Bhavani Benard

PhD student

The hydrothermal system of Piton des Neiges (La Réunion): A comprehensive approach using major, trace elements and stable isotope chemistry of hot springs

Supervisors : Vincent FAMIN and Bertrand AUNAY (BRGM)

adress :Laboratoire GéoSciences Réunion - IPGP
            Université de la Réunion
            15, Avenue René Cassin, CS92003
            97744 Saint Denis messagerie cedex 9 La Réunion

landline: +262 (0)262 93 82 24

mobile: +262 (0)692 04 45 95


In 3 million years of mantle-driven activity, Piton des Neiges volcano (La Réunion) has built a large structure above sea level (>3000m). Its last activity (12 to 20 Ka) is characterized by silicic formations like trachytic lavas and a large syenite intrusive complex. Its hydrothermal system shows potential for geothermal exploitation with a thermal gradient measured at up to 18˚C/100m.

The hydrothermal activity is highlighted by numerous hot springs flowing out of old units with fracture-related permeability induced by volcanic intrusions. In such hydrogeological settings, a good understanding of thermal fluid circulations is needed to locate sufficient fluid flow for geothermal exploitation, which is the aim of my PhD research. 

Prospection has led to the sampling of 71 hot springs, on which we performed analysis on major, trace elements and O, H, C, Cl, Li and Sr isotopes. We also monitored for a full hydrological year the conductivity and temperature of two springs, and aquired monthly data of O and H isotopes on two springs and two rain collectors. With this data, we are able to study the origin of waters and gas, reservoir connectivity and water-rock interaction. From these results, we are building a conceptual model for thermal fluid circulations that will assess the possibility of geothermal eploitation and address the issue of the precise location of the resource.


  • Feb 17 - PhD student - University of La Réunion, Laboratoire Gésociences Réunion, Saint-Denis (La Réunion)
    • See Research tab
  • Sept 15 - Feb 17 Groundwater engineer - BRGM, Mamoudzou (Mayotte Island)
    • LESELAM Project : Fight against soil erosion and siltation of the lagoon in Mayotte Island
    • Monitoring of water resource's quality and availability
    • Optimization of groundwater exploitation in the water supply system
  • Feb 15 - Sept 15 Internship - BRGM and University of La Réunion, Laboratoire Gésociences Réunion, Saint-Denis (La Réunion)
    • Prospection and characterization of hot springs in the cirque of Salazie (La Réunion)
  • Apr 14 - July 14 Internship - Evian Volvic World Sources, Evian-les-Bains (France)
    • Development of a conceptual model of Evian natural mineral water's discharge area
  • June 13 - July 13 Internship - Antea Group, Saint-Denis (La Réunion)
    • Logging of a 150 meters deep borehole


  • 2015  Master's degree in Groundwater, soil and enrironment studies - Class rank: 2/22
    • University of Avignon and lands of Vaucluse (France)
  • 2013  Bachelor's degree in Geosciences - Valedictorian
    • University of La Réunion
  •  2018 - 2019 Environmental geochemistry - Master's students
  •  2018 - 2019 Remote sensing, GIS and GPS - Bachelor's students
  • Bénard B., Famin V., Agrinier P., Aunay B., Lebeau G., Sanjuan B., Vimeux F., Bardoux G., Dezayes C. (2019). Origin and fate of hydrothermal fluids at Piton des Neiges volcano (Réunion Island): A geochemical and isotopic (O, H, C, Sr, Li, Cl) study of thermal springs. Journal of Volcanology and Geothermal Research, 106682.
  • Bénard B., Famin V., Agrinier P., Aunay B., Sanjuan B., Dezayes C. (2018) Origin and fate of thermal fluids at a hot spot volcano (Piton des Neiges, La Réunion) from major, trace elements and O-H-C-Sr isotopes of hot springs, Abstract H33J-2219 presented at 2018 Fall Meeting, AGU, Washington, D.C., 10-14 Dec.
  • Bénard B., Famin V., Aunay B., Agrinier P., Lebeau G. (2018) The hydrothermal system of Piton des Neiges (Réunion Island, Indian Ocean): constraints from geochemistry and stable isotope chemistry. Geophysical Research Abstracts Vol. 20, EGU2018-11971
  • Landemaine V., Lidon B., Lopez J.M., Dejean C., Bozza J.L., Benard B., Parizot M., Desprats J.F., Cerdan O. (2017) Quantification of sediment export from two contrasted catchments of theMayotte Island: a multi-scale observatory to fight against soil erosion and siltation of the lagoon in Mayotte Island. Geophysical Research Abstracts Vol. 19, EGU2017-10504-1
  • Lopez J.M., Lidon B., Bozza J.L., Dejean C., Cerdan O., Bénard B., Parizot M., Puvilland P., Desprats J.F., Colas B., Rinaudo J.D., Saïd K., Mosnier S. (2016) The LESELAM observatory (Fight against Soil Erosion and siltation of the lagoon in Mayotte Island). Geophysical Research Abstracts Vol. 18, EGU2016-11805