bluuebunny/crossref_metadata_2025_split huggingface dataset:
Common Errors in Developing a Ground‐Water Aquifera
Authors: Whitesides D. V. 
Published: July 2006

AbstractThis paper presents some of the more common errors made in the development of ground‐water supplies in the alluvial aquifers along the Ohio River in Kentucky. Ample available literature on proper methods of development of the alluvial aquifers generally seems to have been ignored by the water users in the area. The more common errors made in the typical developments are singled out for discussion.In the typical development the aquifer is treated as an inexhaustible underground river. Wells generally are clustered in small areas remote from the Ohio River, and are likely to be located more for convenience and economy of pipeline or property access than for hydrologic considerations. It is hoped by highlighting these errors and showing alternative methods of development that proper development practices will be fostered.Stages in the development of two hypothetical groundwater aquifers in the Ohio River valley are shown by eight illustrations that stress the common errors made in development and alternative methods of development taking into account hydrologic considerations.
Determining the Sustained Yields of Weils in Carbonate and Fractured Aquifersa
Authors: Parizek Richard R. , Siddiqui Shamsul H. 
Published: July 2006

AbstractCarbonate aquifers with highly developed anisotropic permeabilities and other fractured rocks under water‐table or semiwater‐table conditions present complex hydrologic settings in which to predict the sustained yield of individual wells or groups of wells. Yields of wells in these settings are particularly responsive to the position of the water level and its relationship to one or more producing zones. Often a well's total capacity may be accounted for by one or more openings encountered in drilling which are separated by varying thicknesses of essentially nonproductive rock. A well s yield is determined more by the position of the water table with respect to these openings than to the proportion of saturated rock penetrated by the well bore.A permeability profile must be defined for. these wells along with their available drawdown, and the inclination of water‐yielding openings. Permeability profiles may be roughly estimated from detailed driller's logs and caliper logs, and more precisely determined from flow meter surveys; packer tests and by pumping wells after successive increments of drilling or by a combination of increasing casing lengths and extended drilling. Available drawdown is dependent upon the inclination and position of significant water‐yielding openings exposed within the bore hole and seasonal variations in the water‐table position. In gently dipping carbonate rocks openings may follow bedding planes or selected beds favoring conduit development. Where this is known to be the case, pumping levels may be allowed to approach the top o.f one or another of these zones depending upon which is most productive.Where openings‘are inclined, pumping levels should be kept well above the depth at which the opening was penetrated to minimize the risk of dewatering conduits where they occur higher in elevation adjacent to the well bore compared to where they were penetrated by the well bore, Test holes may be drilled immediately adjacent to the potential production well to define the inclination of individual conduits or wells test pumped when possible at rates sufficient to draw the pumping level to the top of the opening in question. The latter is preferable because reductions in yield can be observed directly as a function of drawdown. To determine available drawdowns in fractured rocks, a permeability or yield profile, the inclination of openings adjacent to the well and seasonal variations in water levels must be known.
Some Limitations of Seismic Refraction Methods in Geohydrological Surveys of Deep Alluvial Basinsa
Authors: Wallace D. E. 
Published: July 2006

ABSTRACTSeismic methods, combined with available well and geologic data, were used to define the subsurface hydrologic and geologic conditions of the Walnut Gulch Experimental Watershed, a deep, alluvial basin near Tombstone, Arizona. Surface geology of the valley indicates an alluvium‐filled area between igneous intrusives and sedimentary rocks that support the Tombstone Hills on che southwest and the Dragoon Mountains on the northeast. Seismic determinations revealed depths to the water table ranging from near zero at the confluence of Walnut Gulch and the San Pedro River to 475 feet in the central portion of the watershed. The accuracy of predicting the depth to either ground water or basement was ± 6 percent, while that for ground water alone was ± 10 percent.Seismic refraction methods failed to produce satisfactory results when certain conditions or combinations of conditions existed. The great depths of alluvium created the problem of estimating the seismic traverse length necessary to accurately determine the alluvium‐basement interface. Increased compaction of alluvium with depth causes additional interpretation difficulties in some areas. Also, water‐table elevation may not always be accurately determined if it is located above, and close to, a highervelocity layer.A minimum of gravity or well log information greatly increases the reliability of seismic information in these problem cases. Other methods may still be necessary to substantiate the seismic data obtained under these conditions.
The Probability of Anomalies on Contour Maps
Authors: Dunn Darrel E. 
Published: July 2006

