Search

Research into land subsidence caused by groundwater withdrawal is hindered by the availability of measured heads, subsidence, and forcings. In this paper, a parsimonious, linked data‐driven and physics‐based approach is introduced to simulate pumping‐induced subsidence; the approach is intended to be applied at observation well nests. Time series analysis using response functions is applied to simulate heads in aquifers. The heads in the clay layers are simulated with a one‐dimensional diffusion model, using the heads in the aquifers as boundary conditions. Finally, simulated heads in the layers are used to model land subsidence. The developed approach is applied to the city of Bangkok, Thailand, where relatively short time series of head and subsidence measurements are available at or near 23 well nests; an estimate of basin‐wide pumping is available for a longer period. Despite the data scarcity, data‐driven time series models at observation wells successfully simulate groundwater dynamics in aquifers with an average root mean square error (RMSE) of 2.8 m, relative to an average total range of 21 m. Simulated subsidence matches sparse (and sometimes very noisy) land subsidence measurements reasonably well with an average RMSE of 1.6 cm/year, relative to an average total range of 5.4 cm/year. Performance is not good at eight out of 23 locations, most likely because basin‐wide pumping is not representative of localized pumping. Overall, this study demonstrates the potential of a parsimonious, linked data‐driven, and physics‐based approach to model pumping‐induced subsidence in areas with limited data. [ABSTRACT FROM AUTHOR]

This paper presents a new approach to the spatiotemporal design of groundwater quality monitoring networks for coastal aquifers. A fusion model combines the outputs of several developed simulation models to make estimates more accurate. A modified GALDIT method is used to incorporate the aquifer vulnerability to saltwater intrusion. The value of information (VOI) theory is applied to determine sufficient monitoring wells. The groundwater quality monitoring network is designed by employing a robust decision-making (RDM) approach under different management strategies and economic considerations. This approach incorporates the deep uncertainties of some critical variables, including water level and total dissolved solids (TDS) concentration at the coastline and pumping flow rates of agricultural wells. The new methodology is implemented in the coastal Qom-Kahak aquifer, Iran. The results illustrate that the combination model has significantly improved evaluation criteria compared to individual prediction models. The fusion model results indicate that thirty monitoring wells would be ideal. The RDM-based analyses in the Qom-Kahak aquifer showed that an optimal network with 30 monitoring wells outperforms the current network regarding various criteria, such as VOI and variance of estimation error. The new well configuration also demonstrates a suitable spatial distribution. Given that the current sampling frequencies are unsuitable for areas with varying vulnerabilities, we recommend sampling every 3 months in areas with moderate vulnerabilities and once every three seasons in areas with low vulnerabilities, based on the information transfer index. Finally, a management strategy in which the pumping rate should be less than 60% of the current rate is suggested to prevent saltwater intrusion into the aquifer. [ABSTRACT FROM AUTHOR]

Accurately gauging the risk of water inrush from underlying aquifers is paramount for ensuring safety in coal mine production. This paper presents an Improved Vulnerability Index Model for water-inrush (IVIM), a risk evaluation system built upon eight factors influencing coal-floor water inrush events. Firstly, the Combined Weight Method (CWM) was utilized to establish static comprehensive weights. Then, the Dynamic Weight Theory (DWT) facilitated the construction of a zoning variable weight model to determine the dynamic weights of controlling factors. Finally, the Uncertainty Analysis Model (UAM) was employed to create a linear uncertainty measure function for determining risk levels. The model was applied to the Qipanjing Mine in Inner Mongolia and compared against the Traditional Vulnerability Index Model (TVIM). Results indicated higher inrush risks in the southern and western parts of the study area compared to the eastern and northern sections, with geological structural regions exhibiting significantly greater risks. Monitoring water pressure and detecting fracture structures represent critical priorities. Compared to TVIM, IVIM yielded a 28% proportion of relative danger and danger zones, surpassing the 19% identified by TVIM. The model's effectiveness was validated utilizing the Fitting Rate of Water-inrush Points (FRWP), with IVIM achieving a 100% FRWP—significantly exceeding TVIM's 66.67%. IVIM effectively addresses the issue of localized weight variation in the study area and risk area outline under uncertain working conditions, aspects overlooked by TVIM. This method demonstrates a significant advantage in assessing the risk of water inrush from aquifers. [ABSTRACT FROM AUTHOR]

A response from the author of the article "Tank-reservoir drainage as a simulation of the recession limb of karst spring hydrographs" is presented.

In this article, the author comments on the article "Groundwater recharge areas of a volcanic aquifer system inferred from hydraulic, hydrogeochemical and stable isotope data: Mount Vulture, southern Italy," by Serena Parisi and colleagues, published in 2011. The author says that the article has identified tree sectors of aquifer systems in Mount Vulture. He argues that it does not improve the proposed hydrological model by G. Spilotro and colleagues as stated in their concluding remarks.

The high-pressure and water-rich confined aquifer occurring in the Ordovician limestone sequence poses great threats to the routine production of underground longwall mining. Considering the intense cooperation of mining disturbance and water pressure, water-conducting fractures within a coal seam floor can connect the lower aquifer and upper goaf, and this hydraulic behavior is considered the root of water inrush hazard and water loss or contamination. In this paper, the panel 4301 of the Longquan coal mine serves as the case where the panel works closely above the floor with high water pressure. By the combination of physical and numerical modelling approaches, the variation characteristics of fracture development and volumetric strain of floor rocks subjected to mining disturbance are analyzed. A numerical computation model is constructed based on the volumetric strain-permeability equation obtained by curve fitting, and on such basis, the impacts of different mining parameters on floor rock permeability are studied. The results show that the floor rocks experience fracture generation, extension, and convergence procedures as the workface advances along the longitudinal direction, and fractures appearing in front of the workface are more developed. In the whole process of coal seam extraction, the volumetric strain profile exhibits "Λ" shape and an inverted saddle shape before and after overburden strata collapse. By controlling a single variable, the paper reveals that panel height is of greater impact on floor permeability changes than panel length and panel width. [ABSTRACT FROM AUTHOR]

