Distribution of fluoride in groundwater of Maku area, northwest of Iran

High fluoride groundwater occurs in Maku area, in the north of West Azarbaijan province, northwest of Iran. Groundwater is the main source of drinking water for the area residents. Groundwater samples were collected from 72 selected points including 40 basaltic and 32 nonbasaltic springs and wells, in two stages, during June and August 2006. The areas with high fluoride concentrations have been identified, and the possible causes for its variation have been investigated. Regional hydrogeochemical investigation indicates that water-rock interaction is probably the main reason for the high concentration of ions in groundwater. The concentration of F⁻ in groundwater is positively correlated with that of HCO₃ ⁻ and Na⁺, indicating that groundwater with high HCO₃ ⁻ and Na⁺ concentrations help to dissolve some fluoride-rich minerals. All of the water samples, collected from the basaltic areas do not meet the water quality standards for fluoride concentration and some other parameters. Hence, it is not suitable for consumption without any prior treatment. Inhabitants of the area that obtain their drinking water supplies from basaltic springs and wells are suffering from dental fluorosis. The population of the study area is at a high risk due to excessive fluoride intake especially when they are unaware of the amount of fluoride being ingested due to lack of awareness.     

Processes of hydrogeochemical evolution of groundwater in the Guanzhong Basin,China

This paper analyzed regional hydrogeochemical evolution characteristics of groundwater with respect to hydrogeological conditions in the Guanzhong Basin, China. Coefficient variation in the subregion between the Shichuan River and Luo River of the Guanzhong Basin is larger than other subregions, reflecting the more complicated hydrogeological conditions of this subregion. The hydrochemical components and hydrodynamic conditions of this area have distinct horizontal zoning characteristics, and hydrodynamic conditions play a controlling role in the groundwater’s hydrochemistry. The relationship between ions, and between ions and TDS (total dissolved solids) can give an indication of many charteristics of grounwater such as evaporation intensity, ion exchange, and the sources of chemical components. Results indicated that for the coefficient of variation (the coefficient of variation is a statistical measure of the distribution or dispersion of data around mean. This measure is used to analyze the difference of spread in the data relative to the mean value. Coefficient of variation is derived by dividing the standard deviation by the mean), the minimum value of pH parameters is 0.03-0.07, the minimum value of HCO3- parameters is 0.24, while the maximum is the SO42- coefficinet at 1.67. A PHREEQC simulation demonstrated that different simulation paths roughly have the same trend in dissolution and precipitation of minerals. Along the direction of groundwater flow, the predminant precipitation is of calcite and gypsum and the cation exchange of Na+ and Ca2+ in some paths. However, in other paths, the precipitation of calcite and dissolution of gypsum and dolomite are the main actions, as well as the exchange of Mg2+ and Ca2+ in addition to Na+ and Ca2+.     

Origin of high fluoride in groundwater in the North Gujarat-Cambay region, India

This paper reports on the origin of high fluoride in a regional alluvial aquifer system under water stress in the North Gujarat-Cambay (NGC) region in western India. This region is severely affected by endemic fluorosis due to ingestion of groundwater containing excessive fluoride. With an objective to understand factors controlling high fluoride concentration in groundwater of this region, 225 groundwater samples have been analysed for various chemical parameters. Samples were collected from different depth zones tapping shallow dug wells, geothermal springs, hand-pumps and tubewells, including free flowing artesian wells up to 450 m depth from the aquifers in the Quaternary alluvial formation covering most of the study area. No relation was found between fluoride concentration and depth of sampled groundwater. However, certain sub-aquifer zones have been identified within the Cambay Basin where groundwater contains relatively high fluoride concentration. In general, areas of high fluoride overlap areas with high electrical conductivity (EC). On the west flank of the Cambay Basin in the low lying belt linking Little Rann of Kachchh-Nalsarovar-Gulf of Khambhat (LRK-NS-GK), high fluoride and EC in shallow aquifers originate from evaporative enrichment. On the east flank of Cambay Basin, some high fluoride pockets are observed which are probably due to preferential dissolution of high fluoride bearing minerals. On this flank high fluoride is also associated with thermal springs. Within the Cambay Basin, alternating belts of low and high fluoride concentrations are ascribed to groundwater recharge during the past wet and arid climatic phases, respectively. This is based on groundwater radiocarbon age contours of ~20 ka overlapping the high fluoride belt.

