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The Yangjiashan landslide is a typical giant ancient rock landslide located in Enshi City, Hubei Province, China. Since the landslide was reactivated in August 1980, it has destroyed more than 630,000 m2 of farmland and 160 houses, and 200 people have been left homeless. At present, the landslide remains at the stage of creep deformation, which seriously threatens the safety of residents and their property. In regard to the formation mechanism of the Yangjiashan landslide, it is generally accepted that the landslide may be attributed to the horizontal push failure phenomenon of horizontal strata. Alternatively, the traction effect caused by the erosion and collapse of the trailing edge of the landslide may enhance the landslide occurrence frequency. Regardless of the landslide formation mechanism, groundwater lubrication of near-horizontal strata and the combined action of hydrostatic and dynamic pressures are important factors influencing landslide stability. In this study, the surface nuclear magnetic resonance (SNMR) geophysical method under large-scale nondestructive detection is applied to determine the groundwater characteristics of the Yangjiashan landslide. The SNMR method can realize the detection of groundwater information by observing the relaxation process of hydrogen nuclei in groundwater. Moreover, the water content per unit volume of underground media can be determined according to the initial amplitude and time constant of the relaxation signal, and important hydrogeological characteristics, such as the permeability coefficient, can be inferred. These results can provide important references for the stability analysis of the Yangjiashan landslide. [ABSTRACT FROM AUTHOR]

Groundwater is a vital resource that accounts for around 30% of the world's freshwater resources. In arid and semi-arid zones, the human dependency on groundwater is comparatively very high, and its quality significantly impacts human health. Both anthropogenic and natural factors have led to changes in hydrodynamics of groundwater resources and water security issues in various regions of the globe. Thus, the bibliometric search methods were conducted to assess the dynamics of "Groundwater Research" in India based on scientific literature published from 1989 to 2020. In this regard, the Web of Science Core Collection database has been used to extract the literature amounting to 3848 document types. Analysis and mapping of the searched data have been compiled using Microsoft Excel, bibliometrix R-Package Biblioshiny, BibExcel, HistCite and VOSviewer tools, which enabled to assess of the development of the literature, identification of documents types, most prolific authors, countries, institutions, highly cited articles, productive journals, bibliographic coupling, keywords and hotspot topics. The significant findings highlight that the number of research publications has increased significantly over the last few decades in India to promote groundwater scientific study and research. The study highlight that the research articles are the most preferred document type, and India's collaboration in groundwater research is highest with the USA. The Journal of the Geological Society of India is the most preferred journal for research publication and the highest count of publication contributions from the Indian Institutes of Technologies. The present review study will assist institutions in providing the current "Groundwater Research" gap in the country and will facilitate the future productive research output in groundwater research. [ABSTRACT FROM AUTHOR]

Available groundwater research work and data levels are very limited due to the wide territory of our country. Potential Groundwater resources need to be calculated by basin to implement Integrated Water Resources Management Plans. For this purpose, previously the calculations were done twice in the Orkhon River Basin. The last calculation was done 10 years ago, therefore Integrated Water Resources Management Plan needs to be redeveloped, using updated research work and data levels. The Orkhon River is one of the biggest rivers in Mongolia, rising from Khangai Mountain Range and flowing into the Selenge River. The Orkhon River Basin includes the Tuul, Kharaa, and Yeruu rivers basins which rise in the Khentii Mountains. For the first time, a hydrogeological structure map of the basin was developed which analyzed and systemized the hydrogeological structure, the morphostructure factors, and the hydraulic properties of the hydrogeological formations distributed in the Orkhon River Basin. There are two types of hydrogeological basins and three types of hydrogeological massifs in the basin. This paper presents the calculation of the Potential Groundwater Resources (PGR) in the Orkhon River Basin based on groundwater well data, reports of groundwater exploration and research works, and the hydrogeological maps at a scale of 1:500,000. As a result of this calculation, there are 1.99 km³ of PGR in this basin. The largest resources are found in the linear intermountain hydrogeological basin which occupies 98 percent of the total PGR. Further improvement of the quality and standards of water research remains an important issue for hydrogeologists today. [ABSTRACT FROM AUTHOR]

