Pumping Tests In Unconfined Aquifers

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Water Well And Aquifer Test Analysis

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Author : Phil Hall
language : en
Publisher: Water Resources Publication
Release Date : 1996

Water Well And Aquifer Test Analysis written by Phil Hall and has been published by Water Resources Publication this book supported file pdf, txt, epub, kindle and other format this book has been release on 1996 with Science categories.

Pumping Tests In Unconfined Aquifers

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Author : Ernst Peter Kauch
language : en
Publisher:
Release Date : 1990

Pumping Tests In Unconfined Aquifers written by Ernst Peter Kauch and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1990 with Aquifers categories.

Numerical Modelling Of Pumping Tests In Unconfined Aquifers

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Author : Ian Timothy Brown
language : en
Publisher:
Release Date : 1996

Numerical Modelling Of Pumping Tests In Unconfined Aquifers written by Ian Timothy Brown and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1996 with categories.

Analysis And Evaluation Of Pumping Test Data

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Author : G. P. Kruseman
language : en
Publisher:
Release Date : 1970

Analysis And Evaluation Of Pumping Test Data written by G. P. Kruseman and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1970 with Groundwater categories.

Aquifer types;hydraulic properties;types of flow equations;pumping tests;perfomance of a pumping test;analysis of data;methods of analysing pumping test data;steady-state flow in confind aquifers;unstead-state flow in confined aquifers;unsteady-state flow in confined aquifers;steady-state flow in semi-confined aquifers;unsteady-state of the thiem method;unsteady-state flow in inconfined aquifers with delayed yield and in semi-inconfined aquifers;steady-state flow in unconfined aquifers;unsteady-state flow in unconfined aquifers;methods of analyzing pumping test data II;aquifers limited by one or more houndaries;anisotropic aquifers;wedge-shaped aquifers;sloping aquifers;aquifers pumped at a variable discharge rate;partially penetrated aquifers;aquifers pumped by a large diameter well;two layered semi-confined aquifers;aproximation methods;free flowing wells;corrections and conversions;corrections for external influences;conversion of units.

Aquifer Testing

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Author : Jonathan D. Istok
language : en
Publisher: CRC Press
Release Date : 1991-05-31

Aquifer Testing written by Jonathan D. Istok and has been published by CRC Press this book supported file pdf, txt, epub, kindle and other format this book has been release on 1991-05-31 with Technology & Engineering categories.

New! A practical, easy-to-use reference for the design and analysis of groundwater pumping and slug tests Aquifer Testing: Design and Analysis of Pumping and Slug Tests is a complete design and analysis reference emphasizing practical solutions for engineers, scientists, consultants, and students knowledgeable in basic ground water theory. The book discusses such models as steady-state, transient flow with constant discharge, slug injection or withdrawal, and step discharge. This valuable book is an expansion on our best seller Groundwater Pumping Tests: Design and Analysis (Walton 1987). Part I contains general information about pumping tests, including how to design a pumping test, select an appropriate model, correct data, and analyze results. Part II is devoted to aquifer models and features hydrogeologic conditions, flow and geometry assumptions, governing differential equations, initial and boundary conditions, and analytical solutions for different models. BASIC coding for computer programs from which type curves may be developed and drawdown predicted are included in an appendix and on diskettes included in the book.

Vadose Zone Response To Pumping In Unconfined Aquifers

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Author : Melissa Irene Bunn
language : en
Publisher:
Release Date : 2011

Vadose Zone Response To Pumping In Unconfined Aquifers written by Melissa Irene Bunn and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2011 with categories.

