References of "Dassargues, Alain"
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See detailMain concepts of the "European approach" to karst-groundwater-vulnerability assessment and mapping
Daly, Donald; Dassargues, Alain ULg; Drew, David et al

in Hydrogeology Journal (2002), 10(2), 340-345

In order to achieve some consistency in the establishment of groundwater intrinsic vulnerability maps in Europe. a new, approach is proposed by Working Group 1 of the European COST Action 620 on ... [more ▼]

In order to achieve some consistency in the establishment of groundwater intrinsic vulnerability maps in Europe. a new, approach is proposed by Working Group 1 of the European COST Action 620 on "Vulnerability mapping for the protection of carbonate (karst) aquifers". A general procedure is offered which provides consistency while allowing the required flexibility for application to a continent and under conditions of varying geology, scale, information availability, time, and resources. The proposed methodology is designed to be clearly more physically based than the existing vulnerability-mapping techniques. It takes the specificity of the karstic environments into account without necessarily excluding the applicability to other geological conditions. Combined "core factors" for overlying layers and for concentration of flow, account for the relative protection of groundwater from contamination while taking into account any bypass of the overlying layers. A precipitation factor is distinguished for describing: characteristics of the input of water to the system. Differentiation is made between groundwater resource intrinsic vulnerability Mapping and Source intrinsic vulnerability mapping. For the latter, a factor describing the karst network development is relevant. This short technical note describes a first stop in the work program of Working Group 1 of the COST Action 620. Future steps are now in progress to quantify the approach and to apply it in various European pilot areas. [less ▲]

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See detailDeterministic and stochastic modelling for protection zone delineation
Rentier, Céline; Dassargues, Alain ULg

in Calibration and Reliability in Groundwater Modelling: A Few Steps Closer to Reality (2002)

Protection zones delimited by isochrones are often computed using calibrated groundwater flow and transport models. In heterogeneous formations, all direct (hard) and indirect (soft) data must be used ... [more ▼]

Protection zones delimited by isochrones are often computed using calibrated groundwater flow and transport models. In heterogeneous formations, all direct (hard) and indirect (soft) data must be used optimally. Approaches involving in situ pumping and tracer tests, combined with geophysical and/or other geological observations, should be developed. In a deterministic framework, the calibrated model is considered to be the best representation of reality at the current investigation stage, but uncertainty of the results is not quantified. Using stochastic methods, a range of equally likely isochrones can be produced, allowing us to quantify the influence of our knowledge on the aquifer parameters on protection-zone uncertainty. Furthermore, integration of soft data in a conditioned stochastic generation process, possibly associated with an inverse modelling procedure, can reduce the resulting uncertainty. Proposed is a stochastic methodology for protection-zone delineation, integrating hydraulic conductivity measurements (hard data), head observations and electrical resistivity data (soft data). [less ▲]

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See detailHydrogeological data requirements for assessment of natural attenuation
Haerens, Bruno; Dassargues, Alain ULg

in Proceedings of the National Colloquium CBGI-BCGI ‘Réhabilitation des zones polluées, inventaire, gestion et assainissement / Herinrichting van verontreinigdde zones, inventaris, beheer en sanering (2002)

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See detailMulticomponent reactive modelling of ammonium contamination at a former coal carbonisation plant
Haerens, B.; Dassargues, Alain ULg; Prommer, H. et al

in Aardkundige Mededelingen (2002), 12

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See detailReactive transport modelling of Ammonium: 1D Conceptual modelling and comparison of reactive transport codes
Haerens, Bruno; Dassargues, Alain ULg; Lerner, David

in Acta Universitatis Carolinae. Geologica (2002), 46(2-3), 27-31

Contamination of NH4+, as main inorganic contaminant, resulted from disposal of ammoniacal liquor at a former coal carbonisation plant at Mansfield, UK. Previous research for evaluating natural ... [more ▼]

Contamination of NH4+, as main inorganic contaminant, resulted from disposal of ammoniacal liquor at a former coal carbonisation plant at Mansfield, UK. Previous research for evaluating natural attenuation (Davison, 1998; Davison and Lerner, 2000; Jones, 2001; Jones et al., 1998; Jones and Lerner, 2001) revealed strong retardation of NH4+ in the aquifer due to cation exchange with existing cations on the sediment. After disposal of ammoniacal liquor, NH4+ entered the aquifer and equilibrium took place between NH4+, the existing cations and the available exchange sites. An existing hydraulic gradient keeps flushing the contaminated aquifer with pristine background water. NH4+ desorbs progressively due to new cation exchange equilibrium when the input of NH4+ decreases or eventually stops. In order to be able to model the reactive transport of NH4+, a reaction module is set up for future 2D/3D reactive transport modelling of NH4+ using PHT3D. In a first approach a conceptual 1D-model example is considered and two multicomponent reactive transport models, PHT3D (Prommer and Barry, 2001; Prommer et al., 1999) and PHREEQC (Parkhurst and Appelo, 1999), are compared. In the 1D-model example, the flushing of ammonium contaminated groundwater by pristine background water is simulated. The included processes are advection, dispersion and cation exchange between NH4+, Ca2+, Mg2+, K+, Na+ and the sediment. As both models are using the same geochemical module, the comparison focuses on the coupling approach between the transport and geochemical modules. Results show that large numbers of pore volumes (i.e., a nondimensional time parameter where elapsed time is divided by the hydrodynamic residence time (Brusseau, 1994)) are needed to flush the NH4+ off the aquifer sediment. From the comparison of simulation results compiled with the two codes it is clear that an appropriate choice of the reaction step size for the sequential coupling between the transport and geochemistry modules, is a major point for accuracy of the model predictions. [less ▲]

