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See detailHeat tracer and solute tests in an alluvial aquifer: field experiment and inverse modelling
Dassargues, Alain ULg; Klepikova, Maria; Jamin, Pierre ULg et al

Poster (2015, December 18)

Using heat as an active tracer in different types of aquifers is a topic of increasing interest. In this study, we investigate the potential interest of using heat tracer tests for characterization of a ... [more ▼]

Using heat as an active tracer in different types of aquifers is a topic of increasing interest. In this study, we investigate the potential interest of using heat tracer tests for characterization of a shallow alluvial aquifer. A thermal tracer test was conducted in the alluvial aquifer of the Meuse River, Belgium. The tracing experiment consisted in simultaneously injecting heated water and a dye tracer in a piezometer and monitoring the evolution of groundwater temperature and tracer concentration in the recovery well and in monitoring wells. To get insights in the 3D characteristics of the heat transport mechanisms the space-filling arrangement of observation wells was used. The breakthrough curves measured in the recovery well showed that heat transfer in the alluvial aquifer is slower and more dispersive than solute transport. Recovery is very low for heat while in the same time it is measured as relatively high for the solute tracer. This is due to the fact that heat diffusion is larger than molecular diffusion, implying that exchange between groundwater and the porous medium matrix is far more significant for heat than for solute tracers. Temperature breakthrough curves in other piezometers are contrasted with what would be expected in an ideal layered aquifer. They reveal strongly unequal lateral and vertical components of the transport mechanisms. The observed complex behavior of the heat plume was explained by the groundwater flow gradient on the site and heterogeneities of hydraulic conductivity field. By using numerical model of heat and flow coupled with pilot points inverse approach main preferential paths were characterized. [less ▲]

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See detailUnderground Pumped Storage Hydroelectricity using abandoned works (open pits and deep mines)
Pujades, Estanislao ULg; Willems, Thibault ULg; Bodeux, Sarah ULg et al

Conference (2015, December 15)

Pumped Storage Hydroelectricity (PSH) is a good alternative to increase the efficiency of power plants, which cannot regulate the amount of electricity generated according to the demand (wind, solar or ... [more ▼]

Pumped Storage Hydroelectricity (PSH) is a good alternative to increase the efficiency of power plants, which cannot regulate the amount of electricity generated according to the demand (wind, solar or even nuclear power plants). PSH plants, which consist in two reservoirs located at different heights (upper and lower), can store energy during low demand periods (pumping water from the lower to the upper reservoir) and generate electricity during the high demand peaks (falling water from the upper to the lower reservoir). Given that the two reservoirs must be located at different heights, PSH plants cannot be constructed in flat regions. Nevertheless, in these regions, an alternative could be to use abandoned underground works (open pits or deep mines) as lower reservoirs to construct Underground Pumped Storage Hydroelectricity (UPSH) plants. To select the best place to construct a plant, two considerations must be taken into account regarding the interaction between UPSH plants and groundwater: 1) the alteration of the natural conditions of aquifers and 2), the efficiency of the plant since the electricity generated depends on the hydraulic head inside the underground reservoir. Obviously, a detailed numerical model must be necessary before to select a location. However, a screening methodology to reject the most disadvantageous sites in a short period of time would be useful. Groundwater flow impacts caused by UPSH plants are analyzed numerically and the main variables involved in the groundwater evolution are identified. The most noticeable effect consists in an oscillation of the groundwater. The hydraulic head around which groundwater oscillates, the magnitude of the oscillations and the time to achieve a “dynamic steady state” depend on the boundaries, the parameters of the aquifer and the characteristics of the underground reservoir. A screening methodology is proposed to assess the main impacts caused in aquifers by UPSH plants. Finally, the efficiency regarding the groundwater evolution inside the reservoir is determined. [less ▲]

