The Experts below are selected from a list of 5406 Experts worldwide ranked by ideXlab platform
Christophe Emblanch - One of the best experts on this subject based on the ideXlab platform.
-
Hydrochemical constraints between the karst Tabular Middle Atlas Causses and the Saïs basin (Morocco): implications of Groundwater Circulation
Hydrogeology Journal, 2018Co-Authors: Helene Miche, Khaoula Qarqori, Abdelilah Dekayir, Konstantinos Chalikakis, Adriano Mayer, Mohamed Rouai, Ginette Saracco, Christophe EmblanchAbstract:The karst Tabular Middle Atlas Causses reservoir is the main drinking-water supply of Fez-Meknes region (Saïs 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 (δ18O, δD and 222Rn) 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 δ18O versus δD characterizes a confined aquifer in the eastern sector. 222Rn results reveal areas of rapid exchanges with an upwelling time of less than 2 weeks. A schematic conceptual model is presented to explain the Groundwater Circulation system and the behavior of this karst system.RésuméLe réservoir des Causses karstiques du Moyen Atlas tabulaire constitue la principale source d’approvisionnement en eau potable de la région de Fez-Meknes (bassin de Saïs) au Maroc. Des analyses récentes ont montré une diminution de la qualité chimique des eaux souterraines associée à une turbidité accrue. Pour comprendre cet hydrosystème, quatre campagnes ont été réalisées en automne et printemps de 2009 à 2011. Des études hydrogéochimiques associées à des analyses isotopiques (δ18O, δD et 222Rn) ont montré que les aquifères situés entre les causses (montagnes) et le bassin de Saïs sont d’origine liasique et d’origine triasique au niveau des extrémités méridionales. Cinq zones de recharge de différentes altitudes ont été définies, y compris deux zones principales de mélange dans le sud. Les résultats en excès en deutérium suggèrent une recharge locale, alors qu’un graphique δ18O versus δD caractérise un aquifère confiné dans le secteur oriental. Les résultats du 222Rn révèlent des zones d’échanges rapides avec un temps de remontées des eaux de moins de deux semaines. Un modèle conceptuel schématique est. présenté pour expliquer le système de Circulation des eaux souterraines et le comportement de ce système karstique.ResumenEl reservorio kárstico Tabular Middle Atlas Causses es el principal suministro de agua potable de la región de Fez-Meknes (cuenca de Saïs) en Marruecos. Los análisis recientes mostraron una disminución en la calidad química del agua subterránea asociada y un aumento de la turbidez. Para comprender este sistema hidrológico, se realizaron cuatro estudios durante el otoño y la primavera del período 2009–2011. Los estudios hidrogeoquímicos asociados a análisis isotópicos (δ18O, δD and 222Rn) mostraron que los acuíferos entre los causses (montañas) y la Cuenca Saïs son de origen Liásico y en las extremidades meridionales son de origen Triásico. Se han definido cinco zonas de recarga a diferentes altitudes, incluyendo dos zonas principales de mezcla en el sur. Los resultados de exceso de deuterio sugieren la recarga local, mientras que un diagrama de δ18O versus δD caracteriza un acuífero confinado en el sector oriental. Los resultados arrojados revelan áreas de intercambio rápido con un tiempo de surgencia de menos de dos semanas. Se presenta un modelo conceptual esquemático para explicar el sistema de circulación de aguas subterráneas y el comportamiento de este sistema kárstico.摘要岩溶Tabular Middle Atlas高原是摩洛哥Fez-Meknes地区(Saïs盆地)主要的饮用水供水地。最近的分析显示地下水化学质量下降及浑浊度增加。为了了解这个水系统,在2009–2011年秋季和春季进行了四次调查。水文地球化学研究结果与同位素分析(δ18O、 δD 及 222Rn)显示,高原(山脉)和 Saïs盆地之间的含水层属于里阿斯统,在最南端属于三叠纪。确定了不同高度的的五个补给带,包括南部的两个混合带。穿超量结果显示出有本地补给,而18O 与 δD图表明在东部有一个承压含水层。222Rn结果揭示了上涌时间不到两个星期的快速交换区。提出了随机概念模型以解释地下水循环系统和这个岩溶系统的特性。ResumoO reservatório cárstico dos Causses Tabulares do Atlas Médio é o principal fornecimento de água potável da região de Fez-Meknes (Bacia de Saïs) no Marrocos. Análises recentes mostraram um declínio na qualidade química associada às águas subterrâneas e ao aumento da turbidez. Para entender este hidrossistema, quatro pesquisas foram realizadas durante o outono e a primavera, 2009–2011. Estudos hidrogeoquímicos, juntamente com análises isotópicas (δ18O, δD e 222Rn), mostraram que os aquíferos entre os causses (montanhas) e a Bacia de Saïs são de origem Liássica e nas extremidades do sul são de origem Triássica. Foram definidas cinco zonas de recargas de diferentes altitudes, incluindo duas zonas principais de mistura no sul. Os resultados de excesso de deutério sugerem uma recarga local, enquanto que o gráfico de δ18O versus δD caracteriza um aquífero confinado no setor oriental. Resultados de 222Rn revelam áreas de trocas rápidas com um tempo de ressurgência menor que duas semanas. Um modelo esquemático conceitual é apresentado para explicar o sistema de circulação de águas subterrâneas e o comportamento deste sistema cárstico.
