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Oscillatory pumping tests presents a potential advancement in aquifer testing as they minimize hydraulic perturbations and result in no net water abstraction or injection. However, aquifer property estimates can be less accurate if they are compromised by well head losses during the pumping test. Currently, oscillatory pumping test models ignore these losses. The objective of this study is to develop and evaluate an analytical solution that can interpret oscillatory pumping test data affected by rate‐dependent skin losses. Accordingly, the sensitivity of the drawdown response to small variations in aquifer and well parameters was analyzed. In addition, a previous field aquifer test was analyzed to evaluate the feasibility of the solution for aquifer parameter estimation. The results indicate that neglecting the rate‐dependent skin effect can lead to substantial errors in the determination of aquifer parameters such as transmissivity and storativity. Additionally, the proposed solution effectively reproduces the sharp groundwater level peaks observed in field data, whereas the solution that does not consider the rate‐dependent skin effect greatly underestimates the peak values. Plain Language Summary: This study looks at a new method called the oscillatory pump test for measuring aquifer properties. There can be problems with obtaining accurate results when testing aquifer properties, because there can be a loss of water at the top of the well. This study aims to solve this problem by creating a new solution that can account for this loss of water and still yield accurate results. The study found that ignoring this loss of water can lead to significant errors in the estimation of the aquifer properties. The study shows that when the value of the loss of water is over 10,000 min/m3, it can have a substantial effect on the accuracy of the results. Overall, this study improves our ability to estimate aquifer properties using the oscillatory pumping test method. Key Points: An analytical solution is developed for oscillatory pumping tests with rate‐dependent skinThe effects of rate‐dependent skin on the head response are evident in field dataNeglecting rate‐dependent skin can lead to biased estimates of aquifer parameters [ABSTRACT FROM AUTHOR]

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Every workday the city of Bílina, with the I/13 road running through it, suffers from traffic congestion. The road is designed as dual carriageway outside Bílina but only as a single carriageway inside the city. Three roundabouts further complicate the situation. As a solution a 1,3 km long tunnel going under the city was proposed. The preliminary geotechnical investigation describes the geological conditions of the area, suggests the most appropriate localisation details of the tunnel, points out several complications that can be expected and finally offers solutions to mitigate them. [ABSTRACT FROM AUTHOR]

Copyright of Yellow River is the property of Editorial Board of Yellow River and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Anuario do Instituto de Geociencias is the property of Universidade Federal do Rio de Janeiro, Instituto de Geociencias and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This paper presents two methods for joint inversion of aquifer test data, magnetic resonance sounding (MRS) data, and transient electromagnetic data acquired from a multilayer hydrogeological system. The link between the MRS model and the groundwater model is created by tying hydraulic conductivities ( k) derived from MRS parameters to those of the groundwater model. Method 1 applies k estimated from MRS directly in the groundwater model, during the inversion. Method 2 on the other hand uses the petrophysical relation as a regularization constraint that only enforces k estimated for the groundwater model to be equal to MRS derived k to the extent that data can be fitted. Both methodologies can jointly calibrate parameters pertaining to the individual models as well as a parameter pertaining to the petrophysical relation. This allows the petrophysical relation to adapt to the local conditions during the inversion. The methods are tested using a synthetic data set as well as a field data set. In combination, the two case studies show that the joint methods can constrain the inversion to achieve estimates of k, decay times, and water contents for a leaky confined aquifer system. We show that the geophysical data can assist in determining otherwise insensitive k, and vice versa. Based on our experiments and results, we mainly advocate the future application of method 2 since this seems to produce the most reliable results, has a faster inversion runtime, and is applicable also for linking k of 3-D groundwater flow models to multiple MRS soundings. [ABSTRACT FROM AUTHOR]

