bluuebunny/crossref_metadata_2025_split huggingface dataset:
Animating Ground Water Levels with Excel
Authors: Shikaze Steven G. , Crowe Allan S. 
Published: December 2005

AbstractThis note describes the use of Microsoft Excel macros (programs written in Excel's internal language, Visual Basic for Applications) to create simple onscreen animations of transient ground water data within Excel. Compared to many specialized visualization software packages, the use of Excel macros is much cheaper, much simpler, and can rapidly be learned. The Excel macro can also be used to create individual GIF files for each animation frame. This series of frames can then be used to create an AVI video file using any of a number of graphics packages, such as Corel PhotoPaint. The technique is demonstrated through a macro that animates changes in the elevation of a water table along a transect over several years.
Stochastic Ground Water Flow Simulation with a Fracture Zone Continuum Model
Authors: Langevin Christian D. 
Published: December 2005

AbstractA method is presented for incorporating the hydraulic effects of vertical fracture zones into two‐dimensional cell‐based continuum models of ground water flow and particle tracking. High hydraulic conductivity features are used in the model to represent fracture zones. For fracture zones that are not coincident with model rows or columns, an adjustment is required for the hydraulic conductivity value entered into the model cells to compensate for the longer flowpath through the model grid. A similar adjustment is also required for simulated travel times through model cells. A travel time error of less than 8% can occur for particles moving through fractures with certain orientations. The fracture zone continuum model uses stochastically generated fracture zone networks and Monte Carlo analysis to quantify uncertainties with simulated advective travel times. An approach is also presented for converting an equivalent continuum model into a fracture zone continuum model by establishing the contribution of matrix block trans‐missivity to the bulk transmissivity of the aquifer. The methods are used for a case study in west‐central Florida to quantify advective travel times from a potential wetland rehydration site to a municipal supply wellfield. Uncertainties in advective travel times are assumed to result from the presence of vertical fracture zones, commonly observed on aerial photographs as photolineaments.
Analysis of Slug Tests in Formations of High Hydraulic Conductivity
Authors: Butler James J. , Garnett Elizabeth J. , Healey John M. 
Published: December 2005

AbstractA new procedure is presented for the analysis of slug tests performed in partially penetrating wells in formations of high hydraulic conductivity. This approach is a simple, spreadsheet‐based implementation of existing models that can be used for analysis of tests from confined or unconfined aquifers. Field examples of tests exhibiting oscillatory and nonoscillatory behavior are used to illustrate the procedure and to compare results with estimates obtained using alternative approaches. The procedure is considerably simpler than recently proposed methods for this hydrogeologic setting. Although the simplifications required by the approach can introduce error into hydraulic‐conductivity estimates, this additional error becomes negligible when appropriate measures are taken in the field. These measures are summarized in a set of practical field guidelines for slug tests in highly permeable aquifers.
Bacterial Transport Experiments in Fractured Crystalline Bedrock
Authors: Becker Matthew W. , Metge David W. , Collins Samantha A. , Shapiro Allen M. , Harvey Ronald W. 
Published: December 2005

AbstractThe efficiency of contaminant biodegradation in ground water depends, in part, on the transport properties of the degrading bacteria. Few data exist concerning the transport of bacteria in saturated bedrock, particularly at the field scale. Bacteria and microsphere tracer experiments were conducted in a fractured crystalline bedrock under forced‐gradient conditions over a distance of 36 m. Bacteria isolated from the local ground water were chosen on the basis of physicochemical and physiological differences (shape, cell‐wall type, motility), and were differentially stained so that their transport behavior could be compared. No two bacterial strains transported in an identical manner, and microspheres produced distinctly different breakthrough curves than bacteria. Although there was insufficient control in this field experiment to completely separate the effects of bacteria shape, reaction to Gram staining, cell size, and motility on transport efficiency, it was observed that (1) the nonmotile, mutant strain exhibited better fractional recovery than the motile parent strain; (2) Gram‐negative rod‐shaped bacteria exhibited higher fractional recovery relative to the Gram‐positive rod‐shaped strain of similar size; and (3) coccoidal (spherical‐shaped) bacteria transported better than all but one strain of the rod‐shaped bacteria. The field experiment must be interpreted in the context of the specific bacterial strains and ground water environment in which they were conducted, but experimental results suggest that minor differences in the physical properties of bacteria can lead to major differences in transport behavior at the field scale.
Air and Water Entrapment in the Vicinity of the Water Table
Authors: Dunn Andrea M. , Silliman Stephen E. 
Published: December 2005

