References of "Dassargues, Alain"
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See detailHeterogeneity and Prior Uncertainty Investigation Using a Joint Heat and Solute Tracer Experiment in Alluvial Sediments
Hoffmann, Richard ULiege; Dassargues, Alain ULiege; Goderniaux, Pascal et al

in Frontiers in Earth Science (2019), 7(108), 15

In heterogeneous aquifers, imaging preferential flow paths, and non-Gaussian effects is critical to reduce uncertainties in transport predictions. Common deterministic approaches relying on a single model ... [more ▼]

In heterogeneous aquifers, imaging preferential flow paths, and non-Gaussian effects is critical to reduce uncertainties in transport predictions. Common deterministic approaches relying on a single model for transport prediction show limitations in capturing these processes and tend to smooth parameter distributions. Monte-Carlo simulations give one possible way to explore the uncertainty range of parameter value distributions needed for realistic predictions. Joint heat and solute tracer tests provide an innovative option for transport characterization using complementary tracer behaviors. Heat tracing adds the effect of heat advection-conduction to solute advection-dispersion. In this contribution, a joint interpretation of heat and solute tracer data sets is proposed for the alluvial aquifer of the Meuse River at the Hermalle-sous-Argenteau test site (Belgium). First, a density-viscosity dependent flow-transport model is developed and induce, due to the water viscosity changes, up to 25% change in simulated heat tracer peak times. Second, stochastic simulations with hydraulic conductivity (K) random fields are used for a global sensitivity analysis. The latter highlights the influence of spatial parameter uncertainty on the resulting breakthrough curves, stressing the need for a more realistic uncertainty quantification. This global sensitivity analysis in conjunction with principal component analysis assists to investigate the link between the prior distribution of parameters and the complexity of the measured data set. It allows to detect approximations done by using classical inversion approaches and the need to consider realistic K-distributions. Furthermore, heat tracer transport is shown as significantly less sensitive to porosity compared to solute transport. Most proposed models are, nevertheless, not able to simultaneously simulate the complementary heat-solute tracers. Therefore, constraining the model using different observed tracer behaviors necessarily comes with the requirement to use more-advanced parameterization and more realistic spatial distribution of hydrogeological parameters. The added value of data from both tracer signals is highlighted, and their complementary behavior in conjunction with advanced model/prediction approaches shows a strong uncertainty reduction potential. [less ▲]

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See detailParametric assessment of hydrochemical changes associated to underground pumped hydropower storage
Pujades, Estanislao; Jurado, Anna; Orban, Philippe ULiege et al

in Science of the Total Environment (2019), 659

Underground pumped hydropower storage (UPHS) using abandoned mines is an alternative to store and produce electricity in flat regions. Excess of electricity is stored in form of potential energy by ... [more ▼]

Underground pumped hydropower storage (UPHS) using abandoned mines is an alternative to store and produce electricity in flat regions. Excess of electricity is stored in form of potential energy by pumping mine water to a surface reservoir. When the demand of electricity increases, water is discharged into the mine (i.e., underground reservoir) through turbines producing electricity. During the complete operational process of UPHS plants, hydrochemical characteristics of water evolve continuously to be in equilibrium successively with the atmosphere (in the surface reservoir) and the surrounding porousmedium (in the underground reservoir). It may lead to precipitation and/or dissolution of minerals and their associated consequences, such as pH variations. Induced hydrochemical changes may have an impact on the environment and/or the efficiency (e.g., corrosions and incrustations affect facilities) of UPHS plants. The nature of the hydrochemical changes is controlled by the specific chemical characteristics of the surrounding porous medium. However, the magnitude of the changes also depends on other variables, such as hydraulic parameters. The role of these parameters is established to define screening criteria and improve the selection procedure of abandonedmines for constructing UPHS plants. This work evaluates the role of the main hydrogeological factors for three different chemical composition of the porous medium. Results are obtained by means of numerical reactive transport modeling. Potential impacts on the environment (mainly on groundwater and surface water bodies) and on the efficiency of the UPHS plants vary considerably from a hydraulic parameter to another showing the need for a detailed characterization before choosing locations of future UPHS plants. [less ▲]

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See detailIntroduction à la géothermie et principes théoriques sur le transfert et le stockage de chaleur dans le sous-sol
Dassargues, Alain ULiege

Scientific conference (2019, February 21)

Introduction à la géothermie - Introduction à la géothermie peu profonde - Efficacité / Impact - Transferts et stockage de chaleur dans le sous-sol Remarques préliminaires, Conduction thermique, Advection ... [more ▼]

