From Hydraulic Simulation to Decision Support: A Multi-Risk Framework for Pluvial Flood and Seismic Risk in Urban Genoa

The increasing frequency and intensity of extreme rainfall events highlight the need to advance pluvial flood risk analysis toward more integrated and comprehensive assessment frameworks. While hydraulic modelling is a well-established tool for analysing urban drainage systems, an effective evaluation of urban resilience requires coupling hydraulic behaviour with the characteristics and vulnerability of the built environment.

This study focuses on the Sampierdarena district in the city of Genoa, Italy, an area characterised by high urban density and a documented exposure to multiple natural hazards. The research investigates how pluvial flood risk can be modelled and systematically integrated within a multi-hazard framework that also considers seismic risk, with the aim of supporting urban resilience assessment and planning.

The proposed approach adopts an area-based methodology that enables the comparison and integration of different hazards through a common spatial framework. Multiple vulnerability dimensions, including population exposure and building use, are incorporated to assess the potential impacts associated with each hazard. With specific reference to pluvial flooding, the study employs an open-source modelling framework that couples two-dimensional surface flow simulations with one-dimensional sewer network modelling, allowing a detailed representation of interactions between overland runoff and urban drainage infrastructure.

Pluvial flood simulations were conducted using a synthetic rainfall event with a 10-year return period. The resulting surface water depth maps were subsequently integrated with building-scale vulnerability indicators, enabling a spatially explicit assessment of flood impacts across the study area. This integration facilitates the identification of areas where hydraulic insufficiencies intersect with high levels of exposure or vulnerability, thereby enhancing the interpretability of flood risk results in an urban context.

In contrast, the seismic risk component of the study follows a different methodological approach, primarily focused on the identification and analysis of strategic elements relevant to emergency planning. The present work builds upon this existing seismic assessment by extending the framework to include pluvial flood risk, thereby contributing to a more comprehensive multi-risk perspective.

This approach enables a more robust performance analysis of strategic buildings and the strategic connections defined within the Emergency Plan of Genoa. By intersecting hydraulic vulnerabilities with the urban emergency network, the study represents a significant step forward in defining targeted Civil Protection actions for an area where pluvial flooding constitutes the primary risk, ensuring that strategic accessibility and functionality are preserved during extreme events.

Overall, this research forms part of broader efforts aimed at developing effective decision-support tools for urban risk management. By framing the relationship between hydraulic system performance, building vulnerability, and multi-hazard exposure, the study contributes to advancing integrated methodologies for assessing and enhancing urban resilience. Specifically, the integration of pluvial flood risk into the strategic framework of Genoa’s Emergency Plan provides a practical instrument for Civil Protection authorities to prioritize mitigation measures and optimize emergency response. Ultimately, this work demonstrates how a multi-risk perspective can transform technical hydraulic modelling into actionable knowledge, strengthening the safety and functionality of strategic urban networks under increasing climatic and environmental pressures.