Pumping Tests In Aquifers Research Articles

Investigating the Representative of Aquifer Transmissivity Determined by Passive Response Methods: A Comparison With Time‐Dependent Hydraulic Parameters Inferred From Different Stages of Pumping Tests

AbstractAquifer pumping tests represent a standard method for estimating hydraulic characteristics, with practitioners often focusing on late period drawdown data because these are less affected by within‐ and near‐borehole effects (e.g., borehole‐storage and skin effects). Alternatively, groundwater responses to natural forcing (e.g., barometric pressure and earth tides) provide a passive method for estimating aquifer parameters at a low cost. However, to the best of our knowledge, no studies have compared parameters calculated from different periods within a pumping test with those from passive methods. Herein, we compare the aquifer transmissivity estimated using both active and passive methods in two wells located in the Beetaloo Region of Northern Australia. The active method estimates aquifer transmissivity during three periods (i.e., the early, middle, and late periods) of an aquifer pumping test, while the passive method employs groundwater responses to barometric‐pressure and earth‐tide fluctuations. We find that the range of best‐fit aquifer transmissivity is 1.18 × 10−5–1.79 × 10−5 m2/s and 1.73 × 10−5–2.14 × 10−5 m2/s for OW1 and OW2, respectively. The transmissivity estimated from the barometric pressure response method is the largest. The aquifer transmissivity using barometric pressure responses are consistent with early‐ and middle‐period estimates. This suggests that barometric pressure responses are more sensitive to within‐ and near‐borehole effects. The scales of the tidal response method are smaller than those of the pumping test method.

Utilizing of aquifer hydraulic parameters to assess the groundwater sustainability in the new reclamation area of Moghra Oasis: Western Desert—Egypt

The sustainability of groundwater aquifers requires evaluating several parameters, the most important of which are hydraulic parameters. Therefore, the essential aim of this research is to develop a management plan for the Moghra aquifer in order to prevent the expanding of water level decline and degradation of groundwater quality due to overexploitation and scarcity of recharge. To achieve this goal, all aquifer hydraulic parameters such as transmissivity, hydraulic conductivity, radius of interference, specific capacity, resulted drawdown, well loss, formation loss, well efficiency, and optimum safe yield had been measured for 40 groundwater wells drilled in the new reclaimed areas of Moghra Oasis. Based on geographic information system (GIS), hydrogeological cross sections and thematic maps for all parameters were created such as aquifer thickness, water table, groundwater flow direction, drawdown and groundwater salinity maps. The results revealed that clay and shale beds separated the three water-bearing formations of the Moghra aquifer. The aquifer-saturated thickness ranged from 30 and 102 m, and the groundwater level was below the mean sea level for all wells (ranges from − 72 to − 26.6 m). The calculated hydraulic parameters based on the analysis of long-duration pumping tests indicated that the studied aquifer has a wide variety of transmissivity (T) between 631 and 3768 m2/day, hydraulic conductivity (K) between 13.4 and 104.6 m/day, radius of influence from 126.3 to 581.3 m and specific capacity between 377.14 and 883.72 m2/day. On the other hand, the evaluation of existing drilled wells performance based on the results of step tests showed that well loss coefficient ranges between 0.0004749 and 0.0676 (h2/m5), formation loss coefficient varies from 3.34 × 10–8 to 4.80 × 10–6 (h/m2), well efficiency (γ) ranged from 50.53 to 98.08%, and optimum safe yield ranged from 40 to 98 (m3/h). Results of aquifer mapping and pumping tests can be more important for solving water scarcity issues, non-polluting water issues, health issues, and source of fresh water on the surface of the earth. The characterization of aquifer parameters in the study area, however, should be a significant component in the scientific planning and sustainability of groundwater.

Determination of Aquitard Storage from Pumping Tests in Leaky Aquifers

The management of groundwater resources requires a thorough understanding of groundwater flow and storage. Aquitards, in particular, can store large amounts of groundwater, but are generally often overlooked or ignored in groundwater surveys. In this study, we show how a pumping test performed in a leaky aquifer can be used to estimate the storage coefficient of an overlying aquitard. A new analytical solution is presented for a constant-rate pumping test in a leaky aquifer taking into account the water released from storage in the aquitard. The utility of the method is demonstrated by a practical application using data from a pumping test conducted in a semi-confined sandy aquifer overlain by an aquitard consisting of a mixture of clay and sand. The results obtained show that the solution enables the accurate calculation of the storage properties of the aquitard.

