Piece 6 - the critical zone
How does the aquifer itself evolve?
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The Critical Zone
Groundwater, weathering, vegetation and erosion
The basement aquifer is part of a much larger critical zone, extending from the vegetation canopy to the depth reached by groundwater circulation. In this system, groundwater is not only stored and transported: it also participates in chemical weathering and the export of dissolved elements.
Key findings
- Although smectites represent only about 4% of the soil volume, their dissolution accounts for approximately 75% of dissolved silica export, while primary silicate dissolution contributes about 15%.
- Vegetation strongly modifies water and solute fluxes. At Mule Hole, evapotranspiration limits runoff, while 80–90% of the annual solute flux exported by the stream passes through vegetation.
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Water budget (in mm yr1) of Mule Hole using long term average rainfall (1100 mm yr1, See Violette et al., 2010a) and processes affecting water and chemical fluxes at the vegetation-soil profile scale.
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The groundwater system is part of a coupled rock–soil–water–vegetation system in which hydrology, weathering and biological processes interact.
Publications related to critical zone
OZCAR: The French Network of Critical Zone Observatories
J. Gaillardet, I. Braud, F. Hankard, S. Anquetin, O. Bour, N. Dorfliger, J.R. de Dreuzy, S. Galle, C. Galy, S. Gogo, L. Gourcy, F. Habets, F. Laggoun, L. Longuevergne, T. Le Borgne, F. Naaim-Bouvet, G. Nord, V. Simonneaux, D. Six, T. Tallec, C. Valentin, G. Abril, P. Allemand, A. Arènes, B. Arfib, L. Arnaud, N. Arnaud, P. Arnaud, S. Audry, V. Bailly Comte, C. Batiot, A. Battais, H. Bellot, E. Bernard, C. Bertrand, H. Bessière, S. Binet, J. Bodin, X. Bodin, L. Boithias, J. Bouchez, B. Boudevillain, I. Bouzou Moussa, F. Branger, J. J. Braun, P. Brunet, B. Caceres, D. Calmels, B. Cappelaere, H. Celle-Jeanton, F. Chabaux, K. Chalikakis, C. Champollion, Y. Copard, C. Cotel, P. Davy, P. Deline, G. Delrieu, J. Demarty, C. Dessert, M. Dumont, C. Emblanch, J. Ezzahar, M. Estèves, V. Favier, M. Faucheux, N. Filizola, P. Flammarion, P. Floury, O. Fovet, M. Fournier, A. J. Francez, L. Gandois, C. Gascuel, E. Gayer, C. Genthon, M. F. Gérard, D. Gilbert, I. Gouttevin, M. Grippa, G. Gruau, A. Jardani, L. Jeanneau, J. L. Join, H. Jourde, F. Karbou, D. Labat, Y. Lagadeuc, E. Lajeunesse, R. Lastennet, W. Lavado, E. Lawin, T. Lebel, C. Le Bouteiller, C. Legout, Y. Lejeune, E. Le Meur, N. Le Moigne, J. Lions, A. Lucas, J. P. Malet, C. Marais-Sicre, J. C. Maréchal, C. Marlin, P. Martin, J. Martins, J. M. Martinez, N. Massei, A. Mauclerc, N. Mazzilli, J. Molénat, P. Moreira-Turcq, E. Mougin, S. Morin, J. Ndam Ngoupayou, G. Panthou, C. Peugeot, G. Picard, M. C. Pierret, G. Porel, A. Probst, J. L. Probst, A. Rabatel, D. Raclot, L. Ravanel, F. Rejiba, P. René, O. Ribolzi, J. Riotte, A. Rivière, H. Robain, L. Ruiz, J. M. Sanchez-Perez, W. Santini, S. Sauvage, P. Schoeneich, J. L. Seidel, M. Sekhar, O. Sengtaheuanghoung, N. Silvera, M. Steinmann, A. Soruco, G. Tallec, E. Thibert, D. Valdes Lao, C. Vincent, D. Viville, P. Wagnon, R. Zitouna
Vadose Zone Journal, vol. 17, 2018, p. 180067
Vegetation impact on stream chemical fluxes: Mule Hole watershed (South India)
Jean Riotte, Jean-Christophe Maréchal, Stéphane Audry, C. Kumar, J.P. Bedimo Bedimo, Laurent Ruiz, Muddu Sekhar, M. Cisel, , M.R.R. Varma, C. Lagane, P. Reddy, Jean-Jacques Braun
Geochimica et Cosmochimica Acta, vol. 145, 2014, pp. 116-138
Jean-Jacques Braun, Jean-Christophe Maréchal, Jean Riotte, Jean-Loup Boeglin, Jean-Pierre {Bedimo Bedimo}, Jules Remy {Ndam Ngoupayou}, Brunot Nyeck, Henri Robain, M. Sekhar, Stéphane Audry, Jérôme Viers
Geochimica et Cosmochimica Acta, vol. 99, 2012, pp. 243-270