bluuebunny/crossref_metadata_2025_split huggingface dataset:
Ground‐Water Computer Models — State of the Arta
Authors: Prickett Thomas A. 
Published: July 2006

ABSTRACTThis paper addresses both the pros and cons of ground‐water modeling and is presented from a neutralist's standpoint. The list of individual modeling pros and cons is extensive but is condensed into three main points for each side of the ledger.The three main characteristics that put the use of ground‐water models into the class of intellectual toys are as follows. First, the wrong model is frequently chosen for problem solving of which overkill by use of an overly sophisticated model is an example. Secondly, the paying agency or client is often disillusioned with the model results because of frequent modeler oversell in the early stages of project planning and budgeting. Thirdly, the problems are often solved with a numerical code that is a mystery to all except the modeler himself.The three main characteristics that make ground‐water models very practical tools are as follows. First, there is no doubt that the models of today can solve extremely complex ground‐water flow problems. Having methods available for solution of complex problems is an advantage that we have not always had Secondly, the models of today are available to virtually everyone in the ground‐water business. The days of specialty laboratories for complex ground‐water model solving are over and the tools are now in the hands of those doing the local work. And thirdly, having a computer code and data deck available is a perfect tool for transferring information to another person as to how a problem was solved. There is no doubt as to the exact assumptions used and the step‐by‐step solution of the problem which produces the results of the entire analysis.This paper also includes a very brief description of the state‐of‐the‐art of ground‐water modeling and a very comprehensive reference list of useable models.
The Effects of Urbanization on Ground‐Water Quality — A Case Study
Authors: Eisena Craig , Anderson Mary P. 
Published: July 2006

ABSTRACTThe results from a 1 1/2‐year study of ground‐water quality in the vicinity of Milwaukee, Wisconsin, support the suggestion by other researchers, that chloride and sulfate are the principal products of urbanization which alter ground‐water chemistry. In addition to chloride and sulfate, ground‐water samples, from the Menomonee River Watershed contained relatively high concentrations of ammonium, fecal coliform and fecal streptococci bacteria. Field data suggest that contamination of ground water is caused by infiltration of surface water polluted by municipal and industrial wastes and (or) leakage from sewer lines. Some additional chloride contamination by infiltration of road salt is also suggested.
Fracture‐Controlled Ground‐Water Circulation and Well Siting in the Vicinity of Laramie, Wyoming
Authors: Huntoon Peter W. , Lundy Don A. 
Published: July 2006

ABSTRACTThe artesian Casper aquifer, comprised of 700 ft of interbedded limestones and sandstones, currently supplies 70 percent (3.5 Mgal/d) of the municipal‐water needs of Laramie, Wyoming. Large transmissivities occur in fracture zones associated with faults and folds in the area, and water discharges from several springs localized along these structures. Transmissivities in fracture zones are 100 times greater than those in unfractured parts of the aquifer. The overlying Satanka Shale is a regional confining unit even in most areas of fracturing, and is a source of poor quality ground water. Prospecting for new ground‐water supplies near Laramie involves mapping the tectonic structures and drilling into them once they are identified.
Ground‐Water Resource Management in Nebraska
Authors: Fricke Carl A. P. , Pederson Darryll T. 
Published: July 2006

ABSTRACTIn order to regulate the use of ground water, State agencies and local government, together with local public participation, have developed a management policy which is now being implemented in Nebraska. A water‐resource agency, a geological survey, and a local, multi‐county governmental unit are combined with several other governmental units to investigate water problems and guide a variety of vested interests toward a common goal of efficient water‐resource management. The key government document delegating the authority and guiding the agencies is the Nebraska Ground Water Management Act of 1975. This Act specifies a procedure whereby local residents concerned about misuse and depletion of their ground‐water supplies can request that official hearings be held, water‐supply evaluations be made, and consideration be given by the Nebraska Department of Water Resources to establish what is called a “control area.” Designation of a control area allows development and enforcement of methods to deal with the water‐resource problem within that area. The management alternatives provided for by this Act include well spacing, rotation of pumping, allocation of water, and moratoriums on drilling. The Act does not, however, address conjunctive use of surface water and ground water, guidelines for management policies, and rights to artificially stored ground water.
Ground‐Water Pollution by Transfer of Oil Hydrocarbons
Authors: Fried J. J. , Muntzer P. , Zilliox L. 
Published: July 2006

