References of "Brouyère, Serge"
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See detailCoupling heat and chemical tracer experiments for estimating heat transfer parameters in shallow alluvial aquifers
Wildemeersch, Samuel ULg; Jamin, Pierre ULg; Orban, Philippe ULg et al

in Journal of Contaminant Hydrology (2014), 169

Geothermal energy systems, closed or open, are increasingly considered for heating and/or cooling buildings. The efficiency of such systems depends on the thermal properties of the subsurface. Therefore ... [more ▼]

Geothermal energy systems, closed or open, are increasingly considered for heating and/or cooling buildings. The efficiency of such systems depends on the thermal properties of the subsurface. Therefore, feasibility and impact studies performed prior to their installation should include a field characterization of thermal properties and a heat transfer model using parameter values measured in situ. However, there is a lack of in situ experiments and methodology for performing such a field characterization, especially for open systems. This study presents an in situ experiment designed for estimating heat transfer parameters in shallow alluvial aquifers with focus on the specific heat capacity. This experiment consists in simultaneously injecting hot water and a chemical tracer into the aquifer and monitoring the evolution of groundwater temperature and concentration in the recovery well (and possibly in other piezometers located down gradient). Temperature and concentrations are then used for estimating the specific heat capacity. The first method for estimating this parameter is based on a modeling in series of the chemical tracer and temperature breakthrough curves at the recovery well. The second method is based on an energy balance. The values of specific heat capacity estimated for both methods (2.30 and 2.54 MJ/m3/K) for the experimental site in the alluvial aquifer of the Meuse River (Belgium) are almost identical and consistent with values found in the literature. Temperature breakthrough curves in other piezometers are not required for estimating the specific heat capacity. However, they highlight that heat transfer in the alluvial aquifer of the Meuse River is complex and contrasted with different dominant process depending on the depth leading to significant vertical heat exchange between upper and lower part of the aquifer. Furthermore, these temperature breakthrough curves could be included in the calibration of a complex heat transfer model for estimating the entire set of heat transfer parameters and their spatial distribution by inverse modeling. [less ▲]

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See detailContexte hydrogéologique de la commune de Sprimont
Gesels, Julie ULg; Gilson, Mylene; Brouyère, Serge ULg et al

in Gilles-Sépulchre, Yvette (Ed.) Sprimont, gravé dans la pierre (2014)

Cadre hydrogéologique de la commune de Sprimont : formations géologiques qui contiennent des ressources en eau intéressantes, variations de la profondeur d'eau dans les différentes nappes, volumes ... [more ▼]

Cadre hydrogéologique de la commune de Sprimont : formations géologiques qui contiennent des ressources en eau intéressantes, variations de la profondeur d'eau dans les différentes nappes, volumes exploités et chimisme des eaux souterraines. [less ▲]

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See detailCombining flux estimation techniques to improve characterization of groundwater–surface-water interaction in the Zenne River, Belgium
Dujardin, Juliette; Anibas, Christian; Bronders, Jan et al

in Hydrogeology Journal (2014)

The management of urban rivers which drain contaminated groundwater is suffering from high uncertainties regarding reliable quantification of groundwater fluxes. Independent techniques are combined for ... [more ▼]

The management of urban rivers which drain contaminated groundwater is suffering from high uncertainties regarding reliable quantification of groundwater fluxes. Independent techniques are combined for estimating these fluxes towards the Zenne River, Belgium. Measured hydraulic gradients, temperature gradients in conjunction with a 1D-heat and fluid transport model, direct flux measurement with the finite volume point dilution method (FVPDM), and a numerical groundwater flow model are applied, to estimate vertical and horizontal groundwaterfluxes and groundwater–surface-water interaction. Hydraulic gradient analysis, the temperature-based method, and the groundwaterflow model yielded average verticalfluxes of–61,–45 and–40 mm/d, respectively. The negative sign indicates upwardflow to the river. Changes in exchangefluxes are sensitive to precipitation but the river remained gaining during the examined period. The FVPDM, compared to the groundwaterflow model, results in two very high estimates of the horizontal Darcyfluxes (2,600 and 500 mm/d), depending on the depth of application. The obtained results allow an evaluation of the temporal and spatial variability of estimated fluxes, thereby helping to curtail possible consequences of pollution of the Zenne River as final receptor, and contribute to the setup of a suitable remediation plan for the contaminated study site. [less ▲]

