Investigating the 7,000 years of Lake Mondsee sediment records, we identified a point process of renewal type, with a significant change point of the flood occurrence pattern around 350 AD, switching from the overlay of two mechanisms of flood recurrences of 5 and 50 years before to 2 and 17 years after this change point. Since the beginning of damage record keeping, a somewhat higher flood frequency has been observed compared to the entire period after the change point. As no further robust change point has been detected in the sediment data, we may conclude that the flood frequency regime has not significantly changed again since 350 AD. From that perspective, damage potentials derived merely from recent damage experience may overestimate actual risks. Estimated average annual damage and Solvency II capital requirements are, for instance, about 30 % higher for the period with damage data available than for the entire period since the change point. On the other hand, change points are usually harder to detect at the borders of the time series. Thus, the flood frequency regime might have changed recently, without the possibility to detect the respective change point in a statistically significant way.

Regarding the atmospheric drivers of flood events in the Mondsee region, the majority of the 20 largest daily precipitation events during summer (1961-2015) were found to be related to the occurrence of type Vb cyclones which develop around Northern Italy south of the Alps. Those top precipitation events correspond very well with the sedimentary Lake Mondsee flood record (1976-2013, up to 80 %) as well. Moreover, a major Cut-Off Low at upper at-mospheric levels directly located across the Alpine Range was identified as a main feature during such events. The resulting floods, which also trigger sediment deposition in Lake Mondsee, are high intensity floods, presenting highest hourly discharges and highest dis-charges lasting at least 13 hours. For the future (2051-2100 compared to 1956-2005), five out of six considered RCP/model-run combinations of the climate model ECHAM6 indicate an increase in the number of precipitation extremes causing flood layer deposition in Lake Mondsee. This translates into expected shifts in average annual damage and Solvency II capital requirements ranging from -19 % to +75 % (assuming no changes in building stock values). Natural variability is, however, higher than the shift expected due to climate change.