How do transitions from dry to wet states propagate to drought-to-flood transitions?

Transitions from dry to wet states challenge water management and can lead to severe impacts on infrastructure and water quality. Such transitions occur both in the atmosphere and hydrosphere, that is, from dry-to-wet spells and from droughts to floods, respectively. While transitions from dry-to-wet spells, i.e. from negative to positive precipitation anomalies, are relatively well studied, it is yet unclear how they propagate to hydrological transitions from negative to positive streamflow anomalies. Here, we address the question of how often, where, when, and why meteorological transitions do propagate to drought-to-flood transitions using a large-sample dataset of precipitation and streamflow observations over Europe. Our analysis of the relationship between meteorological and hydrological transition events shows that only 10% and 25% of the dry-to-wet transitions propagate to drought-to-flood transitions at a monthly and annual time scale, respectively. The limiting factors for transition propagation are clear differences in the seasonality of meteorological and hydrological transitions and the limited propagation of wet spells, in particular those with low precipitation intensities and small volumes. Transition propagation is most likely in small and rainy catchments, that is, catchments with a relatively direct link between precipitation and streamflow and limited storage influences. We conclude that hydrological transitions are only weakly related to meteorological transitions, which highlights the important influence of land-surface and storage processes for the development of hydrological transitions. As a consequence, changes in dry-to-wet transitions are a relatively poor proxy for future changes in drought-to-flood transitions.