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See detailAssessing the effects of spatial discretization on large-scale flow model performance and prediction uncertainty
Wildemeersch, Samuel ULg; Goderniaux, Pascal; Orban, Philippe ULg et al

in Journal of Hydrology (2014), 510

Large-scale physically-based and spatially-distributed models (>100 km2) constitute useful tools for water management since they take explicitly into account the heterogeneity and the physical processes ... [more ▼]

Large-scale physically-based and spatially-distributed models (>100 km2) constitute useful tools for water management since they take explicitly into account the heterogeneity and the physical processes occurring in the subsurface for predicting the evolution of discharge and hydraulic heads for several predictive scenarios. However, such models are characterized by lengthy execution times. Therefore, modelers often coarsen spatial discretization of large-scale physically-based and spatially-distributed models for reducing the number of unknowns and the execution times. This study investigates the influence of such a coarsening of model grid on model performance and prediction uncertainty. The improvement of model performance obtained with an automatic calibration process is also investigated. The results obtained show that coarsening spatial discretization mainly influences the simulation of discharge due to a poor representation of surface water network and a smoothing of surface slopes that prevents from simulating properly surface water-groundwater interactions and runoff processes. Parameter sensitivities are not significantly influenced by grid coarsening and calibration can compensate, to some extent, for model errors induced by grid coarsening. The results also show that coarsening spatial discretization mainly influences the uncertainty on discharge predictions. However, model prediction uncertainties on discharge only increase significantly for very coarse spatial discretizations. [less ▲]

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See detailHeat transfer characterization using heat and solute tracer tests in a shallow alluvial aquifer
Dassargues, Alain ULg; Wildemeersch, Samuel ULg; Jamin, Pierre ULg et al

Poster (2013, December 09)

Very low enthalpy geothermal systems are increasingly considered for heating or cooling using groundwater energy combined with heat pumps. The design and the impact of shallow geothermal systems are often ... [more ▼]

Very low enthalpy geothermal systems are increasingly considered for heating or cooling using groundwater energy combined with heat pumps. The design and the impact of shallow geothermal systems are often assessed in a semi-empirical way. It is accepted by most of the private partners but not by environmental authorities deploring a lack of rigorous evaluation of the mid- to long-term impact on groundwater. In view of a more rigorous methodology, heat and dye tracers are used for estimating simultaneously heat transfer and solute transport parameters in an alluvial aquifer. The experimental field site, is equipped with 21 piezometers drilled in alluvial deposits composed of a loam layer overlying a sand and gravel layer constituting the alluvial aquifer. The tracing experiment consisted in injecting simultaneously heated water and a dye tracer in a piezometer and monitoring evolution of groundwater temperature and tracer concentration in 3 control panels set perpendicularly to the main groundwater flow. Results showed drastic differences between heat transfer and solute transport due to the main influence of thermal capacity of the saturated porous medium. The tracing experiment was then simulated using a numerical model and the best estimation of heat transfer and solute transport parameters is obtained by calibrating this numerical model using inversion tools. The developed concepts and tests may lead to real projects of various extents that can be now optimized by the use of a rigorous and efficient methodology at the field scale. [less ▲]

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See detailPhysically Based Groundwater Vulnerability Assessment Using Sensitivity Analysis Methods
Beaujean, Jean ULg; Lemieux, Jean-Michel; Dassargues, Alain ULg et al

in Ground Water (2013), 52(6), 864-874

A general physically based method is presented to assess the vulnerability of groundwater to external pressures by numerical simulation of groundwater flow. The concept of groundwater vulnerability ... [more ▼]

A general physically based method is presented to assess the vulnerability of groundwater to external pressures by numerical simulation of groundwater flow. The concept of groundwater vulnerability assessment considered here is based on the calculation of sensitivity coefficients for a user-defined groundwater state for which we propose several physically based indicators. Two sensitivity analysis methods are presented: the sensitivity equation method and the adjoint operator method. We show how careful selection of a method can significantly minimize the computational effort. An illustration of the general methodology is presented for the Herten aquifer analog (Germany). This application to a simple, yet insightful, case demonstrates the potential use of this general and physically based vulnerability assessment method to complex aquifers. [less ▲]