The interaction between drainage from the variably saturated zone above the water table, and the response of an unconfined aquifer to pumping has been the source of debate for many decades. While various field tests (Nwankwor et al., 1992 and Moench et al., 2001) have supported the concept that variably saturated flow processes delay drainage above a falling water table, Neuman (1972, 1974, 1975), has asserted that the impact is minimal, delay in response of the water table is due to elastic storage effects, and instantaneous yield above the water table is a reasonable assumption in unconfined aquifer analysis. This assumption results in exceedingly low estimates of specific yield in comparison to other analysis techniques (Neuman, 1987). A 7-day pumping test by Bevan et al. (2005) in the unconfined aquifer at Canadian Forces Base Borden has highlighted the complexity in drainage from above the water table during pumping, as the tension saturated zone was found to increase in thickness as a function of both proximity to the pumping well, and elapsed pumping time. This extended thickness persisted for the 7-day pumping duration. Analytical analysis of the test by Endres et al. (2007) resulted in significant underestimates of specific yield in comparison to laboratory values for most solutions. Narasimham (2007) suggested that the use of numerical simulators which include variably saturated flow may provide the most accurate representation of the test results. An attempt to replicate test results using a numerical simulation of variably saturated flow by Moench (2008) could not provide a complete physical mechanism for the extension observed by Bevan et al. (2005). This study provides a detailed investigation on the effect of heterogeneity, hysteresis, and entrapped air on drainage during unconfined pumping tests using numerical simulations, field experiments, and laboratory observations. The results of the Bevan et al. (2005) pumping test are used as a standard for comparison. Three variably-saturated groundwater flow numerical codes were evaluated for their ability to replicate the variations in soil moisture content observed during pumping by Bevan et al. (2005). Results of the numerical simulations were also analyzed for their similarity to the peak and subsequent decrease in vertical gradients observed during pumping in the Borden aquifer. While the models generated vertical gradients through the capillary fringe during pumping, these gradients dissipated significantly before 1000 min. of pumping. No gradients in the saturated zone generated by the numerical model would be capable of shifting the pressure head sufficiently to cause an apparent capillary fringe extension following the first few hours of pumping. Significant gradients were persistent throughout the test at locations where saturation was less than 85%. Accounting for the formation of vertical gradients, no simulation was able to replicate the soil moisture distributions observed by Bevan et al. (2005). Based on these results, heterogeneity, hysteresis, and entrapped air were proposed as processes with the potential to significantly affect drainage from above the water table during pumping, as their investigation may provide the physical mechanism for the observed capillary fringe extension. Compaction of the aquifer material was dismissed as a potential mechanism based on the results of a proctor test. The effect of heterogeneity on drainage from the Borden aquifer during pumping was investigated numerically using geostatistical methods. A log-normal saturated hydraulic conductivity distribution was used to represent the Borden aquifer. Brooks and Corey parameters were used to describe the pressure-saturation-relative conductivity relationships. The air-entry pressure parameter was scaled to the saturated conductivity using the scaling relationship for Borden sand proposed by Keuper and Frind (1991). The Brooks and Corey lambda parameter was kept constant. A Monte Carlo analysis was performed on the results. While several realizations of the hydraulic conductivity distribution resulted in the formation of perched water during drainage, the ensemble capillary fringe thickness was unchanged from the thickness generated using a homogeneous conceptual aquifer model. No single realization produced a capillary fringe extension in which the magnitude was a function of elapsed pumping time, or distance from the pumping well. Approximation of the effect of air-entry barriers on drainage did not increase the estimated capillary fringe thickness. The presence and location of finer grained layers appeared to have a much greater impact on the thickness of the capillary fringe than the drawdown induced by pumping. Ensemble results for the hydraulic head drawdown provided improved matches to the field observations in comparison to the homogeneous numerical model during intermediate and late times in the pumping test. A mild degree of heterogeneity appears to have sufficient effect on drainage from above the water table during pumping to impact hydraulic drawdown. The effect would be magnified with the greater degree of heterogeneity that is more typical of natural aquifer systems. A 24-hour pumping test was conducted at CFB Borden to gain a better understanding of the nature of drainage during a pumping test. Due to the wet site conditions prior to the test, the moisture profile during pumping was significantly influenced by hysteresis. The hydraulic head drawdown generated during the test was insufficient to generate any drainage due to the lowering of the top of the saturated zone, and the formation of perched lenses could not occur. Hysteresis in the moisture profile was a controlling factor in this result. Although there was no significant drainage initiated due to the lowering of the top of the saturated zone, an inflection point was still apparent in the time-drawdown curve for the four monitoring wells observed. Vertical gradients measured throughout the saturated zone, including the capillary fringe, remained low throughout the duration of pumping, and no significant increase was apparent in the transition from saturated to tension-saturated conditions. Hysteresis has the potential to increase the delay in drainage as the water table falls during pumping. A laboratory tank apparatus was used to determine the effect of entrapped air, grain size distribution, and horizontal gradient on drainage in a primarily horizontal flow regime. The tank was packed on three separate occasions, once with a coarse well sorted silica sand, and twice with sand from the Borden aquifer. For each packing, the tank was drained twice, using two different horizontal gradient magnitudes. Results show that horizontal gradient magnitude has no impact on soil moisture distributions during drainage. Air-entry pressure was elevated in comparison to gravity drainage derived pressure head - saturation curves. This elevation was not transient, nor dependant on gradient or grain size distribution. The increase in air-entry pressure does not appear to be due to insufficient equilibration time between water level drops or flow redistribution around the TDR Rods. Results of this study support a conceptual model of unconfined aquifer response in which drainage from above the water table is a complex and time dependant process. Individually, heterogeneity and hysteresis have been shown to cause a time delay between the lowering of the water table and the subsequent drainage of the tension saturated zone during intermediate to late pumping times. The magnitude and duration of this delay varies by process and is a function of the degree of heterogeneity, moisture conditions in the aquifer prior to pumping, and the drawdown rate of the water table. While no individual process tested could produce the capillary fringe extension observed by Bevan et al. (2005), the investigation of each has led to an improved conceptual understanding of the response to pumping in unconfined aquifers. Due to the complex interaction of these processes it is unlikely that pumping test results, even those which include moisture content observations, could be used to accurately predict unsaturated flow parameters. Storage parameter (i.e. specific yield) estimates made using analytical solutions may not be appropriate unless delayed drainage from above the water table is properly accounted for.