This study aims to illustrate and present various techniques for evaluating the performance of check-dams and proposes some suitable approaches for impact assessment of dams built in the Balochistan province of Pakistan. These dams were built during the last decade to overcome the challenges of water scarcity and depleting aquifers due to excessive Groundwater (GW) extraction. It was expected that these dams would recharge the GW resources and save the aquifer system from collapsing. Check-dams have traditionally been the permanent source of water within the province. A check-dam is used to delay the floodwater runoff to make it available for domestic and agriculture purposes or to recharge GW. The water along these dams permeates into the ground to keep the aquifer genuinely stable throughout the year. The data were collected based on studies of published research papers and reports of international organizations containing key characteristics of performance evaluation techniques. This review will help to evaluate procedures, policy, and governance interventions in Balochistan by comparing them with the adopted practices in other regions of the world and its impact on the well-being of the society. In this paper, the performance evaluation of check-dams for specific cases is presented. The knowledge acquired will be utilized to highlight state-of-the-art practices and to identify the need for further research in this field. [ABSTRACT FROM AUTHOR]

Nitrogen contamination is ubiquitous across the globe; as a result of this, the need to understand and predict the extent and effects of nitrogen contamination on microbial ecosystems is increasingly important. This paper utilises a dataset that provides a rare opportunity to observe varying contamination conditions in a single aquifer and understand the differences between potential background bores and two different types of contamination spread across the other bores. Using physicochemical and microbiological community analysis, this paper aims to determine the impacts of the two contaminants, nitrate and ammonia, on the microbial communities and the differences between polluted and physicochemical background bores. Total nitrogen (N) varied by a factor of over 2000 between bores, ranging from 0.07 to 155 mg L−1. Nitrate (NO3−) concentrations ranged from 150 to <0.01 mg L−1; ammonium (NH4+) concentrations ranged from 26 to <0.1 mg L−1. MANOVA analysis confirmed an overall significant relationship (p = 0.0052) between N variables and the physicochemical data (or status) of the three areas of contamination dubbed 'contamination zones'. The contamination zones were defined by no known presence of contamination in the uncontaminated bores, the presence of NO3− contamination and the presence of NO3− and NH4+ contamination. PERMANOVA analysis confirmed that there was an overall significant difference in the microbial communities between the three contamination zones (p = 0.0002); however, the presence of NH4+ had a significant effect (p = 0.0012). In general, the nitrate-contaminated bores showed a decrease in the abundance of individual OTUs. We further confirmed that NH4+ contamination had a significant relationship with an increased percentage of abundance occupied by the Planctomycetota phylum (specifically the Candidatus Brocadia genus). It was found that one of the two background bores (BS-004) was likely also representative of natural microbial background, and another (BS-002) showed characteristics that may be representative of past or intermittent contamination. This paper demonstrates a possible way to determine the microbial background and discusses the potential uses for this information. [ABSTRACT FROM AUTHOR]

Groundwater flow in shallow aquifer (i.e. groundwater reservoir with large plane extension in relation to the depth) containing lake, pond, groundwater recharge or drainage pit, foundation pit etc., referred further as groundwater extraction/recharge cavity or cavern represent a very important practice-oriented topics. In this regard in a former paper a general mathematical representation of groundwater flow in shallow aquifer is deduced, considering a cavity of arbitrary form bounded by a permeable contour, using the theory of the analytical functions of a complex variable. In the present paper an extension of this problem will be presented, considering a cavity of arbitrary form bounded by a partially permeable contour. This extension allows approach of new aspects and issues of groundwater management. The mathematical representations consider asymptotic conditions determined by a pre-existing initial uniform groundwater flow which has an important influence on the flow processes especially in neighbourhood of cavity. It will be deduced formulas which allow a rapid analysis of the groundwater balance in the modelled region considering the dependence of the recharge/discharge rate of the cavity from and the extension of the impermeable part of the contour and from the preexisting uniform groundwater flow. The obtained mathematical representations and formulas can be applied for cavities of different shape using conformal mapping defined through analytical functions of a complex variable. [ABSTRACT FROM AUTHOR]

Lakes Prespa and Ohrid on the Balkans are considered to be amongst the oldest lakes in Europe. Both lakes are hydraulically connected via karst aquifers. From Lake Ohrid, several up to ca. 15 m long sediment records were studied during the past years. In this study, a first long sediment record from Lake Prespa was studied in order to shed more light on the influence of Lake Prespa on Lake Ohrid and the environmental history of the region. Radiocarbon dating and the occurrence of 3 dated tephra layers provide a good age control and indicate that the 10.5 m long sediment record reaches back to 48 ka. The comparison of the results from this study with those from former studies of the Lake Ohrid cores indicates that Lake Prespa is more susceptible to environmental changes due to its lower volume and water depth. Glacial sedimentation is characterized by low organic matter contents and absence of carbonates in the sediments, which indicate oligotrophic conditions in both lakes. Holocene sedimentation is characterized by particularly high carbonate contents in Lake Ohrid and by particu larly high organic matter contents in Lake Prespa, which indicate a shift towards more mesotrophic conditions in the latter. Long-term environmental changes and short-term events, such as the Heinrich events during the Pleistocene or the 8.2 cooling event during the Holocene, are well recorded in both lakes, but partly expressed in different proxies. [ABSTRACT FROM AUTHOR]

The article discusses papers presented in the AGU Chapman Conference ‘The MADE Challenge for Groundwater Transport in Highly Heterogeneous Aquifers: Insights from 30 Years of Modeling and Characterization at the Field Scale and Promising Future Directions' in Valencia, Spain in October 2015.

Seasonal variation causes regular fluctuations in river water levels and water temperatures, which affects the distribution of temperature fields and seepage fields in riparian zones. In this paper, the monitoring device was used to continuously monitor Dongting Lake for a period of 1 year, and the temperature distribution characteristics of the riparian hyporheic zone under seasonal variation were analysed. Ten riparian hydrothermal coupling models based on different soil thermal conductivity models were verified, and the optimal model was used to simulate the influence of the flood process on the temperature field and seepage field of the riparian hyporheic zone. The results show that the changes in groundwater level and temperature in the riparian hyporheic zone had obvious lag and attenuation phenomena compared with the changes in river water level and ambient temperature. The temperature field of the riparian hyporheic zone changed obviously in the year. The vertical temperature gradient was large in summer and winter, the stratification phenomenon was obvious, and the temperature field fluctuation was small. The effect of the flood process on the temperature field and seepage velocity in the riparian hyporheic zone was obviously hysteretic. The effect of the flood‐withdrawing process on the temperature change of the shallow layer was greater than that of the flood‐rising process, while the response of the deep layer temperature change to flood‐rising and flood‐withdrawing processes was the opposite. The effect of floods on the variation in groundwater velocity was that the flood‐rising process was greater than the flood‐withdrawing process. [ABSTRACT FROM AUTHOR]

Copyright of Hydrogeology Journal is the property of Springer Nature 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.)

