References of "Brouyère, Serge"
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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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See detailCoupling heat and salt tracer experiment for the estimation of heat transfer and solute transport parameters
Wildemeersch, Samuel ULg; Jamin, Pierre ULg; Orban, Philippe ULg et al

Conference (2013, April 22)

Geothermal energy is a promising source of energy in the context of sustainable development. Therefore, very low enthalpy geothermal systems (open or closed) are increasingly considered for heating or ... [more ▼]

Geothermal energy is a promising source of energy in the context of sustainable development. Therefore, very low enthalpy geothermal systems (open or closed) are increasingly considered for heating or cooling houses and offices using groundwater energy. However, prior to the development of such systems, a feasibility study and an impact study of the system on groundwater ressources are required. Thereliability of such studies is highly dependent on the quality of the estimation of heat transfer parameters. This highlights the necessity of estimating properly such parameters. The objective of this study is to combine the use of heat and salt tracers to estimate simultaneously heat transfer and solute transport parameters in an alluvial aquifer. Additionally, coupling heat and salt tracing experiments is particularly useful for comparing heat transfer and solute transport processes occurring in the subsurface. An 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 loess layer (3 m) overlying a sand and gravel layer which constitutes the alluvial aquifer (7 m). The coupled tracing experiment consists in injecting simultaneously heated water and salt in a piezometer and monitoring the evolution of groundwater temperature and salt concentration in a series of control panels set perpendicularly to groundwater flow. This coupled tracing experiment is then simulated using a numerical model. The estimation of heat transfer and solute transport parameters is obtained by calibrating this numerical model using inversion tools. The present study proposes a methodology coupling heat and salt tracing experiment for estimating heat transfer parameters at the field scale. Furthermore, this coupled tracing experiment shows that the comportment of heat and solute in the subsurface presents key differences. [less ▲]

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See detailIs it worth protecting groundwater from diffuse pollution with agri-environmental schemes? A hydro-economic modeling approach
Hérivaux, Cécile; Orban, Philippe ULg; Brouyère, Serge ULg

in Journal of Environmental Management (2013), 128

In Europe, 30% of groundwater bodies are considered to be at risk of not achieving the Water Framework Directive (WFD) ‘good status’ objective by 2015, and 45% are in doubt of doing so. Diffuse ... [more ▼]

In Europe, 30% of groundwater bodies are considered to be at risk of not achieving the Water Framework Directive (WFD) ‘good status’ objective by 2015, and 45% are in doubt of doing so. Diffuse agricultural pollution is one of the main pressures affecting groundwater bodies. To tackle this problem, the WFD requires Member States to design and implement cost-effective programs of measures to achieve the ‘good status’ objective by 2027 at the latest. Hitherto, action plans have mainly consisted of promoting the adoption of Agri- Environmental Schemes (AES). This raises a number of questions concerning the effectiveness of such schemes for improving groundwater status, and the economic implications of their implementation. We propose a hydro-economic model that combines a hydrogeological model to simulate groundwater quality evolution with agronomic and economic components to assess the expected costs, effectiveness, and benefits of AES implementation. This hydro-economic model can be used to identify cost-effective AES combinations at groundwater-body scale and to show the benefits to be expected from the resulting improvement in groundwater quality. The model is applied here to a rural area encompassing the Hesbaye aquifer, a large chalk aquifer which supplies about 230,000 inhabitants in the city of Liege (Belgium) and is severely contaminated by agricultural nitrates. We show that the time frame within which improvements in the Hesbaye groundwater quality can be expected may be much longer than that required by the WFD. Current WFD programs based on AES may be inappropriate for achieving the ‘good status’ objective in the most productive agricultural areas, in particular because these schemes are insufficiently attractive. Achieving ‘good status’ by 2027 would demand a substantial change in the design of AES, involving costs that may not be offset by benefits in the case of chalk aquifers with long renewal times. [less ▲]

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See detailDownscaling transient climate change with a stochastic weather generator for the Geer catchment, Belgium
Blenkinsop, Steve; Harpham, C.; Burton, A. et al

in Climate Research (2013)

The coarse resolution of climate models creates the need for future scenarios which are downscaled to an appropriate spatial scale. Considerable effort has been devoted to the development of downscaling ... [more ▼]

The coarse resolution of climate models creates the need for future scenarios which are downscaled to an appropriate spatial scale. Considerable effort has been devoted to the development of downscaling methods but a number of important issues remain in the development of robust, usable climate scenarios. These include the incorporation of various sources of uncertainty into future scenarios and the production of scenarios at timescales relevant to planners. This paper describes a new procedure which addresses these issues by producing a multi-model ensemble of transient climate change scenarios. This method couples an existing stochastic rainfall model to a new, transient implementation of a weather generator, using changes projected by an ensemble of regional climate model (RCM) experiments. The methodology is demonstrated by the generation of transient scenarios of daily rainfall, temperature and potential evapotranspiration (PET) for the Geer catchment in Belgium for the period 2010 to 2085. The utility of these scenarios is demonstrated by assessing the changes projected by the simulated time series of several temperature indices. The Geer is projected to experience a decrease in the occurrence of frost days with a corresponding shortening of the frost season and lengthening of the growing season. By examining a large ensemble of transient scenarios the range of uncertainty in these projections is assessed, but further, it is suggested that additional information on the projected timing of specified threshold events or system responses may be provided which could aid planners in assessing the likely timescales of required interventions and adaptation responses. [less ▲]