Analysis And Evaluation Of Pumping Test Data

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Author : G. P. Kruseman
language : en
Publisher:
Release Date : 1990

Analysis And Evaluation Of Pumping Test Data written by G. P. Kruseman and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1990 with Aquifers categories.

Electric Analog Of Three Dimensional Flow To Wells And Its Application To Unconfined Aquifers

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Author : Robert William Stallman
language : en
Publisher:
Release Date : 1963

Electric Analog Of Three Dimensional Flow To Wells And Its Application To Unconfined Aquifers written by Robert William Stallman and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1963 with Electromechanical analogies categories.

Suggested Operating Procedures For Aquifer Pumping Tests

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Author : Paul S. Osborne
language : en
Publisher:
Release Date : 1993

Suggested Operating Procedures For Aquifer Pumping Tests written by Paul S. Osborne and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1993 with Aquifers categories.

This document is intended as a primer, describing the process for the design and performance of an “aquifer test” (how to obtain reliable data from a pumping test) to obtain accurate estimates of aquifer parameters. It is intended for use by those professionals involved in characterizing sites which require corrective action as well as those which are proposed for ground water development, agricultural development, industrial development, or disposal activities. The goal of the document is to provide the reader with a complete picture of all of the elements of aquifer (pumping) test design and performance and an understanding of how those elements can affect the quality of the final data.

Aquifer Test Data

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Author : Michael Kasenow
language : en
Publisher: Water Resources Publication
Release Date : 2006

Aquifer Test Data written by Michael Kasenow and has been published by Water Resources Publication this book supported file pdf, txt, epub, kindle and other format this book has been release on 2006 with Technology & Engineering categories.