The September 2024 Flood – Hydrological Analysis, Infrastructure Performance, and Consequences

In September 2024, southwestern Poland was struck by one of the most intense floods in recent years.The main causes of the disaster were prolonged, torrential rains that occurred between 13 and 15 September, with daily totals locally exceeding 300 mm-several times above multi-month precipitation norms.The flood primarily affected the Odra River basin, and the resulting flood wave caused alarm levels to be exceeded on numerous water-courses.Retention reservoirs and dry polders played a key role in flood mitigation, including the Racibrz Dolny reservoir, the Bukw polder, and the cascade of reservoirs on the Nysa Kodzka River, which collectively retained significant volumes of flood-water, helping to prevent more severe damage in cities such as Wrocaw.Despite these efforts, the flood had serious consequences: 9 fatalities, more than 238,000 people affected, estimated damages exceeding PLN 13 billion, and widespread destruction of infrastructure.The flood had fluvial and pluvial characteristics and was accompanied by failures of hydrotechnical infrastructure.In most cases, the extent of flooded areas corresponded to zones outlined on flood hazard maps; however, in some locations (e.g., Guchoazy, Stronie lskie), events occurred beyond previously anticipated scenarios.The findings from this analysis will inform the update of the flood risk assessment as part of the third planning cycle.