Philippe Meus - Academia.edu (original) (raw)

Papers by Philippe Meus

Il Nuovo Cimento C

Based on Lucas cell technique, the portable device named "PRASSI" (SILENA mod. 5S) was used to re... more Based on Lucas cell technique, the portable device named "PRASSI" (SILENA mod. 5S) was used to realise discrete radon measurements in water samples. The calibration factor is (64.766.9) cpm Q Bq 21 and, with the present setup for measuring radon in water, the detection and the determination limits are, respectively, 0.007 and 0.020 Bq. Thus, the device is well adapted for determining low radon content in karstic waters. Several discrete radon samplings were performed nearly every week in the three main springs of the Bastareny karstic system (Catalonian Pyrenees, N-E Spain). Thus, it was possible to estimate the reproducibility of the methodology as well as to characterise every spring of the aquifer in relation to their hydrogeological features. With the portable radon monitor, some useful measurements were achieved to estimate radon loss due to degassing process over short distances, with important consequences for radon studies in karstic waters. Lastly, it was possible to perform intensive sampling during a flood and the results point out the great variability of radon levels, closely related to the flow rate trend. That permitted also an intercomparison with other radon probes installed previously in every spring, for continuous radon measurements.

71st EAGE Conference and Exhibition incorporating SPE EUROPEC 2009, 2009

Field hydrogeologists employ groundwater tracer tests with artificial tracers to demonstrate the ... more Field hydrogeologists employ groundwater tracer tests with artificial tracers to demonstrate the underground interconnection between sinkholes and springs. In surface waters however, and particularly near the injection site, the intense water coloration can arouse legitimate surprise or even fear among the population. There is an increasing demand for "blind" tracer tests. Since the recent offer of LEDs that can radiate UV light at shorter wavelengths (316 nm, and down to 240 nm), field fluorometers can be upgraded to detect a new range of colourless tracers. We describe the characteristics of a flow-through fluorometer equipped with three optical channels. This field instrument detects and measures the individual concentration of as many as three colourless tracers found in a cocktail at concentrations near 1 ppb.

A la demande du Service des Eaux souterraines de la Region wallonne et pour le compte de celle-ci... more A la demande du Service des Eaux souterraines de la Region wallonne et pour le compte de celle-ci, la Commission wallonne d'Etude et de Protection des Sites souterrains (CWEPSS) a organise un tracage d'eaux souterraines en region karstique a Hastiere (Province de Namur). La CWEPSS a effectue l'etude et le travail avec la collaboration de la Societe Geologica de Gembloux pour le tracage et celle de l'Universite de Liege pour divers parametres connexes (analyses des eaux, mesures de debit, spectrofluorimetrie, etc.). Il y a a Hastiere plusieurs resurgences d'eaux karstiques provenant d'un vaste synclinal calcaire complexe; deux captages y prelevent des eaux pour les besoins de la population. Des traceurs fluorescents ont ete injectes dans trois points d'engouffrement naturel des eaux. Trois traceurs differents ont ete utilises simultanement (un dans chaque point de perte) et recherches dans 9 lieux de resurgence potentielle. En une seule campagne d'un m...

Karst aquifers, formed by the dissolution of carbonate rocks such as limestone or dolomite, suppl... more Karst aquifers, formed by the dissolution of carbonate rocks such as limestone or dolomite, supply drinking water to 25% of the global population. Their highly variable sizes and heterogeneous hydrogeological characteristics are difficult to characterize and present challenges for modeling of storage capacities. Little is known about the surface and groundwater interconnection, about the connection between the porous formations and the draining cave and conduits, and about the variability of groundwater volume within the system. Usually, an aquifer is considered as a black box, where water fluxes are monitored as input and output. However, water inflow and outflow are highly variable and cannot be measured directly. A recent project, which began this year, sought to constrain the water budget in a Belgian karst aquifer and to assess the porosity and water dynamics, combining absolute gravity (AG) and water table measurements, the latter giving measurements of pressure head in a conduit. The advantage of gravity measurements is that they integrate all the subsystems in the karst system. This is not the case with traditional geophysical tools like boring or monitoring wells, which are soundings affected by their near environment and its heterogeneity.