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Resumen Este artículo reporta sobre el origen de altas concentraciones de flúor en un sistema regional de acuíferos bajo presión hídrica en la región del norte de Gujarat-Cambay (NGC) del occidente de India. Esta región está afectada severamente por fluorosis endémica debido a la ingestión de agua subterránea que contiene exceso de flúor. Se tomaron 225 muestras de agua subterránea las cuales fueron analizadas por varios parámetros químicos con el objetivo de entender los factores que controlan las elevadas concentraciones de flúor en esta región. Las muestras se colectaron a diferentes profundidades en pozos someros, manantiales geotermales, pozos con bombas de mano, y pozos entubados incluyendo pozos artesianos de flujo libre de hasta 450 m de profundidad emplazados en los acuíferos de la formación aluvial Cuaternaria que cubre la mayor parte del área de estudio. No se encontró ninguna relación entre la concentración de flúor y la profundidad de las muestras de agua subterránea. Sin embargo, se identificaron dentro de la cuenca Cambay algunas zonas sub-acuíferas donde el agua subterránea contiene concentraciones relativamente altas de flúor. En general, las áreas con elevada concentración de flúor están sobrepuestas a áreas de alta conductividad eléctrica (CE). Sobre el flanco occidental de la cuenca Cambay, en la faja baja que une Little Rann con Kachchh-Nalsarovar-Golfo de Khamhat (LRK-NS-GK), las altas concentraciones de flúor y altas CE en acuíferos someros se derivan de enriquecimiento por evaporitas. Sobre el flanco oriental de la cuenca Cambay se observaron algunos cuerpos con alta concentración de flúor los cuales se deben probablemente a la disolución preferencial de minerales con alto contenido de flúor. En este flanco el alto contenido de flúor también se asocia con manantiales termales. Dentro de la cuenca Cambay existen fajas alternantes, con concentraciones altas y bajas de flúor, las cuales se atribuyen a recarga de agua subterránea durante las fases climáticas pasadas, húmedas y áridas, respectivamente. Este planteamiento se basa en contornos de edades de ~20 ka de radiocarbono que están sobrepuestos a la faja alta en flúor.

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Résumé Cet article étudie lorigine des teneurs élevées en Fluorure dans un système aquifère alluvial régional, soumis à un stress hydrique dans le Nord Gujarat–région Cambay (NGC) à lOuest de lInde. Cette région est sévèrement affectée par une fluorose endémique, due à lingestion deau souterraine très riche en fluor. Avec pour objectif de comprendre les paramètres contrôlant les fortes teneurs en fluor, 225 échantillons deau souterraine ont été analysés sur différents paramètres. Les échantillons ont été pris à différentes profondeurs : puits de surface, sources géothermiques, pompes à main, forages artésiens jaillissant dont la profondeur avoisine les 450 m dans les formations alluviales quaternaire recouvrant la plus grande partie de la région étudiée. Il ny a pas de relation entre la profondeur et les teneurs en fluorure. Néanmoins, certaines zones sub-aquifères ont été identifiées dans le Basin de Cambay où leau souterraine présentait des concentrations relativement élevées en fluorure. En général les zones de hautes concentrations en fluorure recouvrent les zones à fortes conductivité électrique (abréviation en anglais: EC). Sur le flanc Ouest du bassin de Cambay dans le mince lit reliant Little Ran de Kachchh-Nalsarovar au golfe de Khambhat (LRK-NS-GK), les fortes teneurs en fluorure et les EC dans la nappe phréatique proviennent de lenrichissement par les évaporites. Sur le flanc Est du bassin, des poches de teneurs élevées en fluorures ont été observées, probablement dues à des dissolutions préférentielles de minéraux fluorés. Sur ce flanc des teneurs sont également associées à la présence de sources géothermales. Dans le bassin de Cambay, les alternances de couches lits à fortes teneurs et de lits à faibles teneurs sont expliquées par la recharge durant les périodes climatiques humides et les périodes climatiques plus sèches. Ceci est corroboré par les datations au radiocarbone (environ 20.000 an) au dessus du lit riche en fluorure.

