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  • 1
    Electronic Resource
    Electronic Resource
    Unsteady Drawdown at a Partially Penetrating Well in a Transversely Isotropic Artesian Aquifer (1973)
    Oxford, UK : Blackwell Publishing Ltd
    Ground water 11 (1973), S. 0 
    Details
    ISSN: 1745-6584
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Geosciences
    Notes: The work described in this paper investigates the effect of aquifer anisotropy on the unsteady drawdown at the face of a partially penetrating well, which is pumped at a constant rate. The aquifer is confined between two parallel aquicludes, and its hydraulic conductivity is assumed to be transversely isotropic. Based on a parametric study of the drawdown equation, it is concluded that the variation in drawdown depends on which of the principal permeabilities is held constant, as well as the ratio between them. For constant radial permeability, the rate of increase of drawdown with time is independent of the permeability ratio; furthermore, unless the well penetration is very small, aquifer anisotropy is of little consequence for permeability ratios close to unity. For constant vertical permeability, well penetration has practically no influence on the drawdown for lower permeability ratios. The effect of aquifer anisotropy increases from a negligible value for a fully penetrating well to a maximum for wells which just tap the aquifer.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1745-6584.1973.tb02991.x
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  • 2
    Electronic Resource
    Electronic Resource
    UNCONFINED FLOW THROUGH JOINTED ROCK (1972)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of the American Water Resources Association 8 (1972), S. 0 
    Details
    ISSN: 1752-1688
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Architecture, Civil Engineering, Surveying , Geography
    Notes: The two-dimensional, steady-state, unconfined flow of a homogeneous fluid through jointed rock is studied for both laminar and turbulent conditions by use of a method which is based on previously developed theoretical and experimental flow relationships. However, only the independent unknowns are selected in order to reduce the complexity of the problem and render it more readily tractable. The intact rock is assumed to be impermeable, and two intersecting systems of plane, parallel joints are used in the mathematical model, taking into account the surface roughness of the joints. The mathematical solution of the resulting nonlinear (due to turbulent flow in some joints) system of equations is obtained by use of a rapidly converging iterative procedure, wherein each iteration takes special advantage of the banded nature of the associated matrix. For the particular case where a free surface exists, the general flow equations are not satisfied, because some of the joints in the vicinity of the free surface do not flow full; therefore, new equations must be established to handle this condition. Once the development of the mathematical model is accomplished, several cases involving different geometric characteristics (width, orientation, and roughness of joints) are solved for a rectangular domain, and graphs are given to illustrate the influence of the various parameters on the manifested flow behavior.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1752-1688.1972.tb05136.x
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    NONSTEADY FLOW TO A WELL WITH TIME DEPENDENT DRAWDOWN (1972)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of the American Water Resources Association 8 (1972), S. 0 
    Details
    ISSN: 1752-1688
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Architecture, Civil Engineering, Surveying , Geography
    Notes: Confined flow toward a single well of finite radius in an extensive aquifer of uniform transmissibility is studied under the assumption of time-dependent drawdown.Three particular cases are considered: (a) linear drawdown (including constant drawdown); (b) exponential drawdown; (c) periodic (sinusoidal) drawdown.The differential equation governing unsteady axial symmetric flow toward a single well in a confined aquifer is solved for the three different situations by the use of the Laplace transform method. The resulting expressions are integrated by adapting a modified Gemant scheme.General computer programs have been developed and operated for several combinations of characteristics. The results are plotted to show the effect of time dependent drawdown on the variation of the well discharge and the piezometric head distribution.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1752-1688.1972.tb05138.x
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  • 4
    Electronic Resource
    Electronic Resource
    DRAWDOWN AT TIME-DEPENDENT FLOWRATE (1973)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of the American Water Resources Association 9 (1973), S. 0 
    Details
    ISSN: 1752-1688
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Architecture, Civil Engineering, Surveying , Geography
    Notes: : The exact solution for the drawdown in and around a well in a homogeneous, isotropic, and confined aquifer is presented if the well discharge is a function of time. The effect of the storage capacity of the well is also taken into consideration. Two types of flowrate functions are studied, namely linear and exponential functions, and the results are plotted in graphs.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1752-1688.1973.tb05814.x
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  • 5
    Electronic Resource
    Electronic Resource
    CRITICAL EVALUATION OF CERTAIN METHODS OF UNSTEADY GROUNDWATER HYDRAULICS (1970)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of the American Water Resources Association 6 (1970), S. 0 
