Bern has learned its lessons from past floods: flood damage can be limited by improved emergency response planning, warnings and intervention. However, a residual risk remains.
Text: Selma Junele
On screen, we watch as a thick, grey-black sludge containing branches and entire tree trunks collects in front of the Schwellenmätteli restaurant. Franz Märki, Head of Communications at Bern’s municipal fire service, is showing us video footage from the night of 7 June 2015. At the time, the River Aare was already carrying a large volume of water, with around 350 m3 flowing out of Lake Thun per second. That is still below the critical 400 m3 that would cause the Aare to burst its banks in Bern (if no other measures were taken), but the calculation does not include the River Zulg, which joins the Aare northwest of Thun. For a short while, this river was flowing at a rate of 230 m3 per second – and carrying a large amount of driftwood.
The driftwood collected in the Tych, a canal in Bern’s central Matte district that supplies water to the Matte power station. It blocked the river flow and caused the water levels to rise dramatically – until the two weir elements were removed by a mobile crane. Then the mass of driftwood slowly started to move away and the situation was resolved within minutes.
A delicate decision
Unlike in a classic flood situation, which often develops over days, in the case of the Zulg, the authorities have only two hours in which to respond: that is how long the flood waters take to reach Bern. In this short time, they have to fetch the mobile crane and assemble it, and the situation upstream has to be carefully monitored because the decision to remove the weir elements is a delicate one. Once they have been removed, they can only be reinstalled when the water level is extremely low, which often means waiting until the following winter. And without the weir elements, the Matte power station can not produce electricity. This means that in an emergency, the fire service’s emergency response officer has to weigh up electricity production against flood protection – and only remove the weir elements if other measures, such as fishing the driftwood out of the water piece by piece, are not effective enough.
The fact that the night of 7 June 2015 ended well is no coincidence. It is a consequence of lessons learned from the floods of 1999 and 2005. In the event analyses, the city identified the weak points in each case and then developed emergency response documents that define very precisely for each situation, which measures are to be taken and who is responsible for what. For “flooding with driftwood” events, the weir system in Matte was identified as a weak point.
Another weak point was found during the event analysis conducted by the Federal Office for Civil Protection (FOCP). Commissioned by Federal Councillor Samuel Schmid following the 100-year flood of 2005, this analysis concluded that the warning and alert systems could be improved. Much has been done since then. In order to coordinate and improve their warning systems, the FOEN, the Federal Office of Meteorology and Climatology (MeteoSwiss), the FOCP, the Swiss Federal Institute for Forest, Snow and Landscape Research (WSL), the Institute for Snow and Avalanche Research (SLF) and the Swiss Seismological Service (SED) have joined forces to form the Steering Committee on Intervention in Natural Hazards (LAINAT). Following the revision of the Ordinance on Issuing Warnings and Raising the Alarm, the FOEN was given the task of issuing warnings of floods and associated landslides, as well as forest fires. Although the FOEN was already active in these areas, it had only been providing a service for the cantons. Now it has much broader responsibilities: in the event of a hazardous situation in one of these categories, the FOEN issues warnings to the cantons and the population. The monitoring networks and forecasting models that provide the basis for the warnings are being improved all the time.
Bern has also improved its warning system. Since the 2005 event, residents in at-risk districts can opt to receive an SMS text warning when there is a risk of flooding. This gives them time to clear their basements or move their cars to safety. The city of Bern uses information supplied by the federal government and the canton for its SMS warnings and flood management.
Not a “dead document”
Flood protection is a joint responsibility that requires collaboration at all three levels of government (federal, cantonal and communal). Depending on the emergency, the fire service, police and civil defence service can be mobilised. The communes face a particularly tough challenge. The natural hazard maps provide the basic information regarding potential threats. And with knowledge about the hazards comes a moral duty to prepare to tackle natural disasters. The FOEN and the FOCP are supporting the communes with a new emergency response planning guide for gravitational natural hazards. The tool, which explicitly covers floods, is due to be published in 2020. It is designed to help communes that do not yet have emergency response planning in place to optimise their disaster preparedness. The federal government also provides financial support for the cantons to take appropriate measures. Markus Müller, who works in the FOEN’s Risk Management Section, warns: “Emergency response planning must not become dead documents that lie around gathering dust.
They have to be put into practice and updated. We can learn from the experiences, which in turn leads us to make improvements to the plan and sometimes even to implement additional structural or planning measures.” Asked about the guide, Alain Sahli, head of planning and emergency response at Protection and Rescue Bern, the city’s centre of excellence for emergency services, says: “Of course, we will study it closely and check whether and where we need to adapt our emergency response documents.” He believes the standardisation work that the federal government is doing in this area is important and essential for facilitating collaboration between the various administrative bodies. It is only through standardisation that you can be sure “you’re talking about the same thing when you use the same words”, he says.
Be prepared for emergencies
In the event of a natural disaster, you must always follow the instructions of the local authorities. If necessary, you can call the emergency services on 112. In addition, you can keep informed of the situation via the radio, TV, apps and the Internet, and pay attention to warnings and alerts. Information on the current natural hazard situation can be found on the naturgefahren.ch website. Alerts, warnings and information on different hazards can be found on alertswiss.ch or the alertswiss app.
In general, there are a number of simple recommended measures you can take to prepare for a natural hazard event (see also naturgefahren.ch / Dealing with natural hazards / General recommendations for action). Specifically, you should:
- find out about the general risk potential where you live and at your place of work (the cantonal hazard maps provide details)
- keep the main emergency telephone numbers somewhere handy
- set up emergency supplies (in the event of a natural disaster, supplies of food, electricity and water cannot always be guaranteed)
- keep a medical kit at home
- check buildings at least once a year for any damage and see that antennas, solar power, satellite dishes, shutters and awnings are firmly attached, and check the stability of porches and canopies
- check what reasonable measures can be taken to protect the building against the natural hazard
- check your insurance cover and adjust it if necessary.
Last modification 03.06.2020