Evin G. auteur aut IRD Hingray B. auteur aut IRD Thirel G. auteur aut IRD Ducharne A. auteur aut IRD Strohmenger L. auteur aut IRD Corre L. auteur aut IRD Tramblay Yves auteur aut IRD Vidal J. P. auteur aut IRD Bonneau J. auteur aut IRD Colleoni F. auteur aut IRD Gailhard J. auteur aut IRD Habets F. auteur aut IRD Hendrickx F. auteur aut IRD Héraut L. auteur aut IRD Huang P. auteur aut IRD Le Lay M. auteur aut IRD Magand C. auteur aut IRD Marson P. auteur aut IRD Monteil C. auteur aut IRD Munier S. auteur aut IRD Reverdy A. auteur aut IRD Soubeyroux J. M. auteur aut IRD Robin Y. auteur aut IRD Vergnes J. P. auteur aut IRD Vrac M. auteur aut IRD Sauquet E. auteur aut IRD text journalArticle eng text/pdf reformatted digital access Multi-scenario, multi-model ensembles of hydrological projections are widely used to describe possible futures of regional hydrology and inform adaptation strategies. The Explore2 dataset is such an ensemble of river flow projections in Metropolitan France. It provides future simulations for 1735 catchments with modeling chains composed of different hydrological models forced by 36 regional climate projections based on bias-adjusted EUROCORDEX simulations. This study assesses the uncertainties of this ensemble with QUALYPSO, a method specifically designed to deal with incomplete ensembles and to disentangle and quantify all uncertainty sources, including that due to internal variability.Focusing on results obtained at the end of the century, this study shows a strong agreement between modeling chains towards decreases in low flows in a large southern part of France for a high-emission scenario, and very uncertain changes for the annual mean and high flows. Emission scenario uncertainty is the dominant source of uncertainty for low flows over the whole of France, and for mean annual flows in southeastern France. The contribution of the global and regional climate models is important for mean and high flows, especially in rainfall-dominated areas. Regional climate models contribute considerable uncertainty to low flows, much more than global models. The contribution of hydrological model uncertainty is large for low flows, moderate for mean annual flows, and small for high flows. For all climate and hydrological indicators, internal variability is often large and cannot be overlooked. It is often of the same order and sometimes larger than the uncertainty on the climate change response. specialized 021 020 062 30 4 1023-1051 2026 1027-5606 https://www.documentation.ird.fr/hor/fdi:010096403 10.5194/hess-30-1023-2026 1027-5606 [F B010096403] https://www.documentation.ird.fr/hor/fdi:010096403 https://horizon.documentation.ird.fr/exl-doc/pleins_textes/2026-03/010096403.pdf IRD - Base Horizon / Pleins textes 2026-03-11 2026-03-11 fdi:010096403 fre