As in other large Andean cities, the population in the Metropolitan District of Quito (MDQ) in northern Ecuador is growing, and groundwater is becoming essential to meet the increasing urban water demand. Quito's Public Water Supply Company (EPMAPS) is promoting groundwater research for sustainable water supply, and geophysical prospecting surveys are used to define aquifer geometry and certain transient groundwater features. This paper examines the usefulness of existing geophysical prospecting surveys in groundwater research in the MDQ. A database was built using 23 representative geophysical prospecting surveys compiled from EPMAPS' public repository, official geotechnical research reports, and the scientific literature. Fifteen EPMAPS-promoted surveys used near-surface electrical techniques (seven used electrical resistivity tomography and eight used vertical electrical sounding) to explore Holocene and Pleistocene sedimentary and volcano-sedimentary formations in the 25–500-m prospecting depth range, some of which form shallow aquifers used for water supply. Four other surveys used near-surface seismic techniques (refraction microtremor) for geotechnical research in civil works. These surveys have been reinterpreted to define shallow aquifer geometry. Finally, four surveys compiled from the scientific literature used electromagnetic techniques (magnetotelluric sounding and other very low-frequency methods) to explore Holocene to late Pliocene formations, some of which form thick regional aquifers catalogued as the larger freshwater reservoirs in the MDQ. However, no geophysical prospecting surveys exploring the complete saturated thickness of the Pliocene aquifers could be compiled. Geophysical prospecting surveys with greater penetration depth are proposed to bridge this research gap, which prevents the accurate assessment of the renewable groundwater fraction of the regional aquifers in the MDQ that can be exploited sustainably. [ABSTRACT FROM AUTHOR]

As in other large Andean cities, the population in the Metropolitan District of Quito (MDQ) in northern Ecuador is growing, and groundwater is becoming essential to meet the increasing urban water demand. Quito’s Public Water Supply Company (EPMAPS) is promoting groundwater research for sustainable water supply, and geophysical prospecting surveys are used to define aquifer geometry and certain transient groundwater features. This paper examines the usefulness of existing geophysical prospecting surveys in groundwater research in the MDQ. A database was built using 23 representative geophysical prospecting surveys compiled from EPMAPS’ public repository, official geotechnical research reports, and the scientific literature. Fifteen EPMAPS-promoted surveys used near-surface electrical techniques (seven used electrical resistivity tomography and eight used vertical electrical sounding) to explore Holocene and Pleistocene sedimentary and volcano-sedimentary formations in the 25–500-m prospecting depth range, some of which form shallow aquifers used for water supply. Four other surveys used near-surface seismic techniques (refraction microtremor) for geotechnical research in civil works. These surveys have been reinterpreted to define shallow aquifer geometry. Finally, four surveys compiled from the scientific literature used electromagnetic techniques (magnetotelluric sounding and other very low-frequency methods) to explore Holocene to late Pliocene formations, some of which form thick regional aquifers catalogued as the larger freshwater reservoirs in the MDQ. However, no geophysical prospecting surveys exploring the complete saturated thickness of the Pliocene aquifers could be compiled. Geophysical prospecting surveys with greater penetration depth are proposed to bridge this research gap, which prevents the accurate assessment of the renewable groundwater fraction of the regional aquifers in the MDQ that can be exploited sustainably.

Nowadays, because of severe droughts, the drilling of new wells, the over-abstraction of groundwater resources, and inattention to resource planning and management, there is an urgent need for paying special attention to groundwater resources and their quantitative and qualitative assessment. The present research assesses the quantitative and qualitative status of groundwater behavior in the Shourdasht basin of Qahavand in Hamadan province, Iran. Quantitative and qualitative groundwater data were collected for the 2001-2016 period and the quantitative and qualitative groundwater maps of piezometric wells data were evaluated using the GIS-based interpolation method. According to the results of the annual Shourdasht hydrograph, an average of 1.7 m decline is observed in the groundwater in the study area. The calculation of hydrodynamic coefficient shows that the studied aquifer had the maximum water transmissibility rate of about 165.23 m/day in the northwestern part of the Shourdasht basin and the minimum transmissibility rate of 16.5 m/day in the north of the basin. The maximum and minimum specific yield coefficients were recorded in the eastern and northeastern parts of the plain, which were about 0.61 and 0.006, respectively. The results of the qualitative study of the area show that according to the Schuler diagram, drinking water quality is mainly within the acceptable to moderate range. Also, according to the Wilcox diagram, the samples are classified to have medium quality. [ABSTRACT FROM AUTHOR]

