Monitoring water accumulation in a glacier using magnetic resonance imaging

• Published in: The Cryosphere
• Main Authors: Legchenko, A., Vincent, C., Baltassat, Jean-Michel, Girard, J.F., Thibert, Emmanuel, Gagliardini, O., Descloitres, M., Gilbert, A., Garambois, S., Chevalier, A., Guyard, H.
• Other Authors: Laboratoire d'étude des transferts en hydrologie et environnement (LTHE), Observatoire des Sciences de l'Univers de Grenoble (OSUG), Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB Université de Savoie Université de Chambéry )-Centre National de la Recherche Scientifique (CNRS)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB Université de Savoie Université de Chambéry )-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Institut National Polytechnique de Grenoble (INPG)-Centre National de la Recherche Scientifique (CNRS), Laboratoire de glaciologie et géophysique de l'environnement (LGGE), Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB Université de Savoie Université de Chambéry )-Centre National de la Recherche Scientifique (CNRS)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB Université de Savoie Université de Chambéry )-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Bureau de Recherches Géologiques et Minières (BRGM), Erosion torrentielle neige et avalanches (UR ETGR (ETNA)), Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA), Département Géotechnique, Environnement, Risques naturels et Sciences de la terre (IFSTTAR/GERS), Institut Français des Sciences et Technologies des Transports, de l'Aménagement et des Réseaux (IFSTTAR)-Université de Lyon-PRES Université Nantes Angers Le Mans (UNAM)-PRES Université Paris-Est-PRES Université de Grenoble, town of Saint-Gervais (France), Prefecture de la Haute Savoie (France), Service de Restauration des Terrains en Montagne (RTM)
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2014
• Subjects: NMR SPECTROSCOPY; IMAGERY; GROUNDWATER; EAU SOUTERRAINE; IMAGERIE; RESONANCE MAGNETIQUE NUCLEAIRE; GLACIER; [SDE]Environmental Sciences; The Cryosphere
• Online Access: https://hal.science/hal-01141631; https://hal.science/hal-01141631/document; https://hal.science/hal-01141631/file/gr2014-pub00043705.pdf; https://doi.org/10.5194/tc-8-155-2014

[Departement_IRSTEA]Eaux [TR1_IRSTEA]RIVAGE International audience Tete Rousse is a small polythermal glacier located in the Mont Blanc area (French Alps) at an altitude of 3100 to 3300 m. In 1892, an outburst flood from this glacier released about 200 000m(3) of water mixed with ice, causing much damage. A new accumulation of melt water in the glacier was not excluded. The uncertainty related to such glacier conditions initiated an extensive geophysical study for evaluating the hazard. Using three-dimensional surface nuclear magnetic resonance imaging (3-D-SNMR), we showed that the temperate part of the Tete Rousse glacier contains two separate water-filled caverns (central and upper caverns). In 2009, the central cavern contained about 55 000m(3) of water. Since 2010, the cavern is drained every year. We monitored the changes caused by this pumping in the water distribution within the glacier body. Twice a year, we carried out magnetic resonance imaging of the entire glacier and estimated the volume of water accumulated in the central cavern. Our results show changes in cavern geometry and recharge rate: in two years, the central cavern lost about 73% of its initial volume, but 65% was lost in one year after the first pumping. We also observed that, after being drained, the cavern was recharged at an average rate of 20 to 25m(3) d(-1) during the winter months and 120 to 180m(3) d(-1) in summer. These observations illustrate how ice, water and air may refill englacial volume being emptied by artificial draining. Comparison of the 3-D-SNMR results with those obtained by drilling and pumping showed a very good correspondence, confirming the high reliability of 3-D-SNMR imaging.