Assessing rainfall hazard and local factors associated with societal flood impacts in Greece

Floods and flash floods are among the most damaging hydrometeorological hazards in the Mediterranean, with impacts shaped by rainfall hazard, exposure, and local susceptibility. This study examines rainfall and local geospatial characteristics associated with documented flood impacts in Greece during 2000–2025 and explores how these characteristics vary by impact severity. The analysis is based on more than 450 flood-related events recorded in the High-Impact Weather Events Database for Greece (HIWE-DB), developed and maintained by the METEO unit of the National Observatory of Athens. The original event reports were systematically reviewed to extract reported affected settlements and localities, yielding approximately 1,700 local impact records. The HIWE-DB impact severity classification was attributed to these local records. Rainfall was extracted from a gridded precipitation dataset with 1 km × 1 km spatial resolution, developed by the METEO unit using observations from its dense surface weather station network across Greece. Two rainfall indicators were calculated for each affected location: precipitation on the day of the reported impact (R24) and accumulated precipitation over the previous day and the day of impact (R48). In addition to this rainfall dataset, rainfall from the MSWEP dataset was also used to estimate the same indicators as a secondary reference to explore how rainfall-product choice may affect the interpretation of impact-generating events. Descriptive and exploratory statistics are used to examine rainfall distributions, selected geospatial and exposure-related indicators, spatial patterns, and relationships with impact severity. The study provides evidence on the local conditions associated with damaging floods in Greece and can inform flood risk assessment, preventive strategies, impact-based warning approaches, and adaptation planning in Mediterranean environments.