Clear regional variations in European river flooding, reported in Nature this week, seem to be associated with regional patterns of climate change. The research provides a continental-scale analysis of why floods are increasing in some European regions and decreasing in others.
River flooding is a costly natural hazard associated with estimated losses of $104 billion per year, which are expected to increase with continued economic growth and urbanization. The impact a changing climate will have on river floods has been difficult to determine, as regional precipitation is expected to vary and large-scale observational data of flooding patterns have been lacking.
Gunter Bloschl and colleagues analysed a published dataset of European river discharge observations from 3,738 gauging stations between 1960 and 2010. They also assessed changes in key drivers of flooding, including maximum precipitation, soil moisture levels and air temperature. Some regions in Europe have seen an increase in flooding of more than 11% per decade while others have decreased by 23%, the authors report. In northwestern Europe flood magnitude is increasing, which the authors suggest is because of increasing extreme precipitation and increasing soil moisture. They show that in southern Europe flood trends are decreasing, potentially owing to decreasing winter rainfall.
These results demonstrate the need to consider climate change impacts when designing flood management strategies, the authors conclude.