ABSTRACTAn important aspect of the pollution of a phreatic aquifer by hydrocarbons is the oil‐water contact and transfer of soluble substances from the oil into the ground water.A systematic study of this transfer of matter in a saturated porous medium (initial condition of contact when the impregnation body is submitted to fluctuations of the piezometric level) is performed with an experimental device made up of a porous matrix containing the oil phase, steady and crossed by a unidirectional flow of water. The transfer is very efficient; for all compounds which have been studied, the maximum possible concentration is reached after a distance of the order of 10 cm with specific flow rates greater than those generally encountered in a gravel‐sand aquifer. The selective impoverishment of the oil product with time, due to differences in the solubility of various hydrocarbons, modifies the dissolved phase composition. Downstream of an in‐situ impregnation body, this phenomenon only appears after a constant concentration has been reached for a long time. A source model is thus obtained, where the pollutant massic flow rate is proportional to the flow rate of the water which crosses the impregnation body. Such an initial condition has a fundamental effect on the determination of the contaminated aquifer domain, with the help of the dispersion scheme, with hydrocarbon concentrations evolving according to a general diffusion‐convection law.
Approximation for Salt‐Water Intrusion in Unconfined Coastal Aquifer
Authors: Panigrahi B. K. , Gupta A. Das , Arbhabhirama A. 
Published: July 2006

ABSTRACTA numerical model based on a finite difference technique has been developed to analyse and solve the problem of an unconfined coastal aquifer of infinite extent with free surface and interface along with the width of outflow face as unknown boundaries. The problem has been formulated in a complex potential plane and a five‐point operator of a finite difference scheme has been used to reduce the governing flow equation into a set of linear algebraic equations which is solved by the Gauss‐Seidel iterative method with an over‐relaxation factor. Results of the analysis provide a generalised dimensionless plot for assessing the fresh‐water flow to the sea from the known field information of aquifer characteristics and water‐table head landward from the shoreline.
Requirements of State Regulatory Agencies for Monitoring Ground‐Water Quality at Waste Disposal Sites
Authors: Clark Thomas P. , Sabel Gretchen V. 
Published: July 2006

ABSTRACTA survey of the requirements of State regulatory agencies responsible for monitoring ground‐water quality at waste disposal sites was conducted in order to gain a concise profile of monitoring practices across the country, and also to provide the basis for a monitoring manual to serve as technical background and guidance for the citizens of Minnesota. The survey considered a variety of topics including the regulatory framework for requiring monitoring, chemical parameters analyzed, recommended methods of monitoring well construction and sample collection, laboratory quality control, data interpretation, and post‐operational monitoring requirements.The survey showed that most State monitoring programs are in their infancy. Many States, however, are beginning to devote serious effort and manpower commitments to the development of monitoring programs, although there is considerable divergence of opinion regarding how these programs should be conducted. Federal legislation establishing minimum performance criteria instead of detailed operating requirements for waste disposal sites will increase the need for sound water monitoring programs at these sites in the future.
Determination of the Location and Connectivity of Fractures in Metamorphic Rock with In‐Hole Tracersa
Authors: Marine I. Wendell 
Published: July 2006

