Original research articles

A 2D electrical resistivity tomography survey of a vineyard plot of the Gaillac appellation (France): interpretation with respect to possible implications on vine water supply

Abstract

Aims: The aim of this 2D electrical resistivity tomography (ERT) survey performed on a vineyard plot of the Gaillac appellation was to investigate spatial and temporal variations in subsurface water supply in relation with pedo-geological and morphological features.

Methods and results: The ERT surveys were carried out under two contrasted - dry and humid - climatic conditions. All the resistivity profiles showed the superposition of two layers: a lower layer characterized by very low resistivity values (< 40 Ω.m) corresponding to a marly molassic subsoil overlaid by an upper layer characterized by moderate to high resistivity values (300 Ω.m to 1500 Ω.m) corresponding to a silty-sandy and gravely-pebbly soil sequence. The resistivity values of the molassic subsoil stayed very low independently of water supply conditions whereas those of the soil sequence decreased by a factor 2 (300/750 Ω.m versus 750/1500 Ω.m) when the plot was close to field capacity.

Conclusion: The ERT results coupled with pedological and morphological data strongly suggest that the water flow is preferentially restricted at the molassic subsoil/soil sequence interface, short-lived and of low amplitude.

Significance and impact of the study: Consequently, the water supply regime, which points out a potential risk of drought stress for vine crops, implies a minimization strategy when choosing vegetal material and viticultural management operations

Authors


Pierre Courjault-Radé

Affiliation : Université de Toulouse, Laboratoire des Mécanismes de Transfert en Géologie (LMTG), 14, avenue E. Belin, 31400 Toulouse, France

pierrecr@lmtg.obs-mip.fr

Muriel Llubes

Affiliation : Université de Toulouse, Laboratoire d'Études en Géophysique et Océanographie Spatiales, (LEGOS) 14, avenue E. Belin, 31400 Toulouse, France


José Darrozes

Affiliation : Université de Toulouse, Laboratoire des Mécanismes de Transfert en Géologie (LMTG), 14, avenue E. Belin, 31400 Toulouse, France


Marguerite Munoz

Affiliation : Université de Toulouse, Laboratoire des Mécanismes de Transfert en Géologie (LMTG), 14, avenue E. Belin, 31400 Toulouse, France


Eric Maire

Affiliation : Université de Toulouse, Laboratoire de Géographie de l'Environnement (GEODE), 5, allées A. Machado, 31058 Toulouse cedex 9, France


Nicolas Hirissou

Affiliation : Domaine du Moulin, chemin de Bastié, 81600 Gaillac (France)

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