RISK MANAGEMENT

flood maps

With the realisation of the constructional flood control the flood prevention in Cologne will be significantly improved. The major part of the city will be protected up to 11.30 m Cologne level and the more endangered parts will be protected up to 11.90 m. The enclosed flood maps show depth and spread of floods at different water levels with and without the planed future flood control construction.

Everyone at interest can inform themselves how much at risk their properties or city districts are. Exemplary chosen are the water levels 10.70m, 11.30m, 11.90m, and 12.50. In 1995 and 1926 there were water levels of 10.69m measured. The statistical probability of a water level of 11.30m is once in 100 years, for 11.90m it is once in 200 years, and 12.50m would be an extreme flood.

How fast such a rare and disastrously flood on the other hand can occur was seen in the past years at Oder and Elbe. The floods do not go by statistics. Therefore we are not able to say if not maybe next year we will have another devastating hundred year flood. Whether or not the flood will occur in the described way depends on different factors.

The digital area model which is basis for the maps has minor height variances, however due to laser scanning and multiple measured maxima there is a high level of accuracy.

Furthermore every flood is different. The flow behaviour of the Rhine stream is affected by the wind pressure, the wave surge, and different construction and plant cultivations. There are also areas shown, which due to their altitude are located lower than the Rhine and are therefore even though they are not directly touching the Rhine at hazard. The planed improvement of the constructional flood control cannot guarantee absolute flood protection

Flood control constructions can fail or be flooded by even higher water levels.

Further informations under: flood prevention