ABSTRACTThe minimum probability that: anomalous bulges and re‐entrants produced by mechanical (as opposed to interpretational) contouring of data on maps actually exist and are not merely the result of measurement errors may be calculated. The calculation consists of computing the compound probability that the value of at least one data point within each anomaly is actually higher or lower than the value of one data point on each flank of the anomaly. The calculation requires multiple data values at one or more locations on che map or a subjective estimate of the variance of the data. It is assumed that the variance of the data does not change from place to place on the map and that the recorded data values are normally distributed about the true value.
Common Stratigraphic Boundaries Associated with Coastal Plain Aquifers
Authors: Hansen Harry J. 
Published: July 2006

ABSTRACTThere is a tendency during the verification stage of aquifer model building to manipulate stratigraphic boundaries. This procedure is acceptable insofar as the geohydrologist is sufficiently knowledgeable to sense the point at which the manipulations encroach upon the integrity of his model.Examples from the Maryland Coastal Plain are used to depict several types of stratigraphic boundaries. These include erosional truncation, overlap (or pinchout), disconformity, and facies change. Defining statements are given for each in order to clarify the stratigraphic implications of boundary modeling.
Hydrogeochemical Effects of Injecting Wastes into a Limestone Aquifer Near Pensacola, Florida”
Authors: Goolsby Donald A. 
Published: July 2006

AbstractAcidic industrial wastes have been injected into deep wells in a limestone aquifer near Pensacola, Florida, since 1963. Prior geohydrologic studies in the area had indicated that the limestone aquifer contained nonpotable water and was overlain by an extensive clay confining layer.Two injection wells are presently being used to inject the waste at a rate of approximately 2,000 gallons per minute. The injection pressures are about 200 pounds per square inch. Over 3 billion gallons have been injected. Data from a current study indicate that the waste may extend outward about 1 mile from the injection wells, and pressure effects may extend outward more than 25 miles. Monitor wells show that pressure changes are following a predictable pattern. No wastes have been detected in a monitor well open to the Floridan aquifer immediately above the Bucatunna Clay Member of the Byram Formation and 100 feet from one of the injection wells.A monitor well open to the receiving formation was constructed about 1,300 feet south of the injection wells. Geochemical effects of the wastes were detected at this well about 10 months after injection began. In early 1968, the pH of the waste was lowered to about 3. Effects of this waste, which included a large increase in calcium, were detected at the monitor well about 5 months later.
Use of Ground Water in Developing the Mekong Delta, Republic of Viet Nam
Authors: Michael Eugene D. 
Published: July 2006

