Bhavani Benard

Postdoctoral researcher


Understanding the hydrosystem of Piton de la Fournaise using major, trace elements and stable isotope chemistry - Geothermal exploration

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


Postoctoral research : Geochemical study of the hydrosystem of Piton de La Fournaise volcano - Geothermal exploration

Piton de la Fournaise, active volcano of Reunion Island, possibly hosts a geothermal resource. The western part of the edifice shows evidence of a dense conductive body and soil gas anomalies that could be due to the presence of an active hydrothermal system. However, there are no known thermal springs. This is possibly due to the high lateral permeability which favors horizontal circulations, thus preventing the upflow of thermal waters. Therefore, there could be hidden hydrothermal circluations, diluted in the global hydrosystem. This geochemical study aims at identifying and characterizing a hydrothermal component in the hydrosystem of Piton de la Fournaise.

PhD : Characterization of the hydrothermal system of Piton des Neiges using geochemical and isotopic methods

Video of the thesis defense :

Piton des Neiges volcano (Reunion Island) shows evidence of a hydrothermal activity that could potentially be used for geothermal energy generation. However, so far, the characteristics of this hydrothermal system (fluid temperature, heat source, recharge, etc.) remain too uncertain to consider exploiting it. To evaluate its geothermal potential, we carried out a vast prospecting campaign for markers of hydrothermal activity, performed geochemical analysis (major, trace elements, δ18O, δD, δ13C, 87Sr/86Sr, δ7Li, δ37Cl) on 38 thermal springs (including 21 new ones) and monitored the resource over time.

Our results show that the hydrothermal activity is concentrated in the cirques of Cilaos and Salazie, along the N30 rift zone and inside a supposed caldera. Recharge is meteoric, local, plurennial and mainly comes from cyclones. There is no hydraulic connection between the two cirques, and barely with the ocean. Thermal waters interact with mantellic CO2, other more superficial magmatic gases (inside the edifice or at its base) and differentiated rocks. Geochemical geothermometers indicate a water-rock interaction temperature of above 210°C. The hydrothermal system of Piton des Neiges thus reaches computed temperatures compatible with high temperature geothermal use.

Our work steers the next exploratory steps toward the geologic structures associated with the supposed caldera and the rift zone. Their geometry, their hydrodynamic property and their relation with the heat source will be decisive in the choice of a drilling site.


  • May 20 - Postdoctoral Researcher - University of La Réunion, Laboratoire Gésociences Réunion, Saint-Denis (La Réunion)
    • See Research tab
  • Feb 17 - May 20 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


  • 2020  PhD in Earth and Planetary Sciences
    • University of La Réunion (France)
  • 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 (France)
  •  2018 - 2020 Environmental geochemistry - Master's students
  •  2018 - 2020 Remote sensing, GIS and GPS - Bachelor's students

Multimedia content

Thesis defense video:

Articles and Conferences:

  • Paquez C., Famin V., Villeneuve N., Michon L., Bénard B. (2020). How do cirques form in ocean island volcanoes: the case of Piton des Neiges (Réunion Island, Indian Ocean). EGU2020-13517.
  • 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