The May 2023 Flood Events in Emilia-Romagna, Italy: A Compound-Event Perspective

In May 2023, two severe hydrometeorological events affected Emilia-Romagna (Italy), on May 2–3 and May 16–17, respectively. These events led to widespread, concurrent flooding across multiple river basins, triggered by levee overtopping and embankment failures, and impacted 37 municipalities throughout the region. This study presents a compound-event analysis of the two events, employing a dual methodological framework. First, a bottom-up, impact-based assessment was conducted, starting from documented damages and tracing back to the underlying meteorological drivers. Subsequently, a top-down, model-based analysis was performed to investigate the dynamics of these events and quantify the relative contributions of hydrometeorological and geomorphological factors to the flood events. In addition, a sensitivity analysis was conducted to assess the influence of the considered forcings and parameter choices on the robustness of the results. This integrated framework provides new insights into the dynamics and drivers of compounding flood hazards.