Beyond direct damage: Cascading disruptions and adaptation in flood-affected socio-economic networks across European cities

Urban risk assessment for natural hazards demands a comprehensive methodology that captures the intricate interdependencies between a city's critical infrastructure and its underlying socio-economic networks. Contextually, it is crucial to incorporate key behavioural mechanisms shaping community resilience and adaptive response to hazardous events. This work proposes a network-based risk model that quantifies the loss of service benefits experienced by users following a flood impact. By combining infrastructure data from various European cities, variations in user flows are modeled through a probabilistic attachment law. This rule describes how users choose services depending on behavioural gains, allowing them to recalculate their socio-economic options and, where possible, adapt by establishing new connections. The findings indicate a critical threshold mechanism: once the hazard intensity exceeds a certain level, it triggers a rapid cascade of disruptions throughout the urban fabric. Nonetheless, this propagation is moderated by adaptive mechanisms, which determine the network's resilience to floods. The proposed framework provides a scalable and transferable tool for assessing and mitigating systemic urban risk, yielding a fine-grained understanding of urban responses to natural hazards and informing resilience strategies aimed at maintaining service continuity.