Flood markers

Flood symbols along the river elbe in Hamburg, Germany


Flood markers and signposts are, for example, marks of past flood levels on walls, gates and church doors. These are traditional means of flood hazard communication.


For example, the City of Hamburg has installed several marks at different locations along the Elbe River to depict the levels of the devastating floods of 1962 and 1976.


To find out how much information these marks communicate, passersby at different locations were interviewed. But before that the marks had to be found, since even the municipality did not know their exact number and location.

The results were rather astonishing. If people had not known about them before, most of them failed to see the symbols even in eye-catching locations, let alone the hidden ones. But when questioned, they began to pay attention and developed an interest in the matter.

In summary, the outcomes of the interview are:

  • The idea of marks is not outdated. But in order to convey their message, they need to stand out from a flood of information and be effectively promoted.
  • Examples of the differences in understanding flood information: Marks like this are not self-explanatory for the uninformed viewer, while the experienced observer would identify their meaning at once.
  • After having spoken to them, people’s view of the location changed. Once they realised that these areas had been heavily flooded in 1962, they were able to discover further marks and to understand their meaning.

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