Concurrent existence of confined and unconfined zones of an aquifer can arise owing to ground water withdrawal by pumping. Using Girinskii's potential function, Chen (1974, 1983) developed an approximate analytical solution to analyze transient ground water flow to a pumping well in an aquifer that changes from an initially confined system to a system with both unconfined and confined regimes. This article presents the details of the Chen model and then compares it with the analytical model developed by Moench and Prickett (1972) for the same problem. Hypothetical pumping test examples in which the aquifer undergoes conversion from confined to water table conditions are solved by the two analytical models and also a numerical model based on MODFLOW. Comparison of the results suggests that the solutions of the Chen model give better results than the Moench and Prickett model except when the radial distance is very large or aquifer thickness is large compared with drawdown.
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http://dx.doi.org/10.1111/j.1745-6584.2008.00436.x | DOI Listing |
Environ Geochem Health
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School of Environmental Science and Engineering, Shandong University, Qingdao, 266237, China.
Groundwater arsenic (As), contamination is a significant issue worldwide including China and Pakistan, particularly in canal command areas. In this study, 131 groundwater samples were collected, and three machine learning models [Random Forest (RF), Logistic Regression (LR), and Artificial Neural Network (ANN)] were employed to predict As concentration. Descriptive statistics helped to conclude that all of the samples were inside the permitted limit of WHO for pH, Ca, Mg, Turbidity, Cl, K, Na, SO, NO, F and beyond limit of WHO for EC, HCO, TDS, and As.
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Department of Water Resource and Ecosystems, IHE Delft Institute for Water Education, Westvest 7, Delft, NH, Netherlands.
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Faculty of Agriculture, Life, and Environmental Sciences, Zhejiang University, Hangzhou 310058, China.
Electron release and transfer are pivotal to the efficiency of multiple biogeochemical and pollutant processes. Despite substantial efforts to develop electron-transfer characterization techniques, visualization of electron transfer remains challenging. This study introduces an innovative strategy for mapping electron-transfer distance using nanoscale zerovalent iron (nZVI) as a case study.
View Article and Find Full Text PDFEnviron Sci Process Impacts
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Department of Civil and Environmental Engineering, University of Pittsburgh, Pittsburgh, PA, USA.
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View Article and Find Full Text PDFAWWA Water Sci
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Department of Civil, Construction, and Environmental Engineering, North, Carolina State University, Raleigh, North, Carolina, USA.
Per- and polyfluoroalkyl substances (PFAS) occur widely in drinking water, and consumption of contaminated drinking water is an important human exposure route. Granular activated carbon (GAC) adsorption can effectively remove PFAS from water. To support the design of GAC treatment systems, a rapid bench-scale testing procedure and scale-up approach are needed to assess the effects of GAC type, background water matrix, and empty bed contact time (EBCT) on GAC use rates.
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