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See detailConception et utilisation de « seepage-meters » artisanaux pour l'étude des interactions «rivière – eaux souterraines » au Burkina Faso
Sauret, Elie ULg; Nitcheu, Martial; Orban, Philippe ULg et al

Conference (2013, September 25)

Situé à l'ouest du Burkina Faso dans la région de Bobo Dioulasso, le bassin du Kou présente un contexte climatique et hydro(géo)logique, favorables à l'accumulation et à la mobilisation d’importantes ... [more ▼]

Situé à l'ouest du Burkina Faso dans la région de Bobo Dioulasso, le bassin du Kou présente un contexte climatique et hydro(géo)logique, favorables à l'accumulation et à la mobilisation d’importantes ressources en eaux souterraines et de surface, en témoigne, les sources de Nasso/guinguette au centre de bassin qui ont un débit d'environ 6000 m3/h. D'un point de vue hydrogéologique, les sources qui constituent les points d’émergences des formations aquifères profonds du bassin se déchargent dans la rivière (Kou) et assurent ainsi sa pérennité tout au long de l’année. D’amont en aval du bassin, le Kou est largement exploité par les agriculteurs installés ça et là de part et d’autre de ses rives. Malheureusement, au cours des vingt dernières années un afflux important de nouveaux agriculteurs a constitué une pression sur les ressources en terres et en eau du bassin, occasionnant une concurrence aigue à tendance conflictuelle entre les différents exploitants agricoles autour de la rivière. Pour mieux caractériser et, quantifier l'évolution dans le temps des ressources en eau du Kou , une série de tests et études hydrogéologiques prenant en compte les deux autres réservoirs : les aquifères sédimentaires profonds et la plaine alluviale déployé tout au long de la rivière, ont été réalisées. Les techniques de mesure directe par seepage meters des volumes d’eau échangés à l’interface «rivière - nappe» ont permis de quantifier localement les transferts d’eau et déceler les directions et sens des échanges entre les différents réservoirs. Les résultats obtenus ont montré qu’il existe des sections où le Kou gagne (1.5 m3/s) ou perd (-0.10 m3/s) de l’eau au profit ou au détriment des eaux souterraines (aquifères sédimentaires profonds et plaine alluviale). Ces résultats ont été validés par des analyses hydrochimiques des échantillons d’eau prélevés. [less ▲]

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See detailRegional urban groundwater body risk assessment of contaminants using remotely sensed multi-resolution land-cover data
Batelaan, Okke; Dujardin, Juliette; Jamin, Pierre ULg et al

Conference (2013, September 15)

Contaminated sites are often the result of past relatively anarchic economical and industrial development. The last decades stakeholders are more aware of the risks posed by these sites. Within the Frac ... [more ▼]

Contaminated sites are often the result of past relatively anarchic economical and industrial development. The last decades stakeholders are more aware of the risks posed by these sites. Within the Frac-Weco project an integrated framework for the assessment, at regional scale, of the risks posed by these contaminated sites on water resources and ecosystems has been developed. The methodology is based on the calculation of contaminant fluxes reaching the receptors providing a way of estimating the level of exposure/degradation of these receptors at the groundwater body scale. The most important contamination problems at regional scale are located around old urban and industrialized areas. The land-cover distribution in these zones is of prime importance because it determines the spatial variation of groundwater recharge, which is the main vector of contaminant leaching from soil surface to groundwater. To obtain detailed information about land cover for groundwater recharge modeling, a stratified satellite image classification approach was adopted combining land-cover mapping at pixel level for the studied area as a whole with sub-pixel estimation of imperviousness within built-up zones. The obtained land-cover data is used as an input in the WetSpass model to simulate groundwater recharge at high resolution in spatially complex urban areas. In the next step the simulated groundwater recharge is used as an input in a regional scale groundwater flow and transport model simulating contaminant dispersion through the aquifer. Modeling results are further used to calculate a quality index for the whole groundwater body based on threshold values defined specifically for each contaminant. The approach proposed has been applied on the RWM073 groundwater body corresponding to the alluvial deposits of the Meuse River, Liège (Belgium). The high-resolution groundwater recharge estimations obtained by integrating remote sensing in the modeling procedure allow a better identification of the potential sources of contaminants and enable a proper quantification of total fluxes of contaminants from brownfields into the groundwater. The developed framework for regional risk assessment results in a global quality indicator for the groundwater body which can be used as input for decision-making. [less ▲]