Copyright of Hydrogeology Journal is the property of Springer Nature 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.)

Water banking in aquifers is an internationally proven, low-cost solution that could improve drought resilience across the Murray Darling Basin. While significant potential for water banking through managed aquifer recharge (MAR) or conjunctive use of surface and groundwater resources has been identified in the Murray Darling Basin Plan, there is a need to establish clear policy and institutional foundations to incentivise adoption. To provide appropriate incentives for schemes, the legal status of rights to recharge, store and recover water, and the rules and costs which apply to groundwater extraction need to be clear and transparent. This paper aims to clarify principles and frameworks to secure water rights for recharge, storage, and recovery within the sustainable limits of water resources currently set under law. The current Basin Plan supports water banking, and banking would be complementary with objective and outcomes sought by future Basin Plans. Existing water accounting systems would need to accommodate this new capacity. Institutional arrangements and financial structures of water banking in the USA provide guidance for Australia. Demonstration sites would enable concurrent policy development and institutional set-up and provide critical experience to serve as models for wider adoption as part of future Murray Darling Basin plans. [ABSTRACT FROM AUTHOR]

This paper presents the use of resistivity method to quantify the thickness of the freshwater aquifer for supply in a coastal region, where saltwater intrusion is constant. The results obtained have unusual clarity and quality in the literature, being a historical case. vertical electrical sounding (VES) technique was used to determine water table and saltwater intrusion depths. Sandy sediments thicker than 120 m and smooth topography are constant, where an area of approximately 2.7 × 2.2 km with 15 well-distributed VES was studied. The area is located between Lagoa dos Patos (brackish water) and the Atlantic Ocean. The only possibility of obtaining fresh water is the exploitation of the water table with the drilling of shallow wells in places, where the freshwater layer is thicker. The VES results quantified the water level depths between 3.5 and 6.0 m and the saltwater intrusion between 12.5 and 21.0 m, obtaining the thickness of the freshwater stratum. This work also approaches considerations about the depth of investigation of the VES, showing that this depth does not depend only on the openings between the current electrodes, but also on the distribution of the geoelectric strata. [ABSTRACT FROM AUTHOR]

Carbonic acid and sulfuric acid speleogenesis describe a dichotomy between epigenetic and hypogenetic caves and carbon and sulfur cycling in karst, but do not acknowledge the global spectrum of cave formation. This paper, part one of a two-part investigation, tests and revises speleogenetic models from a classic karst landscape using dissolved ion concentrations δ13CDIC, and δ34S in water samples collected at four sites across the Bluespring and Lost River karst basins in the Mitchell Plateau, Indiana, USA. Analyses revealed elevated sulfur in both karst basins but differently sourced; H2S (δ34S = −14.2‰) evolved from petroleum seeps in Bluespring Caverns accounted for up to 61% of sulfur in the cave stream, while evaporite beds (δ34S = [+14.50‰, +17.91‰]) of the St. Louis Limestone contributed up to 100% of sulfur at Orangeville Rise, a terminal spring of the Lost River karst basin. These results have implications for carbon–sulfur cycle linkages, particularly the potential acceleration of carbon flux from sulfuric acid dissolution in otherwise epigenetic settings. We suggest a new paradigm for speleogenesis in the North American midcontinent—speleogenesis in the Mitchell Plateau and similar settings is not epigenetic or hypogenetic, but instead polygenetic with competing chemical processes varying across space and time. [ABSTRACT FROM AUTHOR]

The primary aims of this research paper involve the creation and verification of machine learning-based quality models that utilize Integrated Irrigation Water Quality Indices (IIGWQIs) through an integrated GIS approach. We utilize the Least-Squares Support Vector Machines (LS-SVM) and the Pearson Correlation Fuzzy Inference-based System (PC-FIS) to establish forecasts for groundwater quality in the Meknassy basin. This basin serves as a representative case of an irrigated region in a mining environment under arid climatic conditions in central Tunisia. The evaluated factors for groundwater quality encompass the Irrigation Water Quality Index (IWQIndex), Sodium Adsorption Ratio Index (SARIndex), Soluble Sodium Percentage Index (SSPIndex), Potential Salinity Index (PSIndex), Kelley Index (KIndex), and Residual Sodium Carbonate Index (RSCIndex). These factors were determined based on measurements from 53 groundwater wells, which included various physico-chemical parameters. The hydrogeochemical facies identified included Ca-Mg-SO4, mixed Ca-Mg-Cl-SO4, and Na-Cl facies, revealing processes such as carbonate weathering, carbonate dissolution, interactions between rocks and groundwater, and mixing ionic substitution. In terms of the irrigation suitability categories, the IWQIndex, SSPIndex, PSIndex, Kindex, and RSCIndex indicated no limitation or minimal limitation (77.36%), secure (92.45%), favorable to excellent (66.04%), favorable (81.13%), and average to secure (88.68%), respectively. However, only 15.09% were considered favorable, according to SARIndex. The evaluation of the predictive models revealed the effectiveness of both the PC-FIS model and the LS-SVM model in accurately forecasting the IIGWQIs. [ABSTRACT FROM AUTHOR]

The drawdown time is important for the design and assessment of infiltration basins. This paper investigates its dependence on soil heterogeneity, and simple analytical solutions for the mean and the variance are given. The solutions are tested through Monte Carlo simulations in various realistic scenarios, using a modified Green Ampt model for layered soils and a model based on the integration of the 1‐D Richards equation. The impact of the employed approximations is assessed, and the leading role of the spatial distribution of the saturated hydraulic conductivity is emphasized. The effects of other relevant design and natural factors, including the initial water level and water content distribution, are also investigated. Plain Language Summary: Infiltration basins are receiving an increasing interest in water resources management as an alternative to surface water storage in the managed aquifer recharge and as a green infrastructure at the urban scale. One of the main parameters in the design of the infiltration basins is the drawdown time, that is, the time needed to empty the basin after it has been filled with water, for instance, after a flood event or by a managed treatment plant outlet. This work provides simple analytical solutions for the evaluation along a stochastic approach of the drawdown time, accounting for the soil heterogeneity and leading to a probabilistic design of the infiltration structure. Key Points: The time needed to empty infiltration basins, or drawdown time τ, is an important quantity for their design and assessmentThis work proposes analytical solutions for the mean and variance of τ considering the soil heterogeneitySolutions have been tested through a set of Monte Carlo numerical simulations, showing that the probability density function is lognormal and investigating the effects of design and natural factors [ABSTRACT FROM AUTHOR]

