High-Resolution Framework for Urban Pluvial Flood Risk Mapping

We introduce a high-resolution framework for evaluating climate-related risks at the building level, based on the IPCC risk model which conceptualizes risk as a function of vulnerability, exposure, and hazard. The framework focuses on pluvial flood risk, emphasizing impacts on residents’ well-being and mobility. The flood hazard is represented based on a 1-meter resolution hydrodynamic simulation of urban flooding triggered by a 100-year hourly rainfall event. Exposure is nuanced by impact type, considering ground-floor residents’ well-being and proximity to flooded streets affecting mobility and accessibility. Social vulnerability is quantified through socioeconomic indicators such as age, income, and education levels. Applying this framework to empirical data from Hamburg, Germany, we identify perilous hotspots where areas of high social vulnerability are combined with significant flood exposure. The framework was co-designed and tested with stakeholders from the city of Hamburg. To facilitate practical application also for other cities, we developed a Python-based ArcGIS toolbox for automated, building-level risk mapping. The framework’s transparent and adaptable design ensures broad transferability, to support local climate adaptation strategies and informed decision-making in urban resilience planning.