Aquifer Pumping Test Data Analysis for well (B7-3) at Ain–Tamer Area West of Iraq.

Aquifer Pumping Test Data Analysis for well (B7-3) at Ain–Tamer Area West of Iraq.

Regression-Based Interpretation Method for Confined Aquifer Pumping Tests

The constant-discharge pumping test is a widely used aquifer characterization tool for estimating hydrogeological parameters. Various graphical and numerical solution techniques have been devised for interpretation of pumping test results. This study proposes an alternative regression-based solution approach for analyzing pumping tests conducted in nonleaky, confined aquifers. A regression model was developed by making use of the similarity solution that describes the temporal drawdown behavior at a monitoring well within a pumping period. The field curve obtained from a pumping test (drawdown versus time data) and the theoretical type curve (dimensionless drawdown versus dimensionless time) exhibit identical behavior in logarithmic scale. Correspondingly, based on the equivalence of the area above these two curves, the proposed regression equation establishes a link between a selected drawdown value and its dimensionless counterpart. Once this drawdown value is associated with the corresponding dimensionless drawdown, the explored aquifer transmissivity and storativity can be retrieved easily with the similarity solution. The proposed fit equation enables users to retrieve hydrogeological parameters effortlessly by eradicating the difficulties encountered while implementing conventional graphical or optimization-based methods. The method was tested for a large number of hypothetical noise-free and noise-perturbed time drawdown data sets, each synthesized with different aquifer parameters within a wide range, and in all these attempts the proposed algorithm achieved providing highly accurate parameter estimates. In addition, two published test cases were employed to assess the estimation performance of the method in comparison with the existing techniques. The developed solution scheme was revealed to yield results in very good agreement with those reported in previous works. Considering the accuracy of the method and the ease of its implementation, the proposed approach can be a practical tool for analyzing constant-discharge tests performed in confined aquifers.

On the use of late-time drawdown in interpreting aquifer pumping test

The review aims to provide a common understanding of the use of late-time drawdown to interpret aquifer pumping tests. The first part of the review provides an overview of the use of the late-time drawdown in literature to illustrate where and how the term is being used. A discussion on the practical implications of using the term and its significance is then presented. The review shows the use of the late-time drawdown in three main ways: the application of the Cooper and Jacob time-drawdown method, the description of the third segment of the unconfined aquifer drawdown-time curve, and when trying to estimate representative/effective transmissivity parameters in heterogeneous aquifers. Unlike the other two situations, the use of late-time data in typical unconfined aquifers is supported by the groundwater flow principles and hence has a meaningful application. The aspects highlighted in this review are important to improve the theoretical and practical knowledge required for analysing and interpreting aquifer pumping test data.

A novel optimisation framework for interpretation of unconfined aquifer pumping test data

The complex well function formulations developed for unconfined aquifer systems make the determination of aquifer parameters difficult and inefficient using classical methods. In addition, the dimensional dependency of aquifer parameters, as well as the non-linear and non-convex nature of inverse groundwater problems, can make the stand-alone use of the metaheuristic algorithms inefficient in terms of computation time and effort, producing non-unique solutions. Therefore, a novel optimisation framework was established to interpret pumping test data collected from an unconfined aquifer. The proposed approach works with four inputs that are based on the hybrid use of two non-dimensional physical and newly introduced two non-physical parameters. The method has the benefit of the simplicity of traditional methods and the accuracy of the differential evolution algorithm (DEA). The capability of the proposed scheme was broadly examined using several pumping test scenarios, including hypothetical and real field test datasets. Sensitivity analysis was also performed to understand the uncertainty associated with the estimated flow parameters. The results show that the proposed scheme, powered by the DEA, is able to achieve outstanding estimation performance compared with conventional methods and other nature-inspired algorithms.