Advances in Karst Science, 2019

The existence of karst features and conduit flow in silica-rich rocks has been increasingly recog... more The existence of karst features and conduit flow in silica-rich rocks has been increasingly recognized around the world. Well-developed quartzite karst is known in tropical settings, such as southern Venezuela and eastern Brazil. However, little is known about the hydrogeological behavior of these terrains. Pioneering water tracing studies were performed in the Proterozoic quartzites of the Chapada Diamantina (Diamontiferous Plateau) of central-eastern Brazil, using the tracers amino-G and uranine. Tracer detection was performed by four in situ fluorometers, granular-activated charcoal receptors and water analysis. Hydrochemical conditions resulted in contrasting performances of the tracers, with uranine providing some positive results and yielding clear breakthrough curves. Low-pH water and high-fluorescence background levels appear to considerably inhibit tracer performance and add difficulties in the interpretation of some tracer tests. A preliminary assessment of flow routes and...

The highly anisotropic and heterogeneous hydrogeological characteristics of karst aquifers are di... more The highly anisotropic and heterogeneous hydrogeological characteristics of karst aquifers are difficult to characterize and present challenges for modeling of storage capacities. Little is known about the surface and groundwater interconnection, about the connection between the porous formations and the draining cave and conduits, and about the variability of groundwater volume within the system. Usually, an aquifer is considered as

This paper is an attempt to review thé use of artificial tracers in karst environments since thé ... more This paper is an attempt to review thé use of artificial tracers in karst environments since thé early beginning of its history until nowadays. During a long period, tracer tests aimed exclusively to define water catchment areas in karst basins or to localize thé highest transmissive channels. Rallier récent developments in tne metnodoiogy or m tne technique itself hâve largely increased thé potentialities of understanding karst flow mechanisms. Among thèse developments we can find: thé use of boreholes as injection or measuring points thrôugh which a wider range of permeabilities could be investigated, thé progress in tracer sélection and détection, thé introduction of continuons monitoring, thé improvement of conceptualization in karst modelling, or thé application of tracers in thé vadose zone. The rôle that karstic cavities hâve played is almost obvious since those cavities can be associated to fundamental parts of thé drainage structure of a given aquifer, such as drains or ann...

Advances in Karst Science, 2019

The quantification of mass transfer through auxiliary karst systems is addressed by using a speci... more The quantification of mass transfer through auxiliary karst systems is addressed by using a specific point dilution long-term tracer test. The physical functioning of such systems is usually only inferred by hydrodynamical and environmental tracer data, whose interpretation often relies on invalidated assumptions. The new approach is a way for experimentally validating or complementing the classical approaches. The lake of Fontaine de Rivire is an auxiliary karst system in the Frasnian limestones of the Ourthe Valley in Belgium. Its particular confinement was studied by conjunctional use of natural responses and single-point dilution tracer test, with an injection of 41 g of uranine on 22 March 2017. The tracer test was monitored during one year using fluorometers, water and charcoal samplings at five points in the lake and six points at the surface (no connection having been established outside). A slow flow (in the order of magnitude of 1 m/h) of the lake could be observed and som...

Geologica Belgica, 2013

Colourless fluorescent UV tracers are increasingly used in hydrogeological studies in drinking wa... more Colourless fluorescent UV tracers are increasingly used in hydrogeological studies in drinking water catchments, in which classical dyes (uranine, sulforhodamines) can sometimes be of significant concern if unexpectedly exceeding the limit of visibility. Among these colourless tracers, optical brighteners and sulfonates (presently naphthionate and amino G acid) are widely used despite lower fluorescence yields, strong interferences with natural organic matter, as well as oxy- or photo-degradation. As a result, higher amounts of tracer are sometimes used, yielding higher concentrations in drinking water and giving rise to the question of their toxicity and the occurrence of their by-products in waterworks. In this paper, several years of practice and improvement of the detection's performance using combined laboratory spectrofluorometric and field fluorometric techniques are summarized and illustrated with several case studies in different aquifers. The developments of UV LEDs op...

In order to monitor the hydrological strain forces of the karst micro fissure networks and local ... more In order to monitor the hydrological strain forces of the karst micro fissure networks and local fault activities, six capacitive extensometers were installed inside a karstic cave near the midi-fault in Belgium. From 2004 to 2008, the nearby Lomme River experienced several heavy rains, leading to flooding inside the Rochefort cave. The highest water level rose more than thirteen meters, the karstic fissure networks were filled with water, which altered the pore pressure of the cave. The strain response to the hydrological induced pore pressure changes are separately deduced from fifteen events when the water level exceeded six meters. The strain measured from the extensometer show a linear contraction during the water recharge and a nonlinear exponential extension releasing during the water discharge. The sensitivity and stability of the sensor are constrained by comparing continuously observed tidal strain waves with a theoretical model. Finally, a local fault deformation rate around 0.03pm0.0020.03 \pm 0.0020.03pm0.002mm/yr is estimated from more than four years' records.