-
Hydrochemical constraints between the karst Tabular Middle Atlas Causses and the Saïs basin (Morocco): implications of Groundwater Circulation
Hydrogeology Journal, 2018Co-Authors: Helene Miche, Khaoula Qarqori, Abdelilah Dekayir, Konstantinos Chalikakis, Adriano Mayer, Mohamed Rouai, Ginette Saracco, Christophe EmblanchAbstract:El reservorio kárstico Tabular Middle Atlas Causses es el principal suministro de agua potable de la región de Fez-Meknes (cuenca de Saïs) en Marruecos. Los análisis recientes mostraron una disminución en la calidad química del agua subterránea asociada y un aumento de la turbidez. Para comprender este sistema hidrológico, se realizaron cuatro estudios durante el otoño y la primavera del período 2009–2011. Los estudios hidrogeoquímicos asociados a análisis isotópicos (δ^18O, δD and ^222Rn) mostraron que los acuíferos entre los causses (montañas) y la Cuenca Saïs son de origen Liásico y en las extremidades meridionales son de origen Triásico. Se han definido cinco zonas de recarga a diferentes altitudes, incluyendo dos zonas principales de mezcla en el sur. Los resultados de exceso de deuterio sugieren la recarga local, mientras que un diagrama de δ^18O versus δD caracteriza un acuífero confinado en el sector oriental. Los resultados arrojados revelan áreas de intercambio rápido con un tiempo de surgencia de menos de dos semanas. Se presenta un modelo conceptual esquemático para explicar el sistema de circulación de aguas subterráneas y el comportamiento de este sistema kárstico. The karst Tabular Middle Atlas Causses reservoir is the main drinking-water supply of Fez-Meknes region (Saïs 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^18O, δD and ^222Rn) 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^18O versus δD characterizes a confined aquifer in the eastern sector. ^222Rn results reveal areas of rapid exchanges with an upwelling time of less than 2 weeks. A schematic conceptual model is presented to explain the Groundwater Circulation system and the behavior of this karst system. O reservatório cárstico dos Causses Tabulares do Atlas Médio é o principal fornecimento de água potável da região de Fez-Meknes (Bacia de Saïs) no Marrocos. Análises recentes mostraram um declínio na qualidade química associada às águas subterrâneas e ao aumento da turbidez. Para entender este hidrossistema, quatro pesquisas foram realizadas durante o outono e a primavera, 2009–2011. Estudos hidrogeoquímicos, juntamente com análises isotópicas (δ^18O, δD e ^222Rn), mostraram que os aquíferos entre os causses (montanhas) e a Bacia de Saïs são de origem Liássica e nas extremidades do sul são de origem Triássica. Foram definidas cinco zonas de recargas de diferentes altitudes, incluindo duas zonas principais de mistura no sul. Os resultados de excesso de deutério sugerem uma recarga local, enquanto que o gráfico de δ^18O versus δD caracteriza um aquífero confinado no setor oriental. Resultados de ^222Rn revelam áreas de trocas rápidas com um tempo de ressurgência menor que duas semanas. Um modelo esquemático conceitual é apresentado para explicar o sistema de circulação de águas subterrâneas e o comportamento deste sistema cárstico. Le réservoir des Causses karstiques du Moyen Atlas tabulaire constitue la principale source d’approvisionnement en eau potable de la région de Fez-Meknes (bassin de Saïs) au Maroc. Des analyses récentes ont