bluuebunny/crossref_metadata_2025 huggingface dataset:
Techniques for Computing Rate and Volume of Stream Depletion by Wellsa
Authors: Jenkins C. T.
Published: July 2006

The effects on flow of a nearby stream from pumping a well can be calculated readily using dimensionless curves and tables. Computations can be made of: (1) the rate of stream depletion at any time during the pumping period or after the cessation of pumping; (2) the volume induced from the stream during any time, both during pumping or after the cessation of pumping; and (3) the effects, both in rate and volume of stream depletion, of any selected pattern of intermittent pumping. Sample computations illustrate the use of the curves and tables. An example shows that intermittent pumping may have a pattern of stream depletion not greatly different from a pattern for steady pumping of an equal volume.

The residual effects of pumping, that is, effects after cessation of pumping, on streamflow may easily be greater than the effects during the pumping period. Adequate advance planning that includes consideration of residual effects thus is essential to effective administration of a stream‐aquifer system.
Use of the Electrical Resistivity Method for Investigating Geologic and Hydrologic Conditions in Santa Clara County, California
Authors: Page Leo M.
Published: July 2006

The electrical resistivity method has been a valuable tool used in the discovery of ground‐water recharge facilities with percolation capacities in excess of 100,000 acrefeer per year. The procedures used in doing the field work and the methods of plotting the data are described using a typical area where studies were made. Correlations of soil types, recharge rates, and resistivity data for Santa Clara ‐County are included. Ground‐water level data from observation wells are used to measure the regional and long‐term effects of the ground‐water recharge program.
Preliminary Field Studies Using Earth Resistivity Measurements for Delineating Zones of Contaminated Ground Water
Authors: Warner Don L.
Published: July 2006

The measure of earth resistivity is a possible means of detecting and outlining zones of ground‐water contamination where a resistivity contrast exists between contaminated and unconcaminated ground water.

As a preliminary evaluation of the use of electrical resistivity for defining zones of contaminated ground water, five sites on Long Island and three sites in western Texas were examined. The surveys at three of the Long Island sites and at one of the western Texas sites were at least partially successful in their objectives. The lack of success at the other sites is attributed to the particular physical conditions that existed.

Further effort toward developing electrical resistivity as a method for evaluating variations in ground‐water quality is encouraged.
Cost of Pumping Wafera
Authors: Ackermann William C.
Published: July 2006

Use of this material will assist in the determination of cost of pumping water, given the quantity of flow required, the total pumping head, the wire‐to‐water efficiency, and the unit cost of power.

A table of conversions is presented to aid in reducing theoretical equations to simplified equations, and a figure is provided for graphical solutions of the equations.
New Thrusts in Ground Watera
Authors: McGuinness C. L.
Published: July 2006

Four principal trends in ground water are apparent:

(1) Increasing use of ground water for domestic supplies. Geohydrologists must learn to quantitatively evaluate the supply under conditions of maximum development, not merely determine the availability of a supply that does not strain the aquifer. (2) Aquifers will be looked to increasingly as possible storage media for surplus flood water, in place of dams and reservoirs. The key here is economics – optimum utilization of resources. The job of the geohydrologist is to do enough research and experimentation to determine when, where, and how ground‐water reservoirs can be recharged artificially at a reasonable cost. (3) Saline aquifers will be looked at as sources of water supply. The cost curves of developing new supplies of fresh water are ascending while the cost curves for desalinization are declining, and inevitably they will cross in one area after another. There is a paucity of information on saline ground‐water aquifers; hence, the utmost skill must be used in evaluating the resource. (4) With efforts to prevent stream pollution, aquifers will be looked to increasingly as possible storage media for industrial and domestic waste effluents. Control is urgently needed so the effects of waste injection can be predicted, the technology for confining those effects as intended can be developed, and a basis can be provided for a rational decision as to whether waste injection or an alternative use of the chosen aquifer is best for the economy in the long run. However, there is little legal basis for control, and the cost of such control may make the practice unfeasible in many situations.

