Author Archives: Laurent Longuevergne

Thermal-plume fibre optic tracking (T-POT) test for flow velocity measurement in groundwater boreholes

We develop an approach for measuring in-well fluid velocities using point electrical heating combined with spatially and temporally continuous temperature monitoring using distributed temperature sensing (DTS). The method uses a point heater to warm a discrete volume of water. The rate of advection of this plume, once the heating is stopped, equates to the average flow velocity in the well. […]

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2D characterization of near-surface VP/VS: surface-wave dispersion inversion versus refraction tomography

The joint study of pressure (P-) and shear (S-) wave velocities (VP and VS), as well as their ratio (VP/VS), has been used for many years at large scales but remains marginal in near-surface applications. For these applications, VP and VS are generally retrieved with seismic refraction tomography combining P and SH (shear-horizontal) waves, thus requiring two separate acquisitions. Surface-wave […]

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Contribution of the finite volume point dilution method for measurement of groundwater fluxes in a fractured aquifer

Measurement of groundwater fluxes is the basis of all hydrogeological study, from hydraulic characterization to the most advanced reactive transport modeling. Usual groundwater flux estimation with Darcy’s law may lead to cumulated errors on spatial variability, especially in fractured aquifers where local direct measurement of groundwater fluxes becomes necessary. In the present study, both classical point dilution method (PDM) and […]

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ENIGMA Innovative Training Network: 15 thèses à pourvoir

Le projet d’ITN ENIGMA (European training Network for in situ imaGing of dynaMic processes in heterogeneous subsurfAce environments) vise à former une nouvelle génération de chercheurs sur le développement de méthodes innovantes d’imagerie pour mieux contraindre les processus dynamiques dans les systèmes hydrologiques de subsurface, d’améliorer le caractère prédictif des modèles et de transférer ces innovations à la sphère socio-économique. […]

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Inferring field-scale properties of a fractured aquifer from ground surface deformation during a well test

Papers - Publications scientifiques

Fractured aquifers which bear valuable water resources are often difficult to characterize  with classical hydrogeological tools due to their intrinsic heterogeneities. Here we implement ground surface deformation tools (tiltmetry and optical leveling) to monitor groundwater pressure changes induced by a classical hydraulic test at the Ploemeur observatory. By jointly analyzing complementary time constraining data (tilt) and spatially constraining data (vertical […]

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