The natural attenuation behavior of chlorinated solvents and their risks to human health at a contaminated groundwater site in Takahata, Japan, were investigated. It was found that volatile organic compound (VOC) concentrations gradually decreased via two attenuation mechanisms, namely dilution and biodegradation. It was estimated that the VOC concentrations will be below the Japanese limits within 30 years after stopping the active remediation in 2003, which suggests that there is a high possibility that monitored natural attenuation can be adopted as the clean-up method at this contaminated site. The risk levels of VOCs at the present time are much lower than those at the time when the contamination was discovered. Vinyl chloride still presents a risk in some wells, and there were occasional unexpected increases in the risk levels of tetrachloroethylene, trichloroethylene, and cis-1,2-dichloloethylene, which means that continuous monitoring of the groundwater is necessary for forecasting risk levels. [ABSTRACT FROM AUTHOR]

The publication “The water supply of some North Sea spas” by Alexander Herzberg in 1901 is a cornerstone of coastal groundwater research. It was fundamental to the development of the Ghijben-Herzberg principle, which describes the hydrostatic equilibrium between fresh and saline groundwater. Due to its age and the language barrier, the paper is often cited but probably rarely read. Therefore, the original paper has been translated from German into English, accompanied by an introduction and notes explaining the historical context. [ABSTRACT FROM AUTHOR]

Regularities in the formation of mining water chemistry in Eastern Donbass were established and described for the 100-year period from the 1920s to 2010. The total of more than 1500 analyses were used. The changes in the chemistry were largest in the 1940s-1950s in the mines that had been recovered during World War II and after the mass abandonment of mines in the region (2002-2010). The size of groundwater resources acceptable for drinking water supply had decreased considerably; and the volumes of polluted surface water had increased abruptly. The export of dissolved substances by mining waters onto land surface reached its maximum (426 thousand t/year) in 2010. Four main lines of transformation of mine water chemistry were identified and their genesis was interpreted. [ABSTRACT FROM AUTHOR]

This study assesses the performance and robustness of the groundwater potential (GWP) maps produced by the UNICEF model for deep groundwater exploration in Ethiopia. The UNICEF model is a weighted linear combination of hydrogeological parameters including permeability, slope, recharge, and lineament density, which has been calibrated using the expert judgements of local hydrogeologists. In order to assess the performance and robustness of the model, three techniques were employed: the analytic hierarchy process (AHP), logistic regression (LR), and artificial neural networks (ANNs). Three study areas (Dallol, Halaba and Shinelle) were selected on the basis of climatic and geological variation, in addition to the availability of well data pertaining to depth and yield. The performance of the UNICEF model in predicting outcomes of the well data included in the study was assessed by computing the receiver operating characteristic (ROC) curve. The solutions produced by the AHP and ANN were more accurate than the UNICEF model in determining the productivity of deep wells in the study data, whilst the LR model was less accurate than the UNICEF model. The groundwater productivity maps produced by the AHP and ANNs showed clear correlation with the maps produced by the UNICEF model, despite moderate (AHP) and severe (ANN) parameter perturbation, demonstrating the robustness of the UNICEF model. Whilst the AHP and ANN models demonstrated higher accuracy than the UNICEF model, this must be considered against the well data used to assess accuracy, which were drawn from a small sample of non-ideal distribution. Although this study focuses on case studies in Ethiopia the key findings are applicable internationally, namely, that the use of the AHP in data-scarce environments provides robust models, and that with the addition of easily obtainable well data the accuracy of modelling can be significantly increased through the application of ANNs. [ABSTRACT FROM AUTHOR]