AbstractA laboratory tank was used to study entrapment of water in coarse sand lenses above the water table and of air in coarse sand lenses below the water table. Monitoring of these experiments involved a combination of visual inspection, measurement of moisture content, and measurement of air/water pressure. The medium consisted of coarse sand lenses with various degrees of vertical connectivity embedded within a fine sand matrix. Experiments were performed under conditions of both drainage (from a fully saturated medium) and imbibition. Observations during drainage included: (1) water was trapped in the coarse sand zones above the water table at heights significantly greater than anticipated from consideration of capillary rise in the coarse sand; (2) rapid drainage of these same coarse zones occurred when air penetrated into these zones through the surrounding fine sands; and (3) prior to the time of penetration of the coarse sand by air, water pressure in the coarse zone dropped significantly below atmospheric pressure. Observations during imbibition included: (1) entrapment of air within coarse sands below the water table, (2) the pore fluids in these zones varied spatially from predominantly air to predominantly water, and (3) pressure in the trapped air phase was significantly greater than pressure in the water phase in the surrounding fine sand. Overall, these results demonstrated significant sensitivity to the geometry of the coarse sand inclusions, particularly the vertical connectivity of the coarse sand lens.
Correlation Between Nitrate Contamination and Ground Water Pollution Potential
Authors: Chowdhury Shafiul H. , Kehew Alan E. , Passero Richard N. 
Published: December 2005

AbstractAQUIPRO, a PC‐based method, was used to assess aquifer vulnerability using digital water well logs. The AQUIPRO model is a parameter/factor weighting system for rating the pollution potential of an aquifer. This method uses the well depth, as well as the clay and partial clay thickness in a well, to generate pollution potential scores. In this model, aquifer protection increases as the AQUIPRO vulnerability scores increase and ground water pollution potential decreases.Computerized water well records of 2435 domestic wells with partial chemistry data were used to determine the ground water pollution potential of Kalamazoo County, Michigan. Theoretically, low AQUIPRO pollution potential scores should have more frequent occurrences of ground water contamination events than areas with high AQUIPRO scores with similar land‐use, well construction, and well densities. The relative AQUIPRO scores were compared with the frequency of occurrences of nitrate‐N in ground water wells. The average nitrate‐N concentrations within each relative AQUIPRO vulnerability scores category were also compared. The results indicate that domestic wells containing 5 mg/L or more nitrate‐N showed a positive correlation between the frequency of occurrences of nitrate‐N and relative decrease of AQUIPRO (r2= 0.99) vulnerability scores. In other words, as the ground water pollution potential increases, the occurrence frequency of nitrate‐N also increases. Furthermore, the results show that as the relative AQUIPRO (r2= 0.96) vulnerability scores decrease, the mean nitrate‐N concentrations also increase.
Behavior of Gasoline Pools Following a Denatured Ethanol Spill
Authors: McDowell Cory J. , Buscheck Timothy , Powers Susan E. 
Published: December 2005

AbstractIn 1999, ∼72 m3 of denatured fuel‐grade ethanol spilled at a bulk fuel terminal that had existing contamination within the subsurface. An unanticipated increase in the measured depth of the light nonaqueous phase liquid (LNAPL) was observed in nearby monitoring wells following the spill. This paper presents results of a laboratory analysis designed to understand the apparent increase in LNAPL mobility at this site. The two‐dimensional stainless steel and glass tank allowed visual assessment of the potential effects that the addition of denatured ethanol may have on a site with pre‐existing gasoline contamination. Digital images of gasoline and ethanol spill experiments were analyzed for changes in the characteristics of the existing gasoline pool and residual gasoline saturation in the unsatu‐rated zone. Reductions in the surface and interfacial tensions resulted in significant changes in the size, shape, and saturation of the gasoline pool after the addition of ethanol to the system. The final gasoline pool occupied a smaller area and had a higher saturation. In addition, some smearing of the gasoline into the saturated zone occurred as the capillary fringe was depressed.
Simulation of Submarine Ground Water Discharge to a Marine Estuary: Biscayne Bay, Florida
Authors: Langevin Christian D. 
Published: December 2005