The impact of hydrocarbon spills in the unsaturated zone is a significant environmental concern, particularly in locations where contamination arises from leaks in underground fuel storage tanks (USTs). This paper presents the outcomes achieved through the utilization of VLEACH, a finite-difference numerical model, to assess the concentrations of organic contaminants in the solid, liquid, and gas phases within the vadose zone. Additionally, it evaluates the mass transfer of pollutants to the aquifer as part of an environmental assessment for the placement of a forthcoming service station. The study encompasses an analysis of 18 scenarios under realistic conditions based on actual field data. These scenarios were constructed, taking into account various factors, including the nature of the leak (one-time or permanent), the depth of the phreatic level, and the soil conditions and properties. The results highlight the potential environmental consequences of a permanent leak as compared to those resulting from a specific accident. The findings further emphasize the substantial influence of soil moisture on transport phenomena within the vadose zone. Variations in soil moisture significantly alter hydraulic conductivity, impact magnitudes, transport velocities, and even the predominant transport mechanism. Consequently, precise delineation of soil moisture becomes a crucial parameter in such simulations. Additionally, it has been observed that each component of BTEX (benzene, toluene, ethylbenzene, and xylene) experiences varying transport velocities through the vadose zone. Benzene, having a greater propensity to concentrate in the liquid and gas phases, exhibits the swiftest movement through the vadose zone. The detection of benzene in aquifers can serve as an indicator of the potential future arrival of the remaining BTEX compounds. [ABSTRACT FROM AUTHOR]

To study the law of water–heat coupling migration and the frost heave deformation characteristics of soil slopes in seasonal areas under groundwater recharge conditions, this paper constructs a water–heat–stress coupling model considering moisture migration, ice–water phase change, ice resistance, and frost heave effects based on COMSOL modelling software. Then, numerical simulation results are compared with the experimental results to verify the effectiveness of the multi-field coupling model. The results show that the slope temperature change has an evident lag compared with the ambient temperature change. The shallow soil of slopes changes dramatically under external ambient temperature, while the deep soil gradually tends to the ground temperature under the geothermal influence. The slope temperature distribution rules are basically the same in different groundwater recharge levels. The maximum freezing depth of the slope is deeper at a high groundwater level. When the groundwater level is high, the total moisture content of the slope is larger, and the thawing area may be saturated or oversaturated in the spring thawing period. For unsaturated soil slopes in seasonal freezing for a long time, the total moisture content of slopes tends to increase slightly after each freeze–thaw cycle due to groundwater recharge. The problems of slopes in seasonal frozen areas are manifested by the frost heave of the soil at the top of slopes, which may cause frost heave damage. When the groundwater level is high, the maximum horizontal displacement of the slope surface and the frost heave deformation at the top of slopes increase greatly. [ABSTRACT FROM AUTHOR]

We present a discussion of the state-of-the art on modelling geometrical characteristics, hydrogeological behavior and geochemical evolution of karst aquifers of meteoric origin. The considered key karst processes include: (1) the recharge processes, (2) the various hydrodynamic processes in the vadose and phreatic zones, (3) the related transport processes and (4) the speleogenesis processes. Different types of approaches for modelling geometrical characteristics of karst conduit networks are summarized. Integrated numerical studies on hydrogeological behavior of karst aquifers with functional and physically based models are then reviewed. Challenging issues in karst modelling are further discussed based on previous modelling progresses. The paper finally offers recommendations for advancing the modelling of hydrogeological behavior of karst systems and lists several open questions for future research. [ABSTRACT FROM AUTHOR]

Trace metals in the groundwater of coastal sandy aquifers significantly influence the coastal ecosystem, yet the spatiotemporal controls of these metals remain unclear. In this paper, we comprehensively revealed the distribution patterns, key controlling factors, potential ecological risks, and fluxes to the ocean of groundwater trace metals (As, Ba, Cr, Cd, Fe, Mn, Pb, and Zn) in a coastal deep sandy aquifer. The results showed a clear zonation of trace metals in the groundwater in relation to the mixing extent between seawater and terrestrial freshwater. The freshwater zone exhibited a relatively low concentration of trace metals, whereas the freshwater‐seawater transition zone showed a substantial quantity of dissolved Fe, Mn, As, and Ba. Seawater‐groundwater interactions significantly affected the Fe, Mn, As, and Ba concentrations through redox potential and pH gradients. The tide‐driven saline water zone was vulnerable to oceanic environments and anthropogenic activities, resulting in the enrichment of trace metals such as Zn and Cd. Driven by recirculated submarine groundwater discharge (SGD), the concentrations of trace metals in the density‐driven saline circulation zone were found to be higher than those in the surrounding areas. The ecological risk index suggested that the freshwater‐seawater transition zone posted the highest ecological risks. Trace metal fluxes (i.e., Fe, Mn, and As) via SGD significantly contributed to the total input into the sea, which may have potential impacts on the coastal environments. Our study highlighted the importance of seawater‐groundwater interactions on trace element cycling in coastal sandy aquifers. Key Points: The distribution of groundwater trace metals in a coastal deep sandy aquifer with different seasons was investigated, and four zones were identifiedKey controlling factors, ecological risks, and fluxes of trace metals in different zones were evaluatedSeawater‐groundwater interactions aiding trace metal addition/removal insfluenced trace element cycling on a sandy coast [ABSTRACT FROM AUTHOR]

Copyright of Hydrogeology Journal is the property of Springer Nature 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.)

This paper proposes MpIC, an on-manifold derivation of the probabilistic Iterative Correspondence (pIC) algorithm, which is a stochastic version of the original Iterative Closest Point. It is developed in the context of autonomous underwater karst exploration based on acoustic sonars. First, a derivation of pIC based on the Lie group structure of S E (3) is developed. The closed-form expression of the covariance modeling the estimated rigid transformation is also provided. In a second part, its application to 3D scan matching between acoustic sonar measurements is proposed. It is a prolongation of previous work on elevation angle estimation from wide-beam acoustic sonar. While the pIC approach proposed is intended to be a key component in a Simultaneous Localization and Mapping framework, this paper focuses on assessing its viability on a unitary basis. As ground truth data in karst aquifer are difficult to obtain, quantitative experiments are carried out on a simulated karst environment and show improvement compared to previous state-of-the-art approach. The algorithm is also evaluated on a real underwater cave dataset demonstrating its practical applicability. [ABSTRACT FROM AUTHOR]

Thecurrent research investigates the quality of ten different surface water sites in and around Jodhpur using water quality ratings. This paper gives insight into water pollution's qualitative and quantitative extent. The water quality index (WQI)is usedfor assessing and comparing water quality. In each study region, a five-point grading scale was adopted to classify water quality as a single understandable value. Twelveparameters were employed for determining the WQI of different sites: turbidity, TSS, TDS, conductivity, alkalinity, hardness, calcium, magnesium, chloride, fluoride, and nitrate. Multivariate analysis of the samplesrevealed that most of the individual parameters are not in harmony with the standard values prescribed by the regulating authorities. According to the study, seasonal fluctuations play a significant effect in the hydrochemistry of surface water, indicating a change in WQI. Thesamples showed less pollution in the pre-monsoonseason as compared to post-monsoon. Overall, this paper lays forth a strategy for proper utilization and protection, as well as assesses the quality of surface water to determine its suitability for various uses and its impact on groundwater quality. [ABSTRACT FROM AUTHOR]

Copyright of International Journal of Colorectal Disease is the property of Springer Nature 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 author offers clarifications to a discussion of his paper which provided generalized analytical solutions for goundwater head in inclined aquifers in the presence of subsurface drains. The writer expresses his disagreement with the discusser emphasizing that the development of the basic partial differential equations (PDE) of the original paper on the basis of redefinition of the coordinate axes is novel as it does not have the restriction of small aquifer slow for its applicability.

DRASTIC-based vulnerability indices and their variations for an aquifer are investigated in this paper, each of which is regarded as a framework since their rationale of using seven DRASTIC data layers is consensual and lacks empirical or theoretical formulations. The Basic DRASTIC framework (BDF) is implemented by a set of prescribed rules; whereas its three variations involve unsupervised learning from the data, which comprise: (i) learning the rates by the Wilcoxon test (WDF) but using BDF weights; (ii) using BDF rates but learning the weights by Genetic Algorithm (BDF-GA); and (iii) learning rates as in WDF and the weights as in BDF-GA (WDF-GA). These four frameworks are not supervised, but the novelty of the paper is to introduce supervised learning at the second stage by Artificial Intelligence to run Multiple Frameworks (AIMF), for which the paper uses Support Vector Machine (SVM). AIMF uses the outputs of the four frameworks as its input data and a function of observed nitrate-N values as its target data. The AIMF strategy is evaluated in the aquifer of Ardabil plain, which is exposed to anthropogenic contamination such as nitrate-N. The coefficient of correlation (r-values) between the results and nitrate-N values for the above frameworks are: 0.2, 0.37, 0.38 and 0.45; whereas AIMF enhances it to 0.84; attributable to the supervised learning. [ABSTRACT FROM AUTHOR]

Scarcity of water resources is becoming a threatening issue in arid regions like Gulf. Accurate prediction of quantities and quality of groundwater is the first step towards better management of water resources where groundwater is the major source of water supply. Groundwater modelling with respect to its quantity and quality has been performed in this paper using Artificial Neural Networks (ANNs), Adaptive Neurofuzzy Inference System (ANFIS), and hydraulic model MODFLOW. Five types of ANN models with various training functions have been investigated to find the most efficient training function for the prediction of quantity and quality of groundwater, which is an original contribution useful for engineering sector. The results of the hydraulic model, ANFIS, and ANN have been compared. Nash-Sutcliffe Model Efficiency and Mean Square Error have been used for assessing the performance of models. Taylor's Diagram has also been used to compare various models. The part of Saq Aquifer lying in the Qassim Region has been investigated as the study area. Modern tools, including Geographical Information System (GIS) and Digital Elevation Model (DEM) are applied to process the required data for modelling. Climatic, geographical, and quality of groundwater (contaminants) data are obtained from the Ministry of Environment, Water, and Agriculture, Jeddah/Riyadh. ANFIS model is found to be the most efficient for modelling both the quality and quantity of the aquifer. Sensitivity analysis was performed, and then various future scenarios were investigated for sustainable groundwater pumping. The results of the research will be useful for the community and experts working in the field of water resources engineering, planning, and management in arid regions. [ABSTRACT FROM AUTHOR]

The fractured limestone aquifers under coal seams bring great threat to coal production, and grouting engineering before mining is usually used to seal the fractures and prevent water inrushes. However, the grouting mechanism is still a difficult issue since the hidden fissures cannot be observed. In this paper, two characteristics of fractures filled with high-pressure water, deformation, and stiffness are studied to seek some good explanations for grouting. First, an ideal flow model composed of a borehole and a fracture is established with the fracture aperture as the main variable. The estimation methods for the aperture of fractures with high-pressure water before grouting and the stiffness of the fracture filled with slurry consolidating body during high-pressure grouting are proposed, and the millimeter-scale solution of deformation is obtained by using hydrological data and slurry consolidating body. Then, the methods are used for the field grouting practice, and its applicable conditions are given. The estimated apertures of the fractures with high-pressure water range from 2.08 to 2.56 mm. Under the grouting pressure of 15 MPa and the designed slurry diffusion radius of 30 m, the normal stiffness of the fracture filled with slurry consolidating body ranges from 0.5 to 14.4 GPa/m. The results meet the positive relationship between normal stiffness and fracture aperture got by the literature data and can be used for the study of grouting effect of the hidden fractures, including the evaluation of strength and water resistance of the slurry consolidating body. Our method of estimating the aperture and stiffness of fractures is applicable when grouting is used in the fractured limestone aquifers with high water pressure under coal seams before mining. [ABSTRACT FROM AUTHOR]

Ordovician limestone in North China coalfield has the characteristics of karst fissure development and strong water yield. Coal mines in North China have been threatened by Ordovician limestone water for a long time. Taking the mining of 32 coal seam in the first eastern mining area of Qianyingzi coal mine in Anhui Province in China as the engineering geological prototype, this paper uses the self-developed fluid solid coupling similarity model test device to carry out the similarity model test of overburden stress and pore water pressure response of coal mining under Ordovician limestone nappe aquifer. Based on the variation law of pore water pressure and overburden stress in a stope, it can be seen that the variation law of pore water pressure in confined aquifer is jointly affected by two factors: the vertical distance between the monitoring point and coal seam and the horizontal distance between the monitoring point and DF200 fault. According to the analysis of experimental results, the maximum height of a water flowing fracture zone in the stope is fifteen times the mining thickness. Compared with the theoretical calculation results of empirical formula, the coupling effect of seepage field and stress field and the geological structure characteristics of the stope promote the development of a water flowing fracture zone. The research results of this paper have important theoretical and practical significance not only for the safe mining of Qianyingzi coal mine but also for the safe mining of the coal mine facing the double threat of roof Ordovician limestone confined aquifer and reverse fault. [ABSTRACT FROM AUTHOR]

The article discusses a comment on a previous paper by Tu et al. that presents an analytical model for a single recirculation well in a confined aquifer with a finite thickness well skin. The comment argues that Tu et al.'s solution is not new and is a special case of a more general problem solved by Perina. The comment also highlights the inadequacy of the literature review in Tu et al.'s paper and mentions another relevant publication by Morozov. The comment concludes that the Tu et al. solution is equivalent to Perina's well function with a single segment used for each screen. [Extracted from the article]

Dissolution trapping CO2 is thought to be a permanent storage mechanism in deep saline aquifers. Brine saturated with CO2 sinks to the bottom of the aquifer due to density-driven flow and is replaced by fresh brine with the remaining dissolution potential. This convective process persists and can effectively slow the spread of the CO2 plume, thereby reducing the risk of leakage. The density-driven convection process is sensitive to reservoir heterogeneity. In this paper, the dynamics of dissolved CO2 in a fractured saline aquifer are studied using a three-dimensional discrete fracture network matrix (DFM) model. The fracture density and heterogeneity between fractures are systematically analyzed. The highly connected fracture network provides preferential channels for the CO2-rich plume to migrate to deeper regions of the aquifer. Several cases show that the increase of fracture density can effectively increase the dissolution flux in the domain, but the effect becomes less significant when the quantity exceeds a threshold value. The effects of two heterogeneous patterns (the density of high-permeability channels in the system and the correlation of the fracture aperture with the geometric size) in determining dissolution trapping are discussed. The heterogeneity of the fracture aperture is beneficial to finger formation and depth development. The results of this study increase the understanding of the dissolved carbon dioxide and plume dynamics in the fractured saline aquifers used for carbon sequestration. [ABSTRACT FROM AUTHOR]

This study presents the findings derived from a three-year monitoring programme focusing on the hydrochemical composition and stable isotope signatures (Î'18O, Î'2H) within the vulnerable karst groundwater system in Croatia's northern Dinaric karst region. Covering an area of 1980 km2 across Kapela Mountain and its foothills, this groundwater system falls within the Kupa River basin and encompasses the catchment areas of the main springs across two spring levels of the Dobra, Mrežnica, and Slunjčica Rivers (namely the Vitunj, Zagorska Mrežnica, Dretulja, Veliko Vrelo, Gojak, Tounjčica, Mrežnica, and Slunjčica springs). Given the complex hydrogeological framework, prior studies have not extensively addressed the hydrochemical characteristics of this region, thereby necessitating a comprehensive investigation to elucidate system dynamics. This paper outlines the first investigation employing stable isotopic analyses within the karst groundwater system of Kapela Mt. The main results and conclusions of the research include: (i) the aquifers across Kapela Mt. drain mainly limestones, (ii) water-rock interaction and carbonate weathering are significant contributors to water geochemistry, (iii) there is a slight human impact on the Gojak and Tounjčica spring waters, (iv) the mean residence time of water in the observed aquifer is up to 1.5 years, (v) the new LMWL was calculated for Kapela Mt. based on a three-year dataset (June 2018 - May 2021), (vi) in the north Dinaric karst, the predominant origin of precipitation is from the Mediterranean air mass, (vii) Velebit Mt. has a strong influence on the precipitation isotopic composition of the study area. [ABSTRACT FROM AUTHOR]

In this paper, we present a new model as an alternative to the classical 3D Richards model for the description of water flow in shallow aquifers. The new model is designed to achieve three goals. First, it provides a good approximation to the Richards model over a wide range of time scales. More specifically we show that both models characterize a flow with the same dominant components when the ratio of the horizontal length to the depth of the aquifer is small. Second, the new model accurately describes the velocity field. In particular, it is not based on the Dupuit hypothesis, which is often used in the context of shallow aquifers. This allows the new model to be well accurate even in the presence of wells and in aquifers with variable bedrock. Third, the new model can be viewed as a coupling of numerous 1D vertical Richards problems with a 2D elliptic one. In practice, this coupling is treated numerically using a Picard fixed point scheme, avoiding the need to solve any three-dimensional problem. This results in a significant reduction in computational cost compared to solving the 3D Richards problem directly. [ABSTRACT FROM AUTHOR]

