Exploring Vulnerability Dynamics Associated with Compound Flood Impacts Across European Regions

Traditional approaches to disaster risk assessment often consider natural hazards in isolation, overlooking the complex interplay between hazards, which can significantly affect overall impacts. Compound flood events, characterised by co-occurring or preceding anomalous conditions, may exacerbate flood impacts and result in greater damage. This study investigates the effects of five compound flood events—flood sequence, drought-to-flood, cold-to-flood events, hot-to-flood sequence, and compound flood and wind—and their relationship with disaster vulnerability on flood impacts at a sub-national level across Europe from 1981 to 2020. Historical flood records are obtained from the extensive HANZE database, which includes detailed regional information, event timelines, and associated losses. Recorded flood impacts are spatiotemporally matched with associated hazards computed from ERA5, enabling a thorough comparison of isolated versus compound flood impacts. This results in a new dataset of multi-hazard events based on disaster records and climate reanalysis data. Using this dataset, our analysis explores the trends of compounding hazards on flood impacts by examining physical interactions at the hazard level and changes in vulnerability. This approach represents a step forward in disentangling the contributions of these factors to flood risk, with the goal of informing more resilient community strategies and effective disaster risk reduction in an era of complex crises.