More Intense and Longer Torrential Rain and Flood Events During the Recent Past Decade in Eurasia.

Global and regional flood risk is increasing, especially in Eurasia, threatening public security and socioeconomic development. However, the duration, intensity and spatial extent of floods in the past few decades have not been robustly explored, largely because previous identification methods ignored the dual nature of floods in space and time. Here we presented a first comprehensive diagnosis of flood events in Eurasia by developing a novel three‐dimensional Image‐CONnectivity based FLOOD identification (ICON‐FLOOD) approach. By the ICON‐FLOOD approach, we revealed a four‐phase quasi‐interdecadal pattern and significant intensification of flood events in the last 12 years of the study period (1979–2012), contrary to the declining trend derived from two well‐known global data sets. Further analysis indicated that the flood characteristics had switched from "large impacted area but short duration, low intensity" to "high intensity, long duration but small impacted area." Exploring the spatiotemporal evolution of flood events by ICON‐FLOOD will provide a basis for flood risk management and flood adaptation strategy development. Plain Language Summary: The occurrence, development and end of flood events have obvious three‐dimensional characteristics in time (first dimension) and space (longitude and latitude as the second and third dimensions). However, previous dimensionality reduction methods destroyed the overall spatiotemporal structure of flood events and failed to effectively reveal the process and underlying mechanisms of the development and evolution of flood events. The ICON‐FLOOD method proposed in this study can effectively and completely present the three‐dimensional structure of torrential rain and flood events. Also, recent intensification of torrential rain and flood events suggests that climate‐driven changes are already happening and supports calls for the consideration of climate change in flood risk management. Scientifically identifying regional torrential rain and flood events will improve our understanding of where floods are changing and how best to adapt. Key Points: Based on the three‐dimensional perspective, the flood events in the past few decades in Eurasia were comprehensively diagnosedThe study showed that the recent floods had increased significantly, contrary to the declining trend derived from two global data setsThe flood characteristics had switched to greater concentration of flood impacted areas and severer flood extremes in recent past [ABSTRACT FROM AUTHOR]