AbstractVariable density ground water flow models are rarely used to estimate submarine ground water discharge because of limitations in computer speed, data availability, and availability of a simulation tool that can minimize numerical dispersion. This paper presents an application of the SEAWAT code, which is a combined version of MODFLOW and MT3D, to estimate rates of submarine ground water discharge to a coastal marine estuary. Discharge rates were estimated for Biscayne Bay, Florida, for the period from January 1989 to September 1998 using a three‐dimensional, variable density ground water flow and transport model. Hydrologic stresses in the 10‐layer model include recharge, evapotranspiration, ground water withdrawals from municipal wellfields, interactions with surface water (canals in urban areas and wetlands in the Everglades), boundary fluxes, and submarine ground water discharge to Biscayne Bay. The model was calibrated by matching ground water levels in monitoring wells, baseflow to canals, and the position of the 1995 salt water intrusion line. Results suggest that fresh submarine ground water discharge to Biscayne Bay may have exceeded surface water discharge during the 1989, 1990, and 1991 dry seasons, but the average discharge for the entire simulation period was only ∼10% of the surface water discharge to the bay. Results from the model also suggest that tidal canals intercept fresh ground water that might otherwise have discharged directly to Biscayne Bay. This application demonstrates that regional scale variable density models are potentially useful tools for estimating rates of submarine ground water discharge.
Contaminant Transport in Fractured Chalk: Laboratory and Field Experiments
Authors: Witthüser K. , Reichert B. , Hotzl H. 
Published: December 2005

AbstractLaboratory experiments were performed on chalk samples from Denmark and Israel to determine diffusion and distribution coefficients. Batch tests were used to define sorption isotherms for naphthalene and o‐xylene. Linear sorption isotherms were observed and described with Henry‐isotherms. Because of the high purity and low contents of clay minerals and organic carbon, Danish and white Israeli chalk generally have low retardation capacities. Con‐trarily, gray Israeli chalk, with organic carbon fractions as high as 1.092%, remarkably retards organic contaminants. TheKocconcept is not applicable to predicting distribution coefficients based on the organic carbon content in the chalk samples. Effective diffusivities ofo‐xylene, naphthalene, and several artificial tracers were determined using through‐diffusion experiments. Based on measured diffusion coefficients and available literature values, a chalk specific exponent of 2.36 for Archie's law was derived, allowing a satisfactory estimate of relative diffusivities in chalk. A field‐scale tracer test with uranine and lithium was performed in the Negev desert (Israel) to examine the transfer‐ability of diffusivities determined on small rock samples in the laboratory. Due to low recovery rates of the tracer, a modified single fissure dispersion model was used for inverse modeling of the breakthrough curves. Resulting diffusivities deviate insignificantly from the laboratory values, which are considered to be representative for the investigated part of the aquifer and applicable in transport models.
Ground Water Quality Assessment Using Multi‐Rectangular Diagrams
Authors: Ahmad Niaz , Sen Zekai , Ahmad Manzoor 
Published: December 2005

AbstractA new graphical technique is proposed here for classifying chemical analyses of ground water. In this technique, a diagram is constructed using rectangular coordinates. The new diagram, called a multi‐rectangular diagram (MRD), uses adjacent multi‐rectangles in which each rectangle represents a specific ground water type. This new diagram has the capability to accommodate a large number of data sets. MRDs have been used to classify chemical analyses of ground water in the Chaj Doab area of Pakistan to illustrate this new approach. Using this graphical method, the differentiated ground water types are calcium bicarbonate, magnesium bicarbonate, sodium bicarbonate, and sodium sulfate. Sodium bicarbonate emerges as the most abundant ground water type. MRDs also offer a visual display of the Chebotarev sequence of ground water quality evolution.
Dip and Anisotropy Effects on Flow Using a Vertically Skewed Model Grid
Authors: Hoaglund John R. , PoIllard David 
Published: December 2005

