River Flow Dynamics across Europe: Insights from continental to regional scales

Abstract

River flow is affected by change in climate and land use. Today, we see many different magnitudes and directions of trends of change across European rivers with respect to streamflow, which affects water supply and hydrological extremes such as floods and droughts. Moreover, the drivers of change in streamflow and its temporal trends vary on multiple scales from local to regional to continental.  In this study, we identify changes, trends and possible patterns of change in the hydrological response across the whole of Europe, as well as its underlying drivers. We do this by using multi-decadal streamflow data that was collected from more than 15000 European stream flow gauging stations in 39 European countries. This large-sample dataset, named EStreams and set to be published in 2024, provides valuable new perspectives on the hydrological response in Europe. In the analysis, similar catchments across Europe were clustered into groups, based on their hydrological response, as characterised by a wide range of hydrological signatures. This allowed to identify the different controls of hydrological response between the groups, such as climate, landscape and seasonal water balance. Furthermore, the high-resolution streamflow dataset used allowed for the opportunity to zoom in further and gave a meaningful look at the differences within the clustered groups. This ensured that it was possible to investigate the differences in hydrological responses that were primarily dictated by landscape characteristics, as within cluster catchments are assumed to have limited climate variability.  Altogether, mapping out the different hydrological responses across Europe and the differences in hydrological response within nested sub-catchments gave a comprehensive identification and quantitative description of dominant landscape characteristics shaping the hydrological response within clusters of hydro-climatically distinct European regions.