Scenario analysis on the impact of green infrastructure on urban pluvial flood mitigation

Urban surface sealing is limiting infiltration and thus increasing the formation of runoff during heavy rain events. Green infrastructure measures can be used to reduce urban flood risk by promoting decentralized infiltration, water storage and evaporation. In this study, we investigate the impact of green infrastructure on urban runoff formation, flood heights and flow velocities, and the resulting damage to buildings. Our model-based scenario analysis is located in Berlin, in a heavily sealed 3.3 km² catchment. Rain events with a duration of one hour and totals of 15 to 100 mm are considered. The green infrastructure scenarios include different spatial extents and combinations of bioretention cells, green roofs and pervious pavement. The Stormwater Management Model (SWMM) is used for the urban runoff generation and the 2D-hydrodynamic module of TELEMAC for surface runoff concentration. Building damage is modelled with the Flood Damage Estimation Tool (FlooDEsT), a recursive partitioning tool developed with survey data representative of building damage caused by pluvial floods.