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See detailBenzene dynamics and biodegradation in alluvial aquifers affected by river fluctuations
Batlle-Aguilar, Jordi; Morasch, Barbara; Hunkeler, Daniel et al

in Ground Water (2013)

The spatial distribution and temporal dynamics of a benzene plume in an alluvial aquifer strongly affected by river fluctuations was studied. Benzene concentrations, aquifer geochemistry datasets, past ... [more ▼]

The spatial distribution and temporal dynamics of a benzene plume in an alluvial aquifer strongly affected by river fluctuations was studied. Benzene concentrations, aquifer geochemistry datasets, past river morphology and benzene degradation rates estimated in situ using stable carbon isotope enrichment were analysed in concert with aquifer heterogeneity and river fluctuations. Geochemistry data demonstrated that benzene biodegradation was on-going under sulphate reducing conditions. Long-term monitoring of hydraulic heads and characterisation of the alluvial aquifer formed the basis of a detailed modelled image of aquifer heterogeneity. Hydraulic conductivity was found to strongly correlate with benzene degradation, indicating that low hydraulic conductivity areas are capable of sustaining benzene anaerobic biodegradation provided the electron acceptor (SO42-) does not become rate limiting. Modelling results demonstrated that the groundwater flux direction is reversed on annual basis when the river level rises up to two meters, thereby forcing the infiltration of oxygenated surface water into the aquifer. The mobilisation state of metal trace elements such as Zn, Cd and As present in the aquifer predominantly depended on the strong potential gradient within the plume. However, infiltration of oxygenated water was found to trigger a change from strongly reducing to oxic conditions near the river, causing mobilisation of previously immobile metal species and vice versa. Monitored natural attenuation appears to be an appropriate remediation strategy in this type of dynamic environment provided that aquifer characterisation and targeted monitoring of redox conditions is adequate and electron acceptors remain available until concentrations of toxic compounds reduce to acceptable levels. [less ▲]

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See detailAn object-oriented hydrogeological data model for groundwater projects
Wojda, Piotr; Brouyère, Serge ULg

in Environmental Modelling & Software (2013)

Geological and hydrogeological data are expensive to obtain in the field but are crucial for specific hydrogeological studies, from hydrogeological water balances to groundwater flow modelling and ... [more ▼]

Geological and hydrogeological data are expensive to obtain in the field but are crucial for specific hydrogeological studies, from hydrogeological water balances to groundwater flow modelling and contaminant transport, or for more integrated environmental investigations where groundwater plays a role. In this context, hydrogeological data are collected, transformed and exchanged at different scales, from local to international levels and between numerous institutions ranging from environmental consulting companies to the national and international environmental administrations. To guarantee that these exchanges are possible and meaningful, a clear structure and meta-information on applied hydrogeological data models is required. To make one step towards seamless management of groundwater projects, a new hydrogeological data model has been developed: Hg2O. It is described using object-oriented paradigms and it follows the recommendations of the International Organization for Standardization (ISO/TC211), the Open Geospatial Consortium (OGC), and the European Geospatial Information Working Group. Hydrogeological features are organized in packages of spatial feature datasets. The observations and measurements related to these features are organized in a seperate package. A particular focus is on specialized hydrogeological field experiments such as hydraulic and tracer tests. Two first implementations in the proprietary desktop ArcGIS environment and in the open-source web-based Web2GIS platform are presented, focusing on their respective standards support. [less ▲]

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See detailDélivrable 14 (B) : Rapport Final du Projet Pollusol 2 : Introduction générale / Analyse transversale des résultats / Conclusions et perspectives
Pereira, Benoït; Titeux, Hugues; Schneider, Arnaud et al

Report (2012)

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See detailDistribution, leaching and flux measurements of contaminants in the vadose zone of industrial contaminated sites: a review
Fernandez de Vera, Natalia ULg; Vanclooster, Marnik; Brouyère, Serge ULg

Report (2012)

This document is a review of state of science regarding flux measurement technologies in the vadose zone. Initially, a description of distribution and leaching of inorganic contaminants in the vadose zone ... [more ▼]

This document is a review of state of science regarding flux measurement technologies in the vadose zone. Initially, a description of distribution and leaching of inorganic contaminants in the vadose zone is provided. Such description is followed by a review of vadose zone techniques that are applied for measuring contaminant fluxes. At the end of the document the applicability of such techniques to industrial contaminated sites is discussed. [less ▲]

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