The hydrological extremes of the Rhine in history - an european perspective

• Applicant: Dr. Thomas Roggenkamp
• Subject Area: Physical Geography
• Term: since 2025
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 574211654

The proposed research project aims to systematically reconstruct historical flood and drought events in the Rhine catchment area based on anthropogenic sources such as flood marks, hunger stones, and historical written records. The project responds to a key challenge in risk research: available gauge time series are too short to reliably capture the full extent of discharge variability in the Rhine system. As a result, hydrological extreme events are often underestimated — as dramatically demonstrated by the Ahr Valley flood of 2021. The project pursues three overarching objectives: 1: To develop a publicly accessible, quality-assured database of historical flood and drought events in the Rhine system as a basis for research, risk modelling, and hazard mitigation. 2: To reconstruct historical flood and drought events with respect to their peak discharges, spatial extent, and temporal dynamics. 3: To develop and validate a methodological standard for the use of historical sources in discharge reconstruction. To achieve these goals, the project is structured into five work packages (WPs): WP1 compiles and collects information from historical sources. In addition to systematic literature and archival work, on-site measurements of flood indicators are conducted. WP2 assesses the plausibility of the data using established criteria and by cross-checking between physical flood marks and written records. WP3 reconstructs peak discharges of historical extreme events using Manning’s equation, with parameters derived from terrain profiles, maps, paintings, and other visual or cartographic sources. WP4 analyses how simplified assumptions (e.g. regarding topography, bathymetry, or overbank sedimentation) affect reconstruction results. WP5 examines selected extreme events in detail, including their causes, spatial development, and consequences. The project addresses a significant research gap at the intersection of hydrology, historical climatology, and risk modelling. It contributes to fundamental research while also preparing key results in a practice-oriented way for decision-makers, public authorities, and insurance providers.

• DFG Programme: Research Grants