Abstract: The mechanistic understanding of drought‐induced forest mortality hinges on improved models that incorporate the interactions between plant physiological responses and the spatiotemporal dynamics of water availability. We present a new framework integrating a three‐dimensional groundwater model, Parallel Flow, with a physiologically sophisticated plant model, Terrestrial Regional Ecosystem Exchange Simulator. The integrated model, Parallel Flow‐Terrestrial Regional Ecosystem Exchange Simulator, was demonstrated to quantify the susceptibility of riparian cottonwoods (Populus angustifolia, Populus deltoides, and native hybrids) in southwestern Canada to sustained atmospheric drought and variability in stream flow. The model reasonably captured the dynamics of soil moisture and evapotranspiration in both wet and dry years, including the resilience of cottonwoods despite their high vulnerability to xylem cavitation. Unrealistic predictions of mortality could be generated when ignoring lateral groundwater flow. Our results also illustrated a mechanistic linkage between streamflow and cottonwood health. In the absence of precipitation, normal streamflow could sustain 94% of cottonwoods, and higher streamflows would be required to sustain all of the floodplain cottonwoods. Further, the risk of mortality was mediated by plant hydraulic properties. These results underpin the importance of integrating groundwater processes and plant hydraulics in order to analyze the forest response to sustained severe drought, which could increase in the future due to climate change combined with increasing river water withdrawals. [ABSTRACT FROM AUTHOR]

Abstract: The effect of groundwater nutrient inputs on river and estuary water quality and the potential impacts of urbanization on groundwater are central concerns in many coastal areas. It has been previously identified that dissolved organic nitrogen (DON) can be the dominant form of total dissolved nitrogen (TDN) in some aquifers. However, there is a paucity of evidence about the sources and flow paths of DON, relative to inorganic nitrogen in groundwater. DON and dissolved organic carbon/DON were first compared against different landscape variables in this study, and no significant relationships were found. However, the relationships became statistically significant when shallow samples (sampling depth < 10 m) were separated from deep samples. A random forest model and sensitivity analysis were then applied to further our understanding of the ecohydrological drivers and seasonal patterns that shape DON variability. The random forest algorithm was built to classify 171 groundwater wellbores into three classes (low: <0.5 mg/L; medium: 0.5–2.5 mg/L; and high: >2.5 mg/L) which achieved 72% classification accuracy using landscape characteristics, hydrological conditions, and temporal information. The results indicated that the effects of landscapes on sandy shallow groundwater DON were controlled both by certain landscape characteristics and depth to groundwater. A conceptual model of groundwater DON is therefore proposed where the balance of exposure and processing time scales from the surface to groundwater is the critical control on the preservation of landscape signatures; we expect that this conceptual model would be applicable for other sandy, shallow groundwater areas. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Polytechnic is the property of Journal of Polytechnic and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The purpose of this study was to investigate students’ understanding of groundwater as a system, and to further examine whether and how their understanding is related to attitudes towards groundwater use and conservation. A total of 676 junior high school students completed a groundwater survey including a drawing activity and a questionnaire. An additional group of university students with environmental science majors were recruited for the survey for the purpose of determining reasonable expectations and validating interpretations of the results. Analysis of student drawings indicated that students generally held an incomplete and unconnected understanding of the groundwater system. Correlation analysis showed that student levels of understanding were associated with their perceptions of environmental impacts as well as environmental concern regarding groundwater problems. These findings re-emphasised the importance of promoting students’ understanding of environmental systems, as well as their ability to think systemically. [ABSTRACT FROM AUTHOR]

The article discusses the research of the University of California (UC) system regarding sustainable groundwater management. Topics mentioned include the support on innovation in groundwater recharge, the whole-watershed accounting of surface water and groundwater, and the research that gather information on the timing and magnitude of snowmelt by using wireless sensor netpwrks technology.

