Changing flood-generating mechanisms and their impacts on flood characteristics in snow-dominated catchments

Global warming is altering snowmelt dynamics and flood generating mechanisms, yet their compound effects on cold-region floods remain unclear. Here, we investigate flood mechanism transitions and their drivers across 424 Northern Hemisphere snow-dominated catchments. Through comparative analysis, we pinpoint the specific impacts of these shifts on flood characteristics. Our results indicate that 48.3% of the catchments have undergone a snowmelt-to-rainfall transition in flood generating mechanisms. While this has not systematically altered long-term flood magnitude trends, it has significantly steepened the flood rising limb. Furthermore, although rising temperatures have advanced the timing of snowmelt and rain-on-snow floods, the shift toward rainfall dominance has largely offset this trend, leading to a stronger synchronization between flood timing and extreme precipitation. These findings offer critical insights for flood forecasting and water management in snow-dominated regions.