     

A new model (DRARCH) for assessing groundwater vulnerability to arsenic contamination at basin scale: a case study in Taiyuan basin,northern China

A modified DRASTIC model for groundwater vulnerability assessment (abbreviated as DRARCH model by combining the first letters of its six assessment indices) was proposed. It is essentially the specific application of DRASTIC model rather than a new model. Both natural hydrogeological conditions that prevent groundwater from contamination and important intrinsic hydrogeochemical properties of sediments in vadose zone that are related to the retardation of contaminants were considered as vulnerability indices. The DRARCH model consists of six indices: (1) Depth to the water table, (2) net Recharge, (3) Aquifer thickness, (4) Ratio of cumulative thickness of clay layers to total thickness of vadose zone, (5) Contaminant adsorption coefficient of sediment in vadose zone, and (6) Hydraulic conductivity of aquifer. The rating values and the weights of these vulnerability indices were obtained by contaminant transport simulation and factor analysis method respectively. Furthermore, the DRARCH model was applied to evaluate the groundwater vulnerability to arsenic contamination in Taiyuan basin, northern China, where groundwaters with high arsenic concentration occur in some localities. GIS-based mapping of groundwater vulnerability using this model indicates that the distribution of very high and high-vulnerability areas corresponds well to that of high-arsenic groundwaters. The DRARCH model is therefore reliable and useful for guiding groundwater environment management.     

Managing groundwater rise: Experimental results and modelling of water pumping from a quarry lake in Milan urban area (Italy)

An innovative approach to solve the problem of lowering water table was carried out in a quarry lake south of the city of Milan (northern Italy): the project, based upon pumping out water at a rate of 1,000 L/s can be considered a strategic medium to long-term solution to hinder the rise of groundwater level interfering with underground structures (foundation, construction, subway) in urban areas. The basic idea is to pump a high groundwater rate as close as possible to the stagnation point of the piezometric depression located in the city. After a pilot-test was carried out in November 1998, experimental activities started in July 2001 and lasted one year; water withdrawal was discharged into artificial channels used in agricultural practice. Maximum drawdowns measured in the quarry lake by the monitoring network resulted in more than 5 m, and a significant drawdown was registered up to 1.5 km of distance from the quarry in the important historical site of Chiaravalle Abbey, threatened by groundwater rise. The results of this pumping activity confirm the importance of the project, its lower cost compared with traditional solutions (such as drainage by wells) and remarkable effects on the improvement of surface water quality. A groundwater model was implemented to evaluate further scenarios of discharge rate and pumping location, too.     

潜江盐湖盆地生储盖组合特征

潜江盐湖盆地是我国内陆独一无二的高盐度盐湖沉积盆地。本文在分析其岩性韵律特征的基础上,探讨了潜江盐湖生储盖组合特征。研究表明,潜江凹陷潜江组是在干湿频繁交替的古气候条件下,在高盐度、强蒸发、还原—强还原水体中,由北部单向碎屑物源及凹陷周缘卤水与盐源补给形成的盐系地层,岩性组合的有序变化形成了多套生储盖组合系统,不但反映出潜江盐湖沉积的特殊性和复杂性,而且具有十分优越的成油气地质条件。     

The effect of stratigraphic heterogeneity on areal distribution of land subsidence at Taiyuan, northern China

Taiyuan city has experienced serious land subsidence since the 1950s, with the maximum accumulated subsidence of 2,960 mm and a total affected area of 585 km² by 2003. Tectonic settlement was found to contribute about 1% and the major cause is over-exploitation of groundwater. The spatial–temporal relationship between the areal distribution of land subsidence and that of groundwater drawdown from 1956 to 2000 indicates that although land subsidence centers overall match groundwater depression cones, there are local deviations, and that although the time series curves are similar, land subsidence always lags behind groundwater level decline, with different lag time at different sites. The major findings of this work on the control of stratigraphic heterogeneity on the spatial pattern of land subsidence at Taiyuan include: (1) land subsidence centers shift from the corresponding groundwater depression cones to the sides with thicker accumulated clay layers; (2) under the same pumping rate, land subsidence at places with more clay interlayers and thinner individual interlayers is greater and the lag time shorter; and (3) land subsidence is closely related to the physical properties of clay soils. The Interbed Storage Package-1, a modular subroutine of MODFLOW was employed to simulate the areal distribution of individual layer compression. The modeling results show that compression of different clay layers has different contribution to land subsidence. Pumping groundwater from water-bearing zones close to the most compressible clay layers should therefore be carefully controlled.     