Aquifers may have alluvium deposits, weathered layers, fractured zones, and karstic formations separately or in mixture forms. Such geological configurations do not allow classical aquifer test applicability, due to a set of underlying assumptions that are not usually valid in nature. In practice, the Jacob straight line method is the most commonly used approach for aquifer parameter determinations. Constant transmissivity and storativity estimations depend on large time-drawdown plots on semilogarithmic paper as a straight line. A common mistake is that the appearance of a general trend as a straight line on semilogarithmic paper is taken as guaranteed for the application of Jacob method. Since Jacob straight line is the large time extension of Theis type curve, there is only one straight line on the semilogarithmic paper that can represent Jacob method, which is based on the assumption that the aquifer is porous and homogeneous. In such a case, the Jacob method slope should equal to 2.3, which shows its validity. Otherwise, a modification of Jacob method is suggested in this paper. The basis of the methodology is a dimensionless type straight line approach for the aquifer parameter assessment. Its application is presented for aquifer test data from Oude Korendjik porous medium aquifer data. The application results indicate that the classical Jacob straight line method might not be valid without a preliminary check. The dimensionless reevaluation of existing data helps to check the validity. The necessary formulations for the modification of the classical straight line method are derived, which reduce to classical Jacob method for a specific set of parameters. [ABSTRACT FROM AUTHOR]

The solution describing the wellbore flow rate in a constant-head test integrated with an optimization approach is commonly used to analyze observed wellbore flow-rate data for estimating the hydrogeological parameters of low-permeability aquifers. To our knowledge, the wellbore flow-rate solution for the constant-head test in a two-zone finite-extent confined aquifer has never been reported so far in the literature. This article is first to develop a mathematical model for describing the head distribution in the two-zone aquifer. The Laplace domain solutions for the head distributions and wellbore flow rate in a two-zone finite confined aquifer are derived using the Laplace transform, and their corresponding time domain solutions are then obtained using the Bromwich integral method and residue theorem. These new solutions are expressed in terms of an infinite series with Bessel functions and not straightforward to calculate numerically. A large-time solution for the wellbore flow rate is therefore developed by employing the relationship of small Laplace variable versus large time variable and L'Hospital's rule. The result shows that the large-time solution is identical to the steady-state solution obtained after applying the Tauberian theorem into the Laplace domain solution. This large-time solution can reduce to the Thiem equation in the case of no skin. Finally, the newly developed solution is used to investigate the effects of outer boundary distance and conductivity ratio on the wellbore flow rate. Copyright © 2011 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

The hydraulic parameters representative of actual aquifer conditions can be obtained through aquifer tests formerly known as pumping tests. Diverse methodologies based on analytical or numerical solutions have been proposed for the interpretation of aquifer tests; however, measurement and model errors are often neglected, which could lead to hydraulic parameter values that do not reflect the aquifer conditions. In this paper, a new alternative is presented for the interpretation of aquifer tests in confined aquifers based on the Cooper–Jacob solution by means of the dynamic Kalman filter and a nonlinear optimization method. This proposal was tested in two previously published case studies; the measured drawdowns were filtered by considering measurement and model errors to match the Cooper–Jacob solution. For the case studies, the results show that filtering the measured drawdowns leads to variations of up to 49.97% in the values for T and 150% for S when compared to the values determined by methodologies that neglect measurement and model errors. A poor match between filtered and measured data reflects large measurement errors and considerable deviations of the aquifer conditions with respect to the proposed model. [ABSTRACT FROM AUTHOR]

The article presents a study regarding the drawdown solutions for constant-head and constant-flux examinations. It mentions that the study aims to investigate the effectiveness of the solutions in any kind of aquifer. In addition, it presents mathematical and physical interpretations of the test using Thiem equation. According to the researchers, considering time, limited domain solutions for the tests are possible to enlarge immeasurably. Moreover, the researchers likewise examine Theis equation.

Subsurface hydraulic response is controlled by discrete geologic structures in a variety of aquifer settings. In this work, we analyze data from the well-studied alluvial fan system that underlies the Lawrence Livermore National Laboratory. There, subsurface flow and transport behavior is strongly influenced by discrete channel deposits, which are embedded within less permeable floodplain deposits. We model the distribution of these deposits using a multiple-point geostatistical approach that enables simulation of geologically plausible connected permeable bodies consistent with a training image. By coupