ALBERT

Notes: The accuracy of the two most common arrival time functions used in seismic velocity estimation is investigated. It is shown that the hyperbolic arrival time function is more accurate than the parabolic arrival time function for a horizontally layered elastic medium. An upper bound on the difference between the two arrival time functions is given.A maximum-likehood detector for estimating the arrival time of the signals is given. For the signal-in-noise model that is used the maximum-likelihood detector is equivalent to a least-squares detector which corresponds to using the signal energy as coherency measure. The semblance coefficient corresponds to a normalized least-squares detector. The semblance coefficient is very similar to a filter performance measure that is used in least-squares filter design.

Notes: The proposed system works as follows:〈list xml:id="l1" style="custom"〉1By a trial-and-error procedure using a graphic display terminal a geologically relevant layer sequence with parameters (ρj, dj) is adjusted to yield roughly the measured curve.2The resulting layer sequence is used as starting model for an iterative least squares procedure with singular value decomposition. Minimization of the sum of the squares of the logarithmic differences between measured and calculated values with respect to the logarithms of the resistivities and thicknesses as parameters linearizes the problem to a great extent, with two important implications:〈list xml:id="l2" style="custom"〉a) a considerable increase in speed (the number of iterations goes down), thus making it cheap to achieve the optimum solution;b) the confidence surfaces in parameter space are well approximated by the hyper-ellipsoids defined by the eigenvalues and eigenvectors of the normal equations.Since these are known from the singular value decomposition we do in fact know all possible solutions compatible with the measured curve and the geological concept.〈list xml:id="l3" style="custom"〉3It is possible to “freeze” any combination of parameters at predetermined values. Thus extra knowledge and/or hypotheses are easily incorporated and can be tested by rerunning step (2). The overall computing time for a practical case is of the order of 10 sec on a CDC 6400.

Notes: Ott and Meder's prediction error filter can be rederived so that it correctly handles input noise vectors which are of smaller dimension than the state vector. The poor performance obtained by Ott and Meder for their example can be explained by means of the error covariance matrix for the prediction error filter.

Notes: The contribution of electromagnetic phase comparison techniques to distance measuring is reviewed in an historical context. Special emphasis is accorded the new class of near infra-red electro-optic instruments suited to the measurement of distances under 2 km with an accuracy of a few millimetres. Principles of operation, sources of error, and practical applications are discussed.

Notes: A magnetotelluric digital equipment has been designed and built for operation in geophysical and applied geophysical research. The five components of the natural electromagnetic field can be digitized in the frequency range 1/1000 Hz (magnetic sensor's response limits) to some tens Hz.The magnetotelluric (MT) data are directly digitized in the field and stored in a cassette tape recorder.

Notes: An electromagnetic frequency sounding experiment with a rigid horizontal transmitter coil carrying a stabilized oscillating current was carried out in South Tunesia.The field data were interpreted in terms of the mutual impedance ratio in the horizontal coils system. Where the measurements were sufficiently accurate they generally could be interpreted to a high degree of fit. It is concluded that a vehicle-mounted electromagnetic frequency sounding system is suitable for a fast survey.

Notes: The application of approximate rules, whereby apparent resistivity space sections for two dimensional structures can be composited from spaces derived for elementary features is extended to a complex example drawn from a field survey over a fluorite mineral vein.A quantitative solution for the observed resistivity space is presented and the computational sequence involved in matching the observed space is given in detail.The interpreted results are examined in relation to the known geology, supplemented by the results of excavation, and to model tests conducted using a tank analogue.The example also illustrates how successive compositions can be employed in estimating the form of resistivity space in a relatively complex situation.

Notes: The sampling theorem in two dimensions univocally defines a surface, provided that its values are known at points disposed on a regular lattice. If the data are irregularly spaced, the usual procedure is first to interpolate the surface on a regular grid and then to contour the interpolated data: however, the resulting surface will not necessarily assume the prescribed values on the irregular grid.One way to obtain this result is to introduce a transformation of the coordinates such that all the original data points are transferred into part of the nodes of a regular grid. The surface is then interpolated in the points correspondent to the other crosspoints of the regular grid; the contour lines are determined in the transformed plane and then, using the inverse coordinate transformation, are transferred back to the original plane where they will certainly be congruent with the original data points.Nonetheless, the resulting surface is very sensitive to the interpolation method used: two algorithms for that are analyzed. The first (harmonization) corresponds to the determination of the potential of an electrical field whose contour conditions are those defined by the data points. The second method consists in two dimensional statistical estimation (krigeing); in particular, the effects of different choices for the data auto-covariance function are discussed.The solutions are compared and some practical results are shown.

Notes: Optimum stacking filters based on estimates of trace signal-to-uncorrelated noise ratios are assessed and compared in performance with conventional straight stacking. It is shown that for the trace durations and signal bandwidths normally encountered in seismic reflection data the errors in estimating signal/noise ratios largely counteract the theoretical advantages of the optimum filter. The more specific the filter (e.g. the more frequency components included in its design) the more this is true. Even for a simple weighted stack independent of frequency, the performance is likely to be better than a straight (equal weights) stack only for relatively high signal/noise ratios, when the performance is not critical anyway.

Notes: Electromagnetic coupling in grounded electrical prospecting systems has been studied over four decades. Recently, advanced digital electronic systems have been developed which permit both magnitude and phase measurements over four frequency decades (10−2— 102 Hz). This development has stimulated theoretical studies demonstrating behavior of EM coupling for the more commonly-used electrical prospecting arrays a wide frequency range. A comparison is made between field and theoretical results which demonstrates the validity of the fundamental assumptions involved. Additionally electromagnetic coupling is used successfully as a deep-sounding technique in a highly-conductive sedimentary basin environment.

Notes: A polygonal ray path connects the seismic source and detector positions when the intervening medium consists solely of constant velocity layers with plane interfaces which may have arbitrary orientation. The coordinates of the ray vertices satisfy a system of coupled equations resulting from the requirement that Fermat's principle be satisfied along the ray path. Solving the system of equations is equivalent to tracing the ray numerically. A notable feature of this approach is that a ray which is critically refracted over a segment of its path requires no special handling.

Notes: A satisfactory attenuation of the multiples in marine seismic may be obtained by the application of the principle of “Antiaveraging”.This principle in a first step consists in getting the model of the organized noise, which one tries to eliminate by using an averaging method, and in a second step to subtract that model from the initial information.Obviously the elimination of the model should not simultaneously cause the elimination of useful signals.The model may be obtained if the considered organized noise keeps a constant shape or if its time-space deformation is known. Besides one has to assume the time-distance curve of the organized noise can be determined. Thus noise arrivals may be detected on the records.The “antiaveraging” is very often efficient when organized noises are stronger than signals or when a signal, once identified, exploited and then considered as an organized noise, can be attenuated in order to make the detection of the other signals easier.

Notes: The interpretation of total field anomalies becomes somewhat complicated, especially when an arbitrarily magnetized spherical ore mass happens to be the causative body. Even though some attempts have been made to analyze total field anomaly maps, they are often too complicated and their underlying assumptions in respect of permanent and induced components of magnetism are far from realistic. In this note, an attempt has been made to show that vertical magnetic anomalies are capable of yielding interpretation with ease and precision as far as magnetized spheres are concerned. An empirical method has been outlined for computing the magnetization inclination in the plane of the profile using the measured distances between principal maximum, principal minimum, and zero anomaly positions on a magnetic anomaly profile.

Notes: Pseudo velocity logs can be obtained by seismogram inversion, using true amplitude processing and detailed investigation of move-out velocities. The precision of the results depends on the quality of the seismic data and on the possibility of deconvolving without increasing the noise. An investigation is made of the deformation of pseudo logs due to seismic signal variations and to imperfections of deconvolution.Both marine and land examples are shown, in some cases with adjustment on well logs. When the dips are large, time sections must be migrated and pseudo velocity logs must be computed from migrated sections. Comparison of sonic logs with pseudo velocity logs obtained in the same area is usually good enough to obtain information on lithological parameter variations by adjustment of pseudo velocity logs on sonic logs. Even when no well is available, pseudo velocity logs can give some indications on the nature of sediments between seismic horizons.

Notes: The polarization content of a medium, in both the time and frequency domains, can be described by parameters which differ in inherent physical meaning and their practical significance.For real situations, general expressions for the apparent parameters, previously determined for both domains, exist for the general case of soundings on a horizontally multi-layered earth.The comparative analysis of these expressions, here restricted to the simple case of a two-layered earth, shows that the theoretical sounding curves of the frequency-domain are different from those of the time-domain. In particular, for every resistivity or chargeability contrasts examined, the apparent frequency-effect curve lies always over the corresponding apparent chargeability curve, but both curves reach the same asymptotical values for shortest and largest spacings.The important conclusions which can be drawn from this result is that both techniques are suitable to investigate subsoil polarizability anomalies. However, from a practical point of view, it is more convenient to adopt the frequency-domain technique when the polarizability increases with depth, while, on the contrary, the time-domain technique is more efficacious when the polarizability decreases with depth.