Responses of groundwater system to water development in northern China

The increased demands on water resources in northern China have had a significant impact on groundwater systems in the last three to four decades, including reductions in groundwater recharge capacity and overall water quality. These changes limit the potential for groundwater uses in this area. This paper discusses the issues surrounding groundwater system use in the eight basins of northern China as water resources have been developed. The results demonstrate that the recharge zone has shifted from the piedmont to the agricultural area, and that the total recharge rate in the basins tended to decrease. This decrease in arid inland basins was mainly caused by both the excessive use of water in the watershed area and irrigated channel anti-seepage. In semi-arid basins, the decrease observed in the groundwater recharge rate is related to an overall reduction in precipitation and increasing river impoundment. In addition, intensive exploitation of groundwater resources has resulted in disturbances to the groundwater flow regime in arid and semi-arid inland basins. Arid inland basins demonstrated fast falling groundwater levels in the piedmont plains resulting in declines of spring flow rates and movement of spring sites to lower locations. In the semi-arid basins, i.e. the North China Plain and the Song-nen Plain, groundwater depression cones developed and intersected regional groundwater flow. The semi-arid basins of the North China Plain and the Song-nen Plain have experienced significant hydrochemical evolution of groundwater characterized by changing water type including increase of TDS and pollutants.     

Characteristics of karst groundwater system in the northern basin of Laiyuan Spring area

Guided by the theory of groundwater system, based on the groundwater level data from the northern basin of Laiyuan Spring area, the authors took into account factors such as the lithology, geological structure and topography to study the relationship between groundwater recharge, runoff and drainage in this area. It was concluded that the infiltration of atmospheric precipitation is the main source of groundwater supply in this area; the upper layer of the Spring area is distributed with the Cambrian-Lower Ordovician karst water, and the lower layer is filled with the Jixian system karst water. The upper layer of karst water supplies to the lower layer of karst water or the pore water in loose strata through the fault while the lower layer of karst water runs to the three strong runoff belts from the east and west sides of the watershed, southwards into the basin, partially replenishing the pore water in loose strata, or forming fault Springs (e.g. Nanguan Spring, Beihai Spring) when dolomite movement encounters faults. Replenished by atmospheric precipitation and the upper and lower layers of karst waters, the pore water in loose strata joins the groundwater in the southern basin and then flows eastwards, in the end it flows out of the system in Shangfanpu. Through the analyses of groundwater level data and hydrogeological drilling data, based on groundwater D and 18O isotope test results, the karst groundwater circulation system in the northern basin of Laiyuan Spring area is further verified, which provides hydrogeological basis for water resources development and utilization as well as protection in this area.     

Evolution of the groundwater environment under a long-term exploitation in the coastal area near Zhanjiang, China

Aquifers consisting of unconsolidated sediments in the coastal area near Zhanjiang in southern China are grouped into the shallow, middle-deep and deep aquifer systems. Groundwater exploitation began in the 1950s in this district and has increased from year to year since 1980. Measurements of groundwater levels and monitoring data of groundwater chemistry at some 60 wells since 1981 are examined to analyze the evolution of hydrodynamics and hydrochemistry in the coastal aquifers. The results indicate that groundwater levels in the middle-deep and deep aquifer systems have fallen continuously and the extents of the depression cones in water levels have increased in the past two decades, even though the water levels recovered to some degree during the period of 1997–2001. In 2004, the lowest water levels in the middle-deep and deep aquifer systems were 23.58 and 21.84 m below sea level, respectively. The groundwater has TDS ranging from 40 to 550 mg/L, and is of low pH, commonly varies between 4 and 7. Concentrations of total iron and manganese exceed the concentration limits of the drinking water standards. The hardness is in the range of 10–250 mg/L. Chloride contents of the groundwater range from 10 to 60 mg/L. The chloride and TDS do not show systematically increasing trends. Although the water levels in the exploitation center near the coast are significantly lower than the sea level and the depression cones of water levels in the middle-deep and deep aquifer systems have expanded to the sea, sea water intrusion has not been observed until recently. This phenomenon is quite unique in the coastal area near Zhanjiang.     

Current situation and human health risk assessment of fluoride enrichment in groundwater in the Loess Plateau: A case study of Dali County,Shaanxi Province,China

This study aims to investigate the mechanisms and health risks of fluoride enrichment in groundwater in the Loess Plateau, China. By taking Dali County, Shaanxi Province, China as an example, this study obtains the following results through field investigation and the analyses of water, soil, and crop samples. (1) The groundwater can be divided into two major types, namely the Quaternary pore-fissure water and Karst water. The Karst area and sandy area have high-quality groundwater and serve as the target areas for optional water supply. The groundwater in the study area is slightly alkaline and highly saline. Meanwhile, high-fluoride groundwater is mainly distributed in the loess and river alluvial plains in the depression area of the Guanzhong Basin and the discharge areas of the groundwater, with the highest fluoride concentration exceeding seven times the national standard. (2) Fluoride in groundwater mainly originates from a natural source and human activities. The natural source refers to the fluoride-bearing minerals in rocks and soil, and the fluoride from this source is mainly controlled by natural factors such as climate, geologic setting, pH, specific hydrochemical environment, ion exchange, and mineral saturation. Human activities in modern life can be further divided into industrial and agricultural sources primarily. (3) The health risks of fluoride contamination are very high in the Loess Plateau, especially for children compared to adults. Meanwhile, the risks of fluoride exposure through food intake are higher than those through drinking water intake. The authors suggest selecting target areas to improve water supply and ensure the safety of drinking water in the study area. Besides, it is necessary to plant crops with low fluoride content or cash crops and to conduct groundwater treatment to reduce the fluoride concentration in drinking water. These results will provide a theoretical basis for safe water supply in the faulted basin areas in the Loess Plateau.© 2021 China Geology Editorial Office.     

The origin of fluoride in the granitic aquifer of Porto Alegre, Southern Brazil

The Porto Alegre region, Southern Brazil, comprises a fractured aquifer system constituted by pre-Cambrian granitic and gneissic rocks, and a porous aquifer system formed by Cenozoic muddy–sandy to sandy sediments. A model is presented for the origin of the fluoride in the groundwater of the fractured aquifer system, based on ionic interrelations, a statistical analysis of physicochemical parameters and geochemical modeling. The fluoride is present at levels of up to 6.13 mg/L in groundwater and it arises due to the dissolution of secondary fluorite filling fractures in the granitic and gneissic rocks. The dissolution of fluorite occurs at the same time as calcite and dolomite solubilization. The statistical analysis identified three chemically distinct groups (named 1, 2 and 3) and two subgroups (1A and 1B) of groundwater in the fractured aquifer. The most significant differences between these groups are the different concentration ranges of fluoride, calcium, bicarbonate, magnesium, total dissolved solids and chloride and pH values, as well as the correlations between them. The compositional evolution of each groundwater group is governed mainly by how much high-salinity groundwater from the porous aquifer system is mixed with them and the different thermodynamic equilibrium conditions of calcite, dolomite and fluorite.     

苏北沿海地面沉降区地下水资源管理对策探讨

苏锡常地区实例证明,沿用单一的取水许可制度已很难解决地下水资源超采及由此引发的地面沉降地质灾害问题,地下水资源管理目标应定位于地质环境保护前提下的科学适度开采。对苏北沿海盐城、大丰地面沉降区现行的地下水资源管理制度进行了探索性补充设计,重点探讨了地下水开采权交易模型和地下水资源动态规划机制,为该地区今后的地下水资源管理提供了思路。     