An Analytical Solution to Two-Region Flow Induced by Constant-Head Pumping in an Unconfined Aquifer

This paper proposes an analytical solution to the problem of two-region flow induced by constant-head pumping tests in an unconfined aquifer based on the Dupuit assumption. The two-region flow includes a finite non-Darcian pattern near the pumping well and a semi-finite Darcian pattern in the rest region. By Izbash’s equation, the solution to the two-region flow is derived using the Boltzmann method. The reliability of the proposed solution is investigated through comparisons with the numerical solution by COMSOL Multiphysics and the hydraulic head−time data from the pumping test in Wisconsin. The influences of the finite non-Darcian flow pattern on the hydraulic head and pumping rate are also discussed. The results demonstrate that a greater degree of non-Darcian turbulence can effectively increase the pumping flow rate, although such influence can be reduced over time. A method for determining the range of the non-Darcian region has been developed and validated by the specific discharge and Reynolds number.

Approximate solutions for flows in unconfined double porosity aquifers

Although flow in unconfined double porosity aquifers occurs in most part of the world such as in karst and crystalline aquifers, their hydrodynamic behavior is still poorly understood. Especially, analytical or semi-analytical solutions for flow in unconfined double porosity (DP) aquifers are scarce. In this paper analytical solutions are proposed for two configurations involving groundwater discharge to a stream adjacent to an unconfined aquifer, and flow induced by pumping with constant extraction rate, respectively. The analytical solutions are obtained based on an h2-linearization technique of the full mathematical model and using a Laplace transform. The above technique has not been used before to investigate the behavior in DP aquifers. The newly developed analytical solution is in agreement with numerical solutions of the full mathematical model, for small to moderate drawdowns which are as high as 25% of the initial water table (case of the well pumping problem). This confirms on one side the correctness of the analytical solution and on the other side the reliability of the developed h2-linearization technique. On the contrary the conventional confined aquifer equations approach can be used only if the drawdown does not exceed 5% of the initial head values. As potential application examples, the estimation of the flow-rate from an aquifer to an adjacent water body, and the interpretation of pumping tests in unconfined double porosity aquifers, allowing to estimate the values of the models parameters, are proposed.

Characterization of basaltic rock aquifer parameters using hydraulic parameters, Theis’s method and aquifer test software in the hard rock area of Buchakewadi watershed Maharashtra, India

The twelve wells were selected to carry out the various test, duration of pumping (min), maximum draw drown (m), duration of recovery (min), residual drawdown, and aquifer type in the basaltic rock aquifer parameters of Buchakewadi watershed. The source and flow of groundwater are essential concerns in hydrological systems that concern both spatially and temporally components of groundwater discharge and water supply problems. The content and temperature of groundwater flowing through an aquifer might change depending on the aquifer environment. As a result, hydrodynamic analyses can provide valuable information about a region's subsurface geology. The present research attempts of aquifer variables such as transmissivity (T) and storativity (S) estimation are significant for groundwater resource development and evaluation. There are numerous approaches for calculating precise aquifer characteristics (i.e., hydrograph analysis, pumping test, etc.). A most frequent in situ analysis is a well-pumping test, which accurately measures the decline and rise of groundwater levels. During an aquifer pumping test, to characterize aquifer properties in an undiscovered location to forecast the rate of depletion of the groundwater table/potentiometric surface. The shallow, weathering subsurface water accessible above the Deccan traps in an unconfined state is insufficient to satisfy the ever-increasing pressure on water supplies. Maharashtra is similarly dominated by hard rocks, whose rainfall susceptibility is limited by weathering and primary porosity, as is their volume to store and convey water. Based on the hydraulic parameters and Theis method, results are optimized. Aquifer mapping and pumping test results can be more important for solving problems such as water scarcity, nonpolluting water, health issues, and source of fresh water on the earth surface. However, the characterization of aquifer parameters should be significant role in the scientific planning and engineering practices.

Solutions for Groundwater Flow to a Pumping Well with an Exponentially Decreasing Variable-Rate in a Sloping Aquifer.

During aquifer pumping tests in the field, the attenuation process of the pumping rate is generally monitored, and the aquifer may be slanted, especially in riverbank terraces, piedmont plain and other similar terrains. The combination of these two factors (attenuation process and aquifer slope) has not received enough academic attention, therefore, a two-dimensional groundwater flow model is developed for an exponentially decreasing variable rate pumping well in a sloping aquifer in this study. The new semi-analytical solution (based on a linearized free-surface boundary) is obtained using the Laplace transform and finite Fourier cosine transform. Meanwhile, to depict the linearized boundary precisely with the first-order free surface equation, a numerical model that considers the decline of the water table is also developed. Results show that under the effect of the variable rate, the time-drawdown curve presents a downward trend at intermediate times. Additionally, the error caused by the linearization of the free-surface equation on the analytical model is found to be acceptable except when the sloping angle is larger than π/6. Furthermore, since this study extends the work of Huang et al. (2014), who considered a constant pumping rate, the new solution was found better to interpret real pumping test data reported by Antonio and Pacheco (2002), and the laboratory experiment results. Overall, the new solution proves to be useful for parameter inversion accurately as the average pumping rate tended to underestimate hydraulic parameters when fitting short-term pumping data.

Toward Retrieving Distributed Aquifer Hydraulic Parameters From Distributed Strain Sensing

AbstractSubtle elastic rock deformation during aquifer testing may bear hydraulic parameter (permeability and compressibility) information owing to the poroelastic hydromechanical coupling effect. Here we report that such in situ rock deformations (∼50 µε) during an aquifer pumping test are successfully measured along a vertical well by a high‐resolution fiber optic distributed strain sensing (DSS) tool with an accuracy of 0.5 µε. We investigate the feasibility of hydraulic parameter estimation at meter scale using DSS data through a coupled hydromechanical model. Both synthetic and field cases are tested with sensitivity analysis. The results indicate that the simultaneous estimation of permeability and compressibility using DSS data is possible at low noise levels. However, only non‐global near‐optimal solutions can be obtained using the applied gradient‐based inversion algorithm, because of parameter crosstalk and sensitivity problems when the data contain large noise. In particular, estimation is difficult for zones with relatively low permeability due to the low sensitivity to the strain changes. The estimated permeability/compressibility structures for the field test are largely consistent with other geological information from well logs. Our study suggests that DSS data can be quite useful in aquifer characterization and fluid flow profiling in addition to geomechanical monitoring. The obtained hydraulic information is beneficial for the optimized reservoir management of water and oil/gas storage.

Evaluation of aquifer characteristics using well logging tools and pumping tests in a typical khondalitic aquifer in the Northern parts of Eastern Ghats of India

Aquifer parameters from geophysical well logs and pumping tests were used to evaluate the potential of fractured aquifer of khondalitic terrain of Northern parts of Eastern Ghats of India. The parameters under consideration are porosity and formation-water resistivity for the highly weathered material and the fractured khondalitic aquifer. The resistivity of fractured zones ranged between 28 and 30 Ω m. The aquifer porosity varied from 28% in the fractured khondalitic aquifer to 18% for the kaolinized formation. Pumping tests revealed the aquifer transmissivity and storativity in the range of 26–230 m2/day and 1.9 $$\times$$ 10–4–87.5 $$\times$$ 10–4 respectively. High values of transmissivity and storativity were obtained from the flat uplands, whereas low values characterized the low laying areas. The aquifer parameters have to unravelled the hydrogeological characteristics of the khondalitic terrain.

Inverting subsurface flow data for geologic scenarios selection with convolutional neural networks

