Austrian flood expert Prof. Günter Blöschl from TU Wien (Vienna) has led a large international study involving a total of 35 research groups that provides clear evidence that changes in the magnitude of flood events observed in recent decades can be attributed to climate change. However, climate change does not have the same effect on floods everywhere: In northwestern Europe, floods are becoming increasingly severe, in southern and eastern Europe flood magnitudes mostly tend to decrease, although, in small catchments, they may actually increase.
"We already knew from our previous research that climate change is shifting the timing of floods within a year," says Günter Blöschl. "But the key question is: Does climate change also control the magnitude of flood events? So far, the available data had not been sufficient to ascertain whether this is the case or not. We have now examined this question in great detail and can say with confidence: Yes, the influence of climate change is clear."
In central and north-western Europe, between Iceland and Austria, flood magnitudes are increasing because precipitation is increasing and the soils are becoming wetter. In southern Europe, on the other hand, flood levels are decreasing, as climate change results in declining precipitation and the higher temperatures cause increased evaporation of water in the soil. However, for small rivers, floods may actually increase due to frequent thunderstorms and deforestation. In the more continental climate of Eastern Europe, the magnitudes of floods tend to decrease due to shallower snow packs in winter associated with higher temperatures. "Processes differ across Europe -- but the regional patterns all correspond well with predicted climate change impacts," says Blösch.
https://www.sciencedaily.com/releases/2019/08/190828140128.htm
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