This study examines how extreme rainfall in Berlin, Germany, may intensify due to global warming and how that could worsen flooding in a selected part of the city. We assess the role of the drainage system, infiltration from unsealed surfaces, and a potential adaptation scenario with all roofs as retention roofs in reducing flooding under extreme rainfall. Combining climate and hydrodynamic simulations, we provide insights into future challenges and possible solutions for urban flood management.

We used a tracer-aided ecohydrological model to quantify water flux–storage–age interactions for three urban vegetation types: trees, shrub and grass. The model results showed that evapotranspiration increased in the order shrub < grass < trees during one growing season. Additionally, we could show how infiltration hotspots created by runoff from sealed onto vegetated surfaces can enhance both evapotranspiration and groundwater recharge.