Subsurface flow model calibration against dynamic response data is often constrained by a prior conceptual model of geologic scenario that specifies the expected spatial variability and geologic patterns in the solution. However, several sources of uncertainty exist in developing a conceptual geological model, including data limitation, process-based modeling assumptions, and subjective interpretations. Therefore, it is prudent to consider the uncertainty in geologic scenarios during model calibration and to utilize the flow response data in supporting or rejecting the proposed scenarios. We present a novel framework whereby dynamic response data is used to screen a set of proposed geologic scenarios by combining gradient-based inversion for feature extraction and convolutional neural networks for feature recognition. To compactly represent the salient features of each scenario, an extremely low-rank parameterization with the leading elements of the Principal Components Analysis (PCA) is adopted. The PCA basis elements of different scenarios are combined to define the search space for feature extraction, which is implemented via an iterative least-squares inversion formulation to match the observed data. The inversion solution is obtained by selectively combining the PCA representations from different scenarios, and contains the dominant spatial patterns that are needed to match the observed data. Feature recognition to identify the relevant geologic scenarios based on the reconstructed spatial solution of feature extraction inversion is performed using a pre-trained convolutional neural network (CNN). The method offers several advantages, including an efficient implementation that does not require extensive forward simulation runs, use of flow data to identify pertinent geologic scenarios, and the ability to combine geologic scenarios if supported by data. The performance of the proposed approach is evaluated using numerical experiments from pumping tests in groundwater aquifers.

The Effects of Fault-Zone Cementation on Groundwater Flow at the Field Scale.

Fault zones are an important control on fluid flow, affecting groundwater supply, contaminant migration, and carbon storage. However, most models of fault seal do not consider fault zone cementation, despite the recognition that it is common and can dramatically reduce permeability. In order to study the field-scale hydrogeologic effects of fault zone cementation, we conducted a series of aquifer pumping tests in wells installed within tens of meters of the variably cemented Loma Blanca Fault, a normal fault in the Rio Grande Rift. In the southern half of the study area, the fault zone is cemented by calcite; the cemented zone is 2-8 m wide. In the center of the study area, the cemented fault zone is truncated at a buttress unconformity that laterally separates hydrostratigraphic units with a ∼40X difference in permeability. The fault zone north of the unconformity is not cemented. Constant rate pumping tests indicate that where the fault is cemented, it is a barrier to groundwater flow. This is an important demonstration that a fault with no clay in its core and similar sediment on both sides can be a barrier to groundwater flow by virtue of its cementation; most conceptual models for the hydrogeology of faults would predict that it would not be a barrier to groundwater flow. Additionally, the lateral permeability heterogeneity across the unconformity imposes another important control on the local flow field. This permeability discontinuity acts as either a no-flow boundary or a constant head boundary, depending on the location of pumping.

On the practical application of the Cooper and Jacob distance-drawdown method to analyse aquifer-pumping test data

Studies have illustrated how Infinite Acting Radial Flow (IARF) can be used as an objective criterion than the u condition to evaluate the valid of applying the Cooper and Jacob time-drawdown (1946) method. The Cooper and Jacob (1946) time-drawdown and distance-drawdown methods work on the same principle which incorporates the u condition. A similar study to assess the use of IARF as a criterion to determine the applicability of the Cooper and Jacob distance-drawdown (1946) method to analyse aquifer-pumping tests would be beneficial to groundwater practitioners. This study uses numerical groundwater flow modelling to assess and evaluate the application of the Cooper and Jacob (1946) distance-drawdown method to analyse multi-well aquifer pumping tests in ideal homogenous porous and isotropic confined aquifers under unsteady-state flow. Three multi-well aquifer-pumping tests are simulated in ideal one-layer homogeneous and isotropic confined aquifer models using Processing MODFLOW and the data is analysed by the Cooper and Jacob (1946) distance-drawdown method. The results shows that the Cooper and Jacob (1946) distance-drawdown method can only estimate correct transmissivity and storativity parameters when it is applied to observation data after IRAF. The u values calculated for the analysis vary over a wider range and do not satisfy all the literature prescribed u values. The study demonstrates and recommends how IRAF should be used as an objective criterion to determine the validity of applying the Cooper and Jacob (1946) distance-drawdown method.

Geometry and water quality of the unconfined aquifer near the Piracicaba river, Ipatinga/MG, Brazil

Groundwater is the main source of drinking water for the city of Ipatinga/MG, Brazil. However, there is a lack of study about hydrogeology in the region, as well as indications of quality alterations of water resources. The goal is to understand the hydrogeology surrounding the COPASA's Water Treatment Plant and the Piracicaba river areas, where the main water supply wells are located. Maps of potentiometric surface, isobaths and isopachs, hydrogeological cross-section, aquifer pumping tests, and physicochemical analysis interpretations were performed. Results indicate the aquifer is unconfined, with high transmissivity and hydraulic conductivity values, which explain the high values of discharge in the wells. The Piracicaba river can be considered as influent, with its water flow converging to the aquifer. Groundwater shows chemical parameters at low levels, according to Brazilian drinking-water quality guidelines, with local presence of aluminum, iron, and manganese, requiring only conventional treatment processes before distribution.