AbstractThe economic potential of the Mekong Delta is largely unrealized because of the harmful effects of uncontrolled flows of surface water which occur generally during the period August‐October. Interest in the Delta by various government agencies has resulted in preliminary plans for redistributing surface waters to control flooding, facilitate drainage, provide for irrigation, and prevent sea‐water encroachment. Current estimates indicate that construction costs in excess of a billion dollars would be required to develop an initial 2.1 million hectares (5.2 million acres) of the Delta to maximum economic potential; these costs do not cover those for upstream projects upon which the Delta developments depend.The Mekong Delta is underlain by an upper section of Recent alluvium, and a lower section of older alluvium. The older alluvium contains a permeable artesian zone called the 100‐meter aquifer, which is the most productive groundwater reservoir in Viet Nam. Tested well capacities range from about 145 to 635 gallons per minute (gpm); more efficiently designed wells should produce in the range of 500 to 1,000 gpm from this aquifer. Part of the 100‐meter aquifer is intruded by sea water.Current data permit no more than speculation with regard to storage, recharge, and flow in the 100‐meter aquifer. Storage is estimated to be approximately 30 million acre‐feet in the lower Delta, where the total dry season irrigation requirement is about 1.2 million acre‐feet. Piezometric levels in the Delta wells may be due merely to sea‐water pressure gradients acting across a horizontal saline‐fresh‐water interface; they do not necessarily imply ground‐water flow or an area of recharge.A major inconsistency exists in the relation of certain reported piezometric levels and corresponding depths to well intakes assuming conditions of either hydrostatic or hydrodynamic equilibrium, and it is necessary to postulate special circumstances to account for this. The data also indicate conditions conducive to subsidence, although no evidence for subsidence has yet been observed.The most feasible plan for development of the Mekong Delta may involve the conjunctive use of surface water and ground water of the 100‐meter aquifer, even though induced recharge and a ground‐water barrier against sea‐water intrusion might be necessary. Storage capacity is adequate, but more information is needed on recharge and total obtainable well capacities for the 100‐meter aquifer and on the possibilities for occurrence and control of subsidence in the event of widespread ground‐water development.
On the Management of Ground Water in Coastal Aquifers
Authors: Kashef Abdel‐Aziz I. 
Published: July 2006

ABSTRACTManagement of ground water in coastal aquifers is composed of major elements which should be properly evaluated. Emphasis should be made on evaluating these elements by means of basic research; otherwise, the management approaches and research would have no sound foundation. The major elements needed for a proper management are critically discussed and some current misconceptions are pointed out. Special attention is given to leakage and salt‐water encroachment problems. The current means of alleviating salt‐water effects are discussed and a new approach is presented.
Techniques for Quality‐of‐Water Interpretations from Calibrated Geophysical Logs, Atlantic Coastal Areaa
Authors: Brown Donald L. 
Published: July 2006

ABSTRACTIn the fall and winter of 1967–68, a 2,587‐foot test well was drilled at Moore's Bridges Filter Plant, Norfolk, Virginia. The well penetrated rocks of post‐Miocene, late and middle Miocene, late Eocene, Cenomanian, Cenomanian and Albian, Albian and Aptian, and Aptian and Neocomian age.Empirical data must be established in the Tidewater area for the successful calculation of ground‐water quality from calibrated geophysical logs. Chemical analyses of water samples from seven separate zones at depths between 850 feet to 2,500 feet below sea level indicate that the water type changes from a predominantly sodium bicarbonate water above 1,700 feet to a sodium chloride water in the deeper zones. The sodium bicarbonate type water in shallow aquifers must be corrected for divalent cation effects when using the self potential method or for the bicarbonate effect when using the resistivity method of interpretation.Using calibrated geophysical logs, an approximation of the dissolved‐solids and chloride content may be calculated using the formula Rw= Ro/Ff and the appropriate figures in the text. A field formation factor (Ff) of 4.2 is proposed for the Cretaceous aquifers in the Atlantic Coastal area. A K value of 84 should be used to check the validity of the magnitude of the self potential curve for the fresh‐ and brackish‐water aquifers in the Cretaceous. If the amount of dissolved solids is known for the Cretaceous waters, the chloride content may be approximated by the formula Cl = 0.5 (dissolved solids–300), provided the dissolved solids are less than 3,500 mg/l (milligrams per liter), and by the formula Cl = 0.6 (dissolved solids–400), if the dissolved solids are greater than 3,500 mg/l. In the Tidewater area, if the saturated resistivity (Ro) reading on the electric log is less than 25 ohmmeters the total solids and chloride content of the water are probably in excess of Public Health standards for potable water. An empirical method of calculating the quality of water from electric logs is presented.
Aquifers Changing Between the Confined and Unconfined State
Authors: Rushton K. R. , Wedderburn L. A. 
Published: July 2006