Notes: The interpretation of potential field data from two-dimensional structures with a single interface of density or susceptibility contrasts is solved in terms of generalized matrix inversion. The model equations are derived, and important features of generalized matrix inversion are treated. The method is subsequently used to solve two gravity problems, an artificial one where the solution is known, and a geophysical one related to the crust-mantle interface. The solution is shown to compare well with the FFT results of Oldenburg. The method is also used to solve two magnetic problems, an artificial one with the solution known, and a geophysical one from the continental shelf of Greenland. The advantages and limitations of the method are finally discussed.

Notes: Seismic reflection methods are being developed at the University of Manitoba to aid in determining fine crustal structure in the Precambrian of Manitoba and northwestern Ontario. Present-day environmental concern as well as mineshaft conditions necessitate the detonation of several smaller charges repeated, say, I times and followed by ‘vertical’ stacking. To obtain the familiar √I improvement in signal-to-noise (S:N) amplitude ratio applying the straight-sum (SS) method, one assumes, among other things, that both S:N ratio and signal variance are the same on all traces. Dropping these assumptions, as we must for our data, it becomes necessary to apply weighting coefficients to optimize the S:N ratio of the stacked trace. We still assume the signal shapes to be the same for repeated shots, so for the jth trace on the record of the ith shot we model the time series as: tij=ai (sj+nij); where ai is a scaling factor. The proper weights wi are then shown to be proportional to σsi/σ2ni where σ2 is variance, or to γi/ai where γi is S:N power ratio.Applying the weighted-stack (WS) method gives S:N amplitude ratios which are, on average, 55% of the optimal ratios expected from WS theory compared with only 24% for the SS method. The 45% shortfall in WS performance is ascribed mainly to trace-alignment (or time-delay) errors. Varying noise levels on individual traces, slight dissimilarity of signal shape, and correlated noise may also contribute to a lesser extent (in decreasing order of significance). This WS method appears to strike a good practical balance between S:N improvement and processing efficiency.

Notes: The geophysical system of horizontal layers may be considered as a large scale system. A large class of systems is identified which are equivalent to the geophysical processes in horizontal layering. The property of hierarchical aggregation of layers forms a convenient framework within which the peculiarities of such systems can be studied. Geophysical processes in multilayered media may serve as a reference physical model for a specified class of large scale systems, in order to take advantage and to apply geophysical methods of data processing, system analysis, and parameter identification.Specified large scale systems are decomposable, like geophysical systems, by use of recursive schemes. A category particulary susceptible to such a decomposition is any polynomial which is stable inside the unit circle. Sophisticated geophysical concepts, such as anisotropy, equivalence, and disappearance, can be used to approximate or to simplify the system by vanishing or adjusting the decomposition coefficients.

Notes: The gravity effect of an infinite horizontal trapezoidal prism is derived and its Fourier spectrum is analyzed so as to yield information about four parameters of the causative structure, namely the depths to the upper and lower surfaces, width of the upper surface, and the inclination of the sides. In order to test the applicability of the method, synthetic data are constructed by digitizing the theoretical gravity effect. Subsequently, the corresponding Discrete Fourier Transform (DFT) is obtained. The parameters evaluated from the DFT are observed to be sufficiently close to the chosen values.

Notes: The Wiener prediction filter has been an effective tool for accomplishing dereverberation when the input data are stationary. For non-stationary data, however, the performance of the Wiener filter is often unsatisfactory. This is not surprising since it is derived under the stationarity assumption.Dereverberation of nonstationary seismic data is here accomplished with a difference equation model having time-varying coefficients. These time-varying coefficients are in turn expanded in terms of orthogonal functions. The kernels of these orthogonal functions are then determined according to the adaptive algorithm of Nagumo and Noda.It is demonstrated that the present adaptive predictive deconvolution method, which combines the time-varying difference equation model with the adaptive method of Nagumo and Noda, is a powerful tool for removing both the long- and short-period reverberations. Several examples using both synthetic and field data illustrate the application of adaptive predictive deconvolution. The results of applying the Wiener prediction filter and the adaptive predictive deconvolution on nonstationary data indicate that the adaptive method is much more effective in removing multiples. Furthermore, the criteria for selecting various input parameters are discussed. It has been found that the output trace from the adaptive predictive deconvolution is rather sensitive to some input parameters, and that the prediction distance is by far the most influential parameter.

Notes: The advantages and limitations of remote sensing exploration from space platforms are outlined with special reference to the geologic objectives.The enhancement techniques of the multispectral imagery and their effects are illustrated in order to improve the interpretation of geologic linears and the discrimination of soils and rocks.Three cases of application are shown, dealing with different geologic regions.The ability of remote sensing from space to be employed in both regional and local problems is shown.The planning of exploration by airborne and ground geophysical methods can be substantially helped after the results of remote sensing, and large economic gains can be reached.

Notes: The electrical potential generated by a point source of current on the ground surface is studied for a multi-layered earth formed by layers alternatively characterized by a constant conductivity value and by conductivity varying linearly with depth. The problem is accounted for by solving a Laplace's differential equation for the uniform layers and a Poisson's differential equation for the transitional layers. Then, by a simple algorithm and by the introduction of a suitable kernel function, the general expression of the apparent resistivity for a Schlumberger array placed on the surface is obtained. Moreover some details are given for the solution of particular cases as 1) the presence of a infinitely resistive basement, 2) the absence of any one or more uniform layers, and 3) the absence of any one or more transitional layers. The new theory proves to be rather general, as it includes that for uniform layers with sharp boundaries as a particular case. Some mathematical properties of the kernel function are studied in view of the application of a direct system of quantitative interpretation. Two steps are considered for the solution of the direct problem: (i) The determination of the kernel function from the field measurements of the apparent resistivity. Owing to the identical mathematical formalism of the old with this new resistivity theory, the procedures there developed for the execution of the first step are here as well applicable without any change. Thus, some graphical and numerical procedures, already published, are recalled. (ii) The determination of the layer distribution from the kernel function. A recurrent procedure is proposed and studied in detail. This recurrent procedure follows the principle of the reduction to a lower boundary plane, as originally suggested by Koefoed for the old geoelectrical theory. Here the method differs mainly for the presence of reduction coefficients, which must be calculated each time when passing to a reduced earth section.

Notes: An infinitely resistive/conductive horizontal bed is assumed in an otherwise homogeneous and isotropic half space. Schlumberger, three electrode, and unipole profiles are computed at right angles to the strike of the bed. The Schwarz-Christoffel method of conformal transformation and numerical methods of solving non-linear differential equations are used to solve the boundary value problem. It is observed that (i) the three electrode system is the most sensitive gradient electrode configurations for electrical profiling, (ii) the apparent resistivities for Schlumberger, three electrode, and unipole methods become maximum when the depth of the bed is 0.06 L, 0.1 L, and 0.055 L for a resistive bed and minimum when depths are 0.085 L, 0.04 L-0.02 L and indeterminate for conductive beds, respectively, (iii) the limiting depths of detection (defined in the text) by Schlumberger, three electrode, and unipole configurations are respectively 0.9 L, 6.6 L and 2.0 L for resistive beds and 0.58 L, 1.17 L and 1.5 L for conductive beds.The electrode separation L is the distance between the two farthest active electrodes.

Notes: The effect of interactions among spherical inclusions on the effective propagation of long wavelength elastic waves in a two-phase medium is investigated theoretically. Interactions are taken into account in an average sense via a generalized self-consistent scheme. Bounds on the effective elastic moduli are obtained by overestimating and neglecting contributions of neighbouring inclusions. An intermediate model is proposed, which introduces the effect of interactions into the effective properties without requiring more information about the geometry of the medium than the relative volumes of the constituents.

Notes: The transient response of a layered structure to plane wave excitation can be considered to be composed of a series of waves and a ground wave. For the case of a half-space of conductivity σ and permeability μ the maximum in the electric field is found at a depth z and time t when t=z2σμ/2.This formula can be used to estimate the depth to a buried horizontal conductor with an accuracy that depends upon the resistive contrast at the conductor's surface.The above ray type of solution can be converted to a solution composed of a number of modes by the use of a Poisson transform and the transformed solutions yield decay constants that are consistent with the previously reported results.In the case of a finite source, the maximum in the electric field is strongly directed. The direction depends upon the geometry of the source and the air-earth interface. Although the maximum varies with direction it can be shown that in some directions similar laws to that above are valid.The depth to a conductor can be estimated from the early part of the transients when the ground wave is removed. The removal of the ground wave from the transient is facilitated by the use of an apparent conductivity formula.Although these results were obtained under restrictive conditions they do provide some insight into the electrical transients that are encountered by studying more complex models.

Notes: The induced polarization response of a horizontally multilayered earth with no resistivity contrast can rapidly be calculated on a desk calculator or minicomputer for any electrode array. The formulation is a simple series summation of the products of weighting coefficients and the true induced polarization responses for each of the layers. The coefficients are directly derivable from the corresponding resistivity model. This series approach to IP formulation was originally described by Seigel but has not been treated extensively in the present-day geophysical literature. This method can be applied to either time or frequency domain induced polarization measurements. Once the coefficients are known, apparent induced polarization response can readily be obtained by judicious substitution of known, suspected, or assumed values of the true induced polarization of each layer.Basic formulation is presented for the IP potential coefficients (pole-pole or two array) with no resistivity contrast between the layers. From these coefficients, response of any number of layers for any electrode array can be obtained by suitable differentiation. Some examples of Wenner array for a three-layered earth and dipole-dipole array for a four-layered earth are used to illustrate the application.The results of this technique are valid for many natural situations of modest resistivity contrast. However, they definitely cannot be used if there are highly contrasting resistivity layers present. Such an approach is conceptually simple and is useful for survey planning, checking or setting the “depth-of-penetration”of a given array. For field induced polarization data that fits reasonably well to the no-resistivity-contrast model, this simple approach facilitates quantitative interpretation.

Notes: After the sampling of a reflection time contour map, i.e. after times and time gradients at the grid points of a square sampling grid have been determined, its conversion into true depth contours can be performed by normal incidence ray tracing.At each grid point the spatial orientation of the ray is uniquely defined by a corresponding time gradient vector, whereas its continuation into the subsurface is controlled by Snell's law. For arbitrarily orientated velocity interfaces the 3 – D ray tracing problem can systematically be solved with the aid of vector algebra, by expressing Snell's law as an equation of vector cross products. This allows to set up a computer algorithm for migration of contour maps.Reliable sampling of reflection time contour maps in the presence of faults is essential for the realization of a practical map migration system. A possible solution of the relevant sampling problem requires a special map editing and digitization procedure.Lateral migration shifts cause a translation and distortion of the original sampling grid. On the transformed grid the true positions of faults can be related to their apparent ones on the reflection time contour map.Errors in the time domain correlations or an incorrect velocity distribution or a combination of both these effects may cause migration failures due to total reflection and time deficiencies, or give rise to an anomalous distortion of grid cells, the latter signifying a violation of the maximum convexity condition.Emphasis is placed upon the significance of map migration as an interpretive tool for solving time to depth conversion problems in the presence of severely faulted or salt intruded overburdens.

Notes: Six types of vegetation were established successfully on lysimeters containing sanitary landfill materials. The vegetation grew well with the roots penetrating several refuse layers within one year. Leachate analysis indicated that vegetation and evapotranspiration (ET) reduced leachate volume and increased the rate of refuse decomposition. This was accompanied by production of a more potent leachate and a substantial increase in cumulative chemical oxygen demand. Therefore, this study suggests more potential ground-water pollution in a shorter period of time when vegetation is planted on a landfill. The net effect of ET on the stabilization of any particular landfill will be the result of a complex interaction involving climate, vegetation, soil type, cover material, landfill geometry, and other variables. This makes extrapolation of our results to a particular field situation rather difficult.

Notes: The anisotropic, areal hydraulic conductivity of the Felix No. 2 coal (Eocene, Wasatch Formation) has been defined in a four-well pump test at a site in the Powder River Basin of northeastern Wyoming. The direction of maximum hydraulic conductivity of the subbituminous coal bed bears N59°E and is associated with a horizontal hydraulic conductivity of 0.27 m/day. The direction of minimum hydraulic conductivity bears N31°W and is associated with a horizontal hydraulic conductivity of 0.15 m/day. The direction of maximum hydraulic conductivity approximately corresponds to the trend of the prominent face cleat in the coal, while the direction of minimum hydraulic conductivity corresponds to the trend of the butt cleat. The cleat orientation appears related to the alignment of major structural features of the region. Prediction of the direction of both maximum and minimum horizontal hydraulic conductivity in near-horizontal coal beds appears possible. However, either the cleat orientation of the bed or the alignment of the controlling fold structure must be known or obtainable.

Notes: The concept of the observation well as a measuring instrument with its own response characteristics is developed, and a method for response evaluation is derived based on methods of slug-test analysis. The effect of well response time upon the results of semiconfined aquifer tests is calculated and a series of type curves is produced. The ambiguity of observation well response affected leaky aquifer tests is demonstrated.A method for calculating well response time based on estimates of aquifer parameters and observation well dimensions is also presented to aid the proper design of aquifer tests. It is recommended that a slug test should be performed on every observation well used in confined or semiconfined aquifer tests.

Notes: The objective of this study was to develop surface electrical resistivity methods for estimating hydraulic conductivities in glacial outwash materials. Aquifer electrical resistivities were determined from the results of Schlumberger electrical soundings at six sites in southern Rhode Island where pumping tests had previously been made. Hydraulic conductivities and transmissivities determined from pumping tests were then correlated with resistivities obtained from electrical soundings. Results indicate that electrical resistivities determined from soundings can be used to predict aquifer hydraulic conductivities; an empirical relation between aquifer electrical resistivity and aquifer hydraulic conductivity was developed. A semiempirical relation between aquifer formation factor and hydraulic conductivity was also developed.

Notes: Long-term records of ground-water quality indicate that in an unsewered area of southeast Nassau County, New York, certain constituent concentrations increased substantially from 1910 to 1975. Most of the increases virtually parallel the rate of population growth and number of houses that discharge waste water through cesspools and septic tanks. Data sites used for this study were two abandoned infiltration galleries in Wantagh and Massapequa that withdraw water from the shallow aquifer. Ranges in constituent concentrations, in milligrams per liter, during 1910–75 were:

Notes: Subsidence of the land surface due to ground-water overdraft is caused by an increase in the intergranular pressure in unconsolidated aquifers and other underground materials. For unconfined aquifers, this increase is the result of a loss of buoyancy of solid particles in the zone dewatered by the falling water table. For confined aquifers, increases in intergranular pressure are caused by decreases in the upward hydraulic pressure against the bottom of the upper confining layer, due to a drop in piezometric surface. Compression of layers in which the intergranular pressure is increased can be calculated with elastic or logarithmic theory. Sample calculations yield rates of subsidence that agree with those observed, i.e., about 5 to 50 cm (2 to 20 inches) per 10-m (33-ft) drop in ground-water level. Ground-water depletion can also produce surface cracks, particularly above discontinuities in bedrock depth along the periphery or in other parts of subsiding basins. Calculations based on the rotating-slab theory show that the initial surface width of such cracks is about 1 cm (0.5 inch), which agrees with field observations.

Notes: Phosphate retention by soils is especially important for tile fields and rapid infiltration systems near lakes where eutrophication is a problem. The use and application of the phosphate adsorption isotherm test to estimate a soil's phosphate removal ability will be discussed. In New York State, the till soils had a greater phosphate retention ability than the outwash soils. Within the tills and within the outwashes, the more acid soils had a greater phosphate retention than the more basic or calcareous soils. The B horizon of many of the soils had a high phosphate capacity. However, this is often neglected in rapid infiltration systems because the waste water is discharged below the B horizon. The phosphate removal in column studies and field studies in rapid infiltration systems was found greater than predicted by the rapid isotherm test. Intermittent sand filters with two feet sand and underdrains were found to have a limited ability to remove phosphate. Methods to predict and design for phosphate retention by sands and soils are described.

Notes: The recent interest in the disposal of treated sewage effluent by deep-well injection into salt-water-filled aquifers has increased the need for proper disposal of salt water as more wells are drilled and tested each year.The effects on an unconfined aquifer of the improper disposal of salt water associated with the construction of three wells in southeastern Florida emphasize this need. In two of the wells provisions to prevent and detect salt-water contamination of the unconfined aquifer were practically nonexistent, and in one well extensive provisions were made. Of the three drilling sites the one with proper provision for detection presented no serious problem, as the ground water contaminated by the salt water was easily located and removed. The provisions consisted of drilling a brine-injection well to dispose of salt water discharged in drilling and testing operations, using a closed drilling circulation system to reduce spillage, installing shallow observation wells to map the extent and depth of any salt-water contamination of the shallow aquifer, and installing a dewatering system to remove contaminated ground water.

Notes: Generally the geology of the Breton area of Alberta consists of a 5-to 125-ft (1.5- to 38.1-m) veneer of glacial till overlying sandstone and sandy shale units of the Paskapoo Formation. These sandstone units are locally important aquifers. Glacial drift in the Hastings Lake area varies in thickness from 100 to 200 ft (30.5 to 61.0 m) and overlies the Horseshoe Canyon Formation, which consists of bentonitic shale, siltstone and coal units with minor sandstone units. Ground-water yields from drift and bedrock in this area are generally less than 30 gpm (113.6 1/m).Resistivity soundings were completed at 68 and 65 stations in the Breton and Hastings Lake areas, respectively. Profile maps from the Breton area are characterized by broad areas with apparent resistivity values greater than 100 ohm-ft (3048 ohm-cm). Qualitative evaluation of the resistivity soundings and existing borehole data indicated that the high resistivity values resulted from a thick resistive sandstone aquifer less than 25 ft (7.6 m) from ground surface. A reasonably well-defined resistivity pattern was evident on the profile maps of the Hastings Lake area with the highest resistivity values coming from stations located in the hummocky moraine south of the lake. Sounding curves and borehole data indicate that an increase in the sand content of the drift is responsible for these values. However, local variability in the drift lithology produces anomalies in the resistivity patterns. In addition to providing useful information on the geology of an area, surface resistivity methods provide a rapid and relatively inexpensive tool to aid in planning more detailed ground-water studies because of their ability to detect inhomogeneities in the subsurface environment.

Notes: Past ground-water quality monitoring programs have often involved sampling of low-capacity wells near point or line sources of recharge or pollution. However, large-capacity wells produce much of the ground water pumped for municipal, industrial, and agricultural uses. Short-term, seasonal, and long-term fluctuations in quality are common for water pumped from many large-capacity wells. In many cases, there is a considerable difference between in-situ “ground-water quality” and the quality of water sampled at the well discharge.Short-term pump tests for several municipal wells in the San Joaquin Valley, California have indicated that nitrate concentrations decreased exponentially with pumping time. Variability in pump operation creates substantial short-term changes in well-water quality. Short-term changes are most evident for infrequently pumped, shallow wells near point or line sources of recharge or pollution. Seasonal changes in quality have been documented for water from wells in areas of diffuse sources of pollution, such as agricultural return flow and septic tanks. These changes are primarily due to significant changes in depth to water and vertical hydraulic head gradient. Once the short-term and seasonal trends are established, the optimal sampling approach can be determined in order to establish long-term trends.

Notes: The effectiveness of basin ground-water recharge at the Leaky Acres Recharge Facility in Fresno, California for improving the regional ground-water quality was studied as 65,815,000 m3 of high-quality surface water was recharged from 1971 through 1975. Observation wells at the facility showed some variability in chemical parameters associated with each recharge period. The long-term decreases in salinity could be described by a power law decay curve fitted by regression analysis.Without a special network of observation wells outside the facility, scientific evaluation of the enclave of recharged water is not possible. A practical evaluation of water-quality changes is possible from producing water wells around the facility. However, the pumping well discharge-time variations, well depth, aquifer sequence, and prior use of surrounding land must be considered, since all of these factors affect the pumped-water quality and its seasonal variability. Recharge at Leaky Acres had noticeably decreased the ground-water salinity for a distance of up to 1.6 km in the direction of the regional ground-water movement.

Notes: One of the more subtle and dangerous areas of pollution is that occurring in ground water from normal irrigation practices. The pollution from salt buildup is presently one of the unsolved problems in managing stream-aquifer systems. This paper presents several strategies that offer a possibility of controlling this salt buildup. For example, instead of applying irrigation ground water near the site of the well, the ASTRAN Method transfers it downstream to be applied on land where the ground water is a lower quality thereby controlling the increase in salt concentration. Instead of preventing seepage loss in delivery canals, the percolating water is used to maintain ground-water quality. Finally, timed releases of return flow remove salts without exceeding surface-water quality constraints.

Notes: The system of flow into a nonpenetrating well with hemispherical bottom of finite radius in a finite deep artesian aquifer of infinite radial extent is analyzed. The solution is obtained in terms of error function. A method has been suggested for determination of transmissivity, storage coefficient and depth of aquifer from pump-test data of such wells discharging at constant rate. For small values of radial distance to aquifer depth ratio and for small duration test, only a few terms are required in the present solution as compared to the solution of Hantush (1957) developed for such wells.

Notes: The Pinellas Peninsula, an area of 750 square kilometres (290 square miles) in coastal west-central Florida, is a small hydrogeologic replica of Florida. Most of the Peninsula's water supply is imported from well fields as much as 65 kilometres (40 miles) inland. Stresses on the hydrologic environment of the Peninsula and on adjacent water bodies, resulting from intensive water-resources development and waste discharge, have resulted in marked interest in subsurface storage of waste water (treated effluent and untreated storm water) and in future retrieval of the stored water for nonpotable use. If subsurface storage is approved by regulatory agencies, as much as 265 megalitres per day (70 million gallons a day) of waste water could be stored underground within a few years, and more than 565 megalitres per day (150 million gallons a day) could be stored in about 25 years. This storage would constitute a large resource of nearly fresh water in the saline aquifers underlying about 520 square kilometres (200 square miles) of the Peninsula.The upper 1,060 metres (3,480 feet) of the rock column underlying four test sites on the Pinellas Peninsula have been explored. The rocks consist chiefly of limestone and dolomite. Three moderately to highly transmissive zones, separated by leaky confining beds, (low permeability limestone) from about 225 to 380 metres (740 to 1,250 feet) below mean sea level, have been identified in the lower part of the Floridan aquifer in the Avon Park Limestone. Results of withdrawal and injection tests in Pinellas County indicate that the middle transmissive zone has the highest estimated transmissivity-about 10 times other reported values. The chloride concentration of water in this zone, as well as in the two other transmissive zones in the Avon Park Limestone in Pinellas Peninsula, is about 19,000 milligrams per litre. If subsurface storage is approved and implemented, this middle zone probably would be used for storage of the waste water and the zone would become the most extensively used in Florida for this purpose.

Notes: Land subsidence increases the area in the Texas Coastal Zone which will be inundated by marine waters from hurricane flooding. Storm surge from a Carla-sized hurricane in 1976 would flood at least 25 square miles (65 km2) more land than Hurricane Carla did in 1961.Land subsidence in Harris and Galveston Counties results primarily from ground-water production. The two-county area is interlaced with active surface faults with topographic escarpments and surface faults with no topographic escarpments that control drainage patterns and create subtle photographic linear patterns. Ground-water production activates these faults by differential compaction of the aquifer. The faults appear to be partial hydrologic barriers that compartmentalize land subsidence into several individual basins.

Notes: Disposal of industrial process water into an unlined lagoon in permeable Atlantic Coastal Plain sediments resulted in a ground-water contamination problem caused by infiltration of the process water into a major unconfined aquifer which underlies the lagoon at shallow depth. Most of the area water-supply wells terminate in this formation. Before this disposal method was discontinued, traces of the process water appeared in nearby wells.Because of the relatively large area and depths involved, as indicated by preliminary data, delineation of the distribution of contaminant within the aquifer through a systematic well drilling program posed a significant economic problem. To keep costs within a reasonable range, a resistivity survey program was implemented to obtain information on the gross distribution of the contaminant and to provide data for the selective location of monitor wells. Eight wells were constructed to obtain samples of the ground water in order to measure contaminant concentrations and to verify the interpretations of areal contaminant distribution inferred from the resistivity data. The ground-water sampling procedure developed during this investigation is described.The combination of the resistivity survey with the ground-water sampling procedure developed during this investigation proved a valuable and reliable technique for delineating in three dimensions a contaminant body within an aquifer in unconsolidated sediments. Utilization of the resistivity survey data to selectively locate the monitor wells and to define the lateral extent of the contamination increased the efficiency of the investigation and significantly reduced the cost of the program.

Notes: A study of toxic trace metal distribution in ground waters of the Front Range mineral belt, Colorado and adjacent areas was performed in order to determine the relationship of water quality to mineralization and the magnitude of potential health effects. A total of 149 samples were collected and analyzed for arsenic, cadmium, copper, iron, lead, manganese, mercury, silver and zinc. Field determinations of pH, Eh, and specific conductance were also made.The trace element data exhibited a lognormal distribution and are described utilizing the geometric mean and geometric deviation. Four populations were recognized in the samples: (1) samples in the mineral belt with plumbing contamination; (2) samples in the mineral belt without plumbing contamination, (3) samples outside the mineral belt with plumbing contamination, and (4) samples outside the mineral belt without plumbing contamination. Differences in these populations for several elements are observed utilizing the t test.Utilizing the observed data distributions, geochemical abundance estimates are made for the four recognized populations. The data distributions are corrected for analytical error, corrected for determinations below the detection limit and expressed as a predicted central 95% range for each element in each population. The corrected geometric mean, corrected geometric deviation, along with the U.S. Public Health Service limit for each element determined are used to determine the probability of ground water exceeding the specified limit for each constituent. Ground waters in the mineral belt are estimated to exceed the U.S. Public Health Service limit in 14% of the samples for Cd, 1% for Cu, 51% for Fe, 74% for Mn, 2% for Hg, and 9% for Zn. Ground waters outside the mineral belt have a similar probability of exceeding the limit for Hg and lesser probabilities for all other elements.

Notes: A 120-acre sanitary landfill site is being developed in north-central Pennsylvania to serve a six-county area. The design of the site will prevent ground-water contamination by leachate from the refuse through the use of a 20-mil (.5 mm) PVC plastic liner which will lie between two protective layers of sand containing drainpipe networks.Sampling of the composite ground-water flow from the underdrainpipe network in the sand blanket under the liner will provide sensitive monitoring of the liner performance. In the unlikely event of a leak, the pipe draining that area would be diverted to the leachate treatment facility, thus providing a backup leachate collection system. A thick (15 to 75 feet, 4.6 to 22.9 metres) glacial till deposit is present at the site and confines ground-water flow within the underlying shale bedrock. The low permeability of the till and the artesian head within the bedrock flow system provide additional protection against ground-water contamination.Operation of the site will be by the area-fill method; the refuse will be deposited in 8-foot (2.4-metre) lifts up to a maximum height of 120 feet (36.6 metres). Based on an initial refuse deposit rate of 400 tons (363 metric tons) per day, the site is expected to have a 20-year life at a disposal cost of approximately $5.00 per ton.Local residents who felt this project posed a severe threat to their wells strenuously opposed the project and appealed the State permit. The Pennsylvania Environmental Hearing Board upheld the permit; the decision was appealed to Commonwealth Court and was upheld. Residents remain unconvinced the design and site conditions will provide adequate protection and have petitioned the Pennsylvania Supreme Court to consider another appeal.A baseline water-quality monitoring program has been undertaken to establish on-site conditions and a private-well sampling program will begin before the landfill is in operation. Till and bedrock monitoring wells at the site will be used to evaluate the performance of this landfill; analysis of the nearby private wells will be provided to the owners to demonstrate confidence in the design and the satisfactory operation of the ground-water protection measures.

Notes: The best potential aquifers underlying the 600 mi 2 Hualapai Plateau of northwestern Arizona are (1) the Cambrian Rampart Cave Member of the Muav Limestone and (2) interbedded Tertiary sedimentary and volcanic rocks that locally fill old canyons on the plateau. These target aquifers have been identified on the basis of spring locations on the flanks of the plateau, primarily along the walls of the Grand Canyon to the north and east. Total ground-water discharge from springs along the plateau is approximately 4 ft3/sec.To date the largest production from a test well on the plateau is 120 gal/min from Tertiary rocks. The Cambrian rocks have frustrated development in part because of small permeabilities, small recharge (0.1 in/yr minimum), and the fact that the rocks are well drained.The complex stratigraphic nomenclature used to describe the Cambrian rocks in the region has inadvertently contributed to prospecting failures. The Cambrian section is characterized by thick interbedded limestones and shales, with the basal limestone being the principal target aquifer. These relationships have not been adequately conveyed to managers and drillers, with the result that critical test holes have been terminated in shales that overlie the target aquifer. Dry holes have been the result.

Notes: In early September 1975 a Technical Committee was established by the Virginia State Department of Health to clean up and dispose of a manufacturing plant which had produced the pesticide Kepone, in Hopewell, Virginia. The Committee recommended that the hazardous wastes be buried in a virgin section of the new City of Hopewell landfill. The disposal pit was designed to encapsulate the wastes in clay and plastic. The project was completed in early March 1976. The disposal site is monitored by the Virginia State Water Control Board via an observation well and an underdrain system.

Notes: The construction of wells yielding safe, sanitary water in areas of severely folded, fractured, and creviced limestone depends on the retention of enough sediment in the transmission paths to restrict the movement of contaminants. The described research has been directed towards two problems–the identification of terrain and hydrologic features that indicate a lack of adequate sanitary protection of ground water in the formation, and means of improving this protection. Intermittent spring-sinks along streams or in low-lying areas indicate a reversal of ground-water flow in the area. When the water level rises above a critical level sediments that have accumulated in the formation over many years may be discharged in a few days, resulting in a loss of filtering ability.Ground-water levels and bacteriological contamination have been monitored on four wells in Washington County, Maryland, since 1973. Ground-water quality deteriorated after tropical storm Agnes washed sediments from the formation. Techniques for preventing surface contaminant entry, improving filtering ability of the formation, and providing controlled relief of hydrostatic pressure have been studied as ways of protecting ground water in the formation.

Notes: The modelling of the Uluova Plain in southeastern Turkey was a part of training offered to Turkey's State Hydraulic Works' staff within a UNDP project. The modelling of the 341-sq km plain started with the simple steady-state version, but the model was gradually made more and more complex. At the end of modelling, the entire ground-water system was subjected to various automatic controls. The interesting feature of the model was the interaction between surface water (Keban Reservoir) and ground water. Lake Keban started encroaching upon the plain in 1974 and by the middle of 1976 it occupied over 100 sq km of the plain. In its verification phase covering the period from 1967 through 1974, the model amended the conclusions from a previous hydrogeological study. In its prediction phase, the model simulated the ground-water extraction plans for the 1976–1985 period. The modelling showed that the planned increase in ground-water withdrawal from about 17 million cubic meters (MCM) in 1975 to about 30 MCM in 1976 was quite realistic and completely sustained by the aquifer. The maximum drawdowns in the 1974–1980 period are of an order of magnitude of 20 meters. Another sharp increase in ground-water development from 30 to 58 MCM that was foreseen for 1981 would create drawdowns in some areas in excess of 35 m. The results of modelling pointed at several possible management alternatives.Several computation runs, which were repeated with Lake Keban removed from simulation as if it had not existed, made possible the evaluation of actual effects of the lake on ground-water development potentials of the plain. It was demonstrated that the lake improved the situation appreciably over an area of about 48 sq km that was foreseen by planning for additional development.The Uluova model incorporates some advanced and new routines in integrated surface-water–ground-water simulation.

Notes: The electrical resistivity method has been used to delineate shallow zones of ground-water contamination resulting from solid waste disposal sites. Application of this method to sites located in alluvial deposits in Iowa revealed that the degree of success of the method was directly related to the degree of contamination. A detailed investigation of the interrelationship between electrical resistivity, material variation, and water quality was conducted in the alluvial deposits of the Skunk River at Ames, Iowa. The lateral variation of materials at this site resulted in a large, natural scatter in the resistivity response. The decrease in resistivity due to contamination was not greater than this natural scatter and thus could not be detected. These results suggested a relationship between the scatter levels at any site and the minimum degree of contamination necessary to be detected. The minimum level of contamination which can be detected over the natural scatter is herein called the threshold value. The threshold value must be known before the resistivity method can be applied with confidence.

Notes: Mathematical modeling of regional unconfined ground-water flow is most often accomplished by using a linearized Dupuit-Forchheimer (DF) equation. The depth of flow, h, in the general DF equation appears as a squared (h3) term and also as a linear term (h). Linearization of the DF equation is generally accomplished with the first method of linearization presented by Polubarinova-Kochina (PK), in which h2 is replaced with h times some average depth of flow. The resulting equation is then linear in h. The second method of linearization described by PK is accomplished by replacing h with h2 divided by an average flow depth, and hence the resulting equation becomes linear in h2. If the second method of linearization is used, the same “heat conduction type” equation is obtained as that from the first method of linearization, but it tends to yield more accurate predictions of water-table locations. Furthermore, by simply altering the numerical values of boundary condition constants, most existing mathematical models, based on the first method of linearization, can be easily converted to yield solutions to the more accurate equation linearized by the second method.

Notes: An analysis of the unsteady flow in a fresh-water lens on a small tropical island is developed using the Ghyben-Herzberg relationship to determine the lens thickness. An alternative view of the problem to that most commonly given is presented. Results are shown for some lenses on Grand Cayman Island in the Caribbean Sea. The aquifer material is a micro-karst limestone. The chief result of engineering significance is that the conventional steady-state analysis is shown to be a sound basis for estimating the long-term yield if drought sequences are not long.

Notes: The hydraulic characteristics of a layered ground-water system are determined by a modified digital model. Its use provides information on the hydraulic conductivity and storage coefficient of a stratum and on the transmissivity and storage coefficient of the ground-water system as a whole. These characteristics are determined by trial-and-error test runs until the calculated drawdowns reasonably match drawdown data from observation wells which are open to the artesian aquifer and to the confining beds above or below. An aquifer test of a layered ground-water system in Palm Beach County, Florida shows that the transmissivity of the ground-water system as a whole is 50 percent higher than just the transmissivity of the major water-bearing zone in this system.

Notes: The danger from salination poses a significant threat to development of ground-water resources for domestic or irrigation use in near-coastal environments throughout the world. The Dashte-Naz farm area near the Caspian Sea in northern Iran is no exception. Large-scale ground-water development in this region has been limited to wells south of the Caspian Sea near the base of the Alborz mountains where sediments are coarse and natural recharge high. In the northern regions, however, exploitation of the groundwater resources for agriculture and livestock purposes has proven fruitless with most of the high-yielding wells turning saline after only several irrigation pumping seasons. The source of the salination comes not from encroachment of Caspian Sea water but rather from sediments saturated with connate or fossil waters. A wide zone of dispersion separates the salinated aquifers from the fresh-water aquifers nearer the mountains.The Dashte-Naz ground-water barrier and recharge project was conceived for purposes of overcoming the problem of exploitation of fresh ground-water reserves in the vicinity of saline-water fronts. The project presently under construction is a pilot research project on the practicality of using an injection well barrier for storing water underground in areas immediately adjacent to saline ground-water reservoirs. The results from this project will be used to design other water-supply projects in Iran not only

Notes: A plume of contaminated water may extend downstream for several miles in an alluvial aquifer. Hydrologic forces acting on the aquifer generally tend to dilute the contaminant downstream from the source. After the pollution has been stopped, how rapidly will these hydrologic forces flush out the contaminant? The answer to this question may be calculated by using the mass-balance equation herein developed.This mass-balance mathematical model incorporates all the hydrologic forces acting on the alluvial aquifer that affect the concentration of the contaminant. Methods are presented to define and quantify each of the hydrologic forces. These forces include (1) present quantity and quality (with respect to contaminant) of water in the alluvium and the change in the quality downstream, (2) quantity and quality of ground-water inflow, (3) quantity and quality of flood inflow, (4) quantity and quality of base flow, (5) quantity of recharge from precipitation, and (6) quantity of loss from evapotranspiration.The equation is first balanced to agree with past conditions and observed field data and is then used to predict future quality changes after the pollution is stopped.The method is applicable primarily to situations in which the pollution has been taking place over a long period of time and the water quality in the alluvium has reached equilibrium at any given point. Modifications may be possible to permit use of the general approach to short-term or slug-type pollution events.

Notes: Changing land-use patterns are occurring in all areas of the United States, especially those lands surrounding urban centers. Previously farmed land is being converted to residential subdivisions of one-quarter to one-half acre lots with on-site water supply and sewage disposal systems (well and septic). This in itself can present problems which are recognized and usually (now) provided for. There are also hazards resulting from the original uses of the land that have not been anticipated.This paper is concerned with the high nitrate nitrogen levels (U.S.P.H.S., 1962, Note 1) in ground water resulting from long-term farming. Natural chemical and biological activity will break down manure to persistent nitrate that is then leached into the water table. Subsequent subdivision of the land, well installation and consumption of the contaminated ground water constitutes a problem that has been medically recognized since 1945, but not by the drilling industry or environmental health personnel.Regulations of the Maryland State Department of Health and Mental Hygiene (Note 2) provide for a required series of bacteriological and chemical samples prior to the water supply being put into service. To date, the tests are usually conducted after occupancy, if at all. In Harford County, Maryland, at least four subdivisions have been shown to have areas of excessive nitrate nitrogen (up to 60 ppm) showing the need for stringent enforcement of existing regulations.

Notes: C. E. Jacob, noted hydrologist, received patents on his doublet well invention in 1965. Due to his death soon thereafter, no paper was written or published describing his invention. The purpose of this paper is to stir interest in his original doublet theory and make known a technique that can be useful to hydrologists.Jacob's patents are for a single location doublet well that produces fresh water or petroleum from underground reservoir formations without contamination by underlying heavier liquid. By use of packers, water is pumped from one horizon and discharged into a different horizon. A closed cell is created whereby the heavier liquid is recirculated below the streamline boundary, while lighter fluid passes into the well and is raised to the surface.The doublet well as proposed by Jacob has the potential to increase the usefulness of ground water. It permits a greater rate of production of the lighter liquid than previously possible. It is applicable to saline intrusion and oil vs. brine situations. The single doublet is also a possible mechanism for the ground-water heat pump.

Notes: Secondarily treated waste water was added to plastic columns filled with calcareous glacial outwash soil for a period of 10 weeks. More than 99 percent of the phosphorus was retained in the upper 50 centimeters of the soil, primarily due to adsorption. Ammonia, nitrite, and organic nitrogen were biologically nitrified to nitrate nitrogen. There was no measurable mercury in the column effluent, and it was present in only two samples of the waste water. About 30 percent of the cadmium was removed by ion exchange in the soil columns. Lead was not removed, probably due to the prior exhaustion of the lead exchange sites.

Notes: Successful underground storage of large volumes of treated water (sufficient for a period of weeks or months) could provide a temporary, alternative water supply in areas where potable ground water is not available and where surface runoff varies unpredictably in quantity and quality. A small-scale field test of underground storage, using an injection well, was performed in Jefferson Parish, Louisiana. Storage in the tested aquifer was proven to be impractical due to the pre-existing ground-water movement rate of 0.5 ft (15 cm) per day. A mathematical model of the injection-storage-production process accurately predicted the recovery efficiencies observed in the two tests. The quantity of injected water was not adversely affected by geochemical reactions occurring during the tests. The injected water was softened during storage by ion-exchange reactions between injected water and clay particles in the aquifer.

Notes: In areas where bedrock is irregular, greater saturation thickness of aquifer will associate with the depression in the bedrock formation. Wells located upon these depressions can yield significantly higher amounts of water. Hence, finding the bottom of depression in the area will be of interest, and this can be facilitated by drilling test holes. These test holes can be drilled at the nodes of a regular grid; however, more efficient search techniques are available. Fibonacci search in one dimension has recently been proposed and potential saving in drilling cost demonstrated. But the problem is essentially two-dimensional in nature. This paper describes some two-dimensional search procedures for this purpose and shows that potential saving in drilling cost can be dramatic.

Notes: To evaluate the potential of natural clay minerals for attenuating and preventing the pollution of water resources by landfill leachates, leachate was collected by anaerobic techniques from the 15-year old Du Page County sanitary landfill near Chicago, Illinois, and was passed through 44 laboratory columns that contained various mixtures of calcium-saturated clays and washed quartz sand. The columns were constructed to simulate slow, saturated, anaerobic flow, and manometers were placed at five locations in each column to measure any changes in hydraulic conductivity. Leachate was run through the columns for periods ranging from 6 to 10 months, during which time effluents were collected periodically and analyzed for 21 chemical constituents. The columns were then sectioned and the clays analyzed to determine the vertical distribution of the chemical constituents in each column. Sterilized landfill leachate was used in a duplicate set of columns to determine the effects of gross biological activity.Chloride and certain organic compounds were relatively unattenuated by passage through the clay columns; monovalent cations, such as Na, K, and NH4, were moderately attenuated; and heavy metals, such as Pb, Cd, and Zn, were attenuated by even small amounts of clay. Concentrations of Ca and Fe were much higher in the column effluents than they were in the original leachate. The increase in Ca in the column effluents was due to cation exchange with ions in the refuse leachate. The Fe increase probably resulted from reduction of the oxidized Fe on clay surfaces by anaerobic refuse leachate to more soluble reduced Fe.Both biologically active and sterilized leachate reduced the hydraulic conductivity of the clay-mixture columns during the experiment. The active leachate reduced the hydraulic conductivity to a much greater degree than the sterile leachate.Results of the laboratory data were compared with field data from the Du Page County sanitary landfill and from other existing landfills where detailed data are available. The field data show a “hardness halo” corresponding to the Ca release in the columns. The relative attenuation rates of some of the ions were also confirmed by the field data. The change in hydraulic conductivity was not as clearly shown.Ion exchange capacity, hydraulic conductivity, and buffering capacity of the earth materials were all shown to be important in assessing the potential of landfills for water pollution.

Notes: A digital simulation model for the steady-state radial flow towards partially penetrating wells in the alluvial plains is presented. As the deposits in these plains are heterogenous with several good water-bearing formations crisscrossed with silty layers, the deposits are treated as a single anisotropic aquifer with water-table conditions prevailing. The iterative alternate direction implicit technique is used for the solution of the steady-state flow. The digital simulation model is used to study the effects of anisotropy, screen setting, and screen length on the discharge per unit length of screen; and in evaluating the errors involved in determining lateral permeability from distance-drawdown data. The digital simulation model is applied to field pump-test data for purposes of identification of aquifer anisotropy and radius of influence of well, and in evaluation of errors in determining lateral permeability from distance-drawdown data.

Notes: Theoretical travel times are given for a solute to reach a well from an injection point, for wells that fully penetrate confined aquifers of constant thickness and mainly constant conductivity and porosity. Solute is assumed to move along streamlines with the water in piston flow under steady flow conditions. Three cases are considered.〈list xml:id="l1" style="custom"〉1For a “standard” well of external radius of influence re and well radius rw, the travel time varies approximately directly as the square of the distance r of the injection point from the well, as the ratio f/K of porosity to conductivity, and as ln re/rw.2For a well in which the flow region is divided by radius re into two regions, with the region next to the well clogged and of very low conductivity KI the travel time varies approximately directly as r squared, as KI, and as ln rc/rw.3For a well being fed from a line drive (river) at a distance d from the well, the travel time from a point on the line drive to the well varies as the distance d squared, as f/K, as ln 2d/rw, and as a function of the position of the point along the line drive.In each case, the travel time is inversely proportional to he - hw, where he is the head at the radius of influence re (or at the line drive) and hw is the head at the well. In the three cases, doubling the pumping rate halves the travel time. Travel times can affect the extent of chemical changes of the solute (contaminant) during its flow to the well.

Notes: Turbid ground water is rarely observed in domestic or public supply aquifers. At the Leaky Acres Recharge Facility at Fresno, California, water of low salinity (〈50 μmhos/cm) and turbidity (〈5 FTU, Formazin turbidity units) is recharged in the spreading basins. Six months after the start of the third (1973) recharge period, the ground-water salinity was decreased to about 100 μhos/cm from the initial mean of 147 μhos/cm and the ground water became visibly turbid (〉5 FTU). Two months later, some peripheral domestic wells also began to become turbid. After two more recharge periods (1974 and 1975), turbidity at 10 observation wells beneath Leaky Acres averaged 18 FTU and salinity averaged 74/μmhos/cm. By this time, ground-water turbidity in peripheral wells near Leaky Acres had decreased to 〈0.5 FTU. This turbidity was traced to poorly-crystallized and extremely fine colloids, which have leached from the surface soils because of the low salinity of the recharge water. Laboratory and field studies showed that gypsum application will reverse the phenomena, but such treatment is uneconomical. This phenomenon is a transient one, and now turbidity outside the recharge area is insignificant from a water quality viewpoint. However, the magnitude of the mass of material in transit through the profile if stabilized through flocculation or sieving in soil pore space, could greatly change the water transmission and so recharge project performance. However, we have not yet noted this effect at Leaky Acres.

