Extreme Floods in Europe: Multi-Event Empirical Evidence on Cross-Sectoral Interdependencies

Extreme floods and storms can disrupt essential services not just through direct physical damage but also through cascading effects across interconnected critical infrastructure. This study provides multi-event empirical evidence of how flood- and storm-related impacts propagate across sectors, using the sectoral classification of the EU Critical Entities Resilience (CER) Directive as an organising framework. The analysis examines 20 major European flood and storm events that occurred between 2002 and 2024. A harmonised database was developed from peer-reviewed studies, official reports, and post-event documentation. Documented disruptions were classified according to the eleven CER sectors and coded as direct source-sector and target-sector interactions. The final dataset includes 54 documented cross-sector cascading interactions, highlighting interesting patterns. Energy and transport were the dominant cascade-initiating sectors, accounting for 35.2% and 25.9% of all interactions, respectively. Health was the most frequent receiving sector, followed by public administration; digital infrastructure; drinking water; and food production, processing, and distribution. The study highlights the central roles of energy and transport as upstream drivers of disruption propagation, mainly through functional and logistical mechanisms. Overall, the findings show that in order to obtain a more realistic risk assessment, floods and storms should be understood not only as physical hazard events but also as potential systemic disruption processes. In addition, they suggest that critical-entity dependency mapping, scenario-based testing of upstream failures, and cross-sector continuity planning are crucial for CER-aligned risk assessment.