AbstractDarcy flow equations relating vertical and bedding‐parallel flow to vertical and bedding‐parallel gradient components are derived for a skewed Cartesian grid in a vertical plane, correcting for structural dip given the principal hydraulic conductivities in bedding‐parallel and bedding‐orthogonal directions. Incorrect‐minus‐correct flow error results are presented for ranges of structural dip (0 ≤θ≤ 90) and gradient directions (0 ≤φ≤ 360). The equations can be coded into ground water models (e.g., MODFLOW) that can use a skewed Cartesian coordinate system to simulate flow in structural terrain with deformed bedding planes. Models modified with these equations will require input arrays of strike and dip, and a solver that can handle off‐diagonal hydraulic conductivity terms.
Lithium Isotope Geochemistry and Origin of Canadian Shield Brines
Authors: Bottomley D.J. , Chan L.H. , Katz A. , Starinsky A. , Clark I.D. 
Published: December 2005

AbstractHypersaline calcium/chloride shield brines are ubiquitous in Canada and areas of northern Europe. The major questions relating to these fluids are the origin of the solutes and the concentration mechanism that led to their extreme salinity. Many chemical and isotopic tracers are used to solve these questions. For example, lithium isotope systematics have been used recently to support a marine origin for the Yellowknife shield brine (Northwest Territories). While having important chemical similarities to the Yellowknife brine, shield brines from the Sudbury/Elliot Lake (Ontario) and Thompson/Snow Lake (Manitoba) regions, which are the focus of this study, exhibit contrasting lithium behavior.Brine from the Sudbury Victor mine has lithium concentrations that closely follow the sea water lithium‐bromine concentration trajectory, as well as δ6Li values of approximately—28 %o. This indicates that the lithium in this brine is predominantly marine in origin with a relatively minor component of crustal lithium leached from the host rocks. In contrast, the Thompson/Snow Lake brine has anomalously low lithium concentrations, indicating that it has largely been removed from solution by alteration minerals. Furthermore, brine and nonbrine mine waters at the Thompson mine have large δ6Li variations of ∼30 %o, which primarily reflects mixing between deep brine with δ6Li of—35 ± 2‰ and near surface mine water that has derived higher δ6Li values through interactions with their host rocks. The contrary behavior of lithium in these two brines shows that, in systems where it has behaved conservatively, lithium isotopes can distinguish brines derived from marine sources.
Geophysical Expression of Natural Recharge in Different Geological Terrains
Authors: Hodlur G.K. , Singh U.K. , Das R.K. , Rangarajan R. , Chand Ramesh , Singh S.B. 
Published: December 2005

AbstractBehavior of the Dar‐Zarrouk parameters—longitudinal unit conductance, transverse unit resistance, longitudinal resistivity, and transverse resistivity—has been compared with the behavior of the natural recharge in two geological terrains. Contour patterns of the geophysical parameters and those of natural recharge have been analyzed and a qualitative relation in their behavior was recognized. Graphical comparison of the geophysical and hydrogeological parameters clearly illustrates a qualitative relationship between the two parameters. Use of such qualitative relation in the field of ground water exploration and management studies is explained. A modest beginning is attempted to arrive at a quantitative relation between natural recharge and Dar‐Zarrouk parameters.
Radar Determination of the Spatial Structure of Hydraulic Conductivity
Authors: Oldenborger Greg A. , Schincariol Robert A. , Mansinha Lalu 
Published: December 2005