ABSTRACTIn‐hole tracer tests were used in a geohydrologic investigation of metamorphic rock at the Savannah River Plant near Aiken, South Carolina, to locate water‐transmitting fractures and to determine the connectivity of these fractures between boreholes. Only after development of a conceptual model of the fracture occurrence and connection could the proper methods of analysis for the hydraulic parameters be selected.In‐hole tracers were used to locate fractures in a borehole and supplemented other methods, such as core inspection, geophysical logs, borehole wall imaging techniques, dry drilling, and packer tests. The first three of these do not necessarily investigate fluid‐transmitting fractures.In the study of the connectivity of fractures between boreholes, the in‐hole tracer techniques supplemented determinations by the rapidity of hydraulic response and the use of between‐well tracer tests.In hydraulically transmissive rock, fractures were located by changes in the velocity of the tracer pulse in response to adding fluid to the well. In virtually impermeable rock, the movement of the tracer pulse in the rock was normalized to the movement of another tracer pulse in the cased portion of the well because the movement was so slow that direct measurement was difficult. Connectivity of fractures between boreholes was determined by placing an in‐hole tracer in one hole and measuring the movement
Estimating Transmissivity and Well Loss Constant Using Multirate Test Data From a Pumped Well
Authors: Nahm G. Y. 
Published: July 2006

ABSTRACTLinear regression can be applied to multirate pumping test data from a single pumped well to estimate the constants of the equation . An equation has been derived which enables the values of An at various times to be used to estimate the transmissivity of the aquifer adjacent to the pumped well with due allowance for well loss. An extension of method enables estimation of the order of the storage coefficient.
Details of Hydrochemical Variations in Flowing Wells
Authors: Marsh J. Marcus , Lloyd John W. 
Published: July 2006

ABSTRACTDue to chemical reactions between steel casing and stored water in capped artesian wells, the pH, Eh, TDS, major and trace ion concentrations and saturation indices can be significantly, but relatedly altered from their aquifer values. To obtain true aquifer water samples, either all the stored water must be flushed from the well or a sampling tube must be used to ensure that the water is taken from within the aquifer. Flushing time can be calculated from well dimensions and best be monitored in the field by measuring temperature and electrical conductivity.This study has been made of confined wells in a fissured limestone, but the reactions which occur are likely to be common to aquifers of different hydrogeology.
Ground‐Water Modeling: Numerical Modelsa
Authors: Faust Charles R. , Mercer James W. 
Published: July 2006

ABSTRACTPartial differential equations may be used to describe a large number of problems in ground‐water hydrology. Without a solution, however, these equations are of little value. Only a simplified subset of the general equations can be solved by analytical means, and these often describe idealized situations that are limited in application. Numerical solution of these equations using high speed digital computers offers a logical alternative.
Safe Yield in a Coastal Ground‐Water Regime
Authors: Mull Rolf , Battermanna G. 
Published: July 2006

ABSTRACTThe limiting factors for the, safe yield in the investigated coastal area were sea water along the coastline and saline water at about 250 m below sea level. Both types of salt water will intrude into existing wells, when the potential heads are changed sufficiently by increasing pumping. Besides this, the recharge rate due to precipitation affects the potential head.In a hilly central part of the region, water infiltrates into the ground, and seeps to the saturated zone where it flows some kilometers to flat marshy regions near the coast and estuaries. There it comes up to drainage systems near the land surface (long cycle).In the marshy region the infiltrated water exfiltrates into drains and ditches after a short passage of some meters in the upper zone of the aquifer (short cycle).The calibration of a digital ground‐water model gave the existing ground‐water budget. The prognostication of the safe yield was based on these results.The most interesting problem of model calculations was to take into consideration the dependence of the recharge rate on the depth of the ground‐water table below the land surface. If the ground‐water level is lowered by pumping below the drainage system, the short cycle will be interrupted. The downward seeping water flows within a saturated zone to the wells and affects the potential head. The greater the drawdown, the greater is the recharge rate. The depression of the water table by pumping is compensated up to a certain degree.
The Effect of Flyash Disposal on a Shallow Ground‐Water System
Authors: Cherkauer Douglas S. 
Published: July 2006

ABSTRACTAt a flyash landfill in southeastern Wisconsin, dry ash has been placed directly in contact with a shallow sand and gravel aquifer. Substantial modification of ground‐water quality has occurred primarily by sulfates, calcium and magnesium. However, after eight years, the contamination has spread less than 200 meters from the site in a permeable aquifer. In addition, toxic metals contained in the ash have proven quite immobile in the ground water. Fortuitous location of the disposal site in alkaline sediment upflow from ground‐water discharge in a marsh appears to have limited the extent of contamination.
Horizontal Anisotropy Determined by Pumping in Two Powder River Basin Coal Aquifers, Montana
Authors: Stoner Jeffrey D. 
Published: July 2006