Notes: Results of this study indicate that the nitrate and chloride concentrations in the ground water of the central Wisconsin sand plains are significantly above background, and that the main source is the irrigated agriculture in the region. Nitrate-N concentrations ranged from nil to 56 mg/1 and chloride from nil to 68 mg/1. Nitrate-N concentrations exceeded 10 ppm in 15 of 33 irrigation wells and in 2 of 3 domestic wells. Nitrate-N and chloride concentrations varied widely between adjacent wells but the CI/NO3-N ratio was much less variable. This suggests similar relative inputs of nitrogen and chloride presumably from nitrogen and potassium (potassium chloride) fertilizers.The study was conducted at three levels of intensity; a small field during one growing season, a University Experimental Farm over several years, and many local farms during part of a growing season. Differences in concentrations of nitrate-N and chloride in the surface of the ground water underlying the moderately fertilized potato field closely reflected the fertilizer and irrigation management on different parts of the field during that season. This detailed study of one field showed that solute transit times through the 16 feet (5 m) of unsaturated zone to the surface of the ground water are less than a year.Differences in concentration of nitrate-N and chloride between irrigation wells on the Experimental Farm closely reflected the irrigation and fertilizer practices on surrounding fields. Nitrate-N and chloride concentrations in ground water were lower where the adjacent land had been idle for many years and only recently cropped. However, levels were high where fertilizer and irrigation inputs.On a larger scale, the nitrate-N and chloride concentrations in area farmer irrigation wells were as different between wells on the same farm as farm as between the various farms.

Notes: A multiple-aquifer system in the bayfront area of Palo Alto, California is being intruded with seawater from San Francisco Bay. In order to combat this potential degradation of the ground-water supplies in the area, a sea-water intrusion barrier is being constructed consisting of a series of injection wells used to inject 2.0 million gallons per day (7.6 × 106 l/d) of reclaimed wastewater into a shallow aquifer. The injected water is subsequently removed by a similar system of extraction wells to avoid any possible degradation of the water-supply aquifers from this source, and to allow reuse of the reclaimed wastewater. The investigation phase included test drilling, aquifer testing and injection testing to determine the feasibility of the injection/extraction (I/E) concept. The number, spacing and location of I/E doublets were optimized using a digital computer model. The double-cased, double-screened wells were constructed using corrosion-resistant materials and were designed for ease of routine maintenance. In operation, injection and extraction will be computer controlled by sensing piezometric levels in a series of monitor wells. Water pumped from the extraction wells will be sold for industrial and agricultural purposes. The I/E well system has been approved for 87½ percent Federal and State grant funding.

Notes: Marked changes in the occurrence and quality of near-surface ground water in Las Vegas Valley, Nevada result from urban and industrial land and water use practices. In-valley recharge has increased tenfold in the period 1943 to 1973 and now amounts to about 40,000 acre-feet/year (49.3 million m3). Ground-water flows leaving the Valley have increased from 250 acre-feet/year to about 12,000 acre-feet/year.Twenty to 400 tritium units (T.U.) in shallow ground water confirm widespread addition of recent recharge. Trend-surface analysis of recent water-quality data for depth intervals or “slices” of 0 to 50, 51 to 100, and 101 to 300 feet (0 to 15.2 m, 15.5 to 39.5 m, 30.8 to 91.4 m) revealed that natural trends below a depth of 50 feet are explainable in terms of broad hydrogeologic conditions. From 0 to 50 feet quality is highly irregular and markedly more influenced by land and water use practices and waste disposal in particular. Chloride, TDS, and nitrate are particularly diagnostic of return flows as is spring development and (or) a rising water table resulting from increased recharge and low vertical permeability. Statistical tests on water-quality data for the period 1912 to 1968 yielded generally insignificant change with time. However, the extreme paucity of the data base makes any conclusion questionable.More efficient irrigation practices could reduce the present irrigation water demand by 15,000 acre-feet/year and reduce return flows by 11,000 acre-feet/year. Return flows by the year 2000 could easily amount to 75,000 acre-feet/year or about three times the total water budget of the Valley prior to urbanization. Therefore, groundwater problems are likely to worsen and, if present monitoring practices prevail, go unnoticed.

Notes: Sandstone mounds occur in some shallow marine heterolithic deposits from the Late Precambrian Stangenes Formation (N. Norway) and the Cambro-Ordovician Crozon Formation (N. W. France) and Cabos Series (N.W. Spain). The sediments displaying the mounds accumulated in partially protected tidal flat/ lagoonal environments immediately before and during major transgressions.The mounds are erosional features typically occurring on the tops of sheet sandstones (ca. 50–500 mm thick) some of which may have a storm washover origin. Mound genesis related to periodic emergence and late stage run-off is supported by their intimate association with mudcracks and other very shallow water features (e.g. bidirectional current-formed structures, wave ripples, ladder and interference patterns, mudflakes, etc.). Variation in mound morphology suggests that post-depositional dissection began as elongate ridge-gully couplets with secondary erosion of the ridge flanks leading to the development of more characteristic hemispherical geometries. Emergence may have been a function of tidal fluctuations and/or subsidence of storm surge events.Facies sequences point to the repeated filling of these inshore environments by storm washovers superimposed on ambient tidal conditions which possibly resulted from the progressive decay of beach barriers during transgression.

Notes: Alluvial fans of the last glacial age in the lower Derwent Valley in southeastern Tasmania were built by debris flows and stream flows. The deposits were derived from periglacial and nivational slope mantles at the highest altitudes in the fan catchments, and from regolith of uncertain affinities at the lowest elevations. The apical and middle parts of the fans commonly consist of coarse-grained debris flow and water-laid deposits, while the distal deposits are predominantly water-laid sheetflood silts and clays. Channels are important in the proximal parts of the fans and are mostly filled with water-laid sediments, less commonly by debris flow deposits. A first approximation to the mean velocity of the last stage of debris flow in a channel is between 4 m/sec and 6 m/sec. A group of ‘water-laid’ sediments shows very poor separation of particle sizes, and two explanations have been offered for these sediments. Firstly, the large quantities of unsorted debris available from the catchments produced moderately well-sorted slurries, or, secondly, openwork stream gravels were infiltrated by later water flows charged with fines. The streams crossing the fans also produced water flows with relatively low suspended sediment concentrations resulting in reasonably good sorting. The debris flows and ‘water-laid’ muddy sediments cannot be distinguished using CM plots. The debris flows display considerable variation in thickness and grain-size characteristics, which is attributable to properties inherent in debris flow behaviour.

Notes: A study of septarian concretions from late Cretaceous shale sequences of Texas and northern Mexico reveals complex burial-exhumation histories. First generation concretions and pre-fossilized moulds formed in silty clays before significant compaction occurred. Syneresis cracks developed and were filled by length slow fibrous calcite with a decrease in iron content toward the centre of each vein; in some cases this was succeeded by growth of equant or bladed calcite. Subsequent erosion of enclosing sediment caused collapse and break up of concretions, leaving fragments and some unbroken concretions exposed to encrustation and boring on the sea floor. These were subsequently buried and enclosed in a second generation of concretions, which also developed syneresis cracks. The calcite that filled these latter cracks was generally bladed (sometimes followed by equant calcite) and contains more iron toward the centre of the vein. Differences between the calcite filling first and second generation septarian veins indicates changing diagenetic regimes during burial in the marine environment, without a major shift in diagenetic conditions, such as the introduction of meteoric waters. These conclusions have significant implications to cementation in ancient limestones, which show textural and chemical sequences similar to those present in the septarian concretions described.

Notes: In May 1974 a powerful flood flushed the Grand River basin, Ontario. The effects on the bedload were drastic in a narrow (30 m) and deep (40 m) rock walled and floored gorge near Elora, Ontario. Along Irvine Creek, the tributary occupying the gorge, the gravel cover was reworked in several types of bars, predominantly transverse and point bars. The bars formed very rapidly in response to essentially steady, non-uniform flow that developed during a brief period of high flood.Superimposed on major bars are several minor sedimentary features such as coarse transverse ribs, chute channels and bars, longitudinal ribs, imbrication clusters, backsets with well developed imbrication, that were formed under very high stream discharge. Structures like imbrication clusters, transverse ribs and small riffle bars require a ‘live bed’ situation to form, and they develop when stones come to a stop either because they cluster during transport, or because keystone effects occur along shallow channels. In Irvine Creek, very few sedimentary features were formed during waning and low flood stages: only some shadow deposits and a few Ostler lenses. The few fines that were available were lost downstream or filled in lower parts of gravel beds.This study confirms that in streams that experience strong seasonal fluctuations in discharge, bedforms that develop during high floods have a high probability of preservation. In gravelly deposits, foreset structures and plane beds are most commonly preserved, although they may be difficult to recognize in old deposits, which may appear massive, particularly if the gravel has been infilled with finer pebbles and sand. In the case of Irvine Creek, all deposits are organized, and lateral and vertical variations in textures, particularly imbrication and packing, are very useful in the recognition of sedimentary structures.

