ALBERT

Notes: A two-dimensional, passive element electric analog model was used to determine the spatial distribution of natural ground-water recharge in the Santa Cruz River basin of southern Arizona. Existing records were used to draw a ground-water level contour map of the area in its undeveloped condition. The model was made to duplicate these contours by varying inputs from known locations of recharge. Recharge distribution as determined by the model was consistent with previous estimates, but no direct correlation was found with the contributing drainage area.

Notes: The tidal efficiencies of wells tapping the principal artesian aquifer in Glynn County, Georgia decrease with distance from the influencing tidal body and also decrease with well depth. Although the magnitude of water-level fluctuation of these wells is largely dependent upon the distance to a large tidal body, the time of a high or a low water level in the wells is mainly dependent upon the time of a high or a low tide in a small, nearby tidal body. A modified formula for computing tidal efficiency is developed:〈displayedItem type="mathematics" xml:id="mu1" numbered="no"〉〈mediaResource alt="image" href="urn:x-wiley:0017467X:GWAT24:GWAT_24_mu1"/〉 From this formula, tidal efficiency can be calculated rapidly and easily

Notes: A shallow, wide spread perching layer was isolated in the alluvial profiles of western Fresno County, California. Geologic and hydrologic interpretations are given, based on field and laboratory measurements of the physical properties of this layer. Some of the approaches investigated included using existing electrical logs from irrigation wells, head loss observations in wells and piezometers, core drilling, and core analysis. Differences in alluvial profile permeabilities are shown which result in perched water under the existing field flow conditions. The quantity of vertical flow through the layer is estimated using core permeabilities and hydraulic gradients observed in the field.Hydraulic properties and descriptions for the perched zone are presened which can be used to delineate profile flow limitations at other locations in the San Joaquin Valley. The study may be used in estimating the rate at which this perched water table could rise If, in the future, imported water and changes in irrigation patterns cause a large quantity of water to flow vertically.

Notes: The most commonly practiced method of artificial recharge at present is through basins. This spreading method may not be physically feasible or practicable if land values are high or a shallow, densely compacted layer forms a barrier impeding the direct downward percolation of the ponded surface water.For the case of the latter condition, alternative methods of wells or trenches dug down to the pervious aquifer and backfilled with gravel have been investigated. These were explored from the standpoint of construction and operating cost and hydraulic efficiency as influenced by such factors as the depth to the aquifer, the thickness, depth of saturation, permeability and specific yield of the aquifer, interference of closely spaced wells and duration of continuous operation of the wells or trenches. Furthermore, effects of bacterial growth and chemical composition of the recharge water on the hydraulic performance of wells or trenches are discussed.An economic comparison based on field conditions in a prospective recharge site at Stockton, California, is used to illustrate the developed criteria for relative effectiveness of the two methods.As a general conclusion, it was found that while recharge through trenches would be more efficient hydraulically and economically for the case of very shallow subsurface barriers, wells would become more competitive as the thickness of an impervious top layer increases.

Notes: The horizontal viscous flow model with “infinite” areal extent can be used for almost any well flow problem whether two-dimensional or three-dimensional, steady or nonsteady, single aquifer or multiaquifer. This model can also be used in the field of soil mechanics for subsurface drainage problems. The design includes scale model analysis and the application of conformal mapping techniques in order to simulate an ideal aquifer. Construction, calibration, and test procedures for the model are described. The apparatus has proved to be both a valuable research tool and an excellent teaching aid.

Notes: One of the deepest water-exploration wells in the southeastern United States was completed in 1966 at Jacksonville, Florida. It was drilled to a depth of nearly 2,500 feet to supply geologic and hydrologic information on the deeper unexplored part of the Floridan aquifer. This aquifer consists of a series of water producing zones separated by nonproducing zones. An important new fresh-water producing zone was found, and the contact between the fresh water and salt water was located. The well was completed in three separate zones so that it could be used to monitor the the deeper part of the aquifer to detect any salt-water encroachment. This paper describes the objectives, techniques, and results of drilling the test well.

Notes: A rapid graphical technique for the determination of aquifer transmissibility from a variable discharge pumping test is presented. The data required include the variation of discharge with time during the pumping test and a record of the recovery ar an observation well after the well was shut off. An example using a synthetic well data is provided.

Notes: Comparison of the analysis of 3 and 4 day pumping tests with the analysis of water-level changes due to 18 years of pumping suggests that experience in an area can be a critical factor in determining the transmissivity and storativity of an aquifer.

Notes: The rapidly increasing development of ground-water resources in northeastern Illinois has brought about regional and local problems of water supply, thus creating considerable interest in the feasibility of artificial recharge as a partial solution. Artificial ground-water recharge is considered as a partial solution to regional and local problems of water supply in the primarily metropolitan region of northeastern Illinois. Five artificial recharge facilities are now in operation in the area; their average annual recharge rates range from 25,000 to 395,000 gallons per day (gpd). Several additional areas where artificial recharge may be feasible are identified on the basis of criteria established for the region.An initial study in the Park Forest-Chicago Heights area indicates that recharge to the Silurian dolomite aquifer, the source of water supply in the area, is feasible. This study provides guidelines to aid in additional studies of artificial recharge in northeastern Illinois.