Estimation of the hydraulic parameters of leaky aquifers based on pumping tests and coupled simulation/optimization: verification using a layered aquifer in Tianjin, China

Accurate estimates of aquifer parameters are necessary for effective groundwater management and for geotechnical engineering applications. Pumping tests may be employed to estimate the hydraulic conductivity in leaky aquifer/aquitard systems. This work introduces a hybrid algorithm with global search capacity (the Genetic algorithm, GA) and local search capacity—the Levenberg-Marquardt (LM) algorithm—coupled with a modified Neuman-Witherspoon solution for leaky aquifers to estimate the aquifer’s hydraulic parameters from pumping-test data. The GA is employed to determine the initial guesses of the aquifer parameter values. The optimal parameter values are then obtained with the LM algorithm, yielding a mixed GA/LM algorithm, herein named GALMA. Results show that the drawdown trends based on the estimated parameters agree well with measured drawdown. The proposed estimation algorithm identifies aquifer parameters with greater reliability than previous approaches. Verification of the GALMA is carried out based on three pumping tests in a layered aquifer in Tianjin, China, and on four historical case studies involving diverse hydrogeological settings. The excellent match between observed drawdown and GALMA-estimated parameters demonstrates the estimation accuracy and superior performance relative to previously reported estimation methods.

Analysis of Aquifer Pumping Test Data to Determine Deep Groundwater Security in Southeastern Bangladesh

In southeastern Bangladesh, where water quality in the upper aquifers is a serious constraint, future development will likely be confined to deep fresh groundwater. Owing to the importance and pervasive use of deep groundwater, the sustainability of water use has received extensive attention. However, excessive extraction from deep aquifers may pose a threat to the storage as well as the quality of water due to the high susceptibility to salinization and arsenic contamination from upper aquifers. Hence, determining the extension of aquifer units and the characterizing aquifer sediments are very important to ensure sustainable development and management of limited fresh groundwater resources. The study area extends over six districts of the southeastern coastal region of Bangladesh. In order to assess and monitor deep fresh groundwater potential in the study area, aquifer pumping tests were performed at six locations with up to 72 h of constant-discharge prior to recovery. Different methods were used to analyze the drawdown and recovery data considering aquifers as confined or leaky-confined. Based on transmissivity values it was found that the studied deep aquifers have moderate to high potential for potable water supply. However, this deep fresh groundwater may not be safe for a longer period where upper aquifer units contain saline groundwater and where there is no significant aquitard encountered above or below the deep aquifer. Irrigation extraction of the deep groundwater is not recommended.

Abstracts

This chapter addresses the hydraulic properties of soils, which are primarily expressed through the concept of the hydraulic conductivity parameter in Darcy's law. In that respect, it is a companion to Chapter 5 of this book, which provides the background for the material discussed here. Initially, different models to estimate the hydraulic conductivity are presented, followed by laboratory methods of its estimation. The scale effect is particularly emphasized, the discrepancy that has been observed between laboratory and field estimates of hydraulic conductivity, which may range over several orders of magnitude. Field tests, through the pumping of wells in aquifers, are extensively presented. Steady-state solutions are initially discussed, followed subsequently by methods to assess the hydraulic parameters when the test, as is in most cases, has not reached equilibrium flow conditions. Transient radial flow to a well in a confined aquifer is presented through the Theis and the Cooper-Jacob methods. In addition, the Hantush-Jacob method for leaky aquifers, and the Neuman method for pumping tests in unconfined aquifers are described. The chapter also discusses the physical and chemical factors that affect the hydraulic properties of clay mixtures that are used as engineered barriers such as the heterogeneity, soil structure and composition, fracturing, and adsorption capacity, among others. It concludes with the effect that inorganic and organic contaminants may have on the hydraulic properties of soil-based engineered barriers.