新疆库车盆地古近纪—新近纪盐湖成钾与靶区预测

库车前陆盆地位于塔里木盆地北部,属于副特提斯域,古近纪受副特提斯海海水补给,古近纪—新近纪发育巨厚蒸发岩。研究显示,库车盆地始新世和中新世古盐湖卤水已演化至钾盐析出阶段,在地层中广泛发现了原生钾盐矿物,如钾石盐、光卤石、杂卤石等;通过岩芯岩屑地球化学及矿物学分析,基本确定了至少3个富钾层或成钾层位,其中始新统中上部两个和中新统中上部一个,钾离子含量最高达3%,另外,上新统可能存在一个成钾层位。本文在综述此前库车盆地构造、蒸发岩、盐类矿物学、地球化学与盐湖沉积等研究基础上,建立了新的库车盆地古盐湖构造- 沉积演变、成钾模式;提出了4个钾盐成矿区带,即北部克拉苏成矿带、中部秋里塔克成矿带、南部沙雅构造沉降成矿带以及东部阳霞凹地成钾区,这些关键认识为库车盆地的钾盐勘查提供了重要的理论和科学依据。     

Arsenic and fluoride in a loess aquifer in the central area of Argentina

The objective of this study is to analyze the geochemical conditions associated with the presence of arsenic (As) and fluoride (F) in the phreatic aquifer of Coronel Moldes, in the central sector of the Argentine Chacopampean plain. The studied aquifer is composed of silty sand sediments of aeolian origin, typically loess-like sediments. The geochemical composition of water varies from sodium bicarbonate to sodium sulfate-chloride water. As contents range from low concentrations, below detection level, to 250 μg/l. High values of F (up to 12 mg/l) were recorded. A high As–F correlation was found (R ² = 0.84). The pH varied from 7.31 to 8.85 and the nitrates reached concentrations up to 200 mg/l, indicating an oxidant environment. The highest values of As and F agreed with sodium bicarbonate waters as well as with the highest values of pH recorded. There was a high correlation between As and F⁻ as well as between As and the Na/Ca ratio. The composition and texture of loess, low permeability and hydraulic gradients together with the geochemical features of sodium bicarbonate waters are proper conditions for the mobilization of As and F in groundwater in the central area of Argentina.     

Assessment of groundwater quantity and quality and saltwater intrusion in the Damghan basin,Iran

This study describes the groundwater quantity and quality conditions in the Damghan aquifer in Iran. The quantitative analysis of data obtained from observation wells indicates overexploitation of groundwater during recent years, which has resulted in deterioration of water quality. The mean water level has declined about 7.4 m between years of 1966 and 2010. The hydrochemical facies of water collected from sampling wells were investigated though Piper and Chadha diagrams, and the general dominant type of water in the study area was determined as Na-Cl. The quality assessment examined the suitability of groundwater for drinking and irrigation purposes. Compared to the World Health Organization (WHO) guidelines for drinking water, all regions were found to have unpotable groundwater. Furthermore, unsuitability of groundwater for agricultural applications due to high salinity was observed through analysis of major quality indicators. The saltwater intrusion was investigated by ionic ratio analyses and was determined to be the main factor contributing to high salinity and deterioration of the groundwater quality in the Damghan basin.     

Geochemical processes controlling the elevated fluoride concentrations in groundwaters of the Taiyuan Basin,Northern China

High fluoride groundwater with F⁻ concentration up to 6.20 mg/L occurs in Taiyuan basin, northern China. The high fluoride groundwater zones are mainly located in the discharge areas, especially in places where shallow groundwater occurs (the groundwater depth is less than 4 m). Regional hydrogeochemical investigation indicates that processes including hydrolysis of silicate minerals, cation exchange, and evaporation should be responsible for the increase in average contents of major ions in groundwater from the recharge areas to the discharge areas. The concentration of F⁻ in groundwater is positively correlated with that of HCO₃⁻ and Na⁺, indicating that groundwater with high HCO₃⁻ and Na⁺ contents help dissolve some fluoride-rich minerals. The water samples with high F⁻ concentration generally have relatively higher pH value, implying that alkaline environment favors the replacement of exchangeable F⁻ in fluoride-rich minerals by OH⁻ in groundwater. In addition, the mixing of karst water along the western mountain front and the evaporation may also be important factors for the occurrence of high fluoride groundwater. The inverse geochemical modeling using PHREEQC supports the results of hydrogeochemical analyses. The modeling results show that in the recharge and flow-through area of the northern Taiyuan basin, interactions between groundwater and fluoride-rich minerals are the major factor for the increase of F⁻ concentration, whereas in the discharge area of the northern basin, the evaporation as well as the mixing of karst water has greater contribution to the fluoride enrichment in groundwater.     

