Publication Details |
| Category | Data Publication |
| DOI | 10.5880/GFZ.RDOQ.2025.002 |
| Licence |
|
| Title (Primary) | Spatial counterfactuals of the July 2021 flood in the Ahr valley, Germany [Dataset] |
| Author | Vorogushyn, S.; Han, L.; Apel, H.; Nguyen, V.D.; Guse, B.; Guan, X.; Rakovec, O.
; Najafi, H.; Samaniego, L.
; Merz, B. |
| Source Titel | GFZ Data Services |
| Year | 2025 |
| Department | CHS |
| Topic | T5 Future Landscapes |
| Abstract | After a flood disaster, the question often arises: what could have happened if the event had gone differently? For example, what would be the effects of a flood if the path of a pressure system and the precipitation field had taken a different trajectory? In this paper, we use alternative scenarios of precipitation footprints shifted in space, the so-called “spatial counterfactuals” to generate plausible but unprecedented events. We explore the spatial counterfactuals of the deadly July 2021 flood in the Ahr Valley, Germany. We drive the mesoscale Hydrologic Model (mHM) of the Ahr catchment with precipitation fields of this event systematically shifted in space. The resulting discharge is used as a boundary condition for the high-resolution two-dimensional hydrodynamic model RIM2D calibrated and validated for this area. We simulate changes in peak flows, hydrograph volumes, and maximum inundation extents and depths, as well as affected assets, and compare them to the simulations of the actual event. We show that even a slight shift in the precipitation field by 15–25 km eastward, which does not seem implausible due to orographic conditions, causes an increase in peak flows at gauge Altenahr of about 32 % and of up to 160 % at the individual tributaries. Also, significantly larger flood volumes of more than 25 % can be expected due to this precipitation shift. This results in significantly larger inundation extents and maximum depths at a number of analysed focus areas. For example, in the focus area around Altenahr, the increase in mean and maximum depths of up to 1.25 and 1.75 m, respectively, is simulated. The presented results should encourage flood risk managers as well as the general public to meet precautionary measures for extreme and unprecedented events. |
| linked UFZ text publications | |
| Persistent UFZ Identifier | https://www.ufz.de/index.php?en=20939&ufzPublicationIdentifier=31017 |
| Vorogushyn, S., Han, L., Apel, H., Nguyen, V.D., Guse, B., Guan, X., Rakovec, O., Najafi, H., Samaniego, L., Merz, B. (2025): Spatial counterfactuals of the July 2021 flood in the Ahr valley, Germany [Dataset] GFZ Data Services 10.5880/GFZ.RDOQ.2025.002 |
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