An efficient preconcentration technique based on ultrasonic-assisted ionic liquid-based dual microextraction (UA-ILDµE) method has been developed to preconcentrate the lead (Pb +2 ) in ground and stored rain water. In the current proposed method, Pb +2 was complexed with a chelating agent (dithizone), whereas an ionic liquid (1-butyl-3-methylimidazolium hexafluorophosphate) was used for extraction purpose. The ultrasonic irradiation and electrical shaking system were applied to enhance the dispersion and extraction of Pb +2 complex in aqueous samples. For second phase, dual microextraction (DµE phase), the enriched Pb +2 complex in ionic liquid, extracted back into the acidic aqueous solution and finally determined by flame atomic absorption spectrometry. Some major analytical parameters that influenced the extraction efficiency of developed method, such as pH, concentration of ligand, volume of ionic liquid and samples, time of shaking in thermostatic electrical shaker and ultrasonic bath, effect of back extracting HNO 3 volume, matrix effect, centrifugation time and rate were optimized. At the sample volume of 25 mL, the calculated preconcentration factor was 62.2. The limit of detection of proposed procedure for Pb +2 ions was found to be 0.54 μg L −1 . The validation of developed method was performed by the analysis of certified sample of water SRM 1643e and standard addition method in a real water sample. The extraction recovery of Pb +2 was enhanced ≥ 2% with shaking time of 80 s in ultrasonic bath as compared to used thermostatic electrical shaker, where for optimum recovery up to 10 min was required. The developed procedure was successfully used for the enrichment of Pb +2 in ground and stored rain water (surface water) samples of an endemic region of Pakistan. The resulted data indicated that the ground water samples were highly contaminated with Pb +2 , while some of the surface water samples were also have higher values of Pb +2 than permissible limit of WHO. The concentration of Pb +2 in surface and ground water samples was found in the range of 17.5–24.5 and 25.6–99.1 μg L − 1 respectively. [ABSTRACT FROM AUTHOR]

Groundwater reliant and agriculturally dominant environments (GRADEs) utilize exhaustible aquifer resources to supply food and fiber demands. The sustainability of these GRADES is threatened by over‐exploitation of fresher groundwater resources. There is an interest in exploring deeper brackish groundwater resources to sustain agricultural based economies in these regions. Using the southern high plains of Texas (SHP) as a test‐bed, the interlinkages between food‐energy‐water on improving water resiliency through brackish groundwater development is explored. Three scenarios—(1) direct use of deeper formations; (2) blending deeper and shallower groundwaters and 3) desalination of blended resources were evaluated in a spatially explicit manner. The results indicate that direct reuse of deeper water is possible over 30% of the study area, but it is not available in areas of critical need. The parameters limiting the suitability of deeper groundwater for agriculture in the order of decreasing importance are EC > TDS > SAR > B > Na > Cl. Simple blending of water from deeper and shallower aquifers improve water quality over roughly 900,000 acres. While blending greatly reduces the specific ion toxicities caused by sodium absorption ratio (SAR) and boron (B), the limitations of total dissolved solids (TDS) cannot be overcome. The over‐burden pressures in the deeper confined aquifer somewhat alleviate the blending energy requirements, especially in the southern portions of SHP. Desalination increases the energy requirements by several fold and is not suitable to sustain current agricultural practices which are focused mostly on lower valued staple crops. Using desalinated water for municipal and industrial uses can help ameliorate the stresses on the Ogallala Aquifer and enhance its longevity. © 2017 American Institute of Chemical Engineers Environ Prog, 37: 21–36, 2018 Novelty or Significance: The study is focused on the linkages between food, energy and water in groundwater dependent agricultural economies. Using the Southern High Plains of Texas as a test‐bed, the work evaluates whether a deeper brackish groundwater resource (Dockum geological unit) can be used to augment water supplies to sustain intensive agricultural production. The study identifies various factors that limit the use of this deeper resource and quantifies the energy footprint associated with three progressively complex approaches to improve water resiliency in the region and prolong the life of the Ogallala Aquifer. [ABSTRACT FROM AUTHOR]