ABSTRACTThe resistance‐capacitance electrical analogue is used to analyse the time variant behaviour of aquifers which change between the confined and unconfined states. This is achieved using a field effect transistor as a switch which automatically operates as the water table crosses the top of the aquifer.The significance of this change for a particular limestone aquifer is described. In addition a thorough examination is made of the changes to the pumping test time‐drawdown curves when an aquifer, which is initially confined, becomes unconfined. If standard methods are used for this problem, erroneous results will be obtained for the transmissibility and the storage coefficients.
Graphical Interpretation of Water‐Quality Data
Authors: Zaporozec Alexander 
Published: July 2006

ABSTRACTQuality of water is determined by chemical analyses, the data from which are used for various purposes, such as classification, analysis, correlation, etc. For these purposes, the data need to be compiled and statistically evaluated. Graphical and numerical interpretation, a basic tool in hydrochemical studies, is one of the means used for summarizing and presenting water‐quality data. There exist a considerable number of methods and procedures which can be applied. They are relatively simple and can be used without extensive knowledge of chemistry. Main techniques and methods are grouped, for the purpose of discussion, into four categories as to their possible use: classification methods, correlation methods, analytic methods, and synthetic and illustrative methods. The basic graphs and diagrams in each category are accompanied by examples.
Practical Solutions for Pumping Tests in Carbonate‐Rock Aquifers
Authors: Eagon Herbert B. , Johe David E. 
Published: July 2006

ABSTRACTThe validity of standard methods of aquifer test analysis as applied to wells in consolidated‐rock aquifers has long been a subject of debate. In a recent investigation of the carbonate‐rock aquifer in northwestern Ohio, 76 wells were drilled and tested. Control and detailed analysis of such a large number of pumping tests afforded an excellent opportunity to evaluate various techniques. The data from each test were analyzed by the standard analytical methods. The results were viewed with varying degrees of confidence, but realistic values for hydraulic properties usually were obtained.Step‐test data were analyzed by three methods of which a graphical solution is preferred. It was believed in most instances that the CQ2. relationship gave an adequate approximation of well loss for the practical range of pumping rates. Once dewatering occurs, the hydraulic response of a given well may change drastically and well‐loss computations may give meaningless values. However, the analysis reveals the depth of major water‐yielding zones. Step‐test data can also be used to predict well yields when drawdown relationships are distorted by dewatering effects.Time‐drawdown data are preferred for the determination of hydraulic properties of carbonate‐rock aquifers. Data from the pumped well are considered valid for calculating aquifer transmissivity unless dewatering has occurred. Realistic values of transmissivity can be determined by using recovery data wherein distorted relationships caused by dewatering are minimized. The analysis of time‐drawdown data from a fully‐penetrating observation well provides what are believed to be the most reliable values for aquifer transmissivity and storage coefficient. It is best to employ regional concepts where possible and not become bogged down with minor inconsistencies in the test data.
Role of Vertical Shafts in the Movement of Ground Water in Carbonate Aquifers
Authors: Brucker Roger W. , Hess John W. , White William B. 
Published: July 2006

ABSTRACTVertical shafts are roughly cylindrical voids in carbonate rocks. They range in diameter from inches to tens of feet and in height from inches to hundreds of feet. They are produced by vertically descending ground water from perched ground‐water reservoirs or surface water. These features are common throughout the Interior Lowlands and Appalachian Plateaus Provinces. Vertical shafts form the headwater termini of complex drainage networks that aggregate the waters into master drains which carry the water to big springs. The drains evolve through time as base level is lowered but retain a dendritic pattern. Shafts are very short lived and occur only near the edge of the clastic caprock in the study area in south central Kentucky. Shafts are formed by free flowing sheets or films of vadose water streaming down the walls in supercritical flow. These waters are undersaturated with respect to calcite at both top and bottom of the shaft, although there is a measurable uptake of CaCO3 as the water traverses the shaft walls. The shafts act as aeration chambers, and there is much loss of carbon dioxide from the ground water during movement through this segment of the underground route.
A New Technique for Estimating Recharge Using a Digital Modela
Authors: Taylor O. James , Luckey Richard R. 
Published: July 2006

ABSTRACTA new digital‐computer modeling technique uses response curves for discrete regions of a stream‐aquifer system to compute the percentage of applied irrigation water and precipitation that recharges the ground‐water reservoir. The hydrologic system modeled is a part of the Arkansas River valley in southeastern Colorado. A 150‐mile reach of the valley (Pueblo to the State line) was divided into seven smaller reaches. Streamflow, irrigation water applied from canals, ground‐water withdrawal by wells, and precipitation data collected during 1964‐68 were considered. A wide range of assumed values of recharge from applied irrigation water and precipitation were simulated by the model. The differences between computed and measured changes in ground‐water storage were extremely sensitive to the programmed recharge value. Convergence of computed and measured change in ground‐water storage values was obtained for most reaches when 20 to 30 percent of the applied irrigation water and precipitation was computed as recharge to the aquifer.
Specific Capacities of Wells in Crystalline Rocks
Authors: Summers W. K. 
Published: July 2006

ABSTRACTIn the Rothschild area, Wisconsin, most water wells are completed in glacial deposits. When glacial deposits are unsaturated or thin, wells are completed in fractured crystalline rocks of Pre‐Cambrian age. Specific capacity data from 56 wells tapping these fractured rocks reveal:

Yields and specific capacity are generally small, with a median specific capacity of log 0.17 gpm/ft and a mean value of log 0.10 gpm/ft.
Wells which are close together may have substantially different specific capacities.
The occurrence of saturated sand and gravel above the crystalline rocks has no obvious influence on yield or specific capacity.
Specific capacities of wells seem to be inversely proportional to (a) thickness of rocks penetrated below the water table, (b) depth of the wells below the water table, and (c) depth of the wells below the land surface.

Assuming that specific capacities of wells are related to the number of contributing fractures penetrated and that the number of fractures diminishes linearly with depth, the following relation is derived:
image
where Sc= specific capacity, Q = discharge, s = drawdown, B = a constant, b = fracture frequency at the land surface, z = depth, and E = maximum depth of fracturing. In the Rothschild area, E = 100 feet.In exploring for ground water in a fractured rock, the problem is to find the area of maximum b. If sound scientific methods are not available, then exploration will consist of drilling wells at random until a satisfactory well is completed. However, because wells achieve 60 to 80 percent of their yield in the first 20 feet below the water table, test wells should be pump tested when they have reached a depth of about 20 feet below the water table. Unsuccessful wells need not be drilled to completion.
Occurrence and Quality of Ground Water in Crystalline Rocks of the Llano Area, Texas
Authors: Landers R. A. , Turk L. J. 
Published: July 2006

ABSTRACTMedian yield of wells in crystalline rocks of the Llano area is 14 gpm. Near the Highland Lakes the median yield is somewhat higher (17 gpm) owing to continuous recharge from the lakes. Domestic wells near the lakes are not as deep (median depth = 66 feet) as in the rest of the area (median depth = 76 feet). The major ground‐water supplies occur in granite grus and fractured granite.The yield per saturated foot of aquifer decreases with depth, owing to (1) the decreasing degree of weathering and hence of porosity and permeability with depth, and (2) the closing of fractures with depth. The decrease with depth of incremental yield is more marked in the Llano region than in the Sierra Nevada and in the eastern United States. Optimum depth of wells in the area is considered to be 75 to 100 feet. It is commonly more economical from the standpoint of well yield to drill several shallow wells rather than one deep well.Quality of ground water is generally good, but erratic, with median concentrations (in mg/l) of Si, 49; SO4, 61; Cl, 83; NO3, 21; Fe, 0.07; and total hardness (as CaCO3), 302. Schist generally yields water with higher total hardness and sulfate concentrations than other rock types. The water samples with high nitrate concentrations typically are from wells near septic systems or livestock pens. Even in ground water away from pollution sources the dissolved solids content tends to be higher than in water within crystalline rocks of other geographic areas.