Introduction à la géothermie - Introduction à la géothermie peu profonde - Efficacité / Impact - Transferts et stockage de chaleur dans le sous-sol Remarques préliminaires, Conduction thermique, Advection/convection, Dispersion thermique, Equation du transfert de chaleur en milieu souterrain, Simplification, Comparaison avec équation du transport de soluté, Exemple de simulation - Nombres adimensionnels utiles Nombre de Peclet, Nombre de Rayleigh, Nombre de Lewis - Systèmes géothermiques dans d’anciennes mines Faisabilité, Défis - Références [less ▲]

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See detailDegradation mechanisms of chlorinated solvents in groundwater - Application in fractured chalk formation
Boudjana, Youcef ULiege; Brouyère, Serge ULiege; Dassargues, Alain ULiege

Poster (2019, February 18)

At an abandoned industrial site in Belgium, groundwater quality in a chalky aquifer had been impacted by a mixture of chlorinated aliphatic hydrocarbons inducing a significant change in hydrochemistry ... [more ▼]

At an abandoned industrial site in Belgium, groundwater quality in a chalky aquifer had been impacted by a mixture of chlorinated aliphatic hydrocarbons inducing a significant change in hydrochemistry.Based on this case study, the aim of the thesis is to study transport and attenuation mechanisms of chlorinated solvents in the subsurface, considering their effects on the chemistry of the groundwater. The first part is devoted to analyze and interpret the collected data on the contaminated site. It allows to improve our understanding of the processes governing the reactive transport and especially the degradation of aliphatic organochlorines as observed on the site. The influence on the hydrochemistry of groundwater in the vicinity of the study area is studied. In a second part of the research, the use of a numerical model simulating groundwater flow and reactive transport for chlorinated solvents will improve our understanding and clarify the main attenuation mechanisms and their impact on the groundwater chemical composition. [less ▲]

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See detailTransport heterogeneity quantification in heterogeneous fractured media - Chalk
Hoffmann, Richard ULiege; Goderniaux, Pascal; Dassargues, Alain ULiege

Poster (2019, February 18)

The realistic assessment and the quantification of heterogeneity is crucial for transport in fractured rocks. Common solute tracer tests are limited to advection, while smart tracer as dissolved gases or ... [more ▼]

The realistic assessment and the quantification of heterogeneity is crucial for transport in fractured rocks. Common solute tracer tests are limited to advection, while smart tracer as dissolved gases or heat offer new innovative process imaging possibilities for fractured media. Within the PhD program these smart tracers were injected between two adjacent boreholes (7.55 m distance) in the double porosity Chalk at Mons in Belgium. Preliminary fields result shows a diffusion induced variation between the one magnitude higher diffusive Helium and the used dye tracer Uranine. In the heat case, heat is 12.5 hours delayed compared to Uranine, due to matrix storage effects. Also, after stopping the heat injection and a temporary temperature drop down, a temperature rebound was measurable. The preliminary results motivate for further numerical modelling to get a realistic assessment of heterogeneity. [less ▲]

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See detailGroundwater modeling at the catchment scale: mathematical and numerical aspects
Dassargues, Alain ULiege

Scientific conference (2019, January 29)

Terminology and General methodology Groundwater flow equations Flow Boundary Conditions Introduction to solving methods Time integration scheme Solute transport equations Transport Boundary Conditions Pe ... [more ▼]

Terminology and General methodology Groundwater flow equations Flow Boundary Conditions Introduction to solving methods Time integration scheme Solute transport equations Transport Boundary Conditions Pe and Cr numbers Introduction to solving methods References [less ▲]

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See detailTowards a subsurface predictive-model environment to simulate aquifer thermal energy storage for demand-side management applications
Robert, Tanguy ULiege; Hermans, Thomas ULiege; Lesparre, Nolwenn et al

in Proceedings of SSB 2018, 10th International Conference on System Simulation in Buildings (2018, December 12)

Detailed reference viewed: 27 (6 ULiège)
See detailChapter 4 - Copy of the slides for the Hydrogeology course
Dassargues, Alain ULiege

Learning material (2018)

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See detailGeothermal use of old mines: hydrogeological challenges for predicting efficiency and impacts
Vopat, Olivier; Orban, Philippe ULiege; Brouyère, Serge ULiege et al

Conference (2018, September 14)

Groundwater in flooded abandoned mines could be used for geothermal purposes using heat-pumps and an open loop involving pumping and re-injection. Logically, warm water is usually expected to be pumped ... [more ▼]

