Caractérisation de l'organisation spatiale de la couverture pédologique par mesure de la résistivité électrique : Application à la cartographie des sols en contexte agricole

Abstract : The increasing importance of environmental issues has led to a renewed interest in soils. Soils are subjected to numerous hazards that may threaten their quality and affect their properties. An optimal management and protection of soils goes through an accurate knowledge of their spatial variability and the identification of vulnerable areas. The goal of the presented work is to make use of electrical survey data through relying on the discriminating power of electrical resistivity towards the different horizons composing the soil cover in order to characterize their geometrical and typological properties. First of all, modeling of multi-depth electrical resistivity measurements was performed in order to 1)define an optimal survey strategy and 2)assess the efficiency and limitations of electrical method. This step allowed us to estimate what were the minimal dimensions of a pedological heterogeneity that could be detected and the influence of the following different parameters on its detectability: inter-profiles spacing used during measurements, depth and thickness of the heterogeneity, resistivity contrast between heterogeneity and surroundings. The experimental study of a trench dug along several metres, including soil sampling and resistivity measurements, permitted us to characterize the vertical and lateral variability of the soil cover’s horizons. Relationships between electrical resistivity and pedological properties such as mass water content, volume water content or soil bulk density were established. Finally, a new and original method for exploiting data generated by multi-depth electric resistivity survey was put forward. The method is based on the confrontation of geophysical and pedological taxonomies, and on the mapping of vertical apparent resistivity profiles. It allowed finding back soil cartographic unit outlines that were coherent with the previously available soil map. This approach is a valuable tool for studying soil cover spatial variability and has potential for setting up a (semi-)automated method of soil mapping.
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Solène Buvat. Caractérisation de l'organisation spatiale de la couverture pédologique par mesure de la résistivité électrique : Application à la cartographie des sols en contexte agricole. Géophysique [physics.geo-ph]. Université Pierre et Marie Curie (Paris 6), 2012. Français. ⟨tel-01591389⟩

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