Notes: Two case histories are presented which illustrate that by analyzing drill cuttings or bailed samples, by knowing total depth of a test hole and position of the static water level, and by studying the driller's log, not only can a well's yield be predicted—but also drawdown may be predicted for any well in advance of a pumping test.The estimation of specific capacity (gpm/ft of drawdown) is invaluable in well design, particularly in the United States, where drilling contractors work rapidly and efficiently. Knowledge of probable specific capacity can aid in recommending proper screen length, diameter, slot width, and setting. It will enable cost estimates for proper pump size to be made, for casing requirements to be determined, and also for ultimate well diameter and depth to be determined. Test-pump setting can also be anticipated.Case History No. 1 illustrates the above techniques, and how a new well was drilled, developed, designed, and completed adjacent to a poorly designed and equipped water well. The new well proved to be nine times more efficient (i. e., “better”) than the old well. Reasons for this improvement are shown, and the two wells are compared and contrasted.Case History No. 2 shows data from a constant-rate pumping test following calculation of a well's specific capacity using estimates of aquifer permeability. Analysis of dynamic water-level recovery measurements resulted in a transmissibility of 16,150 gpd/ft compared to an estimated 16,000 gpd/ft from a visual inspection of sand analysis grading curves. The well's specific capacity was estimated to be between 8.4 and 8.9 gpm/ft of drawdown. The measured specific capacity was 8.35 gpm/ft with an efficiency of 85 percent. Actual permeability was 230 gpd/ft compared to the estimated 228 gpd/ft2!Six figures are included showing well construction details, sieve analysis curves, a semi-log plot of recovery measurements obtained during an aquifer pumping test, and graphic representations of approximate permeabilities for granular materials ranging from clay/silt to fine gravel. Six tables give characteristics of samples recovered from two test wells, permeability estimates of the disturbed samples, approximate permeabilities of various granular materials, and specific capacities for 100 percent effective water wells with varying diameters, coefficients of storage, and pumping periods. Three photographs further illustrate the principles enumerated.The methods described can give acceptable results (although they may not be as spectacular as the two detailed case histories) if sound judgement is used; if local conditions are somewhat known; if sampling methods are described; and if the procedures are not abused by expecting extreme accuracy. A reasonable estimate, or perhaps, just a close scientific “guesstimate” is all that should be hoped for by the hydrogeologist and his client in predicting well yields. But these techniques are a great advance over the“forked peach stick” philosophy still used for similar purposes by pseudo-scientists in the United States and foreign countries (although no cases where a dowser or “water witch” has successfully predicted drawdown in addition to yield have come to the attention of the writer).The data in this report are derived from approximately 500 wells or more designed by the author in 26 States and in many locations abroad. Rather good success has been obtained regarding close correlation between estimated and measured specific capacities from a variety of geologic environments and aquifer parameters.

Notes: The intensively irrigated Arkansas River Valley in Colorado is underlain by a valley-fill aquifer resting in a U-shaped trough cut in relatively impermeable Cretaceous rocks. Ground water is pumped to supplement surface water; in the last 10 years pumping has more than doubled. Ground water is closely related to the Arkansas River; percolation from irrigation recharges the aquifer, which discharges into the river. Pumping has resulted in a reduction in streamflow because it intercepts water that ordinarily would have reached the river. The 1,500 irrigation wells in the Arkansas Valley withdrew 230,000 acre-feet of water in 1964.An analog model is being used to evaluate the relation of ground water to surface water and to predict effects of changes in water management. The model, simulating a 150-mile reach of the Arkansas Valley (Pueblo to the State line), has a resistor spacing of 8 per modeled mile. The framework for the model was a transmissibility map; transmissibility ranges from less than 50,000 to 700,000 gallons per day per foot. Specific yield averages about 0.2. Hydrologic boundaries, such as the Arkansas River, and the bedrock valley-fill contact were simulated. Applied water, precipitation, evapotranspiration, and ground-water pumping were the independent variables programed. The model is being verified by comparing predicted changes in water level and river discharge with observed changes.

Notes: A method is presented for computing maximum drawdown in a well being pumped intermittently but in accordance with a regular sequence of fixed periods of pumping at constant discharge followed by fixed periods of rest. The method is extended to allow for interruption of the basic pattern by occasional changes such as the elimination of the pumping phase from certain individual cycles.

Notes: The frequency distribution of dissolved-solids content of ground waters in geologically and climatologically homogeneous terrane units commonly approximates a log-normal distribution. A graphic logarithmic transformation is de-scribed which permits rapid calculation of approximate values for the mean, standard deviation, and coefficient of variation. Statistical parameters calculated by this method show good agreement with known physical conditions in the terranes studied and are precise enough for use as a mea-sure of variability of quality of ground waters for national planning purposes.

Notes: Photogeologic study has been useful in the location of ground-water sources in the state of Sao Paulo, Brazil, and could be important to the investigation of water resources in other areas.Until 1963, it was believed that large areas of the state were unsuited for the location of ground-water wells (as in pre-Devonian crystalline formations) and others weregenerally considered too hazardous (Paleozoic and Tertiary: sandstone lenses in shales). Since that time, when aerial photographs of the whole state became available, the authorhas verified an earlier hypothesis of his own that there are actually very few areas in the state which do not have suitable locations for water wells, and that photogeology is a most valuable method of prospecting.The water sources are parts of highly developed fault/ fracture systems which are identifiable on aerial photo-graphs, at least in this warm humid climate with dry season. Over the fractures the rocks are deeply decomposed, the debris are removed in the rainy season, and existence of water in the dry season promotes higher and denser vegeta-tion along aquiferous fractures, which usually are located in deep straight-line valleys. Even where competent beds are overlain by more than 100 m of unconsolidated strata, many discontinuous nets of parallel straight-line segments are detectable probably because all fractures are really faults with significant throw.To be most effective, the method requires stereoscopic study of areas having dimensions on the order of 10 × 10 km. The selection of locations for drilling should be sup-ported by analyses of the dip of fracture planes (hade) and by other geological-geophysical methods, especially by subsoil electrical resistivity surveying.

