This dataset comprises gridded precipitation fields, simulated hourly discharge values and simulated inundation areas and depths in the Ahr catchment in Germany for the reference scenario of the July 2021 flood and 25 spatial counterfactuals. The precipitation dataset contains the observed gridded E-OBS precipitation field and 25 counterfactuals shifted by one cell. Subsequently, the reference scenario and spatial counterfactuals are used as atmospheric forcing for the mesoscale hydrological model mHM set up and calibrated for the Ahr catchment, Germany. The model simulates hourly discharge series at seven gauge locations (Müsch, Kirmutscheid, Niederadenau, Denn, Kreuzberg, Altenahr, Bad Bodendorf) from which the event peak flows and flood event volumes can be derived. These discharge data is used as boundary condition for the RIM2D hydrodynamic inundation model which simulates inundation areas and maximum inundation depths along the Ahr valley between Müsch and Sinzig for the reference scenario and spatial counterfactuals.
Real-time fluid monitoring began in late 2020 in the East Eifel and currently includes 12 sites, such as abandoned CO₂ wells, mofettes, CO₂-rich springs, CO₂-rich soil, and a cold-water geyser in the West Eifel. For the first time, fluid data are being recorded continuously with a high temporal resolution of up to 1 Hz. Depending on the local site conditions, the following parameters are being monitored: instrument temperature and battery voltage; barometric pressure and temperature; meteorological parameters; water level, wellhead pressure, water temperature; radon in free gas phase; CO2 concentration and CO2 flux in soil gas. Data are transmitted hourly via FTP to GFZ. While we generally observe small seasonal variations, short-term transients related to heavy rain or local and distant earthquakes are indicated. Over longer periods, we observe trend changes in helium isotope ratios, radon concentration, and water temperature. For example, two sites exhibited significant helium isotope changes from 2021 to 2025, which appear to correlate with earthquake swarms at depth. These examples demonstrate the necessity of jointly interpreting meteorological, hydrogeological, geophysical, and geodetic data.