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See detailCase study 2: Groundwater – surface water interaction in limestone areas of the GWB BE_Meuse_RWM021 (Belgium)
Brouyère, Serge ULg; Briers, Pierre ULg; Schmit, Flore et al

in Hinsby, Klaus; Schutten, Johan; Craig, Matt (Eds.) et al Technical Report on Groundwater Associated Aquatic Ecosystems (2015)

The achievement of good status in groundwater bodies involves meeting a series of conditions, which are defined in the Water Framework Directive (WFD) and, in the case of good chemical status, are given ... [more ▼]

The achievement of good status in groundwater bodies involves meeting a series of conditions, which are defined in the Water Framework Directive (WFD) and, in the case of good chemical status, are given further detail in the Groundwater Directive (GWD). One of these conditions is to ensure that groundwater inputs to associated surface waters do not result in failure to meet the environmental objectives of those waters or result in significant diminution in status/ecological or chemical quality of those waters. GWAAE (Groundwater Associated Aquatic Ecosystems) are those surface water bodies (SWBs), including rivers, standing waters and transitional waters where the surface water ecology and hydrology is dependent on contributions from groundwater in order to meet their environmental objectives under the WFD. These environmental objectives may vary, and therefore the associated environmental quality standards (EQS) or flow/level requirements of GWAAEs may differ between high status and good status SWBs. As noted in the Blueprint for Water, analysis of the first River Basin Management Plans has shown that Member States (MS) have experienced difficulties in understanding the interactions between groundwater and surface water and undertaking the necessary status assessments. This was highlighted in a survey carried out by Working Group Groundwater (WGGW) in 2014/15, which indicated that only half of the MS had assessed quantitative interactions and very few had addressed chemical pressures, including the derivation of threshold values (TVs) that were appropriate to the WFD objectives for GWAAEs. This report aims to further knowledge on what GWAAE are, how they are aligned to WFD processes, and support Member States to properly include the needs of these ecosystems in river basin management planning. The report clarifies the categories of GWAAE and their relative dependence on groundwater and collates current available knowledge and experience via a number of examples and case studies. Terminology and status assessment procedures are explained and pragmatic approaches are proposed which leave some flexibility for MS to adapt to their own specific needs. This technical report, which is not a "guidance document", makes use of and complements existing CIS documents, including existing technical reports on groundwater dependent terrestrial ecosystems (GWDTEs) and Guidance Document 18 (Guidance on Groundwater Status and Trend Assessment). A number of recommendations for technical users of the report are highlighted in boxes in each Chapter. The common themes from these recommendations are collated in Chapter 8, as issues and questions to WGGW and MS in general. The key message from this is the need for closer interaction between scientific disciplines, practitioners and Working Groups in developing conceptual understanding for GWAAEs and implementation of WFD requirements, including identification of GWAAEs, their characterisation and monitoring, and adopting appropriate status assessment methodologies. [less ▲]

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See detailMéthodologie de diagnostic environnemental autour de captages d’eau potabilisable sensibles qualitativement du point de vue nitrate
Vandenberghe, Christophe ULg; Bah, Boubacar Billo ULg; Orban, Philippe ULg et al

Report (2015)

Le projet s’inscrit dans le cadre des « contrats de captages » dont la mise en oeuvre est assurée par la SPGE (Société Publique de Gestion de l’Eau) et ce, conformément au contrat de gestion qui lie cette ... [more ▼]

Le projet s’inscrit dans le cadre des « contrats de captages » dont la mise en oeuvre est assurée par la SPGE (Société Publique de Gestion de l’Eau) et ce, conformément au contrat de gestion qui lie cette dernière avec le Gouvernement wallon. L’objectif se décline en trois phases : 1. établir une méthodologie commune de détermination et priorisation des actions à entreprendre autour de captages en vue d’y préserver ou de restaurer la qualité de l’eau ; 2. tester la méthodologie (définition des actions à entreprendre) sur six situations jugées représentatives sur des captages de la SWDE (Société Wallonne des Eaux) ; 3. proposer et coordonner des actions à mettre en oeuvre sur deux ou trois des six sites pilotes. La méthodologie est traduite en logigrammes d’actions qui proposent des démarches communes de diagnostic et d’actions à entreprendre autour de captages en vue d’y préserver ou de restaurer la qualité de l’eau. [less ▲]