Notes: The purpose of this paper is to stimulate additional interest in the hydrogeologic aspects of the International Hydrological Decade (IHD) program and to urge the full cooperation and participation of hydrogeologists in the research and educational activities of the Decade. The IHD, 1965–74, will strengthen the scientific base for water use and conservation, stimulate education and training in hydrology, and improve the ability of developing and developed countries alike to cope with their water resources problems. UNESCO provides an international intergovernmental umbrella and the Secretariat for IHD. More than 90 Member States of UNESCO are participating in IHD and a majority of these have established National Committees for IHD.The UNESCO/IHD program will consist primarily of activities of participating countries themselves, catalyzed, coordinated, and supplemented by international intergovern-mental agencies and scientific associations. Activities of Member States of UNESCO include: collection of basic data through data analysis and applied hydrology; applied and basic research; continental and global water balances and the global hydrological cycle; establishment of hydrological networks and the development of technical competence; fundamental research; definition of principal hydrological features of countries such as precipitation, discharge of water, sediment and dissolved load, evapotranspiration, distribution of tritium in precipitation, surface and ground waters; experimental basin studies to provide insight on the interplay of environmental and hydrological parameters in a broad range of geological, climatic, and ecological conditions; distribution of water in the atmosphere, in lakes and rivers, underground, in permanent ice and snow and permafrost; studies of the rate at which water moves through the hydrologic cycle; use of orbiting satellites and remote sensing instruments for measuring phenomena in the atmosphere and at the Earth's surface and for relaying observational data; organization of egional advanced training and study courses and hydrological institutes; exchange of teams of experts, exchange of professors and research scientists; and organization of symposia and regional seminars.The US/IHD program focuses on the following five major objectives: (1) large-scale balances of water and water-borne material studies; (2) hydrological performance of river, lake, and ground-water basin systems studies; (3) studies of specific hydrological processes and their variations in time, and improvement of methods and techniques; (4) education and training; and (5) services providing coordination and administration support. These objectives provide a framework within which the scientific and engineering community can contribute to IHD. A provisional US/IHD program statement identified, among others, the following hydrogeologic activities: estimation of ground-water discharge to the sea, effects of variations in piezometric head on land subsidence, hydrology in limestone areas, radionuclide tracer studies, chemical behavior of ground water, and dispersion in moving ground water.Hydrogeologists are urged to submit proposals concerning activities for possible inclusion in the US/IHD program. The following seven criteria guide the formulation and inclusion of activities in the US/IHD program by the U. S. National Committee for IHD: (1) the activity is sufficiently fundamental or aimed at results so useful that it will interest all hydrologists; (2) the activity requires joint or coordinated work in two or more countries; (3) the activity concerns a problem whose solution and verification would be improved by work in two or more countries; (4) the activity concerns continental, hemispheric, or global phenomena or processes; (5) the activity requires action in international areas such as polar regions, international waters, and multi-national basins; (6) the activity involves the hydrologic use of earth-orbiting satellites; and (7) the activity involves intercountry exchange or visits of personnel (in some instances, the exchange or visit itself may be the main item of interest). Proposals may be of projects already in progress, for expansion or modification of on-going projects, or for new work. Proposals may be submitted as contributions, requiring no financial aid from or through the IHD; for endorsement by IHD as an aid in obtaining financial aid elsewhere; or, when funds become available, as IHD projects receiving financial assistance from the IHD. Further information may be obtained from: U. S. Na-tional Committee for the International Hydrological Decade, National Academy of Sciences, 2101 Constitution Avenue, N. W., Washington, D. C. 20418.

Notes: A type-curve method for determining anisotropy of unconfined aquifers, developed from electric analog simulation, is applied to drawdowns observed near, a well pumping from a glacial outwash aquifer at Piketon, Ohio. The coefficient of vertical permeability, P z'averaged 365 gpd per square foot. Computed drawdown for the pumped well, based on this value, differed by only a small amount from the observed drawdown. The coefficient of storage, determined from type curves for an image well system, averaged 0.20, typical of unconfined aquifers. Application of the method required a thorough knowledge of geohydrologic controls operating at the test site.

Notes: Criteria and factors are considered which affect the design of a Hele-Shaw viscous flow model for use in ground- water studies. Procedures and construction techniques for assembling such a model are outlined. Some of the advantages and drawbacks in using a viscous flow model are discussed, Three examples are used to demonstrate the use of the model

Notes: A nuclear (atomic) explosive, detonated at suitable depth below the land surface, appears to offer substantial advantages and economies as a tool in the development and management of water, under certain special hydrologic situations. It is appropriate, therefore, that we seek to understand not only the potentials, but also the limitations of such a detonation. This paper is a first, small step toward that end.Greatly over-simplified, what does an underground nuclear detonation do that it can become a tool of water development and management? Consider first a detonation at a depth sufficiently great that none of the products vent to the atmosphere. Minimum depth for such “containment,” in feet, is close to: 〈displayedItem type="mathematics" xml:id="m1"〉1〈mediaResource alt="image" href="urn:x-wiley:0017467X:GWAT13:GWAT_13_m1"/〉in which W = explosive energy, in kilotons.

Notes: In this short paper, selected water quality problems and the research efforts aimed at their solution supported under P. L. 88–379 (the Water Resources Research Act of 1964) at State Water Research Centers are presented. The water quality problems and associated research efforts presented are not necessarily of high priority with respect to the national needs for water quality knowledge; rather, the problems and research discussed are presented as typical of local or regional situations and as examples of the awareness of State Water Resources Research Centers to the local or regional needs for improving water quality management.Selected water quality problems associated with urban- ization, modern agriculture, industry, recreation, and natural environments are discussed with respect to the needs for new knowledge leading to improved management of water resources. Selected Water Resources Research Centers' projects with the objectives of discovering some of that new knowledge are discussed with respect to the research approach adopted by the investigators.

Notes: Maximum yields from minimum aquifers can be accomplished only by strict adherence to best known practice procedures while following the three necessary steps to well completion. These steps are well design, well construction and well development.In well design good practice begins with an accurate log and the obtaining and careful testing of formation samples. From such data, optimum depth, diameters, screen settings, and gravel pack gradations for expected yields can be selected.Well construction should incorporate equipment suited for the kind of formation, size of well, and depth to be drilled. It should be operated by competent and reliable personnel capable of faithfully maintaining all specifications and finishing in a reasonable time, with a well in which all measurements shown on the log are correct.Development techniques which are appropriate for the well, aquifer, and drilling equipment should be used, al-though it appears the high velocity horizontal jetting tool, used in conjunction with chemicals and regulated pumping, offers the most promise.

Notes: The nature and extent of movement of ABS (alkylben-zenesulfonate) and other sewage components through natural soils were studied in the laboratory and in the field north of Denver, Colorado. Small amounts of ABS and bacteria pass through soils and reach the zone of saturation, where they move laterally down-gradient several thousand feet. Total dissolved solids show little fluctuation during such movement, possibly because extracted solutes are replaced by other solutes leached from the soils during water infiltration.In laboratory studies Denver sewage-plant effluent was filtered through packed columns of 8 types of soils. ABS was not significantly removed by most of the soils; how-ever, muck, greensand marl, and residual basalt soil ini-tially removed up to 94 percent of the ABS. Some ABS was removed only after development of bacterial slime on the soils; subsequent infiltration caused leaching of the slime and its adsorbed ABS and other constituents. All soils initially removed about 90 percent of the bacteria within a few feet of travel, but a small percentage passed through the soil. Bacterial clogging occurred quickly in the fine soils but only in modest amounts in the coarse sand, even after three months of flow.Field studies included analyses of river and irrigation water contaminated from a sewage-plant effluent, and well water from selected sites down-gradient between unlined irrigation ditches and the river. Concentrations of ABS and bacteria were significantly reduced during infiltration of irrigation ditch water to the water table. As noted in the laboratory the concentrations of both of these contaminants can be reduced through soil filtering action. In addition there may be some dilution of the infiltrate by the ground water. Dissolved solids showed practically no change between the ditches and the wells.