A systems‐analysis approach is needed to develop a working model of a given hydrologie and socio‐economic problem from which quantitative answers can be given to water planners.
A Simplified Technique for Well‐Field Design
Authors: Mount J. Russell
Published: July 2006

The planned development of an individual water supply from a group of wells must take into consideration several controllable and uncontrollable factors. The uncontrollable factors may include aquifer coefficients of transmissibility and storage, aquifer boundaries, static water level, aquifer depth, recharge capabilities, and competing users. The controllable factors often include the acreage allocated to ground‐water development, well locations, and pumping rates. Well‐field design is oriented mainly toward proper selection of the controllable factors.

Water requirements, the cost of water and the life of the well field are related to limitations of acreage, draw‐down of water level, and investment in pumping and transmission facilities. All of these factors, in turn, are influenced by the location of individual wells with respect to one another.

Well‐field design calculations involve the combined interference of water level drawdown among the various wells in the field. Repeated computational trials for various numbers of wells and well spacings may be required. Calculations using conventional methods are, in most cases, rather time‐consuming.

The final design decision can be approached quickly if it is assumed that the wells have regular spacing. Through the use of a simple formula and table developed in this paper, a given well‐field problem can be calculated in a few minutes with a slide rule. When well spacing deviates appreciably from the regular spacing assumed, the final design calculations should be made with computer techniques.
Effects of Mine Drainage on Ground Watera
Authors: Emrich Grover H. , Merritt Gary L.
Published: July 2006

Coal mining in Appalachia has degraded both the surface and ground water. During mining, ground water is drained from the rocks and the pyrite associated with the coal beds is exposed to air. Oxidation of the pyrite produces high iron ana sulfate concentration and a low pH in the water. Some of this polluted water flows directly into nearby streams and some moves into the ground‐water system. When the latter occurs, the iron concentration can increase up to several hundred mg/1 and the sulfates to over one thousand mg/1. Unfortunately, in most cases the cessation of mining does not stop the ground‐water pollution, and it can take many decades before the ground water again becomes usable.

A detailed study of the effects of coal mining on ground water was conducted in the Toms Run drainage basin in northwestern Pennsylvania where coal mining and oil and gas well drilling have occurred for almost 100 years. The rocks of Mississippian and Pennsylvanian Age produce a multiaquifer system–three major aquifers separated by siltstone and shale beds (aquitatdes). The oil and gas wells act as a conduit system permitting acid mine drainage to move downward from the strip mines to underlying aquifers. It then moves laterally down dip and discharges as springs. The acid mine drainage adversely affects the ground‐water quality by increasing the iron and sulfate content of the water especially in the vicinity of the strip mines.
Flow to Wells in the Presence of Radial Discontinuities
Authors: Sternberg Yaron M.
Published: July 2006

An analysis is presented for the nonsteady state problem of a well, pumping a constant discharge, and located at the center of a circular aquifer surrounded by a radial discontinuity. On either side of the discontinuity, the transmissibility and the storage coefficient are constant but may have different values from those on the other side of the discontinuity. The solution is obtained by using an approximate inversion formula for Laplace transforms. This method leads to a relatively simple set of equations which commonly requires only short computer time for solution.
Infiltration Induced Soil Instabilities
Authors: Adrian Donald Dean
Published: July 2006

Theoretical analyses predicted and experimental observations—confirmed a mechanism by which strong capilary forces hindered instead of helped promote infiltration into soils. Infiltration into an unsaturated soil overlying an impermeable barrier displaces the air from the soil interstices. Unable to escape downward, the air may escape upward in bubbles travelling through large pores, or, if the pores are small and the capillary forces are large, the air is compressed between the wetting front and the barrier. This reduces the infiltration rate and may result in an almost stable wetting front. Under certain calculable conditions the air pressure build‐up is sufficient to cause sudden localized horizontal rupturing of the soil at the wetting front and to lift it along with the infiltrating water, forming a cavity. The air‐filled cavity breaks the flow passages and percolation ceases through pores terminating in the cavity. Observations with soil columns have shown that when provision was made fot the displaced air to escape less than one minute was required for the wetting front to move three inches; when the air was not free to escape and the soil raptured, two weeks were required for the wetting front to move this distance. Grain size and packing play a role by limiting the capillary pressure build‐up and the bubbling pressure. This phenomenon should emphasize precautions to be followed in applying laboratory infiltration results to engineering predictions of field conditions.
The Chemical History of Some Spring Waters in Carbonate Rocksa
Authors: Jacobson Roger L. , Langmuir Donald
Published: July 2006

