Atmospheric rivers are associated with nine out of every 10 floods in major global river basins

This publication examines the global role of atmospheric rivers (ARs) in driving major flood events, demonstrating that they are associated with the vast majority of large floods worldwide. Using data from 119 major flood events across 50 large river basins between 1999 and 2018, the study shows that atmospheric rivers coincided with 74% of flood-affected areas and 89% of entire river basins during flood events. Importantly, AR influences were detected not only during floods but also in the days leading up to them, highlighting their dual role as both immediate flood triggers and antecedent preconditioners that saturate catchments and increase flood susceptibility. 

The analysis adopts a basin-scale perspective, examining entire river basins as well as nested sub-basins, to capture upstream–downstream hydrological processes. Results indicate that even when ARs do not directly overlap flooded areas, their presence elsewhere in the basin can significantly contribute to flood generation through enhanced runoff, soil moisture preconditioning, and hydrological connectivity. This finding helps explain why flood impacts often extend beyond the immediate footprint of extreme precipitation.