The hydrological propagation of atmospheric blocking into river floods in Europe

River floods are among the most disastrous and costly extreme weather events around the world. Atmospheric blocking events (persistent, slow-propagating and self-preserved weather systems that 'get stuck' and 'slow down' the atmospheric circulation) are a key feature of the persistent weather regimes over the Euro-Atlantic, playing a central role in shaping the weather and extreme weather of Europe. Notwithstanding this socioeconomic importance, the covariability between atmospheric blocking and river flooding has rarely been examined at the climate and continental scales. Our study explores the hydrological way in which atmospheric blocking propagates into river floods, and how this relationship varies across space and time. We analyse observed flood discharge across the continent together with atmospheric and terrestrial variables derived from reanalysis, resulting in >6000 rivers analysed over the last 60 years. We combine process-based hydrological analysis and climate analytics to obtain the influence of atmospheric blocking on floods in Europe across spatial and temporal scales, characterising the seasonal behavior, temporal dynamics over decades, and spatial patterns of this relationship. Our results clearly demonstrate the large-scale signature of blocking on flood behavior, and how atmospheric blocking has influenced the hydrometeorological drivers of river floods at the regional and continental scales, inducing robust patterns of variability across different flood attributes over the last 60 years. Despite strong decadal variability in the hydrological propagation of atmospheric blocking and blocking activity itself, our analyses reveal significantly changing impacts of atmospheric blocking on floods in Europe. Furthermore, our results demonstrate how the effects of atmospheric blocking interact locally with the regional hydrological characteristics. Overall, our findings link a dynamical mechanism with flood behavior within the climate system, improving the understanding of multiple features of flood variability in Europe over the last 60 years.