Mapping and simulation of urban flooding after heavy rain events

In many regions, the number and intensity of extreme precipitation events will increase as a result of climate change, which will pose major challenges for spatial planning and climate adaptation, particularly for metropolitan regions. Based on a digital terrain model and on a mapping of the flow obstacles relevant for precipitation runoff, hydrodynamic modelling with different precipitation intensities was carried out for an investigation area in the Ruhr area. The simulation tools FloodArea and Hec-Ras were used for geodata processing and to produce hazard maps. The results of the modelling with both programs show similarities in the distribution of the areas with highest flood levels. However, differences can be observed in absolute heights. The approach shown can be used to simulate the effects of future heavy rainfall events and provides urban planning decision support (location of retention areas) for adaptation measures related to climate change.