Integrating Physical Vulnerability and Exposure with User Factors in Flood Risk Assessment and Mitigation for Historic Built Environments

The exposure and vulnerability of users critically influence urban flood risk, particularly considering the spatiotemporal dynamics and patterns shaped by user density and profiles during the utilization of buildings and open spaces. Flood hazard and urban vulnerability are crucial in Historic Built Environments (HUBE), due to their unique physical and construction characteristics, and territorial morphology. Integrating user factors with these considerations is thus essential in flood risk assessment and mitigation. This work introduces a novel spatiotemporal methodology to incorporate user factors into the definition of flood risk scenarios, facilitating improved risk assessment actions. The proposed methodology accounts for user factors such as density loads, age, familiarity with the HUBE, and spatial positioning using hour-by-hour data. Static risk assessment, based on flood hazard and an established physical vulnerability method, is combined here with user factors through the Analytical Hierarchy Process, thereby providing a comprehensive framework for risk evaluation and mapping. The methodology is applied to a case study characterized by high user concentration, complex flood dynamics, and high building vulnerability. Comparisons between risk assessments that include or neglect user factors are provided to demonstrate the capabilities of the proposed methodology. The results reveal that user factors dynamically shift flood risk peaks during daytime hours when public areas experience the most intensive use. This approach generates time-sensitive risk maps, enabling urban planners to identify high-risk areas and implement targeted interventions. By focusing on user dynamics, the proposed framework also supports the selection of adaptive, resilience-oriented strategies for HUBEs.