Groundwater in flooded abandoned mines could be used for geothermal purposes using heat-pumps and an open loop involving pumping and re-injection. Logically, warm water is usually expected to be pumped (or injected) in the deep parts of the open network, and cold water is expected to be re-injected (or pumped) in the shallower parts. However, the feasibility and the durability of future ‘Ground Source Heat Pump system’ (GSHP) must be studied through a deep characterization of the subsoil but also using numerical models able to simulate groundwater flow and heat transfer in these complex geological environments. Depending on the type of abandoned mine, the true geometry of the interconnected network of open galleries and shafts can indeed be highly complex. A high-velocity water flow is expected in this type of network, while low-velocity groundwater flow occurs in less permeable fractured and porous rock massif. The SUFT3D code that allows combining in a single model, and in a fully interacting way, linear or distributed reservoirs to model groundwater flows in mine galleries and classical groundwater flow in the variably saturated equivalent porous surrounding media is developed to model heat transfer using the similarities existing between solute and heat transfer equations. The code is then used to test on simple and synthetic case studies, the impact of the hydrogeological conditions and of technical choices on the feasibility and the durability of these geothermal systems. [less ▲]

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See detailThe double porosity of the chalk and its influence on solute and heat transport
Hoffmann, Richard ULiege; Goderniaux, Pascal; Jamin, Pierre ULiege et al

Conference (2018, September 13)

Fractured rock aquifers like the Belgium chalk can act as important drinking water suppliers and for protection an advanced imaging of double porosity effects is important for transport predictions with ... [more ▼]

Fractured rock aquifers like the Belgium chalk can act as important drinking water suppliers and for protection an advanced imaging of double porosity effects is important for transport predictions with reduced uncertainty. Between two adjacent 50 m-deep 7.55 m distant boreholes a with flowmeter tests and optical imagining figured out open main fracture is for multiple tracer tests isolated using an inflatable double packer system. Injecting in a dipole configuration continuously 50 °C hot water for 70 h jointly with two pulse fluorescent dye tracer (uranine) shows a 12.5 hours arrival delay of the heat compared to the solute. Stopping heat injection shows a strong direct temperature decrease followed by slow temperature rebound over several days. Stored heat around the injection well is pulled and the matrix reacts slowly by contribute stored heat to the colder water drawn from the surroundings. [less ▲]

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See detailApsûGIS : a GIS-tool for groundwater vulnerability assessment using physical criteria
Dollé, Fabien ULiege; Thomas, Caroline ULiege; Orban, Philippe ULiege et al

Poster (2018, September 11)

The Apsû method has been developed since 2004 to produce groundwater intrinsic and specific vulnerability maps based on a quantitative description of contaminant transport processes in the subsurface. It ... [more ▼]

The Apsû method has been developed since 2004 to produce groundwater intrinsic and specific vulnerability maps based on a quantitative description of contaminant transport processes in the subsurface. It is based on the source-pathway-receptor approach, driven by two concepts: land surface dangerosity that accounts for lateral flow on land surface and infiltration and subsurface attenuation capacity. Vulnerability classes are based on physically-based criteria reflecting the sensitivity of groundwater to pollution events, namely contaminant travel time across the unsaturated zone, pollution duration, or contaminant concentration or mass recovery factors at the groundwater table. To facilitate the application of the Apsû method to case studies, GIS-based applications and interfaces have been developed to integrate geodatabases and user interfaces in the same environment software. The main geodatabase contains all the data required for the calculation of the vulnerability coefficient, such as spatial data (topography, land cover, hydrological network, meteorology, soil types…) and specific databases on contaminant properties (i.e. Koc values, degradation constants…), on hydrogeological properties of geological layers constituting the unsaturated zone flow path. Specific user interfaces have been developed to prepare and export spatial data required by the Apsû calculations. Once the groundwater vulnerability factors are calculated, another user interface is available to automatically create and customize different thematic layers related to groundwater vulnerability mapping. This integrated system makes it possible to automate numerous data formatting geoprocessing operations, and to ensure data integrity by minimizing user interactions with the data (spatial frame, data projection, link between spatial data and databases, etc.) and to focus work on the specificities of the areas studied and the interpretation of the vulnerability maps created. The objective of the communication is to describe the general organisation and operation of the GIS-based interface, illustrated with groundwater vulnerability case studies for aquifers of the Walloon Region of Belgium. [less ▲]

