Causes, impacts and changes of extreme river floods

Floods cause enormous damage around the world and affect more people than any other natural hazard. They often come as a surprise for affected people and disaster managers. Risk reduction and adaptation rely on understanding the causes and impacts of floods, and how they may change in the future. This review provides a synthesis of the atmospheric, land surface and socio-economic processes that produce extreme river floods and disastrous damages. We explore the differences in causative mechanisms between extreme floods and smaller floods. Vulnerability and exposure of people and assets to flooding are major controls on flood impacts; vulnerability is a particularly effective lever for reducing the impact. Our review of past changes in flood magnitudes finds spatially coherent trends in some regions of the world, suggesting a climate change signal that is stronger than other drivers of change in these locations. Past and future trends in flood impacts show widespread increases, mostly driven by economic and population growth. However, for the recent decades we find a decrease in fatalities and affected people which is attributed to risk reduction measures, for instance, by improved risk awareness, emergency management and flood defence. Effectively reducing the risks associated with extreme floods requires an understanding of their distinctive generating processes and addressing the sources of surprise, including cognitive biases, in flood risk assessment.

MERZ Bruno;  BLOSCHL Gunter;  VOROGUSHYN Sergiy;  DOTTORI Francesco;  AERTS Jeroen C. J. H.;  BATES Paul;  BERTOLA Miriam;  KEMTER Matthias;  KREIBICH Heidi;  LALL Upmanu;  MACDONALD Elena; 

2021-09-21

SPRINGERNATURE

JRC120240

2662-138X (online),   

https://www.nature.com/articles/s43017-021-00195-3,    https://publications.jrc.ec.europa.eu/repository/handle/JRC120240,   

10.1038/s43017-021-00195-3 (online),