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See detailA heat injection and pumping experiment in a gravel aquifer monitored with crosshole electrical resistivity tomography
Hermans, Thomas ULg; Wildemeersch, Samuel ULg; Jamin, Pierre ULg et al

in EarthDoc - Near Surface Geosciences 2013 - 19th European Meeting of Environmental and Engineering Geophysics (2013, September)

Thermal tracing experiments are becoming common in hydrogeology to estimate parameters governing heat transport processes and to study geothermal reservoirs. Electrical resistivity tomography (ERT) has ... [more ▼]

Thermal tracing experiments are becoming common in hydrogeology to estimate parameters governing heat transport processes and to study geothermal reservoirs. Electrical resistivity tomography (ERT) has proven its ability to monitor salt tracer tests, but few studies have investigated its performances in thermal tracing experiments. In this study, we monitor the injection and pumping of heated water using crosshole ERT in a panel crossing the main flow direction. Difference inversion time-lapse images clearly show the heterogeneous pattern of resistivity changes, and thus temperature changes, highlighting the existence of preferential flow paths in the aquifer. Comparison of temperature estimates from ERT and direct measurements in boreholes show the ability of ERT to quantify the temperatures in the aquifer and to draw the breakthrough curves of the thermal tracer with a relative accuracy. Such resistivity data may provide important information to improve hydrogeological models. Our study proves that ERT, especially crosshole ERT, is a reliable tool to follow thermal tracing experiments. It also confirms that ERT should be included to in situ techniques to characterize heat transfer in the subsurface and to monitor geothermal resources exploitation. [less ▲]

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See detailHeat transfer characterization in a shallow aquifer using heat and dye tracer tests
Wildemeersch, Samuel ULg; Orban, Philippe ULg; Hermans, Thomas ULg et al

Conference (2013, July 22)

Very low enthalpy geothermal systems (open or closed) are increasingly considered for heating or cooling houses and offices using groundwater energy combined with heat pumps. However, the design and the ... [more ▼]

Very low enthalpy geothermal systems (open or closed) are increasingly considered for heating or cooling houses and offices using groundwater energy combined with heat pumps. However, the design and the impact of current shallow geothermal systems are often set up and assessed in a semi-empirical way. In our country, this situation seems accepted by most of the private partners but not by the authorities and responsible administrations evaluating the impact on groundwater with a mid- to long-term perspective. A rigorous methodology is needed based on a physically based estimation of heat transfer parameters. In this study, the simultaneous use of heat and dye tracers allows estimating simultaneously heat transfer and solute transport parameters in an alluvial aquifer. The experimental field site, located near Liege (Belgium), is equipped with 21 piezometers drilled in the alluvial deposits of the Meuse River. These alluvial deposits are composed of a loam layer (3 m) overlying a sand and gravel layer which constitutes the alluvial aquifer (7 m). The tracing experiment consisted in injecting simultaneously heated water and a dye tracer in a piezometer and monitoring the evolution of groundwater temperature and tracer concentration in a series of control panels set perpendicularly to the main groundwater flow. Results showed drastic differences between heat transfer and solute transport due to the main influence of thermal capacity of the saturated porous medium. The tracing experiment was then simulated using a numerical model and the best estimation of heat transfer and solute transport parameters is obtained by calibrating this numerical model using inversion tools. The developed concepts and tests may lead to real projects of various extents that can be now optimized by the use of a rigorous and efficient methodology at the field scale. [less ▲]

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See detailMultivariate statistics to understand the geochemical processes induced by groundwater pollution Multi-scale applying
Gesels, Julie ULg; Joniau, Claire; Batlle-Aguilar, Jordi et al

Conference (2013, June 07)

Different hydrogeochemical approaches (classical diagrams, spatial distribution maps, geochemical equations and multivariate statistics) are combined to obtain a global understanding of the ... [more ▼]