Résumé Les hydrogéologues utilisent les traçages artificiels pour montrer l'interconnexion de... more Résumé Les hydrogéologues utilisent les traçages artificiels pour montrer l'interconnexion de pertes et de sources. Dans les eaux de surface, et particulièrement près du site d'injection, l'intense coloration de l'eau peut provoquer la surprise ou une crainte légitime des voisins. Depuis la récente disponibilité de LED irradiant de l'UV (jusqu'à 240 nm), les fluorimètres de terrain peuvent détecter jusqu'à trois traceurs incolores, jusqu' à des concentrations voisines de 1 ppb. 2 3 4 1 5 Figure 1: Visibilité de traceurs usuels (concentration: 1000 ppb).L'impact est élevé pour l'uranine (vert) et l'amidorhodamine G (rouge), mais nul pour la duasyne, le naphtionate et l'amino G acide. Figure 2: Formules et caractéristiques spectrales de deux traceurs incolores. Les traceurs les plus courants sont l'uranine, l'éosine, la sulforhodamine B, l'amidorhodamine G, la rhodamine WT, la duasyne, le tinopal, l'amino G acide (Käss 19...

Geologica Belgica

Colourless fluorescent UV tracers are increasingly used in hydrogeological studies in drinking wa... more Colourless fluorescent UV tracers are increasingly used in hydrogeological studies in drinking water catchments, in which classical dyes (uranine, sulforhodamines) can sometimes be of significant concern if unexpectedly exceeding the limit of visibility. Among these colourless tracers, optical brighteners and sulfonates (presently naphthionate and amino G acid) are widely used despite lower fluorescence yields, strong interferences with natural organic matter, as well as oxy- or photo degradation. As a result, higher amounts of tracer are sometimes used, yielding higher concentrations in drinking water and giving rise to the question of their toxicity and the occurrence of their by-products in waterworks. In this paper, several years of practice and improvement of the detection’s performance using combined laboratory spectrofluorometric and field fluorometric techniques are summarized and illustrated with several case studies in different aquifers. The developments of UV LEDs optica...

Eos, Transactions American Geophysical Union, 2006

Environmental Earth Sciences, 2013

Il Nuovo Cimento C

Based on Lucas cell technique, the portable device named "PRASSI" (SILENA mod. 5S) was used to re... more Based on Lucas cell technique, the portable device named "PRASSI" (SILENA mod. 5S) was used to realise discrete radon measurements in water samples. The calibration factor is (64.766.9) cpm Q Bq 21 and, with the present setup for measuring radon in water, the detection and the determination limits are, respectively, 0.007 and 0.020 Bq. Thus, the device is well adapted for determining low radon content in karstic waters. Several discrete radon samplings were performed nearly every week in the three main springs of the Bastareny karstic system (Catalonian Pyrenees, N-E Spain). Thus, it was possible to estimate the reproducibility of the methodology as well as to characterise every spring of the aquifer in relation to their hydrogeological features. With the portable radon monitor, some useful measurements were achieved to estimate radon loss due to degassing process over short distances, with important consequences for radon studies in karstic waters. Lastly, it was possible to perform intensive sampling during a flood and the results point out the great variability of radon levels, closely related to the flow rate trend. That permitted also an intercomparison with other radon probes installed previously in every spring, for continuous radon measurements.

71st EAGE Conference and Exhibition incorporating SPE EUROPEC 2009, 2009

Field hydrogeologists employ groundwater tracer tests with artificial tracers to demonstrate the ... more Field hydrogeologists employ groundwater tracer tests with artificial tracers to demonstrate the underground interconnection between sinkholes and springs. In surface waters however, and particularly near the injection site, the intense water coloration can arouse legitimate surprise or even fear among the population. There is an increasing demand for "blind" tracer tests. Since the recent offer of LEDs that can radiate UV light at shorter wavelengths (316 nm, and down to 240 nm), field fluorometers can be upgraded to detect a new range of colourless tracers. We describe the characteristics of a flow-through fluorometer equipped with three optical channels. This field instrument detects and measures the individual concentration of as many as three colourless tracers found in a cocktail at concentrations near 1 ppb.