Notes: The ever-increasing volume of information being collected by the Groundwater Division of the Research Council of Alberta required that a data storage and retrieval system be devised to handle this information in an efficient and economical manner.The HYDRODAT computer-oriented system developed for this purpose is a modification of the format developed by the United States Geological Survey and conforms to the proposed interagency compatibility requirements set forth by the Canada Department of Energy, Mines and Resources.The basic elements of the system are: a well-schedule form for the recording and coding of geologic, hydrologic, and water quality data; and five 80-column IBM punch cards for transferring the coded data to magnetic tape.Selective and rapid retrieval of large volumes of ground-water information using HYDRODAT provides the geologist and engineer with analytical methods which would otherwise be tedious, if not impossible, to apply by conventional methods.

Notes: Water as a natural resource has little value until somebody wants to use it and the dollars and cents value has normally been established by the costs of moving water from its source to the point of beneficial use. The value of water ranges within wide limits from perhaps $2 per million gallons to $70 to $100 per million gallons and an average value might be $20 to $30 per million gallons. Water is no longer free and the costs of providing water in adequate quantity and of suitable quality will increase in the future as the sources of water are more fully utilized and the needs for more extensive treatment increase. The decision to use surface water or ground water is usually based on availability and the costs of providing the water at the point of use for the lowest possible cost. In estimating such costs, however, all costs of development, construction, treatment, operation and maintenance must be included. The principal advantages of ground water include availability close to the point of use, usually lower treatment costs, lower capital outlay, ability to increase the supply by small increments and smaller property requirements for storage. Ground water is often preferred because of its constant chemical quality and temperature. It is the opinion of the author that the effects of the impending water shortage can be minimized by elimination of pollution of our available water supplies and greater use and better management of our ground-water supplies including natural and induced recharge.

Notes: The ground-water aquifer underlying the northeastern corner of Colorado presently is estimated at 80,000,000 acre feet — enough to last several decades at present rates of use. The rate of use has, however, been increasing substantially in recent years and the possibility of depleting this resource is very real. While depletion of stock resources is a common theme in conservation and natural resources literature, only a few empirical studies are available to show the economic consequences of alternative rates of use. As a result, ground-water policy has often lagged behind the needs of developing areas.The Economics Department at Colorado State University, under the auspices of the Office of Water Resources Research is currently engaged in an empirical study of ground-water development problems in Colorado's High Plains area. Research is just beginning, but the following themes will be examined:〈list xml:id="l1" style="custom"〉1The economics of common property resources and the different management problems associated with them.2Problems faced by individual farm operators as they make the switch from dry-land to irrigated farming. Problems of externalities among farm firms will be approached.3Problems likely to be faced by inhabitants of communities in the developing area. The integration of the agricultural with the non-agricultural sectors will be stressed.4Policy recommendations appropriate to areas of rapid ground-water development.While the activities at Colorado State University are confined to a relatively small geographic area, it is assumed that applications will be made broader in scope and will prove useful in other parts of the nation.

Notes: The consultant expects the driller to provide good data and competent performance. Exchanges of views associated with drilling and construction can prove to be mutually beneficial. Contacts between the consultants and the drillers have a tendency to upgrade the quality of the basic datacollected. These contacts may aid the driller in delivering full performance and thus improve the overall quality of thedrilling and construction he performs for the client. As a result, everybody associated with the water well industry-drillers, consultants, and clients - stands to gain by these contacts. It is hoped that these beneficial contacts within the water well industry will become even more common in years to come so we all can gain from one another's knowledge and experience.

Notes: A graduate program in hydrogeology is described, in which the field is defined as encompassing the whole range of processes operating in water and water-mineral mixtures at and near the earth's surface. The interdisciplinary character of this training is insured by requiring both a minor from another department and course work in other sub-disciplines of hydrogeology in addition to the one in which the thesis is carried out. The importance of nonscientific aspects of hydrogeology is recognized by allowing for minors in fields such as economics and business administration.

Notes: The Colorado Assembly passed three laws in 1965 concerning water rights. Two of the new laws pertain directly to ground water and take cognizance of the fact that some wells divert water that would otherwise reach a stream. The use of ground water is now regulated under the doctrine of prior appropriation, which has applied to the administration of surface water in Colorado since 1852. Under the doctrine of prior appropriation, the first person to make beneficial use of water establishes a right to use that water even when there is a shortage of water for later appropriators.This paper discusses the new laws as they relate to hydrologists and others concerned with hydrology. The law sets up administrative processes for implementing the use of water but raises many questions. Proper hydrologic investigations are necessary as a technical base for administration of the laws.

Notes: Measurements of ground-water recharge in sand drift aquifers in northern lower Michigan show that winter and spring precipitation provides a major portion of the annual water yield. In general, the accumulation of snow beneath forest canopies varied inversely with crown density during the winters of 1962 and 1963. Pine plantations with crown densities of over 80 percent in winter had 1.8 inches less water in the snowpack than neighboring deciduous forests, at the time of maximum accumulation. Ground-water recharge during the melt period was proportionally lower beneath the pine forests where snow accumulation was least. The difference in snowmelt recharge was a major factor in the smaller annual water yields measured under these pine forests.

Notes: Watercourse aquifer systems in many areas are adversely affected by wastes disposed into surface-water sources, resulting in either reduced streambed permeability, infiltration of wastes into the aquifer, or both. These conditions are illustrated at Lancaster, Ohio, where low streambed permeability in the vicinity of the municipal well field, resulting from the discharge of wastes to the Hocking River, seriously retards the infiltration of surface water and lessens the available yield of the wells. The wastes consist of brine and iron-laden effluent from the municipal treatment plant, discharged within the area of influence of the pumped wells to a stream already carrying much organic waste and other debris. Upstream from the discharge sewer, muck and organic debris have accumulated thickly on the streambed, while downstream from the sewer the streambed sediments have become tightly cemented by iron and other constituents in the waste water. There is evidence that, despite reduced streambed permeability, wastes have entered the aquifer and have materially contributed to declines in well efficiency and to recurring problems of well maintenance.Conditions such as those illustrated at Lancaster occur also at Dayton and are not uncommon elsewhere in Ohio. Indirect contamination of aquifers and adverse physical and chemical alteration of streambed sediments, resulting from surface-water waste disposal, may in many places pose a threat to the ground-water supply. This fact should not be overlooked in determining water-quality standards to be established under the Water Quality Act of 1965.

