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Fnew was highest in impermeable bedrock catchments (i.e. with a dominance of marls and claystone, Fnew = 4.5 to 11.9 %), increasing with higher specific daily streamflow (Fnew up to 45 % in one catchment). In catchments with an important fraction of permeable sandstone and conglomerates, high Fnew variability with specific streamflow (Fnew rising to 25 % in one catchment) was also found, despite a damped and delayed hydrograph response to precipitation and low Fnew (means of 1.3 to 2.7 %).

In the weathered bedrock catchments (i.e. dominated by schists and quartzites), rapid infiltration led to large fractions of water that was older than 12 weeks (~80 %) and very small fractions of water younger than two weeks (~3.5 %). Fnew variability with streamflow was near zero, contrasting with the rapid response of the hydrograph to precipitation events. At high specific streamflow, Fnew was also correlated with bedrock geology and certain land use types.

The extensive data set of streamflow δ18O enabled us to link water storage and release to bedrock geology. Such information is key for a better anticipation of water storage and release functions under changing climate conditions, i.e. long dry spells and high-intensity precipitation events. ***This entry has been automatically imported via OpenAlex by LIST harvest scripts. Please refer to doi.org/10.5194/egusphere-2025-1530-ac1 for the original and latest version of the publication***