Electronic supplementary material The online version of this article (https://doi.org/10.1007/s10... more Electronic supplementary material The online version of this article (https://doi.org/10.1007/s10040-017-1675-0) contains supplementary material, which is available to authorized users.International audienceThe karst Tabular Middle Atlas Causses reservoir is the main drinking-water supply of Fez-Meknes region (Sais Basin) in Morocco. Recent analyses showed a decline in associated groundwater chemical quality and increased turbidity. To understand this hydrosystem, four surveys were undertaken during fall and spring, 2009-2011. Hydrogeochemical studies coupled with isotopic analyses (δ 18 O, δD and 222 Rn) showed that the aquifers between the causses (mountains) and the Saïs Basin are of Liassic origin and at the southern extremities are of Triassic origin. Five recharge zones of different altitudes have been defined, including two main mixing zones in the south. Deuterium excess results suggest local recharge, while a plot of δ 18 O versus δD characterizes a confined aquifer in the ...
Les eaux souterraines des aquiferes cotiers constituent une ressource de premiere importance pour... more Les eaux souterraines des aquiferes cotiers constituent une ressource de premiere importance pour les besoins d’approvisionnement en eau potable, l’agriculture, l’industrie ou le tourisme. Toutefois, dans la mesure ou elles sont en continuite hydraulique avec la mer, leur exploitation requiert des precautions particulieres afin de ne pas perturber l’equilibre fragile entre ces deux masses d’eau. Les reservoirs cotiers d’eau souterraine sont donc tres vulnerables face aux activites humaines tant du point de vue de la qualite que de la quantite.L’etude du fonctionnement de ces hydrosystemes et la mise en place d’outils de gestion adaptes apparaissent donc essentiels pour garantir la dimension renouvelable des ressources en eau souterraine,enjeu fondamental pour un developpement socio-economique et territorial durable.Cette problematique est particulierement bien illustree en Corse, principalement dans l’extreme-sud. Bonifacio est en effet l’une des villes les plus visitees de l’ile.
Groundwater extracted from the Barthelasse Island aquifer, surrounded by the river Rhône (southea... more Groundwater extracted from the Barthelasse Island aquifer, surrounded by the river Rhône (southeastern France), contributes to the drinking water supplies of 180,000 inhabitants. Owing to its location close to the river and the presence of two backwaters (oxbow lakes), the pumped groundwater is highly vulnerable to river pollution. A pumping test was conducted over 24 h to analyse and quantify the water exchange processes between the river, backwaters and groundwater. During the pumping test, isotopic (δ18O, δ2H and 222Rn), hydrochemical and hydrophysical monitoring of the groundwater was undertaken. Hydraulic heads were measured in pumping wells and at a piezometer located between the wells. Discrete water samples were collected at several observation points in the field, including the backwater and river. The results show mixing between three end-members, as defined by the deuterium excess and silica concentration, led by river Rhône water which had been affected by water–rock interactions over time and mixing with surface evaporated waters. The pumped water resulted from mixing between three end-members, all of which depended on the river Rhône but differed in terms of residence time in the system. Although the groundwater pumping wells are close to each other (<70 m) and have similar depths, the changes in the contributions from end-member waters at each well were different during the pumping test. Comparing isotopic tracers and geochemistry made it possible to quantify the different hydrological compartments that contribute to the groundwater pumped from the boreholes, which is critical in constructing a conceptual flow model.
The use of radionuclide tracers to determine the submarine groundwater discharges has been used w... more The use of radionuclide tracers to determine the submarine groundwater discharges has been used widely but in areas highly anthropized as the Mar Menor surface water tributaries can carry high concentration of Radon, making very difficult to distinguish the radionuclide origin. In this paper a combined approach was applied in the Mar Menor, a towed system was designed to enable the continuous measurement of Radon and Nitrate and a hydrodynamic model was used to establish the influence areas of the surface discharge to the lagoon. The areas were Radon was detected and was out from the area located with the model could be establish as a submarine groundwater discharge point.