A la demande du Service des Eaux souterraines de la Region wallonne et pour le compte de celle-ci... more A la demande du Service des Eaux souterraines de la Region wallonne et pour le compte de celle-ci, la Commission wallonne d'Etude et de Protection des Sites souterrains (CWEPSS) a organise un tracage d'eaux souterraines en region karstique a Hastiere (Province de Namur). La CWEPSS a effectue l'etude et le travail avec la collaboration de la Societe Geologica de Gembloux pour le tracage et celle de l'Universite de Liege pour divers parametres connexes (analyses des eaux, mesures de debit, spectrofluorimetrie, etc.). Il y a a Hastiere plusieurs resurgences d'eaux karstiques provenant d'un vaste synclinal calcaire complexe; deux captages y prelevent des eaux pour les besoins de la population. Des traceurs fluorescents ont ete injectes dans trois points d'engouffrement naturel des eaux. Trois traceurs differents ont ete utilises simultanement (un dans chaque point de perte) et recherches dans 9 lieux de resurgence potentielle. En une seule campagne d'un m...

Karst aquifers, formed by the dissolution of carbonate rocks such as limestone or dolomite, suppl... more Karst aquifers, formed by the dissolution of carbonate rocks such as limestone or dolomite, supply drinking water to 25% of the global population. Their highly variable sizes and heterogeneous hydrogeological characteristics are difficult to characterize and present challenges for modeling of storage capacities. Little is known about the surface and groundwater interconnection, about the connection between the porous formations and the draining cave and conduits, and about the variability of groundwater volume within the system. Usually, an aquifer is considered as a black box, where water fluxes are monitored as input and output. However, water inflow and outflow are highly variable and cannot be measured directly. A recent project, which began this year, sought to constrain the water budget in a Belgian karst aquifer and to assess the porosity and water dynamics, combining absolute gravity (AG) and water table measurements, the latter giving measurements of pressure head in a conduit. The advantage of gravity measurements is that they integrate all the subsystems in the karst system. This is not the case with traditional geophysical tools like boring or monitoring wells, which are soundings affected by their near environment and its heterogeneity.

Advances in Karst Science, 2019

The existence of karst features and conduit flow in silica-rich rocks has been increasingly recog... more The existence of karst features and conduit flow in silica-rich rocks has been increasingly recognized around the world. Well-developed quartzite karst is known in tropical settings, such as southern Venezuela and eastern Brazil. However, little is known about the hydrogeological behavior of these terrains. Pioneering water tracing studies were performed in the Proterozoic quartzites of the Chapada Diamantina (Diamontiferous Plateau) of central-eastern Brazil, using the tracers amino-G and uranine. Tracer detection was performed by four in situ fluorometers, granular-activated charcoal receptors and water analysis. Hydrochemical conditions resulted in contrasting performances of the tracers, with uranine providing some positive results and yielding clear breakthrough curves. Low-pH water and high-fluorescence background levels appear to considerably inhibit tracer performance and add difficulties in the interpretation of some tracer tests. A preliminary assessment of flow routes and...

The highly anisotropic and heterogeneous hydrogeological characteristics of karst aquifers are di... more The highly anisotropic and heterogeneous hydrogeological characteristics of karst aquifers are difficult to characterize and present challenges for modeling of storage capacities. Little is known about the surface and groundwater interconnection, about the connection between the porous formations and the draining cave and conduits, and about the variability of groundwater volume within the system. Usually, an aquifer is considered as

This paper is an attempt to review thé use of artificial tracers in karst environments since thé ... more This paper is an attempt to review thé use of artificial tracers in karst environments since thé early beginning of its history until nowadays. During a long period, tracer tests aimed exclusively to define water catchment areas in karst basins or to localize thé highest transmissive channels. Rallier récent developments in tne metnodoiogy or m tne technique itself hâve largely increased thé potentialities of understanding karst flow mechanisms. Among thèse developments we can find: thé use of boreholes as injection or measuring points thrôugh which a wider range of permeabilities could be investigated, thé progress in tracer sélection and détection, thé introduction of continuons monitoring, thé improvement of conceptualization in karst modelling, or thé application of tracers in thé vadose zone. The rôle that karstic cavities hâve played is almost obvious since those cavities can be associated to fundamental parts of thé drainage structure of a given aquifer, such as drains or ann...

