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Author |
Bobba, A.G. |
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Title |
Mathematical models for saltwater intrusion in coastal aquifers |
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1993 |
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Water Resources Management |
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7 |
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1 |
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3-37 |
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Flow of freshwater and saltwater intrusion in coastal aquifers has drawn the attention of many investigators. Several laboratory, as well as mathematical models have been developed to study the pattern of flow of groundwater in coastal aquifers. Mathematical models have wider range of application and are the concern of this paper. Due to the complex nature of the problem, each of these mathematical models are based on certain simplifying assumptions and approximations. This paper presents a critical review of various methods of solution which have been proposed. The validity of the results abtained and the limitations of these models are also discussed. |
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1573-1650 |
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THL @ christoph.kuells @ Bobba.1993 |
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14 |
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Liu, F.; Wang, S.; Wang, L.; Shi, L.; Song, X.; Yeh, T.-C.J.; Zhen, P. |
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Title |
Coupling hydrochemistry and stable isotopes to identify the major factors affecting groundwater geochemical evolution in the Heilongdong Spring Basin, North China |
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Journal Article |
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2019 |
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Journal of Geochemical Exploration |
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205 |
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Understanding the interference of natural processes and anthropogenic activities in geochemical evolution of groundwater is vital for groundwater sustainable management in water-stressed regions. This study is devoted to the identification of the main factors controlling the evolution of groundwater chemistry by the combined use of hydrogeochemical indicators along with isotope tracers in the Heilongdong Spring Basin, North China. Thirty-nine groundwater samples and twelve surface water samples were collected, and major ions and stable isotopes were measured during the two campaigns (December 2017 and August 2018). The isotope approach indicates that the groundwater is recharged by precipitation infiltration after evaporation, and interacts with surface water along preferential flow paths in fault zones and karst conduits. Currently, the main chemical facies of groundwater evolve from Ca-HCO3 and Ca-Mg-HCO3 types with low TDS, through Ca-Mg-HCO3-SO4 and Ca-HCO3-SO4 types with moderate TDS, to Ca-SO4, Ca-SO4-Cl and CaCl types with high TDS. Apart from natural processes (involving dissolution/precipitation of minerals, cation exchange, and evaporation) regulating the groundwater quality, the stagnant zones also play a crucial role in the formation of severe localized nitrate contamination. The deterioration in groundwater quality can be attributed to anthropogenic factors (including the change in groundwater exploitation, the leaching of solid waste, and the overuse of agricultural fertilizers). The high loads of agricultural fertilizers in irrigation return flows are likely to be the main contributor of the dissolved nitrate in groundwater. The findings of this work not only have important implications for groundwater sustainable utilization, but also could serve as a template for other rapidly industrialized and water-stressed regions. |
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English |
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0375-6742 |
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THL @ christoph.kuells @ Liu2019 |
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29 |
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Moral, F.; Cruz-Sanjulián, J.J.; Olías, M. |
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Geochemical evolution of groundwater in the carbonate aquifers of Sierra de Segura (Betic Cordillera, southern Spain) |
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Journal Article |
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2008 |
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Journal of Hydrology |
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360 |
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1 |
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281-296 |
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Sierra de Segura (Betic Cordillera), with a total area of over 3000km2, is the source of the two principal rivers in southern Spain, the Guadalquivir and the Segura. Due to the orographic effect of these mountains, precipitations are considerably more abundant than in nearby lowland areas, where the climate is semi-arid. Sierra de Segura is constituted of Mesozoic and Cenozoic sedimentary rocks, among which there are thick limestone–dolomitic formations which have given rise to extensive outcrops of permeable materials. In geomorphological terms, there is a large plateau intensively karstified that constitutes the main recharge area. Discharge takes place via a large number of springs, of which the 50 most important add up to a mean spring flow of about 13,500l/s. The active geochemical processes in aquifers of Sierra de Segura, with their corresponding time sequence, are: dissolution of CO2, dissolution of calcite, incongruent dissolution of dolomite, dedolomitization, exsolution of CO2, and precipitation of calcite. More evolved water has higher temperature, magnesium content and Mg/Ca ratio; therefore, these parameters can be utilised as indicators of the degree of hydrochemical evolution. In addition, a good correlation between water temperature and magnesium concentration (or Mg/Ca ratio) indicates that an increase in temperature accelerates the kinetics of the dissolution of dolomite. Finally, the distribution of the temperatures in the vadose zone, determined by atmospheric thermal gradient, implies an apparent stratification of the predominant hydrochemical processes and of the groundwater physical and chemical characteristics. |
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0022-1694 |
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THL @ christoph.kuells @ Moral2008 |
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32 |
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Nogueira, G.; Stigter, T.Y.; Zhou, Y.; Mussa, F.; Juizo, D. |
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Understanding groundwater salinization mechanisms to secure freshwater resources in the water-scarce city of Maputo, Mozambique |
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2019 |
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Science of The Total Environment |
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661 |
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723-736 |
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In this study hydrochemical, isotopic and multivariate statistical tools are combined with a recharge analysis and existing geophysical data to improve understanding of major factors controlling freshwater occurrence and the origins of high salinities in the multi-layered coastal aquifer system of the Great Maputo area in Mozambique. Access to freshwater in this semi-arid area is limited by an inefficient public supply network, scarce surface waters, long droughts and an increasing population growth. Groundwater has a large potential to enhance water security, but its exploitation is threatened by both coastal and inland salinization mechanisms that are poorly understood. A GIS approach is utilized to classify potential recharge zones based on hydrogeological properties and land use/cover, whereas potential recharge rates are estimated through a root zone water balance method. In combination with water stable isotope data results reveal that extreme rainfall events provide the most relevant contributions to recharge, and interception and evaporation play an important role in the low recharge areas. Hierarchical clustering of hydrochemical and isotopic data allows the classification of six water groups, varying from fresh to brackish/salt waters. Corresponding scatter plots and PHREEQC modelling show evaporation and mixing with seawater (up to 5%) as major processes affecting salinity in the area. The co-occurrence of high alkalinity and Cl concentrations, in combination with piezometric and geo-electrical data, suggests that: 1) inland brackish/salt groundwater is caused by mixing with seawater trapped within clay layers; and 2) brackish/salt surface waters result from seepage of brackish groundwater into rivers and wetlands, followed by evaporation, hence increasing salinity and δ18O values. Mixing with small fractions of trapped seawater as main salinity source, rather than halite dissolution, is further corroborated by Br/Cl ratios of brackish/salt water samples near the ocean ratio. Cation exchange upon salinization is mainly observed in the semi-confined aquifer, while freshening takes place in the phreatic aquifer, particularly in areas presenting high recharge rates. |
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0048-9697 |
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THL @ christoph.kuells @ Nogueira2019 |
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34 |
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Author |
Panagopoulos, G. |
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Application of major and trace elements as well as boron isotopes for tracing hydrochemical processes: the case of Trifilia coastal karst aquifer, Greece |
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2009 |
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Environmental Geology |
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58 |
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5 |
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1067-1082 |
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0943-0105 |
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Greece |
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THL @ christoph.kuells @ Panagopoulos2009 |
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36 |
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