Insights into the chemical and Hydrogeologie history of spring waters in carbonate rocks can be gained from a study of the chemical quality of such waters and of the waters which feed springs. The median Ca2+/Mg2+ ratio was 3.4 in 29 spring waters from folded and faulted carbonate rocks near State College, Pennsylvania, indicating ground‐water flow predominantly in limestone. The mean dissolved oxygen content was 7.7 mg/1 or 71% of saturation consistent with subsurface flow chiefly under water table conditions. Most of the dissolved solids (as specific conductance) including pollutants such as Cl and NO3 were added to spring waters during ground‐water flow. Specific conductances ranged from 180 to 476 micromhos, with a mean of 347 micromhos. CO2 pressures were from 10−1.9 to 10−2.6 atm with a mean of 10−2.2. atm. The CO2, which is chiefly introduced as gas by downward diffusion from the soil zone, gives spring waters the capacity to hold about 3 times more hardness and alkalinity than streams in equilibrium with the atmosphere. However, all spring waters were undersaturated with respect to calcite and dolomite because of their short residence times as ground water. Dye tracing of ground‐water feeding springs in two drainage basins gave residence times of 2–6 days for subsurface flows of about 4,000 feet. The specific conductance and carbonate saturation data indicate that ground‐water residence times of the 29 spring waters average somewhat longer than 2–6 days.
Comments on Water Laws in Minnesota
Authors: Walton William C. , Haik Raymond A.
Published: July 2006

A research project “Hydrologic and Other Aspects of Water Laws in Minnesota,” was conducted by the authors during the period July 1, 1967 through June 30, 1969 (see Walton and others, 1968, and Haik and others, 1969). The project was supported by funds provided by the U. S. Department of the Interior as authorized under the Water Resources Research Act of 1964 (Public Law 88–379).

The project was concerned with: a compilation and analysis of the numerous codified and uncodified legislative laws, major court decisions, federal legislation, and ordinances of villages and cities bearing on water and related land resources in Minnesota. This paper briefly summarizes, without citation, the results of the research and presents the authors' views on the following subjects: state water resources administration, water policies as expressed in Minnesota's laws, problems associated with differing scientific and legal classifications of water, conflicting objectives of major resource agencies, provincialism and precedent in court decisions, insecurity of existing water rights, the adequacy of current legislation regulating water permits, the adequacy of the existing riparian doctrine of water rights, conflicts of federal‐state jurisdiction, and constraints on development and management of water and related land resources in Minnesota.
Ground‐Water Velocity Partition
Authors: Dunn Darrel E.
Published: July 2006

The true velocity, V, of ground water at a point in the ground‐water system may be expressed as the sum of a number of partial velocities labeled V1, V2, V3, et cetera. Each partial velocity may be denned as a velocity which results from the presence of certain features of the configuration of the water table. Partial velocities may be used to facilitate the discussion of ground‐water flow systems and associated phenomena.
Common Errors in Developing a Ground‐Water Aquifera
Authors: Whitesides D. V.
Published: July 2006

This 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

Carbonate 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

Seismic 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

The 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

There 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

Acidic 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

The 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

Management 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

In 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

The 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

Quality 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

The 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

Vertical 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

A 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

In 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

Median 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.
Quality of Near‐Surface Waters in Southern Illinois
Authors: Davis Richard W.
Published: July 2006