Difficulties in monitoring groundwater extraction cause groundwater regulations to fail worldwide. In two counties in north-west China local water authorities have installed smart card machines to monitor and regulate farmers’ groundwater use. Data from a household survey and in-depth interviews are used to evaluate the effectiveness of the different regulatory institutions implemented with help of the smart card machines. In the given context, groundwater quota is more effective in curbing farmers’ groundwater use than the tiered groundwater pricing. The study shows that the usefulness of smart card machines depends on their embedding in the societal context and related regulatory institutions. [ABSTRACT FROM PUBLISHER]

Integrating social and hydrologic sciences for understanding water systems is challenged by data management complexities. Contemporary mandates for open science and data sharing necessitate better understanding of the implications of social science data types. In the context of an interdisciplinary water research program that endeavors to integrate and share social science and biophysical data, we highlight the array of data types and issues associated with social water science. We present a multi-dimensional classification of social water science data that provides insight into data management considerations for each data type. Recommendations for cyberinfrastructure, planning, and policy are offered. [ABSTRACT FROM AUTHOR]

Groundwater samples were collected from 44 wells in the Ramganga Sub-Basin (RSB), India, and analysed for major ions, nutrients and trace metals. The primary goal of this study is to evaluate the hydrochemistry and to identify the geochemical processes that govern the water chemistry in the shallow and deep tube wells in the study area using geochemical methods. The knowledge of changes in hydrochemistry of the aquifers is important for both groundwater recharge and use in the region. This study found that there are substantial differences of water chemistry between shallow and deep wells. In the shallow wells, the average concentrations of total dissolved solid (TDS), Na, K, Ca, Mg, HCO, Cl, SO, NO, PO, F, Cu, Mn, Fe and Cr are twofold higher than the deep wells. The concentrations of dissolved silica in the groundwater do not vary with the depth, which implies that the variation in the water chemistry is not due to mineral dissolution alone. Major ion ratios and saturation indices suggest that the water chemistry is predominantly controlled by dissolution of carbonate minerals, silicate weathering and ion exchange reactions. Thermodynamic evaluation (ion activity ratios and stability filed diagrams) indicates that the kaolinite and gibbsite controlled the water chemistry in the both shallow and deep wells. In addition, the groundwater chemistry in the shallow wells is affected by the vertical infiltration of contaminated water from surface contamination sources and nitrification process. In the deep wells, absence of NO and low concentrations of Cl, SO, PO and F imply the role of regional flow and denitrification in the groundwater. Results concluded that proper management plan is necessary to protect the shallow aquifer in the RSB since shallow aquifer pumping is less expensive than the deeper one. [ABSTRACT FROM AUTHOR]

This study developed a new paradigm for groundwater vulnerability assessment by modifying the standard DRASTIC index (DI) model based on catastrophe theory. The developed paradigm was called the catastrophe theory-based DI (CDI) model. The proposed model was applied to assess groundwater vulnerability to pollution index (GVPI) in Perak Province, Malaysia. The area vulnerability index was modeled by considering the DRASTIC multiple vulnerability causative factors (VCFs) obtained from different data sources. The weights and ranking of the VCFs were computed by using the inner fuzzy membership mechanism of the CDI model. The estimated vulnerability index values of the CDI model were processed in a geographic information system (GIS) environment to produce a catastrophe theory-DRASTIC groundwater vulnerability to pollution index (CDGVPI) map, which demarcated the area into five vulnerability zones. The produced CDGVPI map was validated by applying the water quality status-vulnerability zone relationship (WVR) approach and the relative operating characteristic (ROC) curve method. The performance of the developed CDI model was compared with that of the standard DI model. The validation results of the WVR approach exhibits 89.29% prediction accuracy for the CDI model compared with 75% for the DI model. Meanwhile, the ROC validation results for the CDI and DI models are 88.8% and 78%, respectively. The GIS-based CDI model demonstrated better performance than the DI model. The GVPI maps produced in this study can be used for precise decision making process in environmental planning and groundwater management. [ABSTRACT FROM AUTHOR]

Article impact statement: A simple reordering of the modeling workflow, putting the forecast to the forefront, will improve modeling efficiency and effectiveness. [ABSTRACT FROM AUTHOR]

