Rainfall and wave storms interdependence in the western Spanish Mediterranean coast

Spanish peninsular Mediterranean coast. We characterise the dominant main terrestrial and marine drivers of compound flood events in the study region. Due to the prevalence of ephemeral rivers, rainfall represents the terrestrial driver, while waves, more influential than storm surges, represent the marine component. We analyse the frequency, intensity, and interdependence of compound events to identify spatial patterns across the study area. Conditional exceedance analysis estimates probabilities and determines likely driver combinations during multivariate events. Significant regional variability exists in compound flood event drivers. Key hotspots in northern Catalonia and central Valencia are driven by overlapping rainfall and wave patterns. Compound extreme events are around 8–10 % more intense than single-driver events. Seasonal patterns revealed that compound extreme events are rare in summer but more frequent in autumn, winter, and spring, with the strongest wave–rainfall correlation occurring at zero lag time. Areas with stronger statistical dependencies between drivers experienced a higher frequency of compound extreme events. We identified the most likely combinations of event types associated with various joint return periods. The analysis reveals notable regional variations, with some areas predominantly affected by a single extreme driver, typically wave storms, and others equally influenced by both wave and rainfall storms. These findings emphasize the need to incorporate multivariate dependencies and spatial heterogeneity into regional flood risk assessments. • Drivers of compound flood events across the Spanish Mediterranean are characterized. • The spatial distribution of compound events is highly uneven across the study area. • Northern Catalonia and central Valencia are hotspots for compound flooding. • Compound events averaged 8–10 % higher intensities than single driver storm events.