The city of Grimma, Germany, is currently often cited as a positive example of a mature flood warning system. After two flood disasters, those responsible reacted. In addition to a mechanical protection system, a warning system was set up to alert the public in case of floods.
Central components are the outdoor warning sirens as well as an alert by SMS sent to citizens who have registered their mobile number with the city. "The siren is the only effective instrument to warn people over a wide area," Mayor Berger told the Süddeutsche Zeitung, a leading German newspaper. "When it sounds, people should go to the window and wait for announcements." The efforts of the Federal Republic of Germany to promote a nationwide expansion of the siren network are going in the right direction. Other countries with similar threat scenarios are ahead of us here. Austria, Switzerland and Sweden have nationwide siren networks. In the case of floods, there is often little time left, people have to be warned as quickly as possible. Only on 2 June, the outdoor sirens in Grimma were converted from analogue to digital technology by technicians from HÖRMANN Warnsysteme. Electronic outdoor Sirens have a so-called alarm function: if the siren wails, there is danger. HÖRMANN Warnsysteme planned the six locations so that the entire area is covered and everyone can be reached. The sirens are tested once a month. In Grimma, it was important to have modern electronic sirens that can operate independently of the power grid for a fortnight. This ensures that the sirens wail reliably. This is because, in addition to the mobile phone networks, the power grids also frequently fail during floods. Grimma is a prime example of what a warning system for floods can look like: Digital, electricity-independent outdoor warning sirens in combination with modern means of communication and mechanical protection measures.