montré une diminution de la qualité chimique des eaux souterraines associée à une turbidité accrue. Pour comprendre cet hydrosystème, quatre campagnes ont été réalisées en automne et printemps de 2009 à 2011. Des études hydrogéochimiques associées à des analyses isotopiques (δ^18O, δD et ^222Rn) ont montré que les aquifères situés entre les causses (montagnes) et le bassin de Saïs sont d’origine liasique et d’origine triasique au niveau des extrémités méridionales. Cinq zones de recharge de différentes altitudes ont été définies, y compris deux zones principales de mélange dans le sud. Les résultats en excès en deutérium suggèrent une recharge locale, alors qu’un graphique δ^18O versus δD caractérise un aquifère confiné dans le secteur oriental. Les résultats du ^222Rn révèlent des zones d’échanges rapides avec un temps de remontées des eaux de moins de deux semaines. Un modèle conceptuel schématique est. présenté pour expliquer le système de Circulation des eaux souterraines et le comportement de ce système karstique. 岩溶Tabular Middle Atlas高原是摩洛哥Fez-Meknes地区(Saïs盆地)主要的饮用水供水地。最近的分析显示地下水化学质量下降及浑浊度增加。为了了解这个水系统,在2009–2011年秋季和春季进行了四次调查。水文地球化学研究结果与同位素分析(δ^18O、 δD 及 ^222Rn)显示,高原(山脉)和 Saïs盆地之间的含水层属于里阿斯统,在最南端属于三叠纪。确定了不同高度的的五个补给带,包括南部的两个混合带。穿超量结果显示出有本地补给,而^18O 与 δD图表明在东部有一个承压含水层。^222Rn结果揭示了上涌时间不到两个星期的快速交换区。提出了随机概念模型以解释地下水循环系统和这个岩溶系统的特性。
-
Hydrochemical constraints between the karst Tabular Middle Atlas Causses and the Sais basin (Morocco): implications of Groundwater Circulation
Hydrogeology Journal, 2018Co-Authors: Helene Miche, Khaoula Qarqori, Abdelilah Dekayir, Konstantinos Chalikakis, Adriano Mayer, Mohamed Rouai, Ginette Saracco, Christophe EmblanchAbstract:The 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 eastern sector. 222 Rn results reveal areas of rapid exchanges with an upwelling time of less than 2 weeks. A schematic conceptual model is presented to explain the Groundwater Circulation system and the behavior of this karst system.
Peter L. Smart - One of the best experts on this subject based on the ideXlab platform.
-
decoupled fresh saline Groundwater Circulation of a coastal carbonate aquifer spatial patterns of temperature and specific electrical conductivity
Journal of Hydrology, 2007Co-Authors: Patricia A Beddows, Fiona F Whitaker, Peter L. Smart, S L SmithAbstract:Summary The coastal carbonate aquifer of the eastern Yucatan Peninsula discharges Groundwaters to the Caribbean Sea. Temperature and specific electrical conductance (SEC) are used as natural tracers to gain new insight into the fresh and saline Groundwater Circulation along an 80 km section of the Caribbean coastline. The aquifer is density stratified, with a cooler freshwater lens overlying a warmer saline water zone. Non-conduit sites generally have lower temperatures and SEC in the freshwater lens than conduit sites. In conduits 4 km inland). Within the shallow saline water zone, temperature decreases exponentially with distance from the coast, with near equilibrium with the fresh waters reached at 10 km inland, a distance coincident with the known limit of conduit development. This pattern is indicative of the progressive cooling of warm seawater moving inland from the coast, a flow direction opposite to that of both the conventional freshwater flow entrainment and geothermal convection models of coastal aquifer Circulation. a 2007 Elsevier B.V. All rights reserved.