Trace elements (metals, transition elements and non-metals) are an essential component of the human body's functionality. These trace elements include Fe, Mn, Li, Al, Co, Ni, Cu, Ag, Se, As, Cr, V, Zn, Cs, U and others. In general, it is believed that about 25 chemical elements are important for the normal functioning of the human body. Trace elements in fresh drinking water as a biological component remain outside the attention of specialists in the field of therapeutic water. Of course, the content of biologically active trace elements in drinking water is much lower than in therapeutic mineral waters, but it should be taken into account that the amount of drinking water consumed by a person is much higher than that of mineral water during therapy. In this case, the low concentration of biologically active trace elements in drinking water is compensated for by the large amount of this water consumed every day. This can have a certain therapeutic effect. The paper presents the results of an assessment of the possible biologically active effect of domestic fresh water. The research was carried out in the most common and widely used aquifers - the groundwater and Buchak aquifers, which are the first to surface and are most widely exploited in rural and suburban areas. The studies were performed in 6 settlements of the Kyiv region: Hlevakha, Novoselivka, Olenivka, Baryshivka, Sezenkiv, and Liutizh. The analyses were performed using an ICP-MS Element 2 inductively coupled plasma mass spectrometer at the Institute of Geochemistry, Mineralogy and Ore Formation of the National Academy of Sciences of Ukraine. The presence of Fe, Mn, Li, Al, Co, Ni, Cu, Ag, Se, As, which are biologically active trace elements, was determined in the waters of the Quaternary sediments and in the waters of the Buchak aquifer complex. In addition, these waters contain Cr, V, Zn, Cs, U, which do not have medicinal effects but are important for the normal functioning of the human body. Although only 6 locations in the Kyiv region were examined, the results obtained are sufficient for preliminary conclusions that provide reasons to justify a new direction - biological aspects of domestic groundwater. [ABSTRACT FROM AUTHOR]

The object of the study reported in this paper is the parameters of a device for implosion impact on aquifers during well development. The problem of increasing the productivity of aquifers was solved by removing colmatation products formed during the drilling process and restoring the natural permeability of the formations. This could ensure high production of wells and their long-term trouble-free operation. One of the most effective ways to develop wells is implosion impact. However, its use is hampered by the complexity of the structure of existing devices, the high cost of use, and the insufficient reliability of their operation. To overcome this, an original device for implosion impact on aquifers was designed and its operating parameters were determined. A procedure has been devised for determining the maximum permissible sizes of intervals not filled with liquid under the conditions of preventing casing string collapse. The effect of these intervals on reducing the total weight of the casing string was investigated. An optimal well structure was proposed for the conditions of the Tonirekshin field. The critical dimensions of empty intervals were calculated for all wall thicknesses of casing pipes included in the well design. It has been established that the amount of weight reduction of the casing string in the well due to the Archimedean force for field conditions is 43–47 %. Archimedean force increases with increasing pipe wall thickness. Reducing the weight of the casing string reduces the required winch power, allowing the use of lighter drilling rigs. The procedure for preparing for repeated implosion impacts has been studied. The studies performed and the recommendations presented will be effective when drilling and developing wells under the conditions of the Mangistau Peninsula, at the Tonirekshin field. [ABSTRACT FROM AUTHOR]

Aquifer diffusivity is a basic physical parameter used in hydrogeological calculations and is important for the evaluation and rational utilization of water resources, pollution prevention, and wetland protection. In this study, with the assumptions of aquifer isotropy, i.e., no vertical flow and constant saturated aquifer thickness, by using the Fourier transform and convolution theorem, a 1D analytical solution of the phase spectrum for an unconfined aquifer system was derived, which subsequently led to a phase spectrum solution for aquifer diffusivity. To test the efficacy, the proposed method was applied to a study site in the middle reach of the Hutuo River in the North China Plain. The estimated aquifer diffusivity ranged from 1.9 × 103 to 4.9 × 104 m2/d, with a mean of 2.2 × 104 m2/d, which was consistent with the results obtained using power spectral analysis, pumping tests, and inverse numerical models. The phase spectral approach proposed in this paper can estimate the aquifer properties on a larger scale. If long time series of hydraulic heads are available, it can estimate hydrogeological parameters accurately and quickly. Considering the similarity of the linearized governing equations, it can also be applied to the river–aquifer system and the confined aquifer system. [ABSTRACT FROM AUTHOR]

The study sought to assess the suitability of groundwater for domestic and drinking purposes in the Effutu Municipality of Ghana. The paper employed laboratory protocols to analyse the water quality parameters' concentrations for groundwater samples collected from wells. Descriptive statistical analysis was used to analyse the data and the concentrations of parameters compared with the World Health Organisation's (WHO) permissible limits. Principal component analysis using the varimax rotation was employed to explore the main parameters which express groundwater quality in the municipality. Water quality index employing the weighted arithmetic method was also used to score groundwater suitability for domestic and drinking purposes. The study found that the main parameters determining groundwater quality in the Effutu Municipality are conductivity, total dissolved solids (TDS), salinity, hardness, chloride, calcium, magnesium, and sodium. Except for conductivity, manganese, TDS, total hardness, and calcium, the average concentrations for all studied water quality parameters were within limits proposed by WHO. The study further revealed that 48.15%, 44.44%, and 7.41% of the groundwater had excellent, good, and poor water quality indices, respectively. The investigation so advances that the groundwater resources of the Effutu Municipality are suitable for domestic purposes. Despite this, we recommend that abstracted groundwater should be treated by prioritizing the water quality parameters. [ABSTRACT FROM AUTHOR]

The protection of groundwater resources in coastal aquifers is an increasingly important issue worldwide. To establish threshold values and remediation objectives, it is essential to know the natural background concentrations of relevant ions in groundwater. The rationale is to define the Natural Background Level (NBL) of chemical species determined by atmospheric and lithological forces. In many coastal aquifers, this evaluation worsens since atmospheric and lithological salinity combines with many other anthropogenic sources of salinity, including exogenous salinity induced by seawater intrusion (SWI). This paper presents a combination of six well-known statistical techniques and a new methodology (i.e., SITE index) in eight GWBs affected by SWI in Eastern Spain. The chloride ion was the selected conservative chemical specie to assess the qualitative status due to the variable SWI affection. The Natural Chloride Background (NCB) obtained from these methodologies at the GWB scale was compared with regional NCB data calculated with the Atmospheric Chloride Mass Balance (CMB) method in Continental Spain. The CMB method provides atmospherically derived NCB data that are not influenced by SWI or anthropogenic activities or lithological forces. This external evaluation can be considered the atmospheric fraction of NCB, which serves as a regional criterion to validate the more detailed statistical methodologies applied at the GWB scale. As a result, a conceptualization of NCB is obtained by means of a range of values between 115 mg L−1 and 261 mg L−1 in the studied coastal GWBs affected by SWI in Eastern Spain. [ABSTRACT FROM AUTHOR]