Advances in Karst Science, 2019

The quantification of mass transfer through auxiliary karst systems is addressed by using a speci... more The quantification of mass transfer through auxiliary karst systems is addressed by using a specific point dilution long-term tracer test. The physical functioning of such systems is usually only inferred by hydrodynamical and environmental tracer data, whose interpretation often relies on invalidated assumptions. The new approach is a way for experimentally validating or complementing the classical approaches. The lake of Fontaine de Rivire is an auxiliary karst system in the Frasnian limestones of the Ourthe Valley in Belgium. Its particular confinement was studied by conjunctional use of natural responses and single-point dilution tracer test, with an injection of 41 g of uranine on 22 March 2017. The tracer test was monitored during one year using fluorometers, water and charcoal samplings at five points in the lake and six points at the surface (no connection having been established outside). A slow flow (in the order of magnitude of 1 m/h) of the lake could be observed and som...

Geologica Belgica, 2013

Colourless fluorescent UV tracers are increasingly used in hydrogeological studies in drinking wa... more Colourless fluorescent UV tracers are increasingly used in hydrogeological studies in drinking water catchments, in which classical dyes (uranine, sulforhodamines) can sometimes be of significant concern if unexpectedly exceeding the limit of visibility. Among these colourless tracers, optical brighteners and sulfonates (presently naphthionate and amino G acid) are widely used despite lower fluorescence yields, strong interferences with natural organic matter, as well as oxy- or photo-degradation. As a result, higher amounts of tracer are sometimes used, yielding higher concentrations in drinking water and giving rise to the question of their toxicity and the occurrence of their by-products in waterworks. In this paper, several years of practice and improvement of the detection's performance using combined laboratory spectrofluorometric and field fluorometric techniques are summarized and illustrated with several case studies in different aquifers. The developments of UV LEDs op...

In order to monitor the hydrological strain forces of the karst micro fissure networks and local ... more In order to monitor the hydrological strain forces of the karst micro fissure networks and local fault activities, six capacitive extensometers were installed inside a karstic cave near the midi-fault in Belgium. From 2004 to 2008, the nearby Lomme River experienced several heavy rains, leading to flooding inside the Rochefort cave. The highest water level rose more than thirteen meters, the karstic fissure networks were filled with water, which altered the pore pressure of the cave. The strain response to the hydrological induced pore pressure changes are separately deduced from fifteen events when the water level exceeded six meters. The strain measured from the extensometer show a linear contraction during the water recharge and a nonlinear exponential extension releasing during the water discharge. The sensitivity and stability of the sensor are constrained by comparing continuously observed tidal strain waves with a theoretical model. Finally, a local fault deformation rate around 0.03pm0.0020.03 \pm 0.0020.03pm0.002mm/yr is estimated from more than four years' records.

Résumé Les hydrogéologues utilisent les traçages artificiels pour montrer l'interconnexion de... more Résumé Les hydrogéologues utilisent les traçages artificiels pour montrer l'interconnexion de pertes et de sources. Dans les eaux de surface, et particulièrement près du site d'injection, l'intense coloration de l'eau peut provoquer la surprise ou une crainte légitime des voisins. Depuis la récente disponibilité de LED irradiant de l'UV (jusqu'à 240 nm), les fluorimètres de terrain peuvent détecter jusqu'à trois traceurs incolores, jusqu' à des concentrations voisines de 1 ppb. 2 3 4 1 5 Figure 1: Visibilité de traceurs usuels (concentration: 1000 ppb).L'impact est élevé pour l'uranine (vert) et l'amidorhodamine G (rouge), mais nul pour la duasyne, le naphtionate et l'amino G acide. Figure 2: Formules et caractéristiques spectrales de deux traceurs incolores. Les traceurs les plus courants sont l'uranine, l'éosine, la sulforhodamine B, l'amidorhodamine G, la rhodamine WT, la duasyne, le tinopal, l'amino G acide (Käss 19...

Geologica Belgica

Colourless fluorescent UV tracers are increasingly used in hydrogeological studies in drinking wa... more Colourless fluorescent UV tracers are increasingly used in hydrogeological studies in drinking water catchments, in which classical dyes (uranine, sulforhodamines) can sometimes be of significant concern if unexpectedly exceeding the limit of visibility. Among these colourless tracers, optical brighteners and sulfonates (presently naphthionate and amino G acid) are widely used despite lower fluorescence yields, strong interferences with natural organic matter, as well as oxy- or photo degradation. As a result, higher amounts of tracer are sometimes used, yielding higher concentrations in drinking water and giving rise to the question of their toxicity and the occurrence of their by-products in waterworks. In this paper, several years of practice and improvement of the detection’s performance using combined laboratory spectrofluorometric and field fluorometric techniques are summarized and illustrated with several case studies in different aquifers. The developments of UV LEDs optica...

Eos, Transactions American Geophysical Union, 2006

Environmental Earth Sciences, 2013