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See detailIntegrating geophysical and tracer test data for accurate solute transport modelling in heterogeneous porous media
Rentier, Céline; Brouyère, Serge ULg; Dassargues, Alain ULg

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

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See detailReliability of transport models calibrated on field tracer experiments: breakthrough curve sensitivity to tracer injection conditions
Brouyère, Serge ULg; Dassargues, Alain ULg

in in Calibration and Reliability in Groundwater Modelling: A Few Steps Closer to Reality (2002)

The reliability of groundwater transport models depends strongly on accurate identification of hydrodispersive processes and quantification of corresponding parameters. Calibration of these models is ... [more ▼]

The reliability of groundwater transport models depends strongly on accurate identification of hydrodispersive processes and quantification of corresponding parameters. Calibration of these models is often performed using results of field tracer experiments. However, little attention is usually paid to the influence of injection conditions and well-aquifer interactions on resulting breakthrough curves at the sampling well. The tracer input function in the aquifer is often assimilated to a Dirac impulse and the breakthrough curve is supposed to reflect only the hydrodispersive processes affecting the tracer behaviour in groundwater. Actually, flow conditions, aquifer heterogeneity and well-aquifer interactions can have a significant influence on tracer injection. Using a new mathematical approach developed to model well-aquifer interactions and injection conditions in a more physical way, numerical experiments were conducted in order to highlight the potential impact of injection conditions on the results of radially converging flow tracer tests. This analysis clearly shows that neglecting the influence of actual injection conditions can lead to: (a) errors on fitted parameters; (b) misleading identification of the active transport processes. [less ▲]

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See detailGIS-based hydrogeological databases and groundwater modelling
Gogu, Radu Constantin; Carabin, Guy; Hallet, Vincent et al

in Hydrogeology Journal (2001), 9(6), 555-569

Reliability and validity of groundwater analysis strongly depend on the availability of large volumes of high-quality data. Putting all data into a coherent and logical structure supported by a computing ... [more ▼]

Reliability and validity of groundwater analysis strongly depend on the availability of large volumes of high-quality data. Putting all data into a coherent and logical structure supported by a computing environment helps ensure validity and availability and provides a powerful tool for hydrogeological studies. A hydrogeological geographic information system (GIS) database that offers facilities for groundwater-vulnerability analysis and hydrogeological modelling has been designed in Belgium for the Walloon region. Data from five river basins, chosen for their contrasting hydrogeological characteristics, have been included in the database, and a set of applications that have been developed now allow further advances. Interest is growing in the potential for integrating GIS technology and groundwater simulation models. A "loose-coupling" tool was created between the spatial-database scheme and the groundwater numerical model interface GMS (Groundwater Modelling System). Following time and spatial queries, the hydrogeological data stored in the database can be easily used within different groundwater numerical models. [less ▲]

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See detailCarte hydrogéologique, Chastre - Gembloux 40/5-6, 1/25.000 : [notice explicative]
Ruthy, Ingrid ULg; Dassargues, Alain ULg; Monjoie, Albéric ULg

Book published by Ministère de la Région wallonne, Direction générale des ressources naturelles et de l'environnement - Edition provisoire : mai 2001 (2001)

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See detailCarte hydrogéologique de Namur-Champion 47/3-4, 1/25.000 : [notice explicative]
Ruthy, Ingrid ULg; Dassargues, Alain ULg; Monjoie, Albéric ULg

Book published by Ministère de la Région wallonne, Direction générale des ressources naturelles et de l'environnement - Edition provisoire : mai 2001 (2001)

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See detailCarte hydrogéologique de Philippeville - Rosée 53/5-6, 1/25.000 : [notice explicative]
Ruthy, Ingrid ULg; Dassargues, Alain ULg; Monjoie, Albéric ULg

Book published by Ministère de la Région wallonne, Direction générale des ressources naturelles et de l'environnement - Edition provisoire : mai 2001 (2001)

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See detailEvaluation and validation of vulnerability concepts using a physically based approach
Brouyère, Serge ULg; Jeannin, Pierre-Yves; Dassargues, Alain ULg et al

in Mémoire des Sciences et Techniques de l'Environnement (2001), 13

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See detailThe new integrated hydrological model MOHISE: construction, implementation and results
Carabin, G.; Brouyère, Serge ULg; Dassargues, Alain ULg et al

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

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See detailIntrinsic vulnerability maps of a karstic aquifer as obtained by five different assessment techniques: comparison and comments
Gogu, Radu Constantin; Dassargues, Alain ULg

in Mudry, J.; Zwahlen, Fr. (Eds.) Proceedings of the 7th Conf. on Limestone Hydrology and Fissured Media - Sciences et Techniques de l'Environnement (2001)

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See detailQualité de l'eau souterraine dans les aquifères des provinces Limbourg belge, Limbourg néerlandais et Liège
Dassargues, Alain ULg; Péters, Valérie; Vandormael, C. et al

Report (2000)

Detailed reference viewed: 16 (1 ULg)