ABSTRACTHydraulic anisotropic behavior was determined for the Sawyer‐A and Anderson coal aquifers (Tongue River Member of Paleocene Fort Union Formation) by five‐well and four‐well aquifer tests, respectively. The average maximum hydraulic conductivity of 0.65 m/d (2.13 ft/d) for the Sawyer‐A coal aquifer bears N. 85° E. The average minimum hydraulic conductivity, which is perpendicular to the maximum, is 0.26 m/d (0.85 ft/d). Aquifer heterogeneity in the form of poorly developed coal cleat is believed to be responsible for a wide range of principal‐axis orientations determined by a five‐well test performed on the Sawyer‐A coal aquifer. The maximum hydraulic conductivity of the Anderson coal aquifer is 0.20 m/d (0.66 ft/d) and bears N. 32° W. The minimum hydraulic conductivity is 0.07 m/d (0.23 ft/d). When coal cleat orientation and development are unknown, a five‐well aquifer test proves more beneficial than a four‐well test in analyzing the reliability of the results.Well storage and aquifer dewatering affected the drawdowns of the pumped well during both tests. However, such effects were minimal, as indicated by drawdowns in observation wells at a distance as small as 13m (44 ft) from the pumped well. Average hydraulic conductivity determined from drawdowns observed at the pumped wells alone were lower than average values determined from a multiple‐well analysis.
Preliminary Evaluation of an Alternate Electrode Array for Use in Shallow‐Subsurface Electrical Resistivity Studies
Authors: Carringtona Thomas J. , Watson Don A. 
Published: July 2006

ABSTRACTNine electrode arrays were examined under controlled laboratory conditions to evaluate their relative efficiency with regard to time and space requirements, and with regard to effective prediction of subsurface conditions in electrical resistivity surveys. Of the nine investigated, the Wenner and a modification thereof (“Modified Wenner”) were selected for field testing and comparison. To a limited extent the Schlumberger array also was compared.Field testing of the three chosen arrays suggested the superiority of the Modified Wenner over the Wenner array in reliability of data obtained under most conditions examined, speed of completion of a survey and minimal straight‐line distance required for a 100‐foot (30.5‐meter) depth survey. Insufficient data were gathered with the Schlumberger array for proper comparison with the other two arrays.Subsurface conditions predicted by resistivity data were confirmed by subsurface projections of geological features suggested by previous surficial mapping, by drillers'records and by seismic refraction data.
The Relationship Between Fracture Traces and Joints in a Tertiary Basin, Southwest Montana
Authors: Krothe Noel C. , Bergeron Marcel P. 
Published: July 2006

ABSTRACTThe relationship between fracture traces mapped on aerial photographs and joints mapped in the field were examined for a synclinal basin, near Three Forks, Montana, Fracture traces mapped in the southern half of the Milligan Canyon area by stereoscopic examination of aerial photographs show a predominant east‐west and north‐south orientation.A total of 4,675 joint orientation measurements made in the field also showed predominant north‐south and east‐west orientations. The similarity suggests that mapped fracture traces reflect areas of joint and fracture concentrations in the subsurface and may be a valuable water exploration tool in Tertiary basins of Montana.
Waste Heat Balance in Aquifers Calculated by a Computer Programme
Authors: Kley Wolfram , Heekmann Winfried 
Published: July 2006

ABSTRACTBecause of the feeding of waste heat over many years into the aquifers of the city of Cologne, Federal Republic of Germany, a subsurface energy resource has been built up. By analyzing the temperature measurements in ground water by means of a computer programme the isolines of the energy resource and of the recoverable amount of heat can be determined and represented. Practical application of the results of these investigations is important for the planning and design of heat pump units in agglomeration areas. In conclusion, prognoses on future temperature distribution in aquifers of the city of Cologne are made.
Hydrogeology of the Sierra Nevada Foothill Lineament Near Oakhurst, California
Authors: Mack Seymour , Schmidt Kenneth D. 
Published: July 2006