Concepts of simplicity and complexity in modeling have been explored in papers, editorials, and talks. The concept is not well understood because there are at least two flavors of simplicity. Modelers envision simplicity (i.e., elegant simplicity) as the sought-after goal in modeling, but naïve simplicity, which is the focus of this paper, is commonly unrecognized and dangerous. The problem is that naïve or simple ideas are often mistaken for settled science and come with the prospect of being more wrong than right. The concept of the so-called simplicity cycle, in relation to classical problems of carbon-14 age and salinity in closed-basin lakes, is used to illustrate these points. The emerging problems of water-mosquitoes-diseases show the value of mapping new problems to the simplicity cycle. Researchers can 'know what they do not know' and avoid the dangers of naïve simplicity. [ABSTRACT FROM AUTHOR]

Article impact statement: Linear‐based data‐worth analysis is an efficient and straightforward method for identifying the most important data for model forecasts. [ABSTRACT FROM AUTHOR]

Article impact statement: Groundwater data will always be sparse–that is the nature of our science. Determining how, where, and when to collect data in a more informed manner is the best way to advance conceptual understanding and management of groundwater systems. [ABSTRACT FROM AUTHOR]

Groundwater inflow estimation is essential for the design and construction of tunnel and the assessment of the environmental impacts. Analytical solutions used in current engineering practice do not adequately account for the effect of the excavation-induced drawdown, which leads to significant change in pore water pressure distribution and reductions of the water level beyond tunnel. Based on the numerical analysis results, this article proposes semianalytical method to predict the height of lowered water level and groundwater tunnel inflow. The tunnel problem is conceptualized as two-dimensional flow in a plane perpendicular to the tunnel axis. The analytical formula, considering the effect of the excavation-induced drawdown, provides a better prediction of the tunnel inflow compared to the existing analytical formulas, even for the cases with inclined groundwater level. [ABSTRACT FROM AUTHOR]

The hydraulic properties of aquitards are not easily obtained because monitoring wells are usually installed in aquifers for groundwater resources management. Earthquake-induced crust stress (strain) triggers groundwater level variations over a short period of time in a large area. These groundwater anomalies can be used to investigate aquifer systems. This study uses a poroelastic model to fit the postseismic variations of groundwater level triggered by the Chi-Chi earthquake to evaluate the hydraulic properties of aquitards in the Jhoushuei River alluvial fan ( JRAF), Taiwan. Six of the adopted eight wells with depths of 70 to 130 m showed good agreement with the recovery theory. The mean hydraulic conductivities ( K) of the aquifers for the eight wells are 1.62 × 10−4 to 9.06 × 10−4 m/s, and the thicknesses are 18.8 to 46.1 m. The thicknesses of the aquitards are 11.3 to 42.0 m. Under the isotropic assumption for K, the estimated values of K for the aquitards are 3.0 × 10−8 to 2.1 × 10−6 m/s, corresponding to a silty medium. The results match the values obtained for the geological material of the drilling core and those reported in previous studies. The estimated values were combined with those given in previous studies to determine the distribution of K in the first two aquitards in the JRAF. The distribution patterns of the aquitards reflect the sedimentary environments and fit the geological material. The proposed technique can be used to evaluate the K value of aquitards using inverse methods. The inversion results can be used in hydrogeological analyses, contaminant modeling, and subsidence evaluation. [ABSTRACT FROM AUTHOR]