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See detailUnderground Pumped Storage Hydroelectricity (UPSH) using abandoned works
Pujades, Estanislao ULg; Willems, Thibault ULg; Orban, Philippe ULg et al

Poster (2015, September 17)

Underground Pumped Storage Hydroelectricity (UPSH) using abandoned works is an interesting alternative to increase the efficiency of some power plants, which cannot regulate the amount of electricity ... [more ▼]

Underground Pumped Storage Hydroelectricity (UPSH) using abandoned works is an interesting alternative to increase the efficiency of some power plants, which cannot regulate the amount of electricity generated according to the demand. UPSH plants can store (pumping water from an underground to an upper reservoir) or produce energy (releasing water from an upper to an underground reservoir) during the low or high demand periods. Two considerations must be taken into account in order to construct an UPSH plant: 1) the alteration of the natural conditions of aquifers and 2), the efficiency of the plant, which depends on the hydraulic head inside the underground reservoir. Obviously, a detailed numerical model must be necessary to design a plant. However, a screening methodology to apply during the early stages of the design of a UPSH plant in order to reject the most disadvantageous sites in a short period of time would be useful. Groundwater flow impacts caused by UPSH plants are analyzed numerically and the main variables involved in the groundwater evolution are identified. The most noticeable effect consists in an oscillation of the groundwater. The hydraulic head around which groundwater oscillates, the magnitude of the oscillations and the time to achieve a pseudo-steady state (magnitude and head reached during oscillations do not vary anymore with time) depend on the boundaries, the parameters of the aquifer and the characteristics of the underground reservoir. From the numerical study, a screening methodology, which is based on existing analytical procedures (solutions for large diameter wells, methodologies for cyclic pumpings and the image well theory), is proposed to assess the main impacts caused in aquifers by UPSH plants and their efficiency regarding the groundwater evolution inside the reservoir. The procedure can be applied in a relatively short period of time and is useful to select those appropriate sites to construct a UPSH plant. [less ▲]

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See detailOpen pits or deep mines used for Underground Pumped Storage Hydroelectricity (UPSH): impacts on groundwater exchanges
Pujades, Estanislao ULg; Willems, Thibault ULg; Orban, Philippe ULg et al

Poster (2015, July 08)

UPSH using abandoned works is an attractive alternative to improve the efficiency of power plants, which cannot regulate the amount of electricity generated according to the demand (wind, solar or nuclear ... [more ▼]

UPSH using abandoned works is an attractive alternative to improve the efficiency of power plants, which cannot regulate the amount of electricity generated according to the demand (wind, solar or nuclear). UPSH plants can store (pumping water from an underground to an upper reservoir) or produce energy (releasing water from an upper to an underground reservoir) during the low or high demand periods. However, it is mandatory to determine 1) the impacts caused on aquifers and 2) the role played by the aquifer characteristics in order to assess the suitability of UPSH plants. Numerical simulations are developed in order to ascertain the groundwater flow impacts and the variables involved in the process. Given the earlier stages of our study, results are obtained considering regular pumping-injection cycles and simplifying the shape of the mine/open pit. The most noticeable effect consists in an oscillation of the groundwater. The hydraulic head around which groundwater oscillates, the magnitude of the oscillations and the time to achieve a pseudo-steady state (magnitude and head reached during oscillations do not vary anymore with time) depend on the boundaries, the parameters of the aquifer and the characteristics of the underground reservoir. [less ▲]

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See detailOrigine des fortes teneurs en fluorure dans les eaux souterraines du socle précambrien du Bénin central
Tossou, Yao ULg; Gesels, Julie ULg; Alassane, Abdoulkarim et al