AbstractSpatial variability of hydraulic conductivity exerts a predominant control on the flow of fluid through porous media. Heterogeneities influence advective pathways, hydrodynamic dispersion, and density‐dependent dispersion; they are, therefore, a key concern for studies of ground water resource development, contaminant transport, and reservoir engineering. Ground‐penetrating radar contributes to the remote, geophysical characterization of the macroscale variability of natural porous media. On a controlled excavation of a glacial‐fluvial sand and gravel deposit in the Fan‐shawe Delta area (Ontario, Canada), the hydraulic conductivity field of a 45 × 3 m vertical exposure was characterized using constant‐head permeameter measurements performed on undisturbed horizontal sediment cores. Ground‐penetrating radar data were collected along the excavation face in the form of both reflection and common midpoint surveys. Comparison of geostatistical analyses of the permeameter measurements and the radar data suggests that the horizontal correlation structure of radar stack velocity can be used to directly infer the horizontal correlation structure of hydraulic conductivity. The averaging nature of the common midpoint survey is manifest in the vertical correlation structure of stack velocity, making it less useful. Radar reflection data do not exhibit a spatial structure similar to that of hydraulic conductivity possibly because reflections are a result of material property contrasts rather than the material properties themselves.
Deriving TDS Values in Coarse Sediments from Long Normal and Electromagnetic Logs
Authors: Van Meir Nathalie , Lebbe Luc 
Published: December 2005

AbstractThis paper presents an empirical relationship of quantitatively linked electromagnetic (EM) borehole recordings of the total dissolved solids (TDS) in pore water in the Quaternary deposits of the Belgian coastal plain. First, the long normal (LN) logs are linked to EM logs, then the already developed relationships between LN resistivity measurements and the TDS values are rewritten for EM recordings. The main parameter in these equations is the formation factor, which is derived from ground water analyses and LN logs through Archie's law. The EM recording has several advantages compared to the LN logs. The EM analysis allows measuring in PVC‐cased wells and is not hindered by the invasion zone around the well. Furthermore, it has a high vertical resolution. LN logs can be measured only once, after drilling a well; EM recordings can be repeated several times in monitoring wells, which allows the gathering of time‐dependent data over a complete vertical cross section. Such data could be obtained with LN logs only in wells with screens over the full‐depth interval, which causes a hydraulic short circuit. This short circuit can result in a large artificial flow through the well between different levels, resulting in a salinity profile, which is no longer representative for the studied site. Remediation against short circuiting is a reduction of the screened interval, which strongly reduces the gathered information. The application of the derived equations is one of setting up a monitoring network along the Belgian coast to monitor the trend in salinity levels and comparing present salinity levels with older LN recordings to investigate the salinity changes in the last 30 years. Deep wells already present in the Belgian coastal plain can then be used to monitor both the fresh water head changes and the salt water evolution. The technique has also been used for parameter identification for which real concentration measurements were needed.
Salinization of a Fresh Palaeo‐Ground Water Resource by Enhanced Recharge
Authors: Leaney F.W. , Herczeg A.L , Walker G.R. 
Published: December 2005

AbstractDeterioration of fresh ground water resources caused by salinization is a growing issue in many arid and semi‐arid parts of the world. We discuss here the incipient salinization of a 104 km2 area of fresh ground water (<3000 mg/L) in the semiarid Murray Basin of Australia caused by widespread changes in land use. Ground water 14C concentrations and unsaturated zone Cl soil water inventories indicate that the low salinity ground water originated mainly from palaeo‐recharge during wet climatic periods more than 20,000 years ago. However, much of the soil water in the 20 to 60 m thick unsaturated zone throughout the area is generally saline (> 15,000 mg/L) because of relatively high evapotranspiration during the predominantly semiarid climate of the last 20,000 years.Widespread clearing of native vegetation over the last 100 years and replacement with crops and pastures leads to enhancement of recharge rates that progressively displace the saline soil‐water from the unsaturated zone into the ground water. To quantify the impact of this new hydrologic regime, a one‐dimensional model that simulates projected ground water salinities as a function of depth to ground water, recharge rates, and soil water salt inventory was developed. Results from the model suggest that, in some areas, the ground water salinity within the top 10 m of the water table is likely to increase by a factor of 2 to 6 during the next 100 years. Ground water quality will therefore potentially degrade beyond the point of usefulness well before extraction of the ground water exhausts the resource.