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Characterization of subsurface fluxes at the plot scale during flash floods in the Valescure catchment, France
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  • Christophe BOUVIER,
  • Marko Adamovic,
  • Pierre-Alain Ayral,
  • Pascal Brunet,
  • Jean-Francois Didon-Lescot,
  • Jean-Marc Domergue,
  • Rosario Spinelli
Christophe BOUVIER
HydroSciences Montpellier
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Marko Adamovic
HydroSciences Montpellier
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Pierre-Alain Ayral
Ecole des Mines d\'Ales
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Pascal Brunet
HydroSciences Montpellier
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Jean-Francois Didon-Lescot
UMR - 7300 ESPACE CNRS
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Jean-Marc Domergue
UMR - 7300 ESPACE CNRS
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Rosario Spinelli
Ecole des Mines d\'Ales
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Abstract

This study focuses on a 10-m2 plot within a granitic hillslope in Cevennes mountainous area in France, in order to study infiltration and subsurface hydrological processes during heavy rainfalls and flash floods. The monitoring device included water content at several depths (0-70cm for the shallow soil water; 0-10m for the deep water) during both intense artificial and natural rainfall events, chemical and physical tracers, time-lapse electrical resistivity tomography. During the most intense events, the infiltrated water was estimated to be some hundreds of millimeters, which largely exceeds the topsoil capacity (≤40 cm deep in most of the cases). The weathered/fractured rock area below the soil clearly has an active role in the water storage and sub-surface flow dynamics. Vertical flow was dominant in the first 0-10m, and lateral flow was effective at 8-10 m depth, at the top of the saturated area. The speed of the vertical flow was estimated between 1 and 10 m/h, whereas it was estimated between 0.1 and 1 m/h for the lateral flow. The interpretation of the experiments led to a local pattern of the 2D-hydrological processes and profile properties. It suggests that fast triggering of floods at the catchment scale cannot be explained by a mass transfer within the hillslope, but should be due to a pressure wave propagation through the bedrock fractures, which allows exfiltration of the water downstream the hillslope.

Peer review status:Published

04 Nov 2020Submitted to Hydrological Processes
06 Nov 2020Submission Checks Completed
06 Nov 2020Assigned to Editor
06 Nov 2020Reviewer(s) Assigned
25 Jan 2021Review(s) Completed, Editorial Evaluation Pending
27 Jan 2021Editorial Decision: Revise Minor
19 Feb 20211st Revision Received
22 Feb 2021Submission Checks Completed
22 Feb 2021Assigned to Editor
22 Feb 2021Reviewer(s) Assigned
23 Mar 2021Review(s) Completed, Editorial Evaluation Pending
23 Mar 2021Editorial Decision: Accept
Apr 2021Published in Hydrological Processes volume 35 issue 4. 10.1002/hyp.14144