Scientific conference (2015, June 25)

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See detailA hydrochemical - isotopic approach for assessing factors controlling the regional pollution of an urban aquifer
Gesels, Julie ULg; Orban, Philippe ULg; Popescu, Ileana-Cristina et al

Poster (2015, June 24)

The alluvial aquifer of the Meuse River is contaminated at regional scale in the urbanized and industrialized area of Liège in Belgium, in particular inorganics pollutants such as sulfate, nitrate and ... [more ▼]

The alluvial aquifer of the Meuse River is contaminated at regional scale in the urbanized and industrialized area of Liège in Belgium, in particular inorganics pollutants such as sulfate, nitrate and ammonium. The sources of those contaminants are numerous: brownfields, urban waste water, subsurface acid mine drainage from former coal mines, atmospheric deposits related to former pollutants emissions in the atmosphere ... Sulfate, nitrate and ammonium are both typical pollutants of the aquifer and tracers of the possible pollution sources. In the Water Framework Directive context, a detailed hydrogeochemical characterization of groundwater was performed. The aim is to determine the origin of the inorganic contaminations, the main processes contributing to poor groundwater quality and the spatial extent of the contaminations. A large hydrochemical sampling campaign was performed, based on 71 selected representative sampling locations, to better characterize the different vectors (end-members) of contamination of the alluvial aquifer and their respective contribution to groundwater contamination in the area. Groundwater samples were collected and analyzed for major and minor compounds and metallic trace elements. The analyses also include stable isotopes in water, sulfate, nitrate, ammonium, dissolved inorganic carbon, boron and strontium. Different hydrogeochemical approaches are combined to obtain a global understanding of the hydrogeochemical processes at regional scale. Hydrochemical interpretations are based on classical diagrams, spatial distribution maps, geochemical equations, multivariate statistics such as self-organizing maps and isotopic analyses. With this combined approach, the location of the contaminant sources and most contaminated sectors of the alluvial aquifer together with a better understanding of geochemical processes involved are obtained. Redox processes strongly influence the composition of groundwater, specifically for compounds degrading the quality of groundwater in the area (sulfate, nitrate and ammonium). The highest concentrations of sulfate can be associated with the post-mining stage in the acid mine drainage process. Various reactions involving nitrogen compounds have been identified and allow a better understanding of causes of high concentrations of ammonium and nitrate. Denitrification and sulphate reduction are also demonstrated based on isotopic ratios. [less ▲]

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See detailUse and utility of combined solute and heat tracer tests for characterizing hydrogeothermal properties of an alluvial aquifer
Klepikova, Maria; Wildemeersch, Samuel; Jamin, Pierre ULg et al

Conference (2015, June 05)

Using heat as a tracer together with a solute tracer is interesting for characterizing hydrogeothermal properties of the underground. These properties are particularly needed to dimension any low ... [more ▼]

Using heat as a tracer together with a solute tracer is interesting for characterizing hydrogeothermal properties of the underground. These properties are particularly needed to dimension any low temperature geothermal project using an open doublet system (pumping-reinjection) in a shallow aquifer. The tracing experiment, conducted in the alluvial aquifer of the River Meuse (Hermalle near Liège), consisted in injecting simultaneously heated water at 40°C and a dye tracer in a piezometer and monitoring the evolution of temperature and tracer concentration in the recovery well and in nine monitoring piezometers located in three transects with regards to the main groundwater flow direction. The breakthrough curves measured in the recovery well showed that heat transfer in the alluvial aquifer is slower. All measured results show also that the heat diffusivity is larger than the solute dispersion. These contrasted behaviours are stressed in the lower permeability zones of the aquifer. Inverse modelling is applied for calibrating the numerical simulation of the groundwater flow, heat and solute transport. First results are presented showing that the density effect must be taken into account and that, as expected, the most important parameter to be calibrated accurately is the hydraulic conductivity. [less ▲]

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