MANPORIVERS (Management policies for priority water pollutants and their effects on foods and human health: general methodology and application to Chinese river basins), Hydrogeology part, activity report year 2

Report (2003)

Hydrodynamic and hydrodispersive behaviour of variably saturated chalk : a field investigation

Conference (2003, March 19)

The presentation described field investigations on contaminant transport across unsaturated chalk rocks, including tracer tests

Complex Hydrogeological Study of the Alluvial Transboundary Aquifer of Szamos/Somes (Romania-Hungary)

in Water resources management in the 21th century. Subtheme 4, Relevance and sustainability of the intensive groundwater developments (2003)

MANPORIVERS (Management policies for priority water pollutants and their effects on foods and human health: general methodology and application to Chinese river basins), Hydrogeology part, activity report year 1

Report (2002)

Integrating geophysical and tracer test data for accurate solute transport modelling in heterogeneous porous media

in Groundwater Quality: Natural and Enhanced Restoration of Groundwater Pollution (GQ’2001) (2002)

Etude et modélisation du transport et du piégeage des solutés en milieu souterrain variablement saturé. Evaluation des paramètres hydrodispersifs par la réalisation et l'interprétation d'essais de traçage in situ

Doctoral thesis (2001)

The long term protection of groundwater resources implies to study the behaviour of water and contaminants as soon as they penetrate in the underground (recharge) until they leave it at natural outlets ... [more ▼]

The long term protection of groundwater resources implies to study the behaviour of water and contaminants as soon as they penetrate in the underground (recharge) until they leave it at natural outlets (discharge in surface water bodies, springs, …) or at artificial extraction points (pumping wells, …). During this residence in the underground, many physical and chemical processes are likely to play a role on contaminant mobility. The attenuation, retardation and auto-purification capacities of the underground medium have thus to be quantified and considered. Consequences of their effect on contaminant behaviour can be positive (contaminant dispersion, dilution, degradation, …) or negative (difficulties to recover the contaminant, long-term impact of the contamination, …). This research aims at providing a conceptual and mathematical framework for studying on the field and for modelling the migration and retardation of solutes in variably saturated underground media. A classification of physico-chemical processes is proposed, based on three main criteria : (1) a differentiation between “microscopic” processes, playing a role at pore-scale and “macroscopic” processes, playing a role at field scale, (2) a distinction between physical processes (affecting any kind of contaminant, independently from its chemical nature) and chemical processes (affecting some contaminants, according to their specific chemical properties), (3) a distinction between equilibrium processes (independent of time) and kinetic processes (explicitly dependent of time). On that basis, the conceptual model includes three main compounds : advection, hydrodynamic dispersion and a mass exchange process between the mobile water and an immobile phase of aqueous (dual porosity effect) or solid (kinetic sorption) nature. Within this conceptual framework, developments and adaptations made in the SUFT3D code in order to model the behaviour of a contaminant in the variably saturated underground are presented. The evaluation of hydrodispersive parameters governing the migration and the capturing of contaminants relies on the interpretation of field tracer tests, conducted under variably saturated flow conditions. An important part of the research has thus been devoted to an improvement of tracer test techniques and interpretation, more particularly in terms of concentration and mass recovery evolutions, the latter being more appropriate for evaluation and quantification of retardation processes. In order to model more physically and accurately the tracer injection, a new conceptual, mathematical and numerical approach has been developed, considering explicitly well-aquifer interactions. Using this model, numerical tests show the impact of tracer injection conditions on tracer test results, possibly leading to wrong interpretation in terms of both processes identification and parameters quantification. In order to make a correct interpretation of tracer test results, the control of tracer injection conditions is thus essential. Two experimental studies illustrate the developments of this work. A multi-tracer test experiment was conducted under saturated conditions in the sediments of the alluvial plain of the river Meuse at Hermalle-sous-Argenteau. The results of these tests allow to validate and to illustrate the approach developed in order to model accurately tracer injection and well-aquifer interactions, to highlight other practical and conceptual problems encountered when conducting the experiments, to examine the chemical behaviour of several artificial tracers and to quantify the hydrodispersive properties of alluvial deposits. The objective of the second field experiment was to identify and to quantify solute migration mechanisms in the unsaturated zone overlying the chalk aquifer in the Hesbaye Region. These results allow to suggest a unifying conceptual and mathematical approach in order to represent the hydrodynamic and hydrodispersive properties of fissured chalk under variably saturated conditions. They also show the impact of physical properties of aeolian loess materials on their hydrodynamic properties. [less ▲]

The new integrated hydrological model MOHISE: construction, implementation and results

in Book of abstracts of the International Workshop on Catchment Scale Hydrologic Modeling and Data Assimilation (2001)

Modelling the injection of a tracer in a well: a new mathematical and numerical approach.

in Dassargues, Alain (Ed.) Tracers and Modelling in Hydrogeology (2000)

A new mathematical approach is proposed to model the injection of a tracer in a well for field tracer tests. It is based on the water and tracer mass budget integrated over the injection well, for the ... [more ▼]

A new mathematical approach is proposed to model the injection of a tracer in a well for field tracer tests. It is based on the water and tracer mass budget integrated over the injection well, for the different injection steps (tracer injection, water flush and tracer behaviour after the injection). This physical approach deals with well-bore mixing and dilution effects, local distortion of the flow field around the injection well, back-diffusion of the tracer in the injection well after the injection, and tracer capture in the well bore. A numerical solution (finite differences over time) is proposed and implemented in a three-dimensional finite element flow and transport simulator (SUFT3D). A radially converging tracer test is computed to illustrate the adequacy and usefulness of this new mathematical concept to model field results. [less ▲]

Calibration and reliability of an alluvial aquifer model using inverse modelling and sensitivity analysis

in Stauffer, F.; Kinzelbach, W.; Kovar, K. (Eds.) et al Calibration and Reliability in Groundwater Modelling Pre-published Proc. of ModelCARE99 (1999)

3D flow and transport groundwater modelling including river interactions

in Burganos, V. N.; Karatzas, G. P.; Payatakes, A. C. (Eds.) et al Computational Methods in Water Resources XII, Vol. 1: Computational Methods in Contamination and Remediation of Water Resources (1998)