ABSTRACTThirty‐three wells and two springs yielding high chloride water from granitic rocks define a northwesttrending lineament, which extends for 60 miles (100 km) along the western Sierra Nevada foothills of Fresno and Madera Counties. Geochemical evidence indicates that many of the constituents in this water are marine connate in origin. However, the connate water has been strongly diluted with meteoric water. The connate water is believed to have been derived from Paleozoic and early Mesozoic marine clastic rocks (now metamorphosed) in the Sierra Nevada. The lineament marks the location where marine connate water has migrated upward from these rocks along an eastward‐dipping fault zone. A capping of granitic rocks has enhanced the persistence of this connate water for millions of years. The lineament may be structurally related to the Oakhurst‐Fine Gold fault zone, which it parallels for approximately 15 miles (25 km). There is a remarkable correlation in the Oakhurst area between wells yielding high‐chloride water and fracture trends determined from aerial photographs. High chloride ground water is present only in topographically low areas, where little flushing by meteoric water has been possible.
Numerical Simulation of Potentiometric Surface Changes Caused by a Proposed Open‐Pit Anthracite Mine
Authors: Bair E. Scott , Parizek Richard R. 
Published: July 2006

ABSTRACTThe Trescott, Pinder, Larson (Trescott and others, 1976) finite‐difference flow model was modified and used to simulate potentiometric surface changes caused by the development of a proposed open‐pit anthracite mine. The modifications to the program code were made to account for site‐specific hydrogeologic conditions and to simulate the mining operation. In order to account for vertical changes in hydraulic conductivity caused by underground mine voids, the coefficient subroutine (COEF) was modified to permit the value of hydraulic conductivity to vary with depth. The lateral growth and deepening of the mine were simulated by changing the data input subroutine (DATAI) to allow the number, location, and hydraulic head of constant‐head nodes to vary with the time period. The mass balance subroutine (CHECKI) was modified to print out the flux into each constant‐head node at the end of each time period, thereby permitting calculation of changes in the rate of ground‐water flow into the mine.Site‐specific values of hydraulic conductivity, specific yield, aquifer recharge, streambed permeability, and hydraulic head initially were used in the modeling studies. Input parameter values were adjusted within the range of established field values during steady‐state model calibration. It was not possible to calibrate the transient model because the mining operation was in the planning stage and, therefore, no historical data existed. Nonetheless, transient simulations using the adjusted input parameter values and the simulated hydraulic head values were made to show that it is possible to model potentiometric surface changes caused by ground‐water flow into an open‐pit mine. These simulations predicted that, after eight years of mining, a cone of depression approximately 20,000‐feet long, 8000‐feet wide, and 1000‐feet deep would form around the proposed mine. The results of the transient simulations were used in a preliminary manner to assess the potential hydrogeologic impact of the proposed mining operation.
Yield Verification of a Dolomite Aquifer in Northeast Illinois
Authors: Sasman Robert T. , Schicht Richard J. , Benson Curtis R. , Ludwigs R. Scott 
Published: July 2006

ABSTRACTPumpage from shallow aquifers, primarily dolomite bedrock, in northeastern Illinois has exceeded estimates of ground‐water recharge in extensive areas creating concern that ground‐water recharge estimates are too low. Pumpage increased 92 percent during the period 1966‐1978 and was 61.7 million gallons per day (2.33 × 108 liters/day) during 1978. During the period 1966‐1979 water level declines exceeded 30 feet (9.14 meters) in some areas. Based on a ground‐water budget study, it was determined that recharge estimates were in the right order of magnitude and pumpage in excess of recharge was balanced by water taken out of storage from the shallow aquifers. A specific yield of 0.017 was determined for the dolomite bedrock aquifer based on the ground‐water budget study.