Imaging artificial salt water infiltration using electrical resistivity tomography constrained by geostatistical data

JOURNAL OF HYDROLOGY

卷:438

Article

Hermans, Thomas¹  Vandenbohede, Alexander²  Lebbe, Luc²  Martin, Roland³  Kemna, Andreas³ 

[1] Univ Liege, ArGEnCo GEO3, Aspirant FRS FNRS, B-4000 Liege, Belgium

[2] Univ Ghent, Dept Geol & Soil Sci, Res Unit Groundwater Modelling, B-9000 Ghent, Belgium

[3] Univ Bonn, Steinmann Inst, Dept Geodynam & Geophys, D-53115 Bonn, Germany

关键词: Salt water intrusion;    Electrical resistivity tomography;    Geostatistical constraint;    Variogram;    Inversion;    Regularization;   

DOI  :  10.1016/j.jhydrol.2012.03.021

来源: Elsevier

【 摘 要 】

Electrical resistivity tomography is a well-known technique to monitor fresh-salt water transitions. In such environments, boreholes are often used to validate geophysical results but rarely used to constrain the geoelectrical inversion. To estimate the extent of salt water infiltration in the dune area of a Natural Reserve (Westhoek, Belgium), electrical resistivity tomography profiles were carried out together with borehole electromagnetic measurements. The latter were used to calculate a vertical variogram, representative of the study site. Then, a geostatistical constraint, in the form of an a priori model covariance matrix based on the variogram, was imposed as regularization to solve the electrical inverse problem. Inversion results enabled to determine the extension of the salt water plume laterally and at depth, but also to estimate the total dissolved solid content within the plume. These results are in agreement with the hydrogeological data of the site. A comparison with borehole data showed that the inversion results with geostatistical constraints are much more representative of the seawater body (in terms of total dissolved solids, extension and height) than results using standard smoothness-constrained inversion. The field results obtained for the Westhoek site emphasize the need to go beyond standard smoothness-constrained images and to use available borehole data as prior information to constrain the inversion. (C) 2012 Elsevier B.V. All rights reserved.

【 授权许可】

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