Evaluating the impact of infiltration from sealed surfaces and green infrastructure on urban pluvial flooding

Urbanization and climate change are increasing the frequency and severity of urban pluvial flooding. The traditional urban modelling approaches do not take infiltration from sealed surfaces into account, leading to an overestimation of excess runoff. Still, the conventional centralized sewage systems are often overburdened. While municipalities are taking initiatives to utilize green infrastructure as a sustainable way to manage stormwater, the performance of the implemented measures varies from region to region. This study uses the WaSim-ETH physically based hydrological model to investigate runoff and infiltration processes in urban areas and determine how much rainfall contributes to runoff and infiltrates through different types of land use surfaces. It also evaluates the efficiency of green infrastructure to reduce the generated runoff from different rainfall events. The model is applied to study areas in Berlin and Würzburg, both cities have experienced frequent pluvial flooding in the last decades.