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See detailFractured aquifer heterogeneity characterization for advanced transport modelling based on multiple single fracture tracer tests
Hoffmann, Richard ULiege; Goderniaux, Pascal; Poulain, Angélique et al

Conference (2018, September 11)

Assessing fractured rocks, like a complex double porosity chalk, requires an advanced heterogeneity characterization and preferential pathway quantification. This contributes for reducing the uncertainty ... [more ▼]

Assessing fractured rocks, like a complex double porosity chalk, requires an advanced heterogeneity characterization and preferential pathway quantification. This contributes for reducing the uncertainty of transport predictions for protecting this excellent drinking water suppliers. With flowmeter tests and optical imaging, a horizontal main fracture between two adjacent 7.55 m distant wells is figured out. Injecting jointly 70 h heat and two solute pulses in a dipole configuration shows a strong heat delay and temperature rebound due to matrix reactions. Using dissolved gases jointly with a solute show, that the higher the tracer diffusivity the higher the confronted flow heterogeneity. [less ▲]

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See detailExperimental assessment and prediction of short-term aquifer thermal energy storage for energy demand-side management applications
Robert, Tanguy ULiege; Hermans, Thomas; Lesparre, Nolwenn et al

Conference (2018, September 10)

Groundwater heat pump (GWHP) systems are now widely used for space heating and cooling and domestic hot water production. On one hand, GWHP systems are considered as a renewable energy and on the other ... [more ▼]

Groundwater heat pump (GWHP) systems are now widely used for space heating and cooling and domestic hot water production. On one hand, GWHP systems are considered as a renewable energy and on the other hand, their increasing use impacts electrical grid balancing. Since the coupling of electrically-driven heating, ventilation, and air-conditioning (HVAC) systems with thermal energy storage (TES) is seen as a promising tool for demand-side management (DSM) in the low-voltage grid, experimental validation of aquifer thermal energy storage (ATES) capabilities at demand side management (DSM) frequencies (real time, intraday, interday, and interseasonal) is needed for the sector to adopt it. We demonstrated here that hourly to daily ATES can be efficient in terms of energy recovery rate and exergy whereas weekly to seasonal ATES bears the risk of lower recovery rates and presents almost always low exergy. Moreover, energy recovery rates are improved with the increasing use of storage and recovery cycles. To formulate this demonstration, we emulated the operating conditions of GWHP systems with ATES in several well-characterized experimental pilot sites in Wallonia. The standardized experiment we used to estimate the different hydrodynamic parameters and energy recovery at the pilot sites was based on push/pull tests with the injection of heated water, its storage for different DSM periods, and finally its recovery. Fluxes were either measured in-situ by means of the finite volume point dilution method or estimated with the local hydraulic conductivity and gradient. We report here a direct relationship between the energy recovery rate and natural groundwater fluxes. [less ▲]

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See detailSimulation of groundwater and heat transfer for the geothermal use of flooded abandoned old-mines
Vopat, Olivier; Orban, Philippe ULiege; Brouyère, Serge ULiege et al

Conference (2018, September)

Groundwater in flooded abandoned mines could be used for geothermal purposes using heat-pumps and an open loop involving pumping and re-injection. Logically, warm water is usually expected to be pumped ... [more ▼]

Groundwater in flooded abandoned mines could be used for geothermal purposes using heat-pumps and an open loop involving pumping and re-injection. Logically, warm water is usually expected to be pumped (or injected) in the deep parts of the open network, and cold water is expected to be re-injected (or pumped) in the shallower parts. However, the feasibility and the durability of future ‘Ground Source Heat Pump system’ (GSHP) must be studied through a deep characterization of the subsoil but also using numerical models able to simulate groundwater flow and heat transfer in these complex geological environments. Depending on the type of abandoned mine, the true geometry of the interconnected network of open galleries and shafts can indeed be highly complex. A high-velocity water flow is expected in this type of network, while low-velocity groundwater flow occurs in less permeable fractured and porous rock massif. The SUFT3D code that allows combining in a single model, and in a fully interacting way, linear or distributed reservoirs to model groundwater flows in mine galleries and classical groundwater flow in the variably saturated equivalent porous surrounding media is developed to model heat transfer using the similarities existing between solute and heat transfer equations. The code is then used to test on a simplified case study based on the characteristics of the Werister coal mine (Belgium), the impact of the hydrogeological conditions and of technical choices on the feasibility and the durability of these geothermal systems. [less ▲]

Detailed reference viewed: 43 (10 ULiège)