-
Groundwater Circulation and geochemistry of a karstified bank–marginal fracture system, South Andros Island, Bahamas
Journal of Hydrology, 1997Co-Authors: Fiona F Whitaker, Peter L. SmartAbstract:Abstract On the east coast of South Andros Island, Bahamas, a major bank–marginal fracture system characterised by vertically extensive cavern systems (blue holes) is developed sub-parallel to the steep-sided deep-water re-entrant of the Tongue of the Ocean. In addition to providing a discharge route for meteoric, mixed and geochemically evolved saline Groundwaters, a strong local Circulation occurs along the fracture system. This generates enhanced vertical mixing within voids of the fracture system, evidenced by the increasing mixing zone thickness, and the thinning and increasing salinity of brackish lens waters from north to south along the fracture system. Furthermore, tidally driven pumping of Groundwaters occurs between the fracture and adjacent carbonate aquifer affecting a zone up to 200 m either side of the fracture. The resultant mixing of Groundwaters of contrasting salinity and PCO2 within and along the fracture system and with the surrounding aquifer waters, together with bacterial oxidation of organic matter, generates significant potential for locally enhanced diagenesis. Undersaturation with respect to calcite within the fresh (or brackish)–salt water mixing zone is observed in the fracture system and predicted in the adjacent aquifer, while mixing between the brackish fracture lens and surrounding high PCO2 fresh waters causes dissolution of aragonite but not calcite. The latter gives rise to considerable secondary porosity development, because active tidal pumping ensures continued renewal of dissolutional potential. This is evidenced by calcium and strontium enrichment in the brackish lens which indicates porosity generation by aragonite dissolution at a maximum rate of 0.35% ka−1, up to twice the average estimated for the fresh water lens. In contrast saline Groundwaters are depleted in calcium relative to open ocean waters suggesting the formation of calcite cements. The development of a major laterally continuous cavernous fracture zone along the margin of the carbonate platform permits enhanced Groundwater flow and mixing which may result in generation of a diagenetic `halo' at a scale larger than that generally recognised around syn-sedimentary fractures in fossil carbonates. This may be characterised by increased secondary porosity where a relative fall in sea-level results in exposure and formation of a meteoric Groundwater system, or cementation by `marine' calcite both below this meteoric system, and where the bank surface is flooded by seawater.
-
Groundwater Circulation and geochemistry of a karstified bank marginal fracture system south andros island bahamas
Journal of Hydrology, 1997Co-Authors: Fiona F Whitaker, Peter L. SmartAbstract:Abstract On the east coast of South Andros Island, Bahamas, a major bank–marginal fracture system characterised by vertically extensive cavern systems (blue holes) is developed sub-parallel to the steep-sided deep-water re-entrant of the Tongue of the Ocean. In addition to providing a discharge route for meteoric, mixed and geochemically evolved saline Groundwaters, a strong local Circulation occurs along the fracture system. This generates enhanced vertical mixing within voids of the fracture system, evidenced by the increasing mixing zone thickness, and the thinning and increasing salinity of brackish lens waters from north to south along the fracture system. Furthermore, tidally driven pumping of Groundwaters occurs between the fracture and adjacent carbonate aquifer affecting a zone up to 200 m either side of the fracture. The resultant mixing of Groundwaters of contrasting salinity and PCO2 within and along the fracture system and with the surrounding aquifer waters, together with bacterial oxidation of organic matter, generates significant potential for locally enhanced diagenesis. Undersaturation with respect to calcite within the fresh (or brackish)–salt water mixing zone is observed in the fracture system and predicted in the adjacent aquifer, while mixing between the brackish fracture lens and surrounding high PCO2 fresh waters causes dissolution of aragonite but not calcite. The latter gives rise to considerable secondary porosity development, because active tidal pumping ensures continued renewal of dissolutional potential. This is evidenced by calcium and strontium enrichment in the brackish lens which indicates porosity generation by aragonite dissolution at a maximum rate of 0.35% ka−1, up to twice the average estimated for the fresh water lens. In contrast saline Groundwaters are depleted in calcium relative to open ocean waters suggesting the formation of calcite cements. The development of a major laterally continuous cavernous fracture zone along the margin of the carbonate platform permits enhanced Groundwater flow and mixing which may result in generation of a diagenetic `halo' at a scale larger than that generally recognised around syn-sedimentary fractures in fossil carbonates. This may be characterised by increased secondary porosity where a relative fall in sea-level results in exposure and formation of a meteoric Groundwater system, or cementation by `marine' calcite both below this meteoric system, and where the bank surface is flooded by seawater.
Helene Miche - One of the best experts on this subject based on the ideXlab platform.
