will go down in history as the year with no summer. This did not appear to be the case initially as the early weeks of June were warm and dry. Then the temperatures fell and the rain started. Over the entire summer, most regions of Switzerland experienced rainfall at levels ranging between 110 and 140 percent above the norm; in some places they reached as much as 200 percent. The persistent precipitation resulted in floods here and there and sometimes even landslides.

The northern foothills of the Alps were affected on several occasions. However, the damage at national level was limited. According to estimates by the Swiss Federal Institute for Forest Snow and Landscape Research (WSL), the cost of the damage arising from the events in July 2014 was just around 80 million euro.

Luck also played a role: in many cases the precipitation in the catchment areas of the already swollen watercourses decreased precisely as the situation became critical.

Event analysis 2005

The measures that had been taken after the events of August 2005 also took effect in 2014. Following this hundred year flood, the Federal Council – Switzerland's federal government – commissioned the Federal Office for Civil Protection (FOCP) to carry out an event analysis. The FOCP presented its report in 2007. “Its central message was that the authorities were better informed than the population,” said Martin Buser from FOEN’s Risk Management Section. If the population had been better informed, it would have been possible to prevent a lot of damage and suffering. The total damage sum of 2.9 billion euro would have been half a billion lower. For example, several thousand cars could have been brought to safety – this measure alone would have saved 85 million euro in damage costs.

Earlier warning and alerting

Storms, avalanches and floods always give notice of their arrival – usually days but at least hours in advance. This provides time to take safety measures – e.g. to clear cellars and ground floors, move cars, fill and distribute sand bags, and move people to safe locations – assuming, people are warned in good time. Based on the aforementioned report, the Federal Council launched the “Optimisation of Warning and Alerting in the Event of Natural Hazards” project (Optimierung von Warnung und Alarmierung bei Naturgefahren, OWARNA). The aim is to reduce the damage by 20 percent through the timely provision of information – particularly in the case of floods, by far the most common natural hazard event.

Martin Buser is director of the sub-project “Endurance and Crisis Management”. He took up his post at the FOEN on 9 August 2007. Three days later, a two-day period of heavy rainfall began. The water level in Lake Biel exceeded all values recorded since the 1960s – “as if to confirm the urgent need for OWARNA,” commented Martin Buser. The crisis management organisation and structures were defined and implementation step by step in the years that followed.

Better and stronger networks

Networks were established between the hazard authorities at federal and cantonal levels. In addition, infrastructure was created which enables action to be taken in emergency cases. Today, the FOEN has a special control room equipped with the very latest technology. The core committee meets here during major hazard events and communicates directly with the responsible federal and cantonal authorities. The chair of the committee informs the decision makers at federal level about the situation and prepares decision-making support documents for them for the timely warning of the cantonal authorities and population.

The crisis committee is supported by the federal natural hazard authorities. In addition to the FOEN, these include: the Federal Office of Meteorology and Climatology (MeteoSwiss), the Swiss Federal Institute for Forest, Snow and Landscape Research (WSL/SLF) and the Swiss Seismological Service (SED). They constantly monitor and assess the hazard situation in their specialist fields. If there is the threat of a hazard event, they consult each other in compliance with a tried-and-tested procedure and as soon as predefined criteria are fulfilled they join forces in the Special Natural Hazards Committee. The latter develops forecasts, compiles bulletins and warnings, provides recommendations for behaviour and action and issues press releases.

Common Information Platform

“The communication with all levels is guaranteed today,” says Martin Buser. The Common Information Platform for Natural Hazards (GIN) plays a key role in this process for the cantonal and communal authorities. Measurement and monitoring data on wind, water and snow can be accessed on the platform as can the Special Natural Hazards Committee’s forecasts, model calculations, warnings and bulletins.

In addition, the Special Natural Hazards Committee’s 24-hour on-call services is also available to the federal and cantonal experts and management committees. Trained management and intervention forces, supported by natural hazard consultants, are deployed at communal level. “In the event of a hazard, these people and their safety strategies can make a crucial contribution to reducing the scale of the damage caused,” explains Martin Buser.

It is understood that such a widely-based organisation requires additional staff and resources. Since 2007, 20 posts have been created for OWARNA and materials and equipment totally 6.7 million euro have been authorised. The increased investments are cost neutral says Martin Buser: “Instead of investing in protective structures, we spend more money on forecasting, information and warning today.”

More detailed information

As part of the OWARNA project, four employees were added to the staff of the FOEN’s Hydrological Forecasts Section. Therese Bürgi is Head of the section. “In 2005 there was only one person deployed per forecast shift,” she recalls. Today there are always two people on duty and even three in emergency situations. A 24-hour service is also provided at the weekend.

The FOEN also invested in the short term forecasting. The section now has data available to it from far more precipitation, water level and discharge measurement stations. The forecasting models were also refined. “The hydrological model is familiar with the status of the reservoirs, soil, groundwater and snow cover for all of Switzerland,” says Therese Bürgi. “This provides an important basis for the calculation of water level and discharge forecasts.” MeteoSwiss added a station on the Plaine Morte in the western Swiss Alps to its weather radar network and another is being constructed on the Weissfluhjoch summit above Davos.

Finally, the FOEN and affected cantons introduced a forecast regulation for the peripheral Jura lakes – Lakes Murten, Neuenburg and Biel. The possible increase in the water level in Lake Biel is calculated based on a five-day precipitation forecast for the Aare catchment area. If the calculations point to the likelihood of a significant rise in the water level, the discharge from the lake is increased. In this way, additional volume is created to accommodate the forecasted water. In contrast, if a flood is threatened on the Grosser Emme, which enters the Aare below Lake Biel, the discharge is restricted. The aim here is to enable the Aare to absorb the increased flow from the Emme without breaching its banks.

The test

The test came in June 2013. The volume of rain that fell in some regions within a 48 period only arises every ten to 20 years. In eastern Switzerland, discharge volumes were recorded that can only be expected every 50 years. The situation was reminiscent of 2005.

OWARNA passed the test. “The flow of information was exemplary. The federal organisations cooperated smoothly and efficiently,” the Steering Committee Intervention against Natural Hazards (LAINAT) stated in a report on the management of the flood events of 2013. The measures taken were effective: the population was informed about the weather developments every six hours through the media. The local emergency teams were warned and initiated the necessary measures in good time. The regulation of the peripheral Jura lakes also worked perfectly. “Because the responsible authorities (…) placed considerable emphasis on the regulation of the lakes and the prior reduction of the lake water levels, higher water levels and discharges to the Aare, Limmat and Rhine could be avoided,” stated the aforementioned report.

During the rainy summer of 2014, OWARNA was ready for action again. “Two briefings were held every day,” reports Martin Buser. The website www.naturgefahren.ch published an updated federal natural hazards bulletin almost every day. Extensive use was made of it, also in November 2014 when there were floods in Ticino.

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Last modification 20.05.2015

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