Many coastal areas are affected by groundwater salinization due to the unsustainable use of groundwater resources. For a cost‐effective quantitative assessment of groundwater resources, electrical resistivity (ER) tomography is often used as a standalone geophysical technique. In this paper, we present an application of the integration of direct‐current ER and full‐decay‐induced polarization (IP) method at the Pontina Plain (Central Italy). The case study is a coastal area in Central Italy prone to salinization due to both geological and anthropogenic factors. To achieve these goals, we inverted full‐decay time‐domain electrical data for Cole–Cole parameters. The resulting multi‐parameter model provides a first approximation prediction of the permeability, employing well‐established empirical relationships with the electrical parameters. We demonstrated that our approach: (i) can locate highly conductive zones directly related to saline intrusion inland using the resistivity as a fast proxy; (ii) can remove the ambiguity in the detection of clay/silt layers in the near‐surface; and (iii) permit a prediction of the permeability, employing full‐decay inversion of time‐domain electrical data. However, the extremely conductive environment prevents the use of IP data for the reconstruction of deep layers or detection of the salt wedge front. Therefore, this approach can be used for hydro‐geophysical screening and monitoring of salinization‐prone sites, where strong limitations to direct inspection exist due to external constraints (e.g., protected lands). [ABSTRACT FROM AUTHOR]

In 1998, the Permo-Triassic Sandstone aquifer of the West Midlands–Worfe (WMW) area became the subject of one of the first major groundwater modelling projects initiated under the Environment Agency of England's national groundwater modelling framework. The 4R runoff–recharge code that allowed these models to apply a semi-integrated approach to simulating catchment hydrology was developed and trialled in parallel with the WMW project. This combined groundwater and surface water modelling approach has allowed the Environment Agency of England to make complex water resource management decisions in a wide range of aquifers and catchments based, in part, on outputs from such models. Since that time, the Environment Agency has used the framework to develop around a dozen further models of Permo-Triassic Sandstone aquifers, of varying levels of complexity. Many of the older models have subsequently been through one or more cycles of updating and/or recalibration. This paper provides a high-level review of these models based on the personal experience of the author and compares and contrasts their implementation in the US Geological Survey's groundwater modelling code MODFLOW. This includes a discussion of key conceptual issues that are common across the models, or unique to particular models, and the uses to which the models have been put. The paper concludes with a discussion of future opportunities and challenges for the programme. Thematic collection: This article is part of the Hydrogeology of Sandstone collection available at: https://www.lyellcollection.org/topic/collections/hydrogeology-of-sandstone [ABSTRACT FROM AUTHOR]

This paper provides information on the 2022 eruptive activity of Ebeko Volcano. Phreatic explosions had been occurring in the crater lake from January 22 to June 13 due to water seepage through a plug in the upper part of the magma conduit with subsequent boiling. Vulcanian type explosions started since June 14 and dried the lake. The ash particle-size distribution changed toward smaller sizes. Petrographic, mineralogical, and geochemical studies of the tephra define this period as a phreatomagmatic eruption based on the presence of fresh juvenile material. Interaction between magma and waters of the Ebeko hydrothermal system results in its depletion in alkali and enrichment in silica. We hypothesize that the formation of amorphous water-bearing silica in the form of numerous segregations and its subsequent dehydration can favor the volcano's explosive activity. [ABSTRACT FROM AUTHOR]

Large‐scale seepage‐faces occur on small‐slope tidal flats. All previous studies assume that the seepage‐face has only one single exit point. Here we show via numerical simulations of tidally‐influenced groundwater flow that, in a two‐dimensional vertical, homogeneous transect of a tidal flat with gentle beach slope of 1‰, multiple seepage‐faces may occur with at most four unsaturated beach surface segments which separate four seepage‐faces. Salinity‐variation induced density‐dependent flow leads to this complex phenomenon. While the seepage‐faces are the groundwater discharging zones on the beach surface, the unsaturated zones are the recharging zones. The whole aquifer beneath the tidal flat is almost occupied by seawater and forms a wall blocking the horizontal seaward discharge of inland fresh groundwater so that inland freshwater discharges mainly occur near the high tide mark. This is in great contrast with the traditional results that inland freshwater discharge occurs mainly near low tide mark. Plain Language Summary: Tidal flat with very gentle‐slopes distributes extensively around the world, for example, the coastline of Bohai, the Yellow Sea of China, and Willapa bay of USA. Due to small slopes, the intertidal zone can be as wide as several kilometers, leading to large‐scale seepage‐faces (saturated beach surface with groundwater efflux) during ebbing and low tides. All previous studies assume that the seepage‐face has only at most one segment, the upper end of which is the exit point of water table and the other end is the intersection point of seawater and beach surface. Here, we found that in a tidal flat with gentle beach slope of 1‰, multiple seepage‐faces may occur with at most 4 unsaturated beach surface segments which separate 4 seepage‐faces during low and rising tides. The locations of these seepage‐faces and adjacent unsaturated zones are quite dynamic due to the complex, dynamic density‐dependent groundwater flow in the aquifer beneath the tidal flat. Seepage‐faces are kind of complex and important boundary for coastal groundwater flow in order to accurately model the groundwater flow and solute transport in intertidal aquifers, the complex nonlinear boundary conditions on the seepage‐faces should be strictly and accurately implemented. This paper made such an attempt. Key Points: Tidal groundwater flow with strict and explicit seepage‐face boundary conditions were numerically simulatedMultiple seepage‐faces were first found to develop on gentle tidal flat with slope around 1‰Multiple seepage‐faces imply multiple local density‐dependent groundwater‐seawater re‐circulations [ABSTRACT FROM AUTHOR]

Theis' theory (1935), later improved by Hantush & Jacob (1955) and Moench (1971), is a technique designed to study the water level in aquifers. The key formula in this theory is a certain integral transform H [ g ] (r , t) of the pumping function g that depends on the time t and the relative position r to the pumping point as well as on other physical parameters. Several analytic approximations of H [ g ] (r , t) have been investigated in the literature that are valid and accurate in certain regions of r, t and the mentioned physical parameters. In this paper, the analysis of possible analytic approximations of H [ g ] (r , t) is completed by investigating asymptotic expansions of H [ g ] (r , t) in a region of the parameters that is of interest in practical situations, but that has not yet been investigated. Explicit and/or recursive algorithms for the computation of the coefficients of the expansions and estimates for the remainders are provided. Some numerical examples based on an actual physical experiment conducted by Layne-Western Company in 1953 illustrate the accuracy of the approximations. [ABSTRACT FROM AUTHOR]