Notes: The Geological Survey has been the foremost agency in the investigation of ground-water resources in the United States beginning about 1910. Most of the basic principles of modern ground-water hydrology were developed in the Survey's program of cooperative investigations.Use of ground water in the United States in 1960 was about 17½ percent of all water uses, excluding water power. The use will probably increase, though at a decreasing rate. Although amount of use may level off, the need to know about it will not.While coordinating its activities with those of the Office of Water Data Coordination and the Office of Water Resources Research, the Survey expects to step up its work in all three areas of data collection, investigations, and research. However, there will be changes of emphasis.Collection of raw data will tend to stress key observation points, and more and more observation of temperature and quality, including contaminants. Investigations will be aimed at upgrading reconnaissance coverage to general coverage for most of the Nation. The areal basis will be stream drainage basins and special hydrologic terranes, rather than political units. There will be an increase in the preparation of analog models for representative ground-water systems.In research, the problem-oriented basis will continue. Stress will be on basic principles that pertain to artificial recharge, and the natural recharge and discharge of ground-water reservoirs; and also on the application of geologic principles on a regional scale. These are critical elements in the management of surface-water and ground-water resources conjunctively in river basins.

Notes: Acidizing water wells to increase yield has proved to be an uneconomical method of well development or rehabilitation in some cases where the aquifer permeability was low and normal operating head great, in wells affected by methane gas, or where the practical sustained yield of the aquifer had been exceeded. Illinois studies show that controlled pumping tests before, during and after development are necessary to accurately evaluate the effectiveness of rehabilitation methods employed. Geologic definition of aquifers and records of pumpage and water-level information are invaluable aids.

Notes: The relation between water quality and water movement within the ground-water reservoir may be better understood if studies of flow systems are used in conjunction with hydrochemical methods. Within small watersheds, local, intermediate, and regional flow systems may develop, depending upon the shape, the relief, and the thickness of the ground-water reservoir. Lateral and vertical variations of water quality in the ground-water reservoir reflect the difference in length of flow paths within a system. The relative ion concentration of the major ions in solution in ground waters change as water moves from recharge areas to discharge areas. These changes are used to interpret the direction and rate of ground-water movement.Ground-water types mapped in the Two Rivers watershed of northwestern Minnesota indicate that calcium bicarbonate type water occurs near the source of recharge and progressively changes to the sulfate type as water moves downgradient toward the discharge area. Local recharge areas are indicated by the greater penetration of calcium bicarbonate waters into the ground-water reservoir. The calcrum bicarbonate type water of surface streams during low flow indicates that water moves into the stream from the upper part of the ground-water reservoir. Chloride type water moves from the Paleozoic rocks and mixes with water in the glacial drift probably at places where permeable zones in the Paleozoic rocks are in contact with the overlying drift.

Notes: This study of the geometry of limestone solution is based on the following conditions: (1) the limestone is impermeable but contains and transmits water in joints, fractures, bedding-plane partings, and solution channels; (2) at depth, the limestone aquifer is underlain by impermeable rock; (3) ground water in the limestone is under water-table conditions; (4) recharge to the limestone is by infiltration of precipitation through the overlying rock to the zone of saturation; (5) discharge from the aquifer is by seeps and springs; and (6) ground water dissolves the limestone through which it flows, continuously modifying the flow pattern and the hydrologic properties of the medium. These conditions commonly are found in limestone terranes in the eastern and central United States. An electrical analog was constructed conforming to this description of the ground-water flow system and has been used to define the pattern, velocity, and density of ground-water flow and the relative length of time of contact of water with the aquifer. Successive models are used to illustrate progressive limestone solution and changes in ground-water flow in the aquifer. The initial analog indicates a strongly convex water table with the greatest density of flow at shallow depths beneath the water table near the point of discharge. Successive models indicate greater concentration of flow near and on the level of ground-water discharge, an overall lowering of the water table, and a pronounced flattening of the water table near the discharge point.Results of the analog study support the following conclusions:(1) The most active zone of solution is at shallow depths beneath the water table and near the point of ground-water discharge. Consequently, the size of channels generally decreases with depth and increases with proximity to the point of ground-water discharge.(2) Generally, solution channels have a greater lateral than vertical extent.

Notes: It is the purpose of this paper to call ro your attention the existence of the International Hydrogeologic Map Display and the International Legend for Hydrogeologic Maps, and to encourage those in the USA working in the water resources and associated fields to review these recommendations and forward their comments so that they may in turn be relayed to the next meeting of this international commit-tee. It is requested that any maps following the legend be forwarded for addition to the committee's file and use in the Internationa] Display at the next General Assembly meeting of IUGG.

Notes: The Republic of Korea shares the world-wide problems of water supply variability in time and space - they have too little water at some time and in some places, and too much water in others. Drouth is a recurring threat; floods occur nearly every summer. The floods of July 1965 are reported to have been the most costly in history. The population is increasing at a rapid rate and material things are in short supply. However, the people of Korea are making a tremendous effort to modernize facilities, construct an industrial base, improve agricultural practices, control the rivers and develop water supplies, and in general, improve the standard of living. With a per capita income of about $80 per year, Korea has a long way to go in its climb up the economic ladder, but the people are able, intelligent, energetic and avid for learning and progress. They enjoy one of the highest literacy rates in the Far East, and have a trained core of professionals in most fields, except they lack a trained cadre of specialists in ground-water studies and have very few experienced water well drillers. During the Japanese occupation of Korea systematic ground-water studies were begun, and ground-water development followed soon afterwards. But the limited staff of Japanese geologists employed in the effort returned to Japan at the end of World War II in 1945. In the uncertainty of the next 8 years, which included the Korean War, it was impossible to develop trained manpower and an organization.Presently, there is widespread interest on the part of the Korean Government to develop ground water wherever it may be for such uses as irrigation, industrial supply and development, municipalities, villages, and sanitary rural supply. As a result of this interest the author spent four months in Korea in the fall of 1964 and the spring of 1965 at the request of the Agency for International Development, U. S. Department of State, to review the situation and report on the feasibility of a United States supported effort to help the Korean Government to make systematic studies that would lead to ground-water development, and to any necessary improvement of their methods of hydrologic data acquisition and utilization.