L’extreme-sud de la Corse fait face a des difficultes croissantes pour satisfaire ses besoins en ... more L’extreme-sud de la Corse fait face a des difficultes croissantes pour satisfaire ses besoins en eau potable, particulierement en juillet-aout. La commune de Bonifacio (Corse-du-Sud) doit accueillir un afflux touristique d’environ un million de visiteurs par an, pour un territoire de 25 kms et seulement 3 000 residents permanents. Les eaux souterraines de l’aquifere carbonate miocene du causse de Bonifacio constituent la seule ressource alternative permettant de diversifier et de securiser sur le long terme l’alimentation en eau potable de la commune, notamment en ete. La ressource est cependant mal connue, exploitee de facon tres marginale et non coordonnee. Le manque d’elements d’arbitrage risque d’etre rapidement dommageable pour sa gestion durable et engendre deja des conflits d’usages. L’objectif de l’etude est de clarifier l’etat qualitatif de l’aquifere, de determiner le potentiel quantitatif, d’evaluer les temps de sejour et d’identifier les processus de recharge ainsi que les conditions aux limites. Des outils de l’hydrogeologie isotopique (18O, 2H, 3H, 13C, 222Rn et 223,224Ra) et geochimique (ions majeurs, traces, CFCs et SF6) sont utilises mensuellement ou ponctuellement sur un reseau de suivi comportant 3 sources, 2 ruisseaux, 6 puits et 17 forages, dont un traversant la quasi-totalite des 300 m d’epaisseur de sediments. Les premiers resultats montrent que la mineralisation des eaux souterraines est influencee majoritairement par les embruns puis par la dissolution des carbonates. Les gaz anthropiques mettent en evidence deux niveaux aquiferes superposes. Un niveau superieur, dont la composante principale est une eau actuelle issue de l’infiltration verticale directe de la pluie et un niveau inferieur, compose d’eau ancienne originaire du substratum granitique fracture environnant et sous-jacent. Les isotopes du radon et du radium montrent de faibles sorties d’eau douce en mer, localisees au debouche littoral des vallees.
This study deals with the geochemical characterization of salinization in the semi-confined aquif... more This study deals with the geochemical characterization of salinization in the semi-confined aquifer of the southern part of the Venice Lagoon, Italy. Twelve boreholes reaching the aquifer were sampled for stable isotopes (δ 18 O and δD). Electrical conductivity (EC) displays a large range of variation (0.7-40 mS/cm). The more saline groundwaters are located at up to 2 km from the lagoon and Adriatic Sea shorelines. In the δ 18 O vs 8D diagram, the more saline groundwaters plot along a well-defined mixing line, passing through a continental and a seawater end-member. The brackish and fresh groundwaters do not have a clear spatial distribution. Heterogeneous δ 18 O and EC compositions of brackish and fresh groundwater reflect complex exchanges between deep groundwater, surface and/or rain waters. Characterization of the continental end-member(s) in the mixing is not straightforward, revealing a complex hydrodynamic behaviour in this aquifer.
Electronic supplementary material The online version of this article (https://doi.org/10.1007/s10... more Electronic supplementary material The online version of this article (https://doi.org/10.1007/s10040-017-1675-0) contains supplementary material, which is available to authorized users.International audienceThe karst Tabular Middle Atlas Causses reservoir is the main drinking-water supply of Fez-Meknes region (Sais Basin) in Morocco. Recent analyses showed a decline in associated groundwater chemical quality and increased turbidity. To understand this hydrosystem, four surveys were undertaken during fall and spring, 2009-2011. Hydrogeochemical studies coupled with isotopic analyses (δ 18 O, δD and 222 Rn) showed that the aquifers between the causses (mountains) and the Saïs Basin are of Liassic origin and at the southern extremities are of Triassic origin. Five recharge zones of different altitudes have been defined, including two main mixing zones in the south. Deuterium excess results suggest local recharge, while a plot of δ 18 O versus δD characterizes a confined aquifer in the ...
Les eaux souterraines des aquiferes cotiers constituent une ressource de premiere importance pour... more Les eaux souterraines des aquiferes cotiers constituent une ressource de premiere importance pour les besoins d’approvisionnement en eau potable, l’agriculture, l’industrie ou le tourisme. Toutefois, dans la mesure ou elles sont en continuite hydraulique avec la mer, leur exploitation requiert des precautions particulieres afin de ne pas perturber l’equilibre fragile entre ces deux masses d’eau. Les reservoirs cotiers d’eau souterraine sont donc tres vulnerables face aux activites humaines tant du point de vue de la qualite que de la quantite.L’etude du fonctionnement de ces hydrosystemes et la mise en place d’outils de gestion adaptes apparaissent donc essentiels pour garantir la dimension renouvelable des ressources en eau souterraine,enjeu fondamental pour un developpement socio-economique et territorial durable.Cette problematique est particulierement bien illustree en Corse, principalement dans l’extreme-sud. Bonifacio est en effet l’une des villes les plus visitees de l’ile.