-
Hydrochemical constraints between the karst Tabular Middle Atlas Causses and the Saïs basin (Morocco): implications of Groundwater Circulation
Hydrogeology Journal, 2018Co-Authors: Helene Miche, Khaoula Qarqori, Abdelilah Dekayir, Konstantinos Chalikakis, Adriano Mayer, Mohamed Rouai, Ginette Saracco, Christophe EmblanchAbstract:The karst Tabular Middle Atlas Causses reservoir is the main drinking-water supply of Fez-Meknes region (Saïs 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 (δ18O, δD and 222Rn) 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 δ18O versus δD characterizes a confined aquifer in the eastern sector. 222Rn results reveal areas of rapid exchanges with an upwelling time of less than 2 weeks. A schematic conceptual model is presented to explain the Groundwater Circulation system and the behavior of this karst system.RésuméLe réservoir des Causses karstiques du Moyen Atlas tabulaire constitue la principale source d’approvisionnement en eau potable de la région de Fez-Meknes (bassin de Saïs) au Maroc. Des analyses récentes ont montré une diminution de la qualité chimique des eaux souterraines associée à une turbidité accrue. Pour comprendre cet hydrosystème, quatre campagnes ont été réalisées en automne et printemps de 2009 à 2011. Des études hydrogéochimiques associées à des analyses isotopiques (δ18O, δD et 222Rn) ont montré que les aquifères situés entre les causses (montagnes) et le bassin de Saïs sont d’origine liasique et d’origine triasique au niveau des extrémités méridionales. Cinq zones de recharge de différentes altitudes ont été définies, y compris deux zones principales de mélange dans le sud. Les résultats en excès en deutérium suggèrent une recharge locale, alors qu’un graphique δ18O versus δD caractérise un aquifère confiné dans le secteur oriental. Les résultats du 222Rn révèlent des zones d’échanges rapides avec un temps de remontées des eaux de moins de deux semaines. Un modèle conceptuel schématique est. présenté pour expliquer le système de Circulation des eaux souterraines et le comportement de ce système karstique.ResumenEl reservorio kárstico Tabular Middle Atlas Causses es el principal suministro de agua potable de la región de Fez-Meknes (cuenca de Saïs) en Marruecos. Los análisis recientes mostraron una disminución en la calidad química del agua subterránea asociada y un aumento de la turbidez. Para comprender este sistema hidrológico, se realizaron cuatro estudios durante el otoño y la primavera del período 2009–2011. Los estudios hidrogeoquímicos asociados a análisis isotópicos (δ18O, δD and 222Rn) mostraron que los acuíferos entre los causses (montañas) y la Cuenca Saïs son de origen Liásico y en las extremidades meridionales son de origen Triásico. Se han definido cinco zonas de recarga a diferentes altitudes, incluyendo dos zonas principales de mezcla en el sur. Los resultados de exceso de deuterio sugieren la recarga local, mientras que un diagrama de δ18O versus δD caracteriza un acuífero confinado en el sector oriental. Los resultados arrojados revelan áreas de intercambio rápido con un tiempo de surgencia de menos de dos semanas. Se presenta un modelo conceptual esquemático para explicar el sistema de circulación de aguas subterráneas y el comportamiento de este sistema kárstico.摘要岩溶Tabular Middle Atlas高原是摩洛哥Fez-Meknes地区(Saïs盆地)主要的饮用水供水地。最近的分析显示地下水化学质量下降及浑浊度增加。为了了解这个水系统,在2009–2011年秋季和春季进行了四次调查。水文地球化学研究结果与同位素分析(δ18O、 δD 及 222Rn)显示,高原(山脉)和 Saïs盆地之间的含水层属于里阿斯统,在最南端属于三叠纪。确定了不同高度的的五个补给带,包括南部的两个混合带。穿超量结果显示出有本地补给,而18O 与 δD图表明在东部有一个承压含水层。222Rn结果揭示了上涌时间不到两个星期的快速交换区。提出了随机概念模型以解释地下水循环系统和这个岩溶系统的特性。ResumoO reservatório cárstico dos Causses Tabulares do Atlas Médio é o principal fornecimento de água potável da região de Fez-Meknes (Bacia de Saïs) no Marrocos. Análises recentes mostraram um declínio na qualidade química associada às águas subterrâneas e ao aumento da turbidez. Para entender este hidrossistema, quatro pesquisas foram realizadas durante o outono e a primavera, 2009–2011. Estudos hidrogeoquímicos, juntamente com análises isotópicas (δ18O, δD e 222Rn), mostraram que os aquíferos entre os causses (montanhas) e a Bacia de Saïs são de origem Liássica e nas extremidades do sul são de origem Triássica. Foram definidas cinco zonas de recargas de diferentes altitudes, incluindo duas zonas principais de mistura no sul. Os resultados de excesso de deutério sugerem uma recarga local, enquanto que o gráfico de δ18O versus δD caracteriza um aquífero confinado no setor oriental. Resultados de 222Rn revelam áreas de trocas rápidas com um tempo de ressurgência menor que duas semanas. Um modelo esquemático conceitual é apresentado para explicar o sistema de circulação de águas subterrâneas e o comportamento deste sistema cárstico.