Notes: The digital computer is used on a routine basis in the ground-water program in Kansas for tasks ranging from the listing of water-quality data in tabular and publishable form to statistically and graphically analyzing a mass of data.In the past year a number of computer programs in FORTRAN IV have been developed by Charles O. Morgan and Jesse M. McNellis using an IBM-7040 computer to store, retrieve, and manipulate water-quality data. These programs:(1) Tabulate data at the rate of 40 chemical analyses of water per minute in a format similar to that found in the Kansas ground-water publications.(2) Perform necessary calculations and print Stiff diagrams at the rate of 30 per minute.(3) Perform necessary calculations and print Piper diagrams, including a square modification of the normally diamond-shaped cation-anion diagram, and trilinear diagrams of the cations and anions. The symbol representing the analyses located on the diagrams can be designated by either an analysis number or a geologic unit number. A cation-anion diagram showing the average chemical composition of water for an aquifer can also be printed. These diagrams for 50 analyses can be produced in 1.5 minutes.(4) Plot maps of 42 individual, combined, or calculated parameters obtained from the data cards. These maps can be plotted to any specified scale and for as many as 10 designated geologic units. Computer time involved for one map with 50 plotted points is 15 seconds.It is estimated that the use of these programs will save several man-months during a ground-water study, and the error inherent in the manual manipulation of data is greatly reduced. The present cost for running 50 analyses through the four water-quality programs on the computer is approximately $20.

Notes: In the past 20 years, since 1945, there has been a substantial increase in the application of electric well logging to water wells. In the early days, there were very few water wells being logged, principally city supply wells and other larger commercial wells. Now, it is not uncommon to be called to service water wells of all sizes, even the small back yard well. The well drilling industry is becoming more and more aware of the benefits that can be derived from use of the electric log, and there will almost certainly be an increase along these lines in the years ahead. There are some very good reasons for this growth and acceptance of the electric log, and pointing out some of these reasons and applications of the electric logs to water well drilling is the purpose of this paper.

Notes: This paper is concerned with the development of the application of theoretical aquifer concepts to the administration of water rights from ground-water sources, and exam- ples of the application are given. Kansas operating under the Appropriation Doctrine is applying the rule of priority of right, the first in time is the first in right, to the administra- tion of water rights from ground-water sources. The application is not absolute in that some mutual interference pre-scribed by the reasonable raising and lowering of the water level must be allowed as specified in the law.The application of hydrologic considerations in the administration of problems between individual wells is first given. The scope is then expanded and data presented for the application to large basin development where pumpage is largely from storage, using the current situation in the high plains area of western Kansas for the example.An addition to the normal ground-water basic data collection program called a “Key Well” program is proposed where the key well is a production well. This well is to be fully instrumented to give information on diversion costs and evaluate methods of construction, as well as identify any changes in aquifer characteristics with respect to time.

Notes: Chemical analyses of ground-water samples taken from differing depths in a four-county area in east Texas showed a general stratification with respect to dissolved iron, pH and hardness. On the basis of this stratification the waters of the ground-water reservoir were divided into a shallow zone of oxidation, A; a deep zone of reduction, C; and an intermediate and unstable zone, B, in which waters from above and below are mixed. Ground water from zones A and C generally is almost free of iron, whereas water from zone B generally contains objectionable amounts. This zoning is explained by recent laboratory work and theoretical data on iron in natural waters. Wells constructed to draw only from zones A or C should yield water relatively free of iron.

Notes: During a three-month trial period, 70 million gallons of industrial wastes were successfully injected at moderate pressures into a deep limestone in the westernmost part of Florida. The movement of these wastes is expected to be predominantly southward toward the natural discharge area which is presumed to be far out in the Gulf of Mexico. The limestone lies between two thick beds of clay (aquicludes) and contains 13,000 parts per million salty water. A series of aquifers and aquicludes appear capable of preventing contamination of the overlying fresh-water aquifers.

Notes: The need for investigating the economics of groundwater pumpage was developed to aid in the interpretation and administration of the Kansas Water Appropriation Act. The Act requires that in determining impairment from the lowering of static water level, the economics of pumping water shall be considered. No comprehensive treatment of the subject matter has been found.The investigative work is presented in three parts consisting of ground-water interference, the definition of general cost functions, and the effect of interference on costs. The physical process of ground-water pumpage for a single well in both steady-state and nonsteady systems is used as a beginning basis for both interference and associated costs. Interference between multiple wells is then developed for both idealized states of condition. In the second part, economic parameters with associated costs, primarily for irrigation use of water, are developed and generalized cost functions given in terms of discharge, total head, and operating time. In the third part, an analytic model is developed to define the costs associated with mutual interference. The procedure has been tested on a limited number of examples to find the relative sensitivity of different parameters on costs.

Notes: The Sokoto basin in semiarid northwestern Nigeria contains Cretaceous and Tertiary semiconsolidated deposits that dip gently northwest off an oldland of pre-Cretaceous crystalline rocks. Until recent years the dug well has been the chief source of ground water for the Hausa cultivators and the pastoral Fulani inhabitants of the region. Borehole exploration sponsored by US AID and the Geological Survey of Nigeria with technical guidance from the writers of the U. S. Geological Survey has revealed that the basal section of the Gwandu Formation contains a productive artesian sand aquifer throughout a 5,700 square mile area. Transmissibilities of the aquifer proved to be as high as 180,000 Imperial gallons a day per foot but generally decrease towards the west. The free flow areas total about 1,000 square miles with pressure heads in boreholes up to + 83 feet above land surface and individual flows as great as 12,000 gallons per hour. Beneath the Gwandu, pressure aquifers in the Rima Group and the Gundumi Formation also produce flowing water in the lowland (fadama) of the Sokoto River. In the southern part of the basin, however, only one aquifer is present in the Cretaceous sequence, because the Gundumi aquifer is absent and the Rima aquifer apparently grades into the upper permeable section of the Illo Group. The quality of the water from all the pressure aquifers is generally quite good, although the iron content is high in places and salinity increases in the very deep aquifers.In Sokoto Province more than 2 million people and their livestock use less than 5 mgd of water drawn from dug wells and about 1 mgd from boreholes. The newly discovered flowing artesian water can do much to improve the water supplies of remote villages in the province and even supplement river irrigation during the dry season in the fertile fadama.

