A critical zone observatory dedicated to suspended sediment transport: The meso-scale Galabre catchment (southern French Alps) |
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| Authors: | Cédric Legout Guilhem Freche Romain Biron Michel Esteves Oldrich Navratil Guillaume Nord Magdalena Uber Thomas Grangeon Nico Hachgenei Brice Boudevillain Céline Voiron Lorenzo Spadini |
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| Institution: | 1. Université Grenoble Alpes, Institut des Géosciences de l'Environnement, Grenoble, France;2. Université Lumière Lyon 2, Laboratoire Environnement Ville Société, Bron, France;3. Département Risques et Prévention, Bureau de Recherches Géologiques et Minières, Orléans, France |
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| Abstract: | The 20 km2 Galabre catchment belongs to the French network of critical zone observatories (OZCAR; Gaillardet et al., Vadose Zone Journal, 2018, 17(1), 1–24). It is representative of the sedimentary lithology and meteorological forcing found in Mediterranean and mountainous areas. Due to the presence of highly erodible and sloping badlands on various lithologies, the site was instrumented in 2007 to understand the dynamics of suspended sediments (SS) in such areas. Two meteorological stations including measurements of air temperature, wind speed and direction, air moisture, rainfall intensity, raindrop size and velocity distribution were installed both in the upper and lower part of the catchment. At the catchment outlet, a gauging station records the water level, temperature and turbidity (10 min time-step). Stream water samples are collected automatically to estimate SS concentration-turbidity relationships, allowing quantification of SS fluxes with known uncertainty. The sediment samples are further characterized by measuring their particle size distributions and by applying a low-cost sediment fingerprinting approach using spectrocolorimetric tracers. Thus, the contributions of badlands located on different lithologies to total SS flux are quantified at a high temporal resolution, providing the opportunity to better analyse the links between meteorological forcing variability and watershed hydrosedimentary response. The set of measurements was extended to the dissolved phase in 2017. Both stream water electrical conductivity and major ion concentrations are measured each week and every 3 h during storm events. This extension of measurements to the dissolved phase will allow progress in understanding both the origin of the water during the events and the partitioning between particulate and dissolved fluxes of solutes in the critical zone. All data sets are available at https://doi.osug.fr/public/DRAIXBLEONE_GAL/index.html . |
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| Keywords: | critical zone hydrochemistry hydrology meteorology observatory sediment fingerprinting sediment sources sediment transport |
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