-
Hydrochemical constraints between the karst Tabular Middle Atlas Causses and the Saïs basin (Morocco): implications of Groundwater Circulation
Hydrogeology Journal, 2018Co-Authors: Helene Miche, Khaoula Qarqori, Abdelilah Dekayir, Konstantinos Chalikakis, Adriano Mayer, Mohamed Rouai, Ginette Saracco, Christophe EmblanchAbstract:El reservorio kárstico Tabular Middle Atlas Causses es el principal suministro de agua potable de la región de Fez-Meknes (cuenca de Saïs) en Marruecos. Los análisis recientes mostraron una disminución en la calidad química del agua subterránea asociada y un aumento de la turbidez. Para comprender este sistema hidrológico, se realizaron cuatro estudios durante el otoño y la primavera del período 2009–2011. Los estudios hidrogeoquímicos asociados a análisis isotópicos (δ^18O, δD and ^222Rn) mostraron que los acuíferos entre los causses (montañas) y la Cuenca Saïs son de origen Liásico y en las extremidades meridionales son de origen Triásico. Se han definido cinco zonas de recarga a diferentes altitudes, incluyendo dos zonas principales de mezcla en el sur. Los resultados de exceso de deuterio sugieren la recarga local, mientras que un diagrama de δ^18O versus δD caracteriza un acuífero confinado en el sector oriental. Los resultados arrojados revelan áreas de intercambio rápido con un tiempo de surgencia de menos de dos semanas. Se presenta un modelo conceptual esquemático para explicar el sistema de circulación de aguas subterráneas y el comportamiento de este sistema kárstico. The karst Tabular Middle Atlas Causses reservoir is the main drinking-water supply of Fez-Meknes region (Saïs 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^18O, δD and ^222Rn) 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^18O versus δD characterizes a confined aquifer in the eastern sector. ^222Rn results reveal areas of rapid exchanges with an upwelling time of less than 2 weeks. A schematic conceptual model is presented to explain the Groundwater Circulation system and the behavior of this karst system. O reservatório cárstico dos Causses Tabulares do Atlas Médio é o principal fornecimento de água potável da região de Fez-Meknes (Bacia de Saïs) no Marrocos. Análises recentes mostraram um declínio na qualidade química associada às águas subterrâneas e ao aumento da turbidez. Para entender este hidrossistema, quatro pesquisas foram realizadas durante o outono e a primavera, 2009–2011. Estudos hidrogeoquímicos, juntamente com análises isotópicas (δ^18O, δD e ^222Rn), mostraram que os aquíferos entre os causses (montanhas) e a Bacia de Saïs são de origem Liássica e nas extremidades do sul são de origem Triássica. Foram definidas cinco zonas de recargas de diferentes altitudes, incluindo duas zonas principais de mistura no sul. Os resultados de excesso de deutério sugerem uma recarga local, enquanto que o gráfico de δ^18O versus δD caracteriza um aquífero confinado no setor oriental. Resultados de ^222Rn revelam áreas de trocas rápidas com um tempo de ressurgência menor que duas semanas. Um modelo esquemático conceitual é apresentado para explicar o sistema de circulação de águas subterrâneas e o comportamento deste sistema cárstico. Le réservoir des Causses karstiques du Moyen Atlas tabulaire constitue la principale source d’approvisionnement en eau potable de la région de Fez-Meknes (bassin de Saïs) au Maroc. Des analyses récentes ont montré une diminution de la qualité chimique des eaux souterraines associée à une turbidité accrue. Pour comprendre cet hydrosystème, quatre campagnes ont été réalisées en automne et printemps de 2009 à 2011. Des études hydrogéochimiques associées à des analyses isotopiques (δ^18O, δD et ^222Rn) ont montré que les aquifères situés entre les causses (montagnes) et le bassin de Saïs sont d’origine liasique et d’origine triasique au niveau des extrémités méridionales. Cinq zones de recharge de différentes altitudes ont été définies, y compris deux zones principales de mélange dans le sud. Les résultats en excès en deutérium suggèrent une recharge locale, alors qu’un graphique δ^18O versus δD caractérise un aquifère confiné dans le secteur oriental. Les résultats du ^222Rn révèlent des zones d’échanges rapides avec un temps de remontées des eaux de moins de deux semaines. Un modèle conceptuel schématique est. présenté pour expliquer le système de Circulation des eaux souterraines et le comportement de ce système karstique. 岩溶Tabular Middle Atlas高原是摩洛哥Fez-Meknes地区(Saïs盆地)主要的饮用水供水地。最近的分析显示地下水化学质量下降及浑浊度增加。为了了解这个水系统,在2009–2011年秋季和春季进行了四次调查。水文地球化学研究结果与同位素分析(δ^18O、 δD 及 ^222Rn)显示,高原(山脉)和 Saïs盆地之间的含水层属于里阿斯统,在最南端属于三叠纪。确定了不同高度的的五个补给带,包括南部的两个混合带。穿超量结果显示出有本地补给,而^18O 与 δD图表明在东部有一个承压含水层。^222Rn结果揭示了上涌时间不到两个星期的快速交换区。提出了随机概念模型以解释地下水循环系统和这个岩溶系统的特性。
-
Hydrochemical constraints between the karst Tabular Middle Atlas Causses and the Sais basin (Morocco): implications of Groundwater Circulation
Hydrogeology Journal, 2018Co-Authors: Helene Miche, Khaoula Qarqori, Abdelilah Dekayir, Konstantinos Chalikakis, Adriano Mayer, Mohamed Rouai, Ginette Saracco, Christophe EmblanchAbstract:The 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 eastern sector. 222 Rn results reveal areas of rapid exchanges with an upwelling time of less than 2 weeks. A schematic conceptual model is presented to explain the Groundwater Circulation system and the behavior of this karst system.