    Details
    ISSN: 1752-1688
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Architecture, Civil Engineering, Surveying , Geography
    Notes: The basic theories and fundamental assumptions usually employed in the solution of unsteady groundwater flow problems are reviewed critically. The best known method of analysis for such problems is based on the Dupuit-Forchheimer approximation and leads to a nonlinear parabolic differential equation which is generally solved by linearization or numerical methods. The accuracy of the solution to this equation can be improved by use of a different approach which does not employ the Dupuit Forchheimer assumption, but rather is based on a semi-numerical solution of the Laplace equation for quasi-steady conditions. The actual unsteady process is replaced by a sequence of steady-state conditions, and it is assumed that the actual unsteady flow characteristics during a short time interval can be approximated by those associated with “average” steady state flow. The Laplace equation is solved by a semi-discretization method according to which the horizontal coordinate is divided into subintervals, while the vertical coordinate is maintained continuous. The proposed method is applied to a typical tile drainage problem, and, based on a comparison of calculated results with experimental data, the method is evaluated and practical conclusions regarding its applicability are advanced.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1752-1688.1970.tb00492.x
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    Paper (German National Licenses)
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  • 6
    Electronic Resource
    Electronic Resource
    Drawdown in a Well Group Along a Straight Line (1971)
    Oxford, UK : Blackwell Publishing Ltd
    Ground water 9 (1971), S. 0 
    Details
    ISSN: 1745-6584
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Geosciences
    Notes: Procedures are developed and charts are presented to determine the unsteady drawdown in a group of wells which are located along a straight line and fully penetrate a homogeneous, isotropic, artesian aquifer. Based on the linearity of the governing field equation, the principle of superposition is used to combine the effects of individual wells, and solutions are obtained by using a digital computer to evaluate an exponential integral. The concepts of equivalent radius, coefficient of interference, and degree of uniformity are introduced, and quantitative graphical relationships are given as functions of the independent variables, which are the number of wells, well spacing, and time.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1745-6584.1971.tb03554.x
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  • 7
    Electronic Resource
    Electronic Resource
    Analysis of leaky sheetpile by Summary Representation (1980)
    New York, NY [u.a.] : Wiley-Blackwell
    International Journal for Numerical and Analytical Methods in Geomechanics 4 (1980), S. 199-213 
    Details
    ISSN: 0363-9061
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Architecture, Civil Engineering, Surveying , Geosciences
    Notes: A numerical technique called Summary Representation was used to solve the problem of seepage through a leaky sheetpile; this particular method was selected owing to its accuracy and computational speed. Seepage parameters were evaluated quantitatively and the influence of the leakiness of sheetpiles in a porous medium underlain by an impervious horizontal stratum was determined. The case of a single sheetpile was first considered, and the effect of the depth of penetration and coefficient of leakiness on the total rate of flow and on the values of the exit gradient was analysed. Next, the flow under an impervious dam was considered to assess the accuracy of the method. Finally, the case of seepage under a dam with leaky sheetpiles at both ends was studied, including the effect of the leaky sheetpiles on the uplift pressure acting along the foundation of the dam. Patterns of seepage through the flow line deformation that is caused by the leakiness of the sheetpiles.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/nag.1610040302
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    Paper (German National Licenses)
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  • 8
    Electronic Resource
    Electronic Resource
    Simulation of air storage aquifer by finite element model (1982)
    New York, NY [u.a.] : Wiley-Blackwell
    International Journal for Numerical and Analytical Methods in Geomechanics 6 (1982), S. 339-351 
    Details
    ISSN: 0363-9061
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Architecture, Civil Engineering, Surveying , Geosciences
    Notes: A finite element model is developed to simulate the behaviour of an aquifer used as storage space for a compressed air energy storage (CAES) system. The governing equations describing a two-phase flow of air and water are coupled non-linear partial differential equations and are solved by the Galerkin approach. The resulting computer model is applied to a gas percolation problem. Upon verification of the numerical results, the model is employed to simulate the air-water displacement in a storage reservoir during daily air cycling. The corresponding saturation variations and the effects of reservoir permeability on the system are presented. The results obtained are essential in establishing storage design and stability criteria for long-term operation of compressed air energy storage systems.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/nag.1610060306
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    Paper (German National Licenses)
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