Flash floods in southern France

Topics: Dr. Kron, what makes flash floods so unpredictable and dangerous?
River flooding occurs when there is heavy rain over a large area, the rain converges in the main river and thus builds up a flood wave over a period of several days. Flash floods are entirely different. What counts here is not the amount of rain but its intensity, for example in the case of local storms. The total amount of rainfall in these cases is secondary. Within a short period of time, a stream can turn into a raging torrent or flat terrain become completely submerged. Flash floods are sudden and over quickly, usually after just a few hours.

How frequently do such events occur?
Since 1980, Munich Re has systematically documented events and processed this information so that it can be used for statistical analyses. Our research has revealed that storms resulting in floods occur much more frequently than “classic” cases of river flooding, and are likely to increase even more in the future. Typically, floods from local storms usually produce losses ranging from thousands to hundreds of thousands of euros, sometimes even in the millions. As there are literally hundreds of these events every year in Germany alone, we believe that, over a longer period of time, the large number of smaller losses from flash floods are pretty much on a par with the million-euro losses from river flooding.

For example, in June 2008, after extreme rainfall, a small stream in the Killertal in Baden-Württemberg, tore through the village of Jungingen, destroying houses and carrying off cars (in one of which two women drowned) and flooded parts of the nearby town of Hechingen, located at the foot of the Hohenzollern castle. Losses here totaled nearly €100m.

Would structural measures help combat flash flooding?
Only in certain circumstances. With river flooding, we know where the danger comes from and can build a dyke to protect ourselves. A flash flood can occur anywhere. I know an inn near Munich located at the top of a hill and it still suffered flood damage. Protection against incoming water is possible by building the ground floor a foot or so above ground level. In older buildings it is possible to seal basement windows. Generally speaking, you should try and ensure that all paved areas slope downwards away from the house so they can carry away water as easily as possible. However, even this will not guarantee you escape unscathed.

That raises the question of the most effective form of risk reduction?
This involves a whole range of measures. In terms of construction, do what you can afford. Also, do not store valuable objects or items vulnerable to water in the cellar, ask yourself whether you really need to have a carpet or parquet flooring in the basement. You must realise that you are never 100% safe from flooding. And then of course insurance. There is no way round that.

To what do you attribute the lack of risk awareness regarding flash floods?
If you live a long way from any water, the flood risk is not necessarily the first thing that springs to mind. Most people will rarely, if ever, face flood damage. But then it does hit some people and that spells disaster for them. We need to inform and convince people. So as not to reduce people’s willingness to take their own precautionary measures, it is important that suitable deductibles are agreed. This means that small claims with their relatively high administrative costs are eliminated. In this respect, I also suggest a no-claims bonus. For example, ten claimsfree years result in an annual deductible reduction of 20% from the eleventh year onwards.