Josefa Sepulveda - One of the best experts on this subject based on the ideXlab platform.
-
exploring the shallow geothermal resources in the chilean southern volcanic zone insight from the liquine thermal springs
Journal of Geochemical Exploration, 2020Co-Authors: Linda Daniele, Matias Taucare, Enoi Viguie, Gloria Arancibia, Diego Aravena, Tomas Roque, Josefa SepulvedaAbstract:Abstract Southern Volcanic Zone (SVZ) hosts numerous thermal springs (25–85 °C), related to Liquine-Ofqui Fault System (LOFS) and Andean Transverse Faults (ATFs), suggesting the feasibility of low- to high-enthalpy geothermal exploitation. However, the local understanding of processes and factors controlling the high-temperature Groundwater Circulation remained undefined, which limits its exploitation. Following a brief review of SVZ, we address the previous issue by a hydrogeochemical and isotopic analysis of 15 thermal springs at Liquine area (representative of SVZ), supplemented by geochemical simulations. We demonstrate that fault zones and derived hydraulic properties have a predominant control on the ascending high-temperature Groundwater Circulation and hydrogeochemical processes. Spring discharges and outflowing temperatures are higher along the LOFS damage-zone and ATF than those along the LOFS fault core-zone. Albite dissolution is the main water-rock interaction that is enhanced by absorbed geothermal gases (H2S and CO2 in LOFS; CO2 in ATF). Trace element contents (Li, Rb, Cs, As, Mo) are influenced by hydraulic properties and geothermal gases within faults. Intrinsic hydraulic properties of fault zones, where damage-zone is more permeable than the core zone, affect the Li, Rb, Cs contents. While As and Mo solely differ according to the gases presence. Water stable isotopes point that steam heating processes enhance the hydrogeochemical reactions through the LOFS damage-zone and ATF, whereas only low-temperature processes occur through the LOFS core-zone. LOFS damage-zone and ATFs are great targets for the shallow geothermal resource exploitation. But simulations indicate an elevated risk of scaling with consequences on the operation plants due to silicate mineral precipitations. Finally, Liquine thermal springs provide interesting insights to respond to the current and future energy challenges in Central-South Chile.
Zhonghe Pang - One of the best experts on this subject based on the ideXlab platform.
-
fault affected fluid Circulation revealed by hydrochemistry and isotopes in a large scale utilized geothermal reservoir
Geofluids, 2020Co-Authors: Yanlong Kong, Zhonghe Pang, Jumei Pang, Jie LiAbstract:A new significant aspect in the utilization of hydrothermal energy in China is the large-scale exploitation using multiwells from a single geothermal site. This requires detailed hydrogeochemical investigations to gain insight about deep Groundwater Circulation. At the Xiongxian karst geothermal site in North China, where the demonstration project of large-scale utilization was conducted, 40 boreholes with depths from 1000 to 1800 m were drilled in a region of 50 km2. A total of 25 water samples were collected, and temperature loggings were conducted in 16 of these wells. At the site scale, the hydraulic head was observed to decline from SW to NE, i.e., orthogonal to that at the regional scale. Moreover, the geothermal Groundwater temperature, borehole temperature gradient, and heat flow in the caprock all exhibited the same spatial trend with the Groundwater head. Based on the hydrogeochemical and temperature logging data, this was explained by mixing of lateral recharging Groundwater with ascending thermal fluids through the Xiongxian Fault, after excluding the causes of pumping activities and geologic structure. In addition, geothermal Groundwater 81Kr age was estimated to be approximately 760 k yr, which is much older than the 14C age of 20 to 30 k yr. The older 81Kr age implies a low renewability of deep Groundwater Circulation, which should be considered in terms of sustainable management in relation to the large-scale utilization of geothermal resources.
