In CLEVER Cities’ partner city Hamburg, adaptation to the consequences of climate change necessitates dealing with the consequences of increasingly intense heavy rainfall events. NbS can play a crucial role in adaptation and mitigation efforts by helping to restore the natural water cycle and prevent local flooding through increased retention, infiltration, and evaporation. In an urban environment, the challenge is to predict the consequences of certain heavy rainfall events as accurately as possible in order to be able to select the locations of effective NbS. 

In the CLEVER Cities project, a drainage analysis for heavy rainfall was developed for the pilot project area that not only takes into account highly accurate topographic data for modelling water runoff, but also complements this with available data on the various drainage facilities. The project has exemplary and pilot character due to the methodology carried out and especially due to the application of coupled hydrodynamic runoff modelling to a relatively large catchment area. Thus, it represents a method that is already being transferred to other districts of Hamburg as well as other municipalities. The drainage analysis for heavy rainfall will be used to identify flooding hotspots and thus priority locations for NbS. It thus also forms the basis for further participative processes for the co-creative development of the appropriate intervention. 

More insights and details can be found in the full report, available in both English and German.

Overview map of the focus and retention areas (©Hamburg Wasser)

Drainage analysis presenting the 2D surface model and considered rainwater harvesting network (© Hamburg Wasser)

Simulation results max. water level. Left: in the actual state, right: with measures. (© Hamburg Wasser)