Extreme, large-scale river floods typically affect more than one river basin. Although such trans-basin floods are highly relevant for national disaster risk reduction and insurance, the knowledge about the processes triggering these extremes is very limited. In particular, the role of anthropogenic climate change on changes not only of the meteorological precursors but also of hydrological response and resulting flood impacts remains unclear. In Phase I of the ClimXtreme project, the project FLOOD investigated future changes in large-scale flooding in Germany. Based on the developed methodology – the Regional Flood Model (RFM) – we address the question of attribution of floods and their impacts to past and on-going climate changes. For this purpose, we compare the probability that an impact indicator for the effects of an event exceeds the value of an actual flood (factual world) with the probability that this indicator exceeds the threshold in counterfactual worlds where it is assumed that the driving forces of change were not present or behaved differently. To estimate these probabilities, many realizations of flood impacts will be generated by downscaling CMIP6 GCM output for both the factual and counterfactual worlds using a non-stationary weather generator and propagated through the RFM model chain. The project intends to extend the attribution methodology from triggering precipitation down to flood impacts.

FLOOD project is part of the research network ClimXtreme on climate change and extreme events funded by the German Federal Ministry of Education and Research (BMBF) in the framework programme Research for Sustainable Development (FONA3)

Rapid assessment of the Winter flood 2023 / 2024

Rapid assessment of the June 2024 flood