Notes: Valley City, North Dakota, has an average daily water use of 750,000 gallons, which is obtained from wells tapping pattly confined gravel deposits in the Sheyenne River valley. These deposits at Valley City have a maximum thickness of more than 50 feet and an areal extent of approximately 1 square mile. The aquifer has been artificially recharged successfully since 1932 by diversion of water from the Sheyenne River to an abandoned gravel pit. During this time the piezometric surface in the aquifer has been raised more than 22 feet.Prior to 1958, the recharge system was operated from January until June; however, when the piezometric surface rose to within about 8 feet of the surface, the recharge operation was discontinued. Between June and January the piezometric surface declined as ground water was withdrawn. During the recharge-discharge cycle, the average annual fluctuation of the piezometric surface was 10 feet, amounting to a change in storage of about 1,000 acre-feet of water. Since 1958, the recharge system has been operated throughout the year. There has been a gradual improvement in the quality of the water in the aquifer since the installation of the recharge system.

Notes: Observations of temperature, pll, specific conduction, and discharge, and concentrations of calcium, magnesium, potassium. lithium, and sodium in the discharge of a flowing well reveal that geochemistry of aquifers should be based on sample wells which have been allowed to discharge for an extended period.

Notes: A systematic investigation of the steady-state discharge to wells that partially penetrate a homogeneous and isotropic non-leaky artesian aquifer was made using an electrolyte-tank model. The experimental results were compared with the discharge calculated by methods developed by several previous writers. This comparison showed that the formula of Li, Bock, and Benton (1954) gave the most reliable results over the widest range of the appropriate geometric variables.

Notes: The States of Nebraska and Kansas are negotiating a compact for apportionment of the waters of the Big and Little Blue Rivers. So that the negotiating officials could allocate the water equitably, the amount of streamflow depletion caused by ground-water withdrawals upgradient from the State line needed to be determined. At the request of the Nebraska officials, the U. S. Geological Survey constructed an electric analog model which could be used to determine the amount of streamflow depletion expected to occur in the next 60 years.The model simulates hydraulic conditions in an area of 7,400 square miles which includes the entire area drained by the Big and Little Blue Rivers in Nebraska. The trans-missibility of the aquifer (Pleistocene in age) ranges from less than 1,000 to as much as 300,000 gallons per day per foot, and the storage coefficient averages about 0.20. The transmissibility values are based on examination of test- hole samples from more than 400 test holes in and adjacent to the basin.Analysis of the model indicates that predicted maximum ground-water withdrawals between 1962 and 2022 will not deplete the base flow of the Big or Little Blue Rivers by more than 5 percent.

Notes: California has an enormous stake in the Colorado River. In the southern portion of the State, 80 percent of the water used is furnished by the Colorado River, and this area needs still more water in the immediate years ahead. But it cannot get more from the natural supply of the Colorado. The river is already over-committed, and California in fact may have to cut back on its present take from that source. This is not the Colorado River in Texas; Los Angeles has gone hundreds of miles to get water, but has not reached that far east-yet.

Notes: A simplified method for determining the coefficient of transmissibility of an aquifer being pumped intermittently is developed by applying Stirling's Approximation Formula to the factorial functions in the Theis and Brown equation for drawdown in a well due to intermittent or cyclic discharge. A table of values of K, a term used in the simplified method, corresponding to the fraction of each cycle during which time discharge occurs is also presented.

Notes: During February and March 1964, the U. S. Geological Survey ran caliper, conductance, and temperature logs on several wells in the Sarasota area. The Florida Geological Survey had previously run gamma ray and electric logs on the same wells. Two flowing wells were selected for packer testing. The two wells are about the same depth, penetrate essentially the same geologic horizons, and are about 16 miles apart. The packers were set in the wells between the producing horizons of the formations penetrated and each of the horizons was tested for head, amount of production, and quality of water. One of the tests produced excellent results, indicating that the various producing zones were effectively isolated by the packers and that different quality of water, quantity of water, and a different head was available from each zone. The other test did not show sharp differences but did indicate the extent of contamination of the producing horizons in a flowing well which had been capped for approximately two years. These tests indicate that packer testing can measurably add to knowledge of the separation of permeable zones.

Notes: Quicksand is no myth, nor is it a rare phenomenon, either on the surface or in the subsurface. There is probably quicksand in every State of the U.S.A. where enough gradient is available to produce upward moving ground water. Surface quicksand is likely to occur in hilly country, especially in regions of calcareous rocks which often con-tain solution openings and favor the occurrence of springs. It is often present near stream banks and stream beds, either along their shorelines, under water, or occasionally in the bottom of an apparently “dry” river.Subsurface qurcksand rs found in loosely consolidated or uncemented alluvial, fluvio-glacial, or lacustrine sediments, which are usually well sorted and clean. It has been reported to depths as great as several hundred feet, and from a few feet to as much as 200 feet thick.In water wells, a “quick” or “heaving” condition may exist (as much as 150 feet) if a confined, permeable, loose silt, sand or gravel stratum is continuous to distant higher ground, and is subject to a greater head of water existing at the higher elevation, i. e., if artesian conditions exist.Similar material may heave in a water-table (unconfined) well, due to the natural tendency of granular materials to move toward a drill hole when lateral support is removed (the drill cuttings). Heaving results from a loss of shearing strength as pressure is reduced when a drill hole upsets natural equilibrium. Suction produced by suddenly withdrawing bailer or tools further contributes to disturbing natural conditions.Quicksand is commonly sand (usually fine to medium grained) with an effective size ranging from less than 0.001 inch to 0.005 inch. It is often finer than sugar, which has an average effective size of 0.008 inch, to which it is often compared by drillers. Stoke's Law explains why fine, round- ed grains become “quick” much more readily than coarser sand or gravel.If sufficiently permeable, quicksand aquifers can successfully be used for water supplies, providing proper screening devices are available. However, representative driller's samples; sieve analyses; choice of(or omission of) sand filter pack; proper slot selection; low (0.1 fps) en- trance velocity; and careful, patient development techniques are important prerequisites.Permeability of quicksand varies widely, but might range from approximately 50 gpd/ft to 800 gpd/ft, and average between 100 or 175 gpd/ft2. From a 5-feet thick quicksand bed, and at shallow depths, 1 to 10 gpm may be obtained for domestic or farm supplies using screened wells and drive points. Sufficient yields (250 gpm or more) for municipal wells are also possible.Drilling and completion problems with cable-tool wells can usually be overcome by: 1) watching casing alignment; 2) running bailer slowly; 3) keeping a continual high head of water inside casing; 4)using a heavy string of drill tools; 5) allowing controlled sand-heaving; 6) using short casing drives; 7) jetting with high-pressure water to wash-free tools if seized by a sudden heave; 8) avoiding thin-walled casing; 9) drilling with a mixture of bentonite or native clay and water sludge; and 10) casing above the surface if the well is flowing.Rotary drilling and completion problems are minimal, but unless unusual pressures are encountered, quicksand aquifers may be overlooked. Caving can be prevented by providing sufficient hydrostatic differential pressure, and by using a heavy weighted drilling fluid.Well screens can be set by bailing them down through a quicksand “plug” which may have formed, and completing using the standard pull-back method. A self-closing bottom (washdown fitting) can also be used to jet-down a screen while utilizing a high-velocity water flow.In some cases a sand filter-pack surrounding a continuous-slot well screen may not be advisable in quicksand, especially if the aquifer's effective grain size is approxi-mately 0.004 inch. A naturally developed well completed with a screen having a slot as narrow as 0.005 inch may be preferable, allowing 50 to 60 percent of the aquifer to be developed slowly and carefully through the screen. A case history comparing two well design methods is presented.Both cable-tool and rotary sampling methods in quick- sands are discussed. The techniques are basically similar, whether the material is “quick” or stable.

