Articles | Volume 25, issue 2
https://doi.org/10.5194/nhess-25-581-2025
https://doi.org/10.5194/nhess-25-581-2025
Research article
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10 Feb 2025
Research article | Highlight paper |  | 10 Feb 2025

Causes of the exceptionally high number of fatalities in the Ahr valley, Germany, during the 2021 flood

Belinda Rhein and Heidi Kreibich

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Aceto, L., Pasqua, A. A., and Petrucci, O.: Effects of damaging hydrogeological events on people throughout 15 years in a Mediterranean region, Adv. Geosci., 44, 67–77, https://doi.org/10.5194/adgeo-44-67-2017, 2017. 
Ahmed, M. A., Haynes, K., and Taylor, M.: Vehicle-related flood fatalities in Australia, 2001–2017, J. Flood Risk Manage., 13, e12616, https://doi.org/10.1111/jfr3.12616, 2020. 
Apel, H., Vorogushyn, S., and Merz, B.: Brief communication: Impact forecasting could substantially improve the emergency management of deadly floods: case study July 2021 floods in Germany, Nat. Hazards Earth Syst. Sci., 22, 3005–3014, https://doi.org/10.5194/nhess-22-3005-2022, 2022. 
Diakakis, M. and Deligiannakis, G.: Flood fatalities in Greece: 1970–2010, J. Flood Risk Manage., 10, 115–123, https://doi.org/10.1111/jfr3.12166, 2017. 
DKKV: Opfer- und Schadensdaten der Flut 2021 in Rheinland-Pfalz, German Committee for Disaster Reduction, 1–4, https://dkkv.org/wp-content/uploads/2023/02/Anfrage_Opfer-_und_Schadensdaten_der_Flut_2021.pdf (last access: 4 February 2025), 2022. 
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Executive editor
The paper explains the factors which made the Ahr flood event of 2021 the deadliest one in Germany, causing more fatalities than all flood events of the previous 40 years together. It points out that 75% of the fatalities occurred outside of the established flood hazard zones. On the basis of individual fatality reports, factors additionally to early warning and evacuation deficits are identified. A particular result is that beyond danger zones like campsites and cellars the percentage of deaths on the ground floor of buildings (37 %) or outside on the street (18 %) were particularly high. Recommendations for improving emergency management of such unprecedented floods are given.
Short summary
In July 2021, flooding killed 190 people in Germany, 134 of them in the Ahr valley, making it the deadliest flood in recent German history. The flash flood was extreme in terms of water levels, flow velocities and flood extent, and early warning and evacuation were inadequate. Many died on the ground floor or in the street, with older and impaired individuals especially vulnerable. Clear warnings should urge people to seek safety rather than save belongings, and timely evacuations are essential.
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