Résumé
Intermittent and ephemeral streams are found across different climate, bedrock, and land use types(Messager et al., 2021). Across these gradients and the various size of intermittent catchments, drivers ofintermittency usually result from the complex interaction of meteorology, geology and land cover (Costiganet al., 2015). Climate aridity is a good predictor of flow cessation and occurrence of non-permanent streamsat the global scale while in wet and temperate regions, the occurrence of flow cessation is usually associatedwith small catchment sizes and steeper topography (Messager et al., 2021; Snelder et al., 2013; Sauquet etal., 2021). In this work, we hypothesized that at the scale of headwater catchments (< 20 km2) and targetingnon-permanent streams as recommended by Costigan et al. (2015), it would be possible to identify factorscontrolling flow intermittence across climates, geologies and land covers. We computed several metrics offlow intermittence from long-term flow records at 16 French CZO (OZCAR-RI) catchments and analyzedhow these metrics were correlated with proxies of climate, catchment size, hydrological characteristics, landuse and geology types. We found a diversity of flow intermittence regimes across these 16 catchments and formost of them, the interannual variability at a given catchment was higher than the variability among them.The spatial variability of no-flow metrics among catchments was highly correlated with the seasonal indexfor precipitation, and meteorological indices (e.g. mean annual rainfall, reference ET, temperature). Theinter annual variability was not correlated to the same meteorological variables for all catchments, whichsuggests different processes might be responsible for flow cessation in the different streams. We discuss thesensitivity to threshold values used for no-flow identification and the importance of acquiring accurate lowflow values in Observatories to study climate evolution especially droughts. a more integrated approach ofsuch intermittent streams is needed to investigate whether their diversity can be explained by the characteristicsof groundwater-stream or riparian zone-stream interfaces, and to which extend this diversity of flowregime is associated to different ecological functions.Costigan, K. H., Jaeger, K. L., Goss, C. W., Fritz, K. M., and Goebel, P. C. (2016) Understanding controlson flow permanence in intermittent rivers to aid ecological research: integrating meteorology, geology andland cover. Ecohydrol., 9: 1141–1153. doi: 10.1002/eco.1712.Messager, M.L., Lehner, B., Cockburn, C. et al. (2021) Global prevalence of non-perennial rivers andstreams. Nature 594, 391–397, https://doi.org/10.1038/s41586-021-03565-5Sauquet, E., Shanafield, M., Hammond, J.C., Sefton, C., Leigh, C., Datry, T. (2021). Classification andtrends in intermittent river flow regimes in Australia, northwestern Europe and USA: A global perspective,Journal of Hydrology, 597, 126170, https://doi.org/10.1016/j.jhydrol.2021.126170Snelder, T. H., Datry, T., Lamouroux, N., Larned, S. T., Sauquet, E., Pella, H., and Catalogne, C. (2013)Regionalization of patterns of flow intermittence from gauging station records, Hydrol. Earth Syst. Sci.,17, 2685–2699, https://doi.org/10.5194/hess-17-2685-2013