The growing complexity of human systems and the increasing frequency of climate-driven hazards have transformed some disasters from isolated events into cascading phenomena which propagate through critical infrastructure networks, disrupting essential services and amplifying systemic risk. This work examines the impacts of extreme storms and subsequent flooding on critical entities as defined under the new EU Directive (Critical Entities Resilience, CER). This study introduces a structured Critical Entities Disruption Database—Greece (CEDD-GR), as a methodological framework for systematically recording and analysing disruptions to critical entities, and applies it to the case of Storm Daniel (2023), one of the most severe flood events recorded in Greece. The analysis identified direct impacts across eight of the eleven sectors defined in the CER Directive, namely, energy, transport, health, drinking water, wastewater, public administration, digital infrastructure and food production, processing and distribution. A total of 21 different types of critical entities were documented, revealing the mechanisms through which failures affected different subsectors. The results underscore the systemic fragility of critical entities when exposed to extreme storms, compound flooding, and mass wasting processes (landslides, ground subsidence) and highlight the need for integrated resilience planning in line with the CER framework.

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.