Notes: A map should treat the critical problems in a way understandable to the intended reader. Some maps appropriately show only one or two pertinent hydrogeologic parameters. Point-data maps make little or no interpretation of the data. Four-dimensional maps-those that include an elapsed span of time or projection of hydrogeologic variables into the future-represent a high degree of interpretation of data; they are most useful to the map reader. The hydro-geologist has an obligation to his reader to design maps that are as useful as possible.

Notes: The outlook for Congressional legislation resolving iong-time controversies over waters of the Colorado River, optimistic in 1966, has been dimmed by political misunderstanding. The essential ingredient of progress -harmony between Arizona and California water leaders -has been lost. They worked together on a bill to bring peace to the river and economic advantage to themselves and all Lower Colorado River Basin States. They got to the threshold, but not across it.Unless falling short of complete success has irreparably upset the delicate balance of Arizona-California interests, they must inevitably rejoin forces to reach their mutual goals. When and if they do, we believe the background for action and the proposed legislation outlined here will continue to be their best means of compromise.

Notes: A method is presented for determining values of u and W(u) for u greater than 0.01 from time-drawdown data without the use of graphical approximations or type-curves. The method utilizes the function Z(u) which is defined in the paper and makes possible the application of statistical analyses of test data for bounded aquifers and other types of complex field problems. If the field data are taken so that t is a consecutive multiple of two, the method can be applied directly to the drawdown observations. An example of this method used to analyze test data for a bounded aquifer and a table of values of W(u) and Z(u) for selected values of u between 0.01 and 4.6 are also presented.

Notes: Estimates can be made of the distances to hydrologic boundaries by using water-level measurements from pumping wells and by assuming in each case the possible range of the coefficient of storage. Interpretation of pumping test data from Well 6 (J-13) at the Nevada Test Site implies that a fault 1200 feet from the well acts as the closest of the impermeable boundaries. In a case where no boundary has been felt the areal extent or volume of rocks affecting the drawdown pattern of a well can be estimated by assuming that a hypothetical boundary is just about to be felt at the time pumping stopped.

Notes: Criteria and formulas are presented for scheduling cyclic pumping operations, to maintain a given minimum drawdown as required for drainage purposes. Keeping the total cycle length constant, the pumping periods are successively shortened and the shutoff periods lengthened. Solutions of the equation for the relative length of the shutoff periods are presented in a family of curves, which greatly simplifies the scheduling procedure.

Notes: In this paper a way of estimating the probable character of the water in sand aquifers is explained with examples. Comparative chemical quality of water from many types of sand formations generally encountered during drilling may be predicted with considerable accuracy by observing the color of an aquifer sand and its depth. This approximate method of “guessing” water chemistry, if properly used, can do much to guide the water well contractors. It may often fail due to incorrect application of the technique rather than a failure of the technique.

Notes: The failure or “breaking up” of pavement in cuts in glacial till is a phenomenon commonly observed in northeastern Illinois and other areas in the midwest. Failure commonly follows periods of significant ground-water recharge, especially when such periods are concomitant with freezing and thawing conditions.Water levels in piezometers installed in glacial till in northeastern Illinois indicate that during periods of high precipitation or rapid snow melt, the potential surface normally occurs at shallow depths. Therefore, cuts of appreciable depth intersect the zone of saturation and establish local, gravity, ground-water flow systems with the bottom of the cut acting as a ground-water discharge zone. Such shallow gravity flow systems may bring about pavement failure by facilitating the growth of thick ice lenses or by developing high pressure beneath the pavement due to poor drainage.

Notes: The scope of area1 investigations of water resources in New York has changed within the last 4 years. Prior 1962, most investigations covered only counties or smaller areas and were mainly restricted to ground-water resources Since 1762, investigarions have covered largebasin (2,000-4,000 square miles) with the purpose of defining total water resources so that basin-wldc comprehensive plans for water development can be prepared.Ground water has been intensively studied in the basin investigations, both because of its large potential for future development, and becaus e of it sinterre lation with the surface-water resources. The latter reason is particularly important because the principal aquifers are numerous u nconnect edglacials and andgravel deposits that are crossed by streams. This ground-water regimen to a large degree determines the flow characteristics and water quality of streams. Conversely, streamflow data provide acon-venient means of assessing ground-water availability.Some approaches used in basin studies are:(1)(1) numerous quantitative and qualitative observations of low streamflow to define the principal areas of ground-water discharge and to define the quantity and quality of discharging ground water(2)estimation of total ground-water dischar gepas stream gages from daily streamflow records by correlation with ground-water levels and by analysis of the records(3) assessment of recharge to particular sand and gravel deposit swith inbroadlimits, using the data on ground-water discharge to streams(4) estimation of a daily chemical quality hydrograph on the basis of quantity and quality of both ground-water discharge and overland runoff

Notes: Passive-element electric analog models have been used for many years as a means of tudying cause and effect relationships in the regional development of ground-water resources. Although successful use of such models has been demonstrated by several investigators, certain inherent characteristics designed into some electric analog models lead to significant error at particular boundaries of the model.Errors that exist at the pumped well junctions of non-steady-state two-dimensional flow electric analog models are analyzed. The results of the analysis indicate that practical sustained yields and water-level data derived from pumped well junctions of electric analog models lead to overly optimistic estimates of aquifer and well yielding capabilities. This paper presents design methods for simulating pumped wells having different radii, screen lengths, partial penetrations, gravel pack sizes, and well-loss constants.