During the March-May 2014 Colorado River Delta pulse flow, approximately 102 × 10 6 m 3 (82,000 acre-feet) of water was released into the channel at Morelos Dam, with additional releases further downstream. The majority of pulse flow water infiltrated and recharged the regional aquifer. Using groundwater-level and microgravity data we mapped the spatial and temporal distribution of changes in aquifer storage associated with pulse flow. Surface-water losses to infiltration were greatest around the Southerly International Boundary, where a lowered groundwater level owing to nearby pumping created increased storage potential as compared to other areas with shallower groundwater. Groundwater levels were elevated for several months after the pulse flow but had largely returned to pre-pulse levels by fall 2014. Elevated groundwater levels in the limitrophe (border) reach extended about 2 km to the east around the midway point between the Northerly and Southerly International Boundaries, and about 4 km to the east at the southern end. In the southern part of the delta, although total streamflow in the channel was less due to upstream infiltration, augmented deliveries through irrigation canals and possible irrigation return flows created sustained increases in groundwater levels during summer 2014. Results show that elevated groundwater levels and increases in groundwater storage were relatively short lived (confined to calendar year 2014), and that depressed water levels associated with groundwater pumping around San Luis, Arizona and San Luis Rio Colorado, Sonora cause large, unavoidable infiltration losses of in-channel water to groundwater in the vicinity. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Soil Sciences & Agricultural Engineering is the property of Egyptian National Agricultural Library (ENAL) and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Compared to other geophysical techniques, the surface nuclear magnetic resonance (SNMR) method could provide unique insights into the hydrologic properties of groundwater in the subsurface. However, the SNMR signal is in the order of nanovolts (10-9 V), and the complex environmental noise, i.e., the spike and the harmony noise (10-4 V), can reach up to 105 times the signal amplitude. Saturation of the amplifier is therefore a serious problem in current SNMR systems. In this study, we propose an anti-saturation method based on an instantaneous floating-point amplifier. The gain of a programmable amplifier is controlled by the value of the input signal. A regulating speed of 50 kS/s is thus achieved to satisfy the self-adaptive adjustment of the real-time SNMR system, which replaces the original man-made setting gain. A large dynamic range of 192.65 dB with a 24-bit high speed analog-digital converter module is then implemented. Compared to traditional SNMR instruments, whose magnification factor is fixed during the experiment, our system can effectively inhibit the distortion of the SNMR signal in both laboratory and field settings. Furthermore, an improved SNR, which is realized by the real-time SNMR system, enables the accurate inversion of the aquifer. Our study broadens the applicability of SNMR systems to use in and around developed areas. [ABSTRACT FROM AUTHOR]

GIS technology gives a wide-ranging support to environmental modeling, especially to groundwater modeling. Numerous GIS applications have been developed to define the hydrogeological conceptual model as well as the numerical model. However, there is a scarcity of tools to implement the conceptual model in numerical modeling platforms. This transition needs of specific methodologies to adapt the geometries and alphanumerical data from the conceptual model to the numerical model to get optimal numerical results. Although most necessities can be satisfied with inherent GIS tools, there are particular steps in the implementation of hydrogeological conceptual model into the numerical modeling software that have not been automatized and put together yet. They are mostly related to finite element mesh generation. To overcome this gap, we present a set of tools, named ArcArAz, which focuses on the configuration of geometry and parameterization for groundwater numerical models, which can be used in other environmental sciences. [ABSTRACT FROM AUTHOR]

Wybong Creek discharges salts into the agriculturally and industrially important Hunter River in New South Wales, Australia. Abrupt increases in salinity occur periodically in the mid-Wybong Creek catchment. In order to understand the processes which cause these abrupt increases, changes in surface and groundwater were investigated. It is shown that salinity increases can be attributed to highly discrete groundwater discharge directly into the river from below. Hourly electrical conductivity data measured in the river showed regular, diurnal electrical conductivity fluctuations of up to 350 μS cm. These fluctuations could not be attributed to barometric pressure, temperature, or evapotranspiration. Instead, a similar periodicity in surface water electrical conductivity and groundwater height in nearby groundwater wells was found. Fluctuations were of similar periodicity to the orthotides which cause fluctuations in surface water height and are induced by Earth tides. The geology in the mid-catchment area indicates conditions are optimal for Earth tides to impact groundwater. The reporting of orthotidal changes in water chemistry in this article is believed to be the first of its kind in the scientific literature, with the large fluctuations noted having important implications for water monitoring and management in the catchment. Further research investigating Earth-tide-induced phases of groundwater heights will better constrain the relationships between surface water chemistry and groundwater height. [ABSTRACT FROM AUTHOR]