-
deep Groundwater cycle in xiongxian geothermal field
2015Co-Authors: Yanlong Kong, Zhonghe Pang, Jumei PangAbstract:The deep karstic aquifer containing hot water is ideal for space heating and maybe also for geothermal power generation. The hot water is characterized by high single-well yield, low salinity, gravity injection and less impact on environment when it is exploited. In order to run a karstic geothermal field sustainably, it is of high importance to identify the local Groundwater Circulation pattern in the field. Here we take Xiongxian geothermal field as an example to get insights into the characteristics of local Groundwater Circulation in karstic aquifers. Groundwater samples and surface water samples were collected, and analyzed for their hydrochemical and isotopic contents. Results show that the TDS of Groundwater in karstic aquifers is between 1.9 and 2.6 g/L. According to the data of water table, the local Groundwater flow direction is from Southwest to Northeast. This is confirmed by the TDS data, which increases gradually in this direction. However, this is orthogonal to the regional Groundwater flow direction that is from Northwest to Southeast. This phenomenon highlights the control of aquifer lithology and geological structures on the Groundwater flow field. Isotopic data illustrates some oxygen isotope shifts, although the reservoir temperature is less than 90 ℃. Finally, a conceptual model is proposed to depict the deep Groundwater cycle in Xiongxian geothermal field, which will serve as a basis for the further simulated model for exploitation strategy and could be used as a reference in similar karstic aquifers.
-
Groundwater Circulation relative to water quality and vegetation in an arid transitional zone linking oasis desert and river
Chinese Science Bulletin, 2013Co-Authors: Tianming Huang, Zhonghe Pang, Yaning Chen, Yanlong KongAbstract:In Groundwater-dependent ecosystems, Groundwater Circulation controls the overall water quality and ecosystem dynamics. Groundwater and vegetation across a 30-km Groundwater transect linking oasis, desert and river in an extremely arid area were investigated with a series of soil profiles drilled into the unsaturated zone to understand Groundwater Circulation and its control on Groundwater quality and surface vegetation in the extremely arid Lower Tarim River, NW China. Measurements have included water-table depth, water chemistry and water isotopes (2H, 18O, 3H) for 15 water samples, soil moisture and chloride content for 11 soil profiles, and vegetation investigation. Results show that the Groundwater in desert zone is characterized by slow recharge rate (pre-modern water), great water-table depth (6.17–9.43 m) and high salinity (15.32–26.50 g/L), while that in oasis (uncultivated land) and riparian zone is characterized by relatively fast recharge rate (modern water), small Groundwater-table depth (3.56–8.36 m) and low salinity (1.25–1.95 g/L). Stable isotopes show that secondary evaporation takes place during irrigation in oasis. The vegetation characteristics (coverage, richness, evenness and number of plants) are closely related to soil moisture and water-table depth. Groundwater recharge from irrigation in oasis and from river in riparian zone sustains a better ecosystem than that in the desert area, where lateral and vertical Groundwater recharge is limited. The more evapotranspirative enrichment may occur in the vegetated and water-rich riparian zone as compared to desert. This study also demonstrates the effectiveness of environmental tracers in studying ecohydrological processes in arid regions.
-
hydrogeochemistry and Groundwater Circulation in the xi an geothermal field china
Geothermics, 2005Co-Authors: Dajun Qin, Zhonghe Pang, Jeffrey V TurnerAbstract:Abstract Geothermal waters from the Tertiary aquifers located at 1000–3000 m beneath Xi’an city, Shaanxi Province, China, show unique isotopic composition as compared to local Groundwaters from shallower Quaternary aquifers. Positive oxygen shifts of as much as 8‰ VSMOW are observed, while the corresponding δ 2 H values remain essentially constant at about −80‰ VSMOW, which is significantly different from those of waters in the Quaternary aquifers with a mean δ 2 H value of −60‰ VSMOW. The strong 18 O shift is a result of isotope exchange between geothermal water and carbonate minerals such as calcite over a residence time of several thousand years up to 30,000 years, based on 14 C dating. A comparison of the isotopic composition of geothermal waters with neighbouring Groundwater units on both sides of the Guanzhong Basin indicates that the geothermal reservoirs are recharged by rain that falls on the northern slope of the Qinling Mountains, south of the Xi’an geothermal field, but not from the North Mountains to the north of the field. Based on chemical geothermometers the highest temperature estimated for the Tertiary aquifers of the Xi’an area is around 130 °C.
