The Aller is 260 kilometers long. The river has its source in Saxony-Anhalt and flows into the Weser near Verden. Many residents still remember a severe Aller flood, even if it was almost 20 years ago. In any case, the citizens’ interest in the flood prevention action day in Oldau, Lower Saxony, is great. Also included: the information mobile of the “Flood Competence Center Cologne” (HKC). For years it has been traveling all over Germany with a lot of material to draw attention to the topic at events, but also to present protection concepts: from various drainage pumps to mobile walls to automatic faecal backflow systems.
An elderly couple takes a close look at everything, then the woman pulls out her smartphone with pictures of her house, which is not far from the Aller, holds it in front of the expert’s nose and asks him: “We have never had water in our house, but how can we protect ourselves in extreme cases? ” Michael Czernetzki hears such questions again and again, more often than before since the terrible flooding on the Ahr this summer. More and more people are becoming aware that the supposed floods of the century are likely to increase everywhere in the future as a result of climate change. Czernetzki is happy about the growing interest. He is a co-founder of the HKC – this is a non-profit association that wants to educate people about possible dangers and protective measures.
With the HKC Infomobile, however, he is not entirely selfless, because he represents the Norwegian company Aqua Fence in Germany. Among other things, the company manufactures devices for windows and doors made of aluminum and wood, which are supposed to protect against heavy rain and floods. They have to be specially adapted depending on the size and shape of the windows and doors and cost around 1000 euros each. Such mobile solutions, which can be used by customers themselves in an emergency, must above all be quick and easy to install, says Czernetzki.
For a one meter high dam you need 100 sandbags
The HKC has developed a flood pass, which is intended to help those interested in better assessing the possible endangerment of their property when it comes to river floods, heavy rain, canal backwater and ground floods. To do this, you can send a completed questionnaire to the HKC, from which you will then receive a brief assessment. On the website www.hochwasser-pass.com there are also references to specialized engineering offices and other specialist companies throughout Germany who recommend, plan and implement specific protective measures.
“We developed this pass with the insurance industry. You can find out from your insurer whether he will grant a discount on the premium if you implement the recommended measures,” says Reinhard Vogt, longstanding HKC managing director. He is addressing the natural hazard insurance, which covers damage caused by heavy rain, flooding, backwater and flooding, among other things. Depending on the insurance company, different conditions apply as to when which damage is covered.
Vogt prefers fixed to mobile solutions, for example bricking up cellar windows instead of temporarily installing protective devices for windows and doors. “With mobile solutions there is always the risk that something will be done wrong in the rush and excitement of sudden heavy rain or flooding and that the protective devices are not used absolutely tight,” says Vogt.
Expensive solutions such as the installation of particularly watertight windows are also not necessarily the best protection. “It is often cheaper and nicer to divert the water away from the house by redesigning the property. This can be done, for example, by surrounding the terrace,” says Vogt. He doesn’t believe in building a supply of sandbags – they are only suitable for low water levels: “Most of them are not storable. For a one meter high dam you need 100 sandbags. A foldable wall is better, but it has to be specially made . “
“The market for pumps, emergency power generators and dryer devices has been swept clean”
When the HKC experts give advice in their infomobile, they are primarily asked about backflow valves. They should prevent the water from an overcrowded sewer system from pushing through the sewer pipes into the house. In heavy rainfall, depending on the model, you either have to close the backflow flap yourself or it closes automatically. Then, however, the water from the washing machine can no longer drain into the laundry room. Such backflow stops, which are located at the drain and can be recognized by a red and green point, are found in many houses, but the residents often do not even know that. “It is important that the valves are regularly checked for their functionality. They can also be retrofitted, but in the right place, otherwise they will not do anything,” says Vogt. “Even in apartments without a basement, the water can come in from below, for example through the shower.”
Such advice is met with open ears. Many interested parties are ready to invest in the near future – and must first be patient because of the great demand for the Ahr flood and the general scarcity of raw materials. “The market for pumps, emergency power generators and dryer devices has been swept clean, and prices are also rising,” says Vogt.
There is no one hundred percent protection against the consequences of heavy rain. Vogt drew his conclusions from this – he argues that new buildings should no longer be built on the ground: “I am in favor of stilt houses in all endangered areas.”