Effect of saltwater intrusion on groundwater environment in Weihe River downstream,Shandong Province,China

Based on the geological and hydrogeological conditions along with dynamic changes of groundwater level,this paper analyzes the hydrodynamic characteristics of saltwater intrusion in the study area.According to monitoring data of groundwater quality,the distribution characteristics of macro component are analyzed,and then fuzzy comprehensive evaluation method is adopted to evaluate the impact of saltwater intrusion on groundwater environment.Concerning the influence degree of groundwater environment,the study area is divided into brine area,seriously influenced area,moderately influenced zone,slightly influenced zone and uninfluenced zone.The results can offer references for prevention and control of saltwater intrusion as well as the protection of water resources.     

Characterization of water bursting and discharge into underground mines with multilayered groundwater flow systems in the North China coal basin

A conceptual framework for characterization of water bursting and discharge into underground mines with multilayered groundwater flow systems is presented, based on the features of the site conditions and analyses of the water bursting and mine inundation events of the North China coal basin. Comprehensive analyses of the hydrogeological conditions for establishment of the three-dimensional groundwater flow systems of the North China coal basin revealed different vertical hydraulic connection paths or channels. These connections include karst collapse columns, fault or fracture zones, buried weathering zones, and fracture networks in aquitards, within the multilayered groundwater flow systems. Also examined, was the effect of the primary features of the flow system and those different connection paths on water bursting and discharge into the underground coal mines. It was demonstrated that appropriately identifying and adequately understanding the three-dimensional multilayered groundwater flow systems and those various vertical hydraulic connection mechanisms are critical for appropriately preventing water bursting hazards and predicting water discharge into underground mines. A valuable guideline is presented on characterization of water bursting and discharge into underground mines with multilayered groundwater flow systems.

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Resumen Un cadre de travail conceptuel pour la caractérisation du jaillissement et de la vidange des eaux dans les mines à plusieurs niveaux d'écoulement est présenté, basé sur les conditions et l'analyse sur site du jaillissement des eaux et des inondations dans les bassins charbonneux du Nord de la Chine. L'analyse compréhensive des conditions hydrogéologiques des systèmes d'écoulement tridimensionnel de ces bassins, révèle des trajets ou des chenaux qui sont autant de connections hydrauliques verticales. Ces connections comprennent des effondrement karstiques en colonne, des zones de fractures et de failles, des zones d'altération, des réseaux de fractures dans les aquitards, dans le système hydrogéologique multicouche. L'influence des caractéristiques primaires du système d'écoulement et de ces différentes connections sur le jaillissement et la vidange dans les mines, est également examiné. Il a été démontré que l'identification appropriée et la compréhension adéquate du système d'écoulement souterrain multicouche et tridimensionnel, et des mécanismes variés de connection hydraulique verticale est critiquée pour prévenir de manière appropriée les risques de jaillissement et de vidange dans les mines. Des guidelines valorisables sont présentées, pour la caractérisation du jaillissement et de la vidange dans de tels systèmes.

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Résumé Se presenta un marco conceptual para la de caracterización de la despresurización y descarga de agua a minas subterráneas con sistemas de acuíferos de múltiples niveles, el cual se basa en las condiciones del sitio, análisis de la despresurización de agua e inundaciones de minas en la cuenca de carbón del norte de la China.Un análisis comprehensivo de las condiciones hidrogeológicas para el establecimiento de los sistemas de flujo de agua de tri-dimensionales en la cuenca de carbón del norte de la China ha revelado diferentes canales hidráulicos verticales. Estas conexiones incluyen columnas de karst colapsadas, fallas o zonas de fracturas, zonas de regalita hundida y redes de fracturas en zonas de poca permeabilidad dentro de los sistemas de flujo de múltiples niveles.También se investigó el efecto de los rasgos primarios del sistema de flujo y los diferentes canales conectivos sobre la despresurización y descarga de agua a minas subterráneas. Se demostró que el entendimiento e identificación adecuada de los sistemas de acuíferos de múltiples niveles en tres dimensiones es crítico para prevenir apropiadamente la despresurización y descarga de agua a minas subterráneas. Se presentan lineamientos valiosos en relación con la despresurización y descarga de agua a minas subterráneas en sistemas de flujo de múltiple nivel.