Papers

Interpretation of magnetic resonance measurements in the varying earth’s magnetic field

At the scale of a magnetic resonance sounding (MRS) field setup, the earth’s magnetic field in the subsurface may vary laterally with depth and over time. These variations can be caused by different natural factors and generally cannot be compensated for by accurate tuning of the measuring device. The varying geomagnetic field (GMF) causes nonresonance conditions of excitation that affect […]

Papers geophysics

Distributed Temperature Sensing as a down-hole tool in hydrogeology

Distributed Temperature Sensing (DTS) technology enables down-hole temperature monitoring to study hydrogeological processes at unprecedentedly high frequency and spatial resolution. DTS has been widely applied in passive mode in site investigations of groundwater ow, in-well flow, and subsurface thermal property estimation. However, recent years have seen the further development of the use of DTS in an active mode (A-DTS) for which heat sources are deployed. […]

Papers geology, groundwater, high frequency, hydrogeology

Using DGT passive samplers and MC-ICPMS to determine Pb and Zn isotopic signature of natural water

Increasing numbers of studies use zinc (Zn) and lead (Pb) isotopic compositions to track anthropogenic pollutions in surface water and groundwater. However, given the low content in Pb and Zn in natural waters, we are often restricted for analysis by MC-ICPMS. One solution is to use passive Diffusive Gradients in Thin films (DGT) samplers for in-situ preconcentration of these metals. […]

Papers chemical, dissolution, groundwater, mineral

Field Continuous Measurement of Dissolved Gases with a CF-MIMS: Applications to the Physics and Biogeochemistry of Groundwater Flow

In the perspective of a temporal and spatial exploration of aquatic environments (surface and groundwater), we developed a technique for field continuous measurements of dissolved gases with a precision better than 1% for N2, O2, CO2, He, Ar, 2% for Kr, 8% for Xe, and 3% for CH4, N2O and Ne. With a large resolution (from 1 × 10–9 to […]

Papers, WP8 - Tracing methods groundwater, high frequency, hydrology, riparian zone

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 […]

Papers, WP7 - Deep waters geophysics, hydrogeophysics, hydrology

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 […]

Papers, WP6 - Subsurface exploration geophysics, hydrogeophysics

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

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 […]

Papers, WP2 - Water pulsations geophysics, hydrogeology, hydrogeophysics

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. […]

Papers, WP3 - Temperature groundwater, hydrogeology

Inversion of generalized relaxation time distributions with optimized damping parameter

Retrieving the Relaxation Time Distribution (RDT), the Grains Size Distribution (GSD) or the Pore Size Distribution (PSD) from low-frequency impedance spectra is a major goal in geophysics. The “Generalized RTD” generalizes parametric models like Cole–Cole and many others, but remains tricky to invert since this inverse problem is ill-posed. We propose to use generalized relaxation basis function (for instance by […]

Papers, WP6 - Subsurface exploration geophysics, hydrogeophysics

Detecting different water table levels in a shallow aquifer with combined P-, surface and SH-wave surveys: Insights from VP/VS or Poisson’s ratios

When applied to hydrogeology, seismicmethods are generally confined to the characterisation of aquifer geometry. The joint study of pressure- (P) and shear- (S) wave velocities (VP and VS) can provide supplementary information and improve the understanding of aquifer systems. This approach is proposed here with the estimation of VP/VS ratios in a stratified aquifer system characterised by tabular layers, well-delineated […]

Papers, WP6 - Subsurface exploration geophysics, groundwater, hydrogeology, hydrogeophysics, sediment

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