Changes in river flood hazard in Europe: a review

Despite costly flood risk reduction efforts, material damage and death toll caused by river floods continue to be high in Europe. In the present review paper, after outlining a process-based perspective, we examine observed and projected changes in flood hazard. Spatial and temporal variability of large floods is analyzed, based on a time series of flood information, collected by the Dartmouth Flood Observatory in 1985–2016. Model-based projections of future flood hazard are critically reviewed. It is difficult to disentangle the climatic change component from strong natural variability and direct human impacts. The climate change impact on flood hazard is complex and depends on the river flood generation mechanism. It has not been possible to detect ubiquitous changes in flood characteristics in observation records in Europe, so far. However, we found an increasing tendency in the number of floods with large magnitude and severity, even if year-to-year variability is strong. There is a considerable spread of river flood hazard projections in Europe among studies, carried out under different assumptions. Therefore, caution must be exerted by practitioners in charge of climate change adaptation, flood risk reduction, risk insurance, and water resources management when accommodating information on flood hazard projections, under considerable uncertainty.