Climate Change, changes in flood types and future changes in flood probabilities

The frequency of events belonging to specific flood types varies strongly with time. It is expected that this variability will increase with climate change (e.g. for snow-induced flood events). This task force will investigate the impact of climate change on flood types and their frequencies with regard to possible consequences for flood statistics. While, in the first phase results from the Mulde, Inn and a few smaller catchments in Austria have indicated that changes in the frequency and magnitude of flood types can be detected and it is possible to attribute the drivers, in the second phase these findings will be generalised to a broader set of catchments across Germany and Austria, and to predictions of future scenarios. SP2 will provide downscaled global climate simulations, and findings on how relationships between climate drivers and heavy precipitation will change with a special focus on Vb weather patterns and atmospheric blocking. These climate scenarios will be used by SP4 to simulate future event type occurrences and to link changed climate variables with changes in the flood types. The change point test for changes in the flood frequencies developed by SP1 will be applied to quantify the significance of changes in the frequency, while the method of record breaking floods will be used to detect significant increases in flood magnitudes. These changes will be linked with the flood attribution model and the spatial patterns of variability of flood change mechanisms detected by SP6. The final task will be the consideration of the impact of these changes on flood probabilities. The statistical model, developed by SP1, will quantify the changes of single flood types of extreme events and their impact on flood statistics. These results will be compared to the probabilistic model of SP6 that explicitly represents the mechanisms of change for a specific flood type. SP7 will investigate the performance of current flood prediction tools under changes and modify the weather generator parameters to consider projections in future climates. Possible future changes in flood probabilities will be contrasted to past changes and their drivers in order to understand whether findings from the past can be extrapolated to the future.

The head of the task force will be R. Merz (SP4), members are S. Fischer (SP1), B. Ahrens (SP2), G. Blöschl (SP6) and U. Haberlandt (SP7).