Extreme hydrological events are generally predicted to become more frequent and damaging in Europe due to warming climate. Researchers from TU Delft and Rice University (Houston) have now shown that, correcting for economic and demographic changes, there has been no increase in financial losses and fatalities from floods in the last 150 years. They have reported on their findings in Nature Communications.

Correcting

An analysis of long-term trends in flood losses should account for changes in size and distribution of population and assets. Without correcting reported losses for changes in exposure, studies (logically) report a significant upward trend in losses. ‘Such ‘normalization’ processes have also proven to be important for explaining trends in other natural hazards’, says Dominik Paprotny, researcher at TU Delft and lead author of the paper in Nature Communications.

So adverse consequences of floods change are influenced by both natural and socio-economic trends and interactions. In Europe, previous studies of historical flood losses that were corrected for demographic and economic growth (‘normalized’) have been limited, leading to an incomplete representation of trends in losses over time. ‘After adjusting nominal losses for demographic and economic growth, no significant trends in flood losses, both on European scale and for individual countries were observed.’

Less fatalities

Paprotny and his colleagues utilized a gridded reconstruction of flood exposure in 37 European countries and a new database of damaging floods since 1870. ‘Our results indicate that, after correcting for changes in flood exposure, there has been an increase in annually inundated area and number of persons affected since 1870, but we have also found a substantial decrease in flood fatalities. For more recent decades we found a considerable decline in financial losses per year. We estimate, however, that there is large underreporting of smaller floods beyond most recent years, and show that underreporting has a substantial impact on observed trends.’

Changes

Extreme hydrological events are generally predicted to become more frequent and damaging in Europe due to warming climate and there seems to be large consensus regarding the trajectory of future climatic developments. ‘There is however less confidence in the changes in flood losses as a result of climate change so far’, says Paprotny. ‘Qualitative and quantitative hydrological studies for Europe have indicated no general continental-wide trend in river flood occurrences, extreme precipitation, or annual maxima of runoff. However, substantial variations between different catchments have been observed, ranging from an increase in north-western Europe to no trend or a decrease in other parts of the continent. Similar findings were reported for storminess along the European coasts.’

Information

Dominik Paprotny, D.Paprotny@tudelft.nl
Carola Poleij, Press-officer Technical University of Delft, C.Poleij@tudelft.nl , +31 (0)15 27 87538, +31 (0)6 41611510
Publication: www.nature.com/articles/s41467-018-04253-1