Notes: Illite, illite-montmorillonite (I-M) mixed layer, kaolinite and chlorite are the principal clay minerals identified in the carbonate and terrigenous carboniferous rocks in the South Wales coalfield. Mineralogic changes and illite crystallinity are the main modifications in the studied rocks. Progressive illitization of I-M mixed layers (decrease in their expandabilities) towards the western part of the coalfield (i.e. in the direction of increase in coal-rank and grade of metamorphism), and the development of vermicular kaolinite, dickite, allevardite and pyrophyllite in the anthracite area are the main mineralogic changes. Illite crystallinity was determined by Weaver's sharpness ratio (S.R.) and isosharpness ratio maps of illite in the carbonate and terrigenous rocks are produced showing a gradual increase in illite crystallinity towards the west. Illites in the terrigenous rocks tend to be aluminous (evidenced by the increase in their intensity ratios, ‘I.R.’) with increase in coal-rank and grade of metamorphism towards the west. These changes are controlled to some extent by lithology. Correlation of illite S.R. with either its I.R. or expandability of I-M mixed layer, has outlined two diagenetic zones in the coalfield: zone I, the Diagenetic zone, in the eastern and southern regions; and zone II, the Metadi-agenetic zone, covering the central and northern parts of the central region. The Anchimetamorphic zone (zone III), which corresponds to the anthracite area in the northwestern region, was differentiated by correlating the illite S.R. with coal-rank. The occurrence of the above mentioned diagenetic zones and modifications of the clay minerals in the carboniferous rocks of the South Wales coalfield are mainly lateral without variation with increase in depth.

Notes: This short note reports a series of density current experiments designed to model turbidity underflows caused by flood-stage discharge of lake-tributaries. In a 5.8 m long tank filled with freshwater, saltwater was fed in continuously, flowing down a 15°‘delta’ slope onto a horizontal floor. These density currents maintained steady state characteristics. The main objectives of this investigation were to determine (1) the flow regime of the density currents and (2) the underflow-induced movements in the freshwater. Reynolds numbers for thirty-five runs ranged from 70 to 4100. Experiments with laminar flow reproduced kinematic (Froudian) models of underflows measured in the Walensee (Switzerland). Flow was rapid on the slope (Froude number, Fr 〉 1) and tranquil (Fr〈1) on the floor. Turbulent flow experiments yielded velocity profiles (with a maximum at the flow interface) which approximate natural conditions. Movements in formerly stagnant water body are induced by interfacial shear stress: a layer of freshwater is dragged along by the density current and replaced by the backward flow of an equal amount of overlying water (mass conservation). Extrapolated to a natural setting, circulation induced by underflows is probably an important mechanism for oxygenating deep lacustrine basins.

Notes: Carefully selected data for the threshold of sediment movement under unidirectional flow conditions have been utilized to re-examine the various empirical curves that are commonly employed to predict this threshold. After a review of the existing data, we employed only that data obtained from open channel flumes with parallel sidewalls where flows were uniform and steady over flattened beds of unigranular, rounded sediments. Without these restrictions, an unmanageable amount of scatter is introduced.This selected data is used to develop a modified Shields-type threshold diagram that extends the limits of the original diagram by three orders of magnitude in the grain-Reynolds number. The equally general but more easily employed Yalin diagram for sediment threshold is also examined. Although the Shields and Yalin diagrams are general in that they apply to a wide range of different liquids, in both cases somewhat different curves are obtained for threshold under air than for the liquids.The often used empirical curves of the friction velocity u*, the velocity 100 cm above the bed u100, the bottom stress θt, and Shields’ relative stress θt, all versus the grain diameter D, are limited in their ranges of application to certain combinations of grain density, fluid density, fluid viscosity and gravity. These conditions must be selected before the curves are generated from either the more general Shields or Yalin curves. For example, on the basis of the data selected for use in this paper, empirical threshold relationships for quartz density material in water are 〈displayedItem type="mathematics" xml:id="mu1" numbered="no"〉〈mediaResource alt="image" href="urn:x-wiley:00370746:SED507:SED_507_mu1"/〉 where the velocity u100 measured 100 cm above the sediment bed is given in cm/sec and the grain diameter D is in cm.The limitations on any of the threshold relationships are severe. These limitations should be properly understood so that the empirical curves and relationships are not improperly employed.

Notes: Nous avons étudié la minéralogie et la composition chimique de cherts à Radiolaires (radiolarites) du Dogger-Malm, liés ou non à des affleurements de roches volcaniques. Les échantillons proviennent du Maroc (Rif), d'Italie (Bassin Lombard et Appenins), de Grèce (Zone du Pinde et Massif du Vourinos) et de Californie (Baie de San Francisco). A titre de comparaison, nous avons également étudié des cherts crétacés du Pacifique (Leg 32) et des boues à Diatomées miopliocènes de la Mer du Japon (Leg 31).La silice des radiolarites est exprimée sous forme de quartz ou de calcédoine. Ces roches renferment en outre des feldspaths et, souvent, de l'hématite. La phase argileuse est constituté d'illite et/ou de chlorite, accompagnée fréquemment d'édifices gonflants et, très localement, de kaolinite. Dans les śediments océaniques le degre d'organisation de la silice est très variable (depuis l'opale jusqu'au quartz), les minéraux argileux sont à peu près identiques à ceux des radiolarites, les feldspaths sont également fréquents.Du point de vue chimique, on peut distinguer, parmi les radiolarites: des faciès massifs, des pélites a Radiolaires et des radiolarites ferrugineuses. Celles-ci se rencontrent généralement à la base des séries associées à des formations volcaniques. Les cherts du Leg 32 et les boues à Diatomées de la Mer du Japon ont une composition très voisine de celle des radiolarites massives.La minéralogie de ces formations peut ètre expliquée par plusieurs modèles: héritage, diagenèse de boues pélagiques, etc.… Le caractère détritique d'une partie des argiles semble certain.L'origine de la silice est discutee: la position latitudinale de la Téthys au Jurassique, son caractère relativement confiné et d'eventuels apports volcaniques doivent être pris en consideration. Par contre, compte tenu de la composition chimique et minéralogique des radiolarites, la diagenèse des argiles n'est pas susceptible de fournir des quantités notables de silice. L'accumulation de boues à Diatomées dans la Mer du Japon et en d'autres lieux montre que ni l'éloignement des côtes ni de très grandes profondeurs ne sont indispensables au développement d'une sédimentation hypersiliceuse.

Notes: Framboidal pyrite is identified in clayey Holocene sediments in the northwestern part of the Barents Sea, and also in clasts of black Jurassic (?) shale within these sediments. Two types of framboidal pyrite are distinguished. Framboids in the Holocene sediments lack a matrix between the microcrystals whereas the Jurassic specimens have a matrix. In contrast to the rest of the clastic sedimentary material in the area, the framboidal pyrite in the Holocene sediments is not reworked from the underlying Mesozoic rocks, but has formed recently. In some Holocene sediments the microcrystals are well organized and crystal-like faces are developed. The framboidal texture is probably a result of pyrite crystallization. The matrix is concluded to be due to diagenetic alteration and is not a primary feature of the framboidal pyrite.

Notes: Clinoptilolite, a zeolite of the heulandite group, occurs commonly in sediments as an authigenic mineral. In the Middle Eocene of southern Israel, it constitutes from a few per cent up to 80 per cent of the insoluble residue of the chalks and limestones. It is associated with opal C-T, montmorillonite and palygorskite. These chalks and limestones overlie the Danian-Palaeocene Taqiya marls which also contain a well-established clay mineral sequence consisting of opal C-T, montmorillonite, palygorskite, sepiolite, and clinoptilolite.This paragenesis of minerals is shown to be typical of the Upper Cretaceous to Eocene times. It is world-wide, occurs in deep-sea sediments as well as in shallow water sediments, and results from the abundance of silica which probably reflects a warmer climate during this time period.The concentration of magnesium in the sea-water and its ratio to the other cations seem to determine which authigenic silicate will be formed.

Notes: History of the Earth Sciences during the Scientific and Industrial Revolutions with Special Emphasis on the Physical Geosciences. By D. H. Hall. Stromatolites. Edited by M. R. Walter. Calcareous Algae. Developments in Paleontology and Stratigraphy, Vol. 4. By John L. Wray.

Notes: In growing sedimentary sequences range and velocity of vertically ascending pore water (advection) can be determined quantitatively by using a simple graphical method. During continuing deposition and maintenance of compaction equilibrium, the pore water from deeper layers cannot reach the sediment-water interface. Range and velocity of advective flow decrease from top to bottom of a sequence and depend on the thickness affected by compaction. The velocity of pore water flow as well as the transport of solutes by advective flux are proportional to the sedimentation rate. Compaction flow can also result from under-con-solidation and diagenetic reduction of pore space. At the sediment-water interface, a direct contact between the ascending pore water and the overlying water body is feasible only under special conditions (interrupted sedimentation over under-consolidated material, erosion). These results are demonstrated on geometric models of sedimentary sequences, on experimentally deposited clay, and on selected examples of the Deep Sea Drilling Project.