The German harbour city of Hamburg is looking for measures to limit the negative effects of storm water. In future, local flooding must be minimised. Hamburg has always been a green city renowned for its watersides. However, surface sealing has increased due to the expansion of residential and industrial areas. This has lead to excessive peaks of polluted storm water runoff into watercourses that contain little if any flowing water in dry periods.

Three pilot projects

Three pilot projects have been set up on watercourses into which separated or combined sewerage systems are discharged. Possibilities for mitigating the pollution and peak discharge are being investigated as well as options for ensuring the water flows in dry periods so that it remains clean and rich in oxygen.

Concrete measures and an injection of knowledge

The concrete measures taken must reduce flooding and increase the flow of living, oxygen-rich water. However, an injection of knowledge is just as important. Ways of combining source-control measures and end-of-pipe treatments for storm water runoff must lead to the implementation of many larger-scale plans in the future. Although most of the techniques used are known in Hamburg, the synergies obtained from combining various approaches are leading to new opportunities. Yet a lot of input is also expected from the partners in Urban Water Cycle, particularly in the areas of managing high groundwater levels and the use new filter and infiltration techniques. These pilots must set the agenda for a complete strategy that will enable Germany’s second largest city to manage the quality and quantity of its storm water in an appropriate manner.

above: example of a measure to limit the negative effects of storm water

below: project area