The “ring average” method of generating trend surfaces has been applied to water chemistry data from shallow water wells in southern Illinois. The method is a slight modification of a well‐known geophysical technique. Basically the method acts as a filter which removes anomalies with dimensions smaller than the diameter of the ring. The trend maps generated by the technique are presented and discussed in this paper. Between the Salem‐Woodward structural block and the Wabash Valley Fault Zone water chemistry shows marked changes. These changes suggest that this is a zone of upward moving waters from deep stratigraphic units. The process of reverse osmosis filtration appears to explain some observed phenomena, but by no means all of them. The reasons why the bounding structural features are so effective is not clear either.
Bacterial Movement Through Fractured Bedrock
Authors: Allen Martin J. , Morrison S. M.
Published: July 2006

The movement of bacteria‐laden waters percolating through fractured crystalline bedrock in mountainous terrain was examined to determine whether effluent originating from domestic waste disposal systems could contaminate shallow ground‐water supplies. Inoculated waters were injected into holes and/or wells at two geologically different test sites (granitic, metamorphic) to evaluate the extent of microbial filtration in or along bedrock fractures. Microbiological examination of tracer waters, sampled both above and below the zone of saturation, was made.

Field studies showed that the direction and rate of movement of contaminated ground waters were controlled largely by the anisotropic nature of the geologic stratum, particularly by the orientation of major bedrock fracture sets. Inoculated waters were found to be readily transported by the ground‐water gradient into a downslope well. At one test site, a tracer bacterium traversed a horizontal distance of 94 feet in 24‐30 hours. Continued bacteriological analysis of the contaminated well found the organism to be present for at least five days after inoculation of the upslope well.

In the zone of aeration, bacteria‐laden effluent was found to percolate in or along fractures with inadequate filtration prior to entering the ground water. Studies conducted in metamorphic rock demonstrated that while fecal‐type bacteria decreased slightly during percolation through bedrock fractures, total bacterial densities were generally unchanged.

From the hydrogeological and microbiological data obtained at both test sites, it can be concluded that moderate percolation rates and minimum distances between water wells and leachfield type waste disposal units are inadequate to protect potable ground‐water supplies from contamination in mountainous terrain.
Salt Pollution of a Shallow Aquifer —Indianapolis, Indiana
Authors: Dennis Howard W.
Published: July 2006

Application of deicing salts to streets and highways is a common phenomena to those living in the northern and border States. This paper points out one problem that can occur from runoff from large quantities of deicing salts. Tests of water samples from shallow wells in 1967, 1968, and 1973 document the loss of a water supply in an Indianapolis, Indiana, suburban housing development and the subsequent natural purging of high chlorinity waters.
Problems Associated with Development of Ground Water in Igneous and Metamorphic Rocks — A Case Study in Ghana
Authors: Bannerman Robert R.
Published: July 2006

The “kaolinic porridge” is described as one of the saturated zones within the weathering profile of most igneous and metamorphic rocks in Ghana. The zone is comprised of clay and fine‐grained micaceous materials and is regarded as an important ground‐water reservoir. Due to its fluid nature and the fact that its depth and thickness cannot be predicted, precautionary measures are taken when drilling. Special well design, construction and completion techniques have been adopted to exploit this aquifer successfully. Yields averaging 220 gallons (about 1 cubic meter) per hour can be produced from such aquifers.
Pipe Flow Models of a Kentucky Limestone Aquifer
Authors: Thrailkill John
Published: July 2006

A digital computer program which simulates a limestone aquifer as a pipe network was written and compared with the Sinkhole Plain aquifer of west‐central Kentucky. Model 1, which considers the flow in the network to be laminar, yielded values of head, flow in the network, and discharge at the bounding streams which are in reasonably good agreement with field observations. The over‐all hydraulic conductivity of the aquifer appears to be about 5600 meinzers if the zone of active flow is 30 meters thick, but the northeastern portion of the aquifer probably has a higher transmissivity. The indicated location of the principal ground‐water divide agrees well with data derived from wells and from tracing underground‐water flows. A second model (Model 2) was constructed which considers flow in the network to be turbulent. Although this model yields values which differ from Model 1, the differences are too small to allow the mode of flow in the aquifer to be distinguished using observational data.
The Future of Ground‐Water Resources in DuPage County
Authors: Sasman Robert T.
Published: July 2006