Groundwater extracted from the Barthelasse Island aquifer, surrounded by the river Rhône (southea... more Groundwater extracted from the Barthelasse Island aquifer, surrounded by the river Rhône (southeastern France), contributes to the drinking water supplies of 180,000 inhabitants. Owing to its location close to the river and the presence of two backwaters (oxbow lakes), the pumped groundwater is highly vulnerable to river pollution. A pumping test was conducted over 24 h to analyse and quantify the water exchange processes between the river, backwaters and groundwater. During the pumping test, isotopic (δ18O, δ2H and 222Rn), hydrochemical and hydrophysical monitoring of the groundwater was undertaken. Hydraulic heads were measured in pumping wells and at a piezometer located between the wells. Discrete water samples were collected at several observation points in the field, including the backwater and river. The results show mixing between three end-members, as defined by the deuterium excess and silica concentration, led by river Rhône water which had been affected by water–rock interactions over time and mixing with surface evaporated waters. The pumped water resulted from mixing between three end-members, all of which depended on the river Rhône but differed in terms of residence time in the system. Although the groundwater pumping wells are close to each other (<70 m) and have similar depths, the changes in the contributions from end-member waters at each well were different during the pumping test. Comparing isotopic tracers and geochemistry made it possible to quantify the different hydrological compartments that contribute to the groundwater pumped from the boreholes, which is critical in constructing a conceptual flow model.
The use of radionuclide tracers to determine the submarine groundwater discharges has been used w... more The use of radionuclide tracers to determine the submarine groundwater discharges has been used widely but in areas highly anthropized as the Mar Menor surface water tributaries can carry high concentration of Radon, making very difficult to distinguish the radionuclide origin. In this paper a combined approach was applied in the Mar Menor, a towed system was designed to enable the continuous measurement of Radon and Nitrate and a hydrodynamic model was used to establish the influence areas of the surface discharge to the lagoon. The areas were Radon was detected and was out from the area located with the model could be establish as a submarine groundwater discharge point.
L’extreme-sud de la Corse fait face a des difficultes croissantes pour satisfaire ses besoins en ... more L’extreme-sud de la Corse fait face a des difficultes croissantes pour satisfaire ses besoins en eau potable, particulierement en juillet-aout. La commune de Bonifacio (Corse-du-Sud) doit accueillir un afflux touristique d’environ un million de visiteurs par an, pour un territoire de 25 kms et seulement 3 000 residents permanents. Les eaux souterraines de l’aquifere carbonate miocene du causse de Bonifacio constituent la seule ressource alternative permettant de diversifier et de securiser sur le long terme l’alimentation en eau potable de la commune, notamment en ete. La ressource est cependant mal connue, exploitee de facon tres marginale et non coordonnee. Le manque d’elements d’arbitrage risque d’etre rapidement dommageable pour sa gestion durable et engendre deja des conflits d’usages. L’objectif de l’etude est de clarifier l’etat qualitatif de l’aquifere, de determiner le potentiel quantitatif, d’evaluer les temps de sejour et d’identifier les processus de recharge ainsi que les conditions aux limites. Des outils de l’hydrogeologie isotopique (18O, 2H, 3H, 13C, 222Rn et 223,224Ra) et geochimique (ions majeurs, traces, CFCs et SF6) sont utilises mensuellement ou ponctuellement sur un reseau de suivi comportant 3 sources, 2 ruisseaux, 6 puits et 17 forages, dont un traversant la quasi-totalite des 300 m d’epaisseur de sediments. Les premiers resultats montrent que la mineralisation des eaux souterraines est influencee majoritairement par les embruns puis par la dissolution des carbonates. Les gaz anthropiques mettent en evidence deux niveaux aquiferes superposes. Un niveau superieur, dont la composante principale est une eau actuelle issue de l’infiltration verticale directe de la pluie et un niveau inferieur, compose d’eau ancienne originaire du substratum granitique fracture environnant et sous-jacent. Les isotopes du radon et du radium montrent de faibles sorties d’eau douce en mer, localisees au debouche littoral des vallees.
This study deals with the geochemical characterization of salinization in the semi-confined aquif... more This study deals with the geochemical characterization of salinization in the semi-confined aquifer of the southern part of the Venice Lagoon, Italy. Twelve boreholes reaching the aquifer were sampled for stable isotopes (δ 18 O and δD). Electrical conductivity (EC) displays a large range of variation (0.7-40 mS/cm). The more saline groundwaters are located at up to 2 km from the lagoon and Adriatic Sea shorelines. In the δ 18 O vs 8D diagram, the more saline groundwaters plot along a well-defined mixing line, passing through a continental and a seawater end-member. The brackish and fresh groundwaters do not have a clear spatial distribution. Heterogeneous δ 18 O and EC compositions of brackish and fresh groundwater reflect complex exchanges between deep groundwater, surface and/or rain waters. Characterization of the continental end-member(s) in the mixing is not straightforward, revealing a complex hydrodynamic behaviour in this aquifer.
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