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UPDATE: How Switzerland’s flood planning helped it avoid disaster

UPDATE: How Switzerland's flood planning helped it avoid disaster
A woman walks past a car in a flooded waterway in the Swiss town of Lyss, near Bern, in 2007. Unlike the 2005 and 2007 floods, Switzerland was spared the wrath of the 2021 floods. Photo: FABRICE COFFRINI / AFP
Despite geographical proximity and similar topography, Switzerland suffered less damage from recent floods than its northern neighbour. This is why.

After days of unrelenting torrential rain over the past two weeks, water levels in many Swiss lakes and rivers are slowly dropping.

In the the worst flooding in more than a decade, banks on Lake Zurich broke, while levels on Lakes Lucerne, Biel and Thun rose dangerously high.

READ MORE: Weather update: Lake Zurich bursts banks, Lucerne preparing for flooding

But even though some areas of the country were flooded, the damage was far less significant than during the Swiss floods of 2005 and 2007. 

In 2021, Switzerland suffered no weather-related casualties — unlike western Germany, where at least 175 people were found dead as of July 29th. 

Dozens of people also died in Belgium, bringing the total in Western Europe to over 200. 

As both Germany and Switzerland have similar topography experienced similar weather, why was Switzerland affected less than its neighbour?

Why did Switzerland escape the worst of the floods?

Despite some amateur weathermen and women pointing out that Switzerland is in the alps and is therefore upstream, things are a little more complicated than that. 

Anyone who’s lived in Switzerland for more than a couple of years would know how prevalent flooding can be. 

The major reasons for Switzerland’s success was a combination of flood preparation – and sheer luck with the weather. 

Experts say the intensity of rain and the volume of water dumped on both nations made a huge difference.

Switzerland has spent heavily in recent years – and in particular since 2005 – to protect from catastrophic flooding events. 

Despite fields, cellars, basements and train stations being under water, “flood protection has proven itself”, Adrian Schertenleib, head of the flood protection section at the Federal Office for the Environment, told 20 Minutes

A major part of that was the strategic draining of the lakes. 

“After the heavy rainfall from June 20th, the way the population was alerted worked perfectly. From July 7th, when the rain was so prolonged, the regulation of the lakes – for example at Lake Thun or the three Jura lakes – worked very well.

“And most importantly there were no injuries.”

READ MORE: Switzerland drains lakes ahead of predicted weekend rainfall

Schertenleib said Switzerland had accounted for the risks “through the optimal combination of measures: structural-technical, spatial planning, organisational, but also biological.”

Andri Bryner, a trained hydrologist, told 20 Minutes that Switzerland had successfully sought to “build with nature, rather than against it”. 

Giving the example of the Suhre in Aargau and Lucerne, Bryner pointed out how Switzerland adopted an innovative flood prevention method which focused on allowing the river more space in case of floods rather than building barriers. 

“If water is directed through a narrow channel, then it flows faster, has more power and rises higher. If the channel is wider, the water will flow more slowly and rise less,” he said.

“That means: dams or walls have to be less high and less strong and it still works.”

The grassed area where the Aare, Reuss and Limmat rivers meet had been an agricultural area which was regularly flooded, with crops continually failing in the region. 

Bryner said rather than attempting to divert the water around or find other means to stop the flow, the land had been converted to grazing land for cattle. 

Another important factor was simply that Switzerland experienced less rainfall than Germany. 

Switzerland’s Tages Anzeiger noted that the situations in Switzerland and Germany were less comparable, with Switzerland’s flood disaster of 2005 closer to what Germany has experienced in the past two weeks. 

“In Switzerland, the cumulative amount of water over the last two days of rain was 50 to 70 millimetres, while in Germany about 160 millimetres fell over the same period —two to three times more”, hydraulic engineer Philippe Heller told RTS public broadcaster.

Levels similar to those in western Germany were measured in Ticino, which was lashed by 200 millimetres of rain.

However, this kind of precipitation is more common on the southern side of the Alps because of the region’s proximity to the Mediterranean, according to Yves Karrer from the Federal Office of  Meteorology and Climatology.

“The natural rivers are adapted to such quantities. In Germany, on the other hand, it was probably the event of the century”, he said in an interview with Tages-Anzeiger.

In 2005, floods in Switzerland caused major damage. Photo by BRUNO FERRANDEZ / AFP

“The fact that the damage is much smaller now than it was then is a consequence of the measures taken. The federal government and the cantons have invested 4.5 billion francs in flood protection since the 2005 floods”.

READ MORE: Climate change: Glacial melt in Switzerland has created 1,000 new lakes


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