Different hydrogeochemical approaches (classical diagrams, spatial distribution maps, geochemical equations and multivariate statistics) are combined to obtain a global understanding of the hydrogeochemical processus at regional and at local scale. [less ▲]

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See detailTime variyng groundwater flux measurement using a single well tracer technique
Jamin, Pierre ULg; Brouyère, Serge ULg; Bour, Olivier et al

Poster (2013, April 24)

Contaminant mass discharge measurements are often performed at given times or integrated over a certain period of time, using active or passive sampling techniques. One problem arising is that such ... [more ▼]

Contaminant mass discharge measurements are often performed at given times or integrated over a certain period of time, using active or passive sampling techniques. One problem arising is that such measurements may not be representative of the temporal dynamics of the mass discharge variations. These variations can be caused by fluctuations in contaminant concentrations or, more frequently, by changes in the groundwater fluxes. Pollutant mass fluxes are typically estimated through a combination of solute concentrations and groundwater fluxes measured across a control plane made of several multi-level wells. Accurate measurements of local transient Darcy fluxes have been recognized as the weakest points in most of the developed techniques for groundwater contaminant mass flux measurements. The main objective here is to extend the FVPDM technique for temporal monitoring of groundwater fluxes and to demonstrate its ability to be used in combination with passive sampling devices for measurement of contaminant mass fluxes in groundwater. The Finite Volume Point Dilution Method (FVPDM) is a single well tracer technique for the measurement of local groundwater fluxes based on the continuous injection of tracer at very low injection rate (Brouyère et al. 2008). These developments are based on the application of the adapted technique on a case study in a fractured granitic aquifer in Ploemeur (France). This application investigates transient groundwater fluxes that are controlled by pumping in a well nearby the tested piezometers. Long monitoring time series have been recorded under these controlled conditions of transient groundwater flow. Results show the high sensivity of the FVPDM technique to small variations in groundwater flow velocities and its aptitude for long term monitoring of groundwater fluxes. The comparison between the results of FVPDM and classical point dilution tests performed in same conditions shows close correlation. Interpretation of FVPDM tests in transient conditions have been developed together with an evaluation of the uncertainties that can happen if the frequency of the groundwater flow variations is high. The tests carried on the Ploemeur site also illustrate the first ever application of the FVPDM technique between a double-packer system used for the investigation of a defined layer of an aquifer. This innovative application of the FVPDM using packers opens concrete perspectives for investigation of vertical heterogeneities of groundwater fluxes across a well. [less ▲]

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See detailA combined hydrochemical, isotopic and multivariate statistics approach for pollutant source identification in a regional aquifer
Gesels, Julie ULg; Joniau, Claire; Knöller, Kay et al

Conference (2013, April 23)

In an urban and industrial context, a detailed hydrogeochemical characterization of groundwater has been performed in an alluvial aquifer, with the aim of determining the origin of the inorganic ... [more ▼]

In an urban and industrial context, a detailed hydrogeochemical characterization of groundwater has been performed in an alluvial aquifer, with the aim of determining the origin of the inorganic contaminations and the main processes involved that contribute to a poor groundwater quality. [less ▲]

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See detailDiffuse urban and industrial groundwater pollution with metallic trace elements A comparison between affected and unaffected areas
Gesels, Julie ULg; Dollé, Fabien ULg; Leclercq, Julie et al

Poster (2013, April 22)

For metalic trace elements, spatially distributed background concentrations will be defined as a function of geological and hydrogeological context and considering the impact of diffuse pollution.

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See detailIntegrated field assessment of contaminant fate and transport in the unsaturated and saturated zone
Fernandez de Vera, Natalia ULg; Peña Hernandez, Juan Angel ULg; Jamin, Pierre ULg et al

Poster (2013, April 22)

In the poster, a multidisciplinary methodology is presented with the aim of characterizing fate and transport of pollutants in the vadose and the saturated zone of industrial sites. The methodology used ... [more ▼]

In the poster, a multidisciplinary methodology is presented with the aim of characterizing fate and transport of pollutants in the vadose and the saturated zone of industrial sites. The methodology used for the vadose zone consist in the combination of the Vadose Monitoring System, cross-hole and surface geophysics at a local scale. For saturated zone studies, the approach consist in the chemical and isotopic analysis of the various contaminants present on site at regional scale. [less ▲]

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