DuPage County, one of the major counties of the Chicago metropolitan area, obtains all of its water supply from ground‐water resources. In 1972, pumpage was 56.6 mgd, 18 percent more than the combined potential yield of shallow aquifers and the practical sustained yield of deep aquifers. Total pumpage from shallow aquifers almost equals the potential yield. In some areas, yields of shallow wells have declined drastically as a result of excessively heavy pumpage. Pumpage from deep aquifers is more than double the practical sustained yield. Demands for water are projected to increase more than 250 percent by the year 2020. Alternative methods of developing supplies to meet the anticipated demands include artificial recharge of shallow and/or deep aquifers, mining of deep aquifers, increased diversion of water from Lake Michigan, demineralizing Mt. Simon sandstone water, and importation of underdeveloped surface or ground‐water resources in north central and northwestern Illinois. Increased coordination of development programs becomes of greater importance as locally available supplies lose the capability to meet growing demands.
Dissolved Organic Carbon (DOC), an Index of Organic Contamination in Ground Water Near Barstow, California
Authors: Hughes Jerry L. , Eccles Lawrence A. , Malcolm Ronald L.
Published: July 2006

The alluvial aquifer underlying and adjacent to the Mojave River near Barstow, California, has been subjected to degradation from percolation of industrial and municipal wastes for more than 60 years. Effluents discharged to the aquifer have contained high concentrations of both organic (detergents, oil and grease, phenols, humic compounds, and others) and inorganic (chromium, chloride, phosphates, and others) substances. The concentration of dissolved organic carbon (DOC), as determined by a wet combustion technique, has been shown to be a definitive parameter in identifying ground water affected by waste disposal. DOC concentrations ranged from 0.1 to 0.8 milligram per liter in the nondegraded ground water and exceeded 6 milligrams per liter in the ground water affected by the waste discharge.

The general distribution of DOC in the degraded ground water has been defined both areally and vertically. The vertical distribution of DOC and other constituents indicates that two plumes of degraded water occur at different depths. A comparison of the areal distribution of DOC and detergents (as MBAS) suggests that some organic compounds may have been adsorbed by the aquifer sediments.
Geochemistry and Genesis of Fluoride‐Containing Ground Waters in India
Authors: Handa B. K.
Published: July 2006

The fluoride content of ground water in India varies considerably. Among factors which control the concentration of fluoride are the climate of the area and the presence of the accessory minerals, fluorite and (or) apatite in the rock mineral assemblage through which ground water is circulating. Regional and tectonic factors also play some part in affecting the fluoride concentration of ground waters. In general, there is a negative correlation between calcium and fluoride concentrations and a positive correlation between fluoride and bicarbonate concentration in ground waters with high fluoride content. Thermodynamic calculations show that some of these high fluoride ground waters are supersaturated with respect to fluorite.

In water sources from Rajasthan, high fluoride concentrations are generally accompanied by high nitrate concentrations. A solution‐evaporation‐base exchange hypothesis is put forward to explain the genesis of these ground waters.

In some parts of India, the fluoride content of ground waters is below 0.5 mg/1, indicating that fluoridation of water supplies may be desirable in these places.
Water Zoning — Tool for Ground‐Water Basin Managersa
Authors: Dutcher Lee C. , Peterson Lee R.
Published: July 2006

Water zoning is not new in arid areas. Many States have laws limiting pumping. However, most of the existing ordinances do not achieve their stated purpose. Many enforce conservation of scarce resources for benefit of future users. Some purport to ensure a continuous water supply to the rights holders. Existing ordinances that limit pumping to the so‐called safe yield do not take costs or recoverable benefits into consideration, and the period of use is not stipulated. Therefore, where pumping is regulated under such ordinances, the basins cannot be managed to obtain maximum benefits to present users of the available supply. Two types of ordinances are discussed: general‐purpose and management‐plan ordinances, which are designed to make possible the achievement of specific objectives. Examples are given of how the latter can be designed to: limit stream depletion and protect existing rights; disperse pumping to increase economic return; force conjunctive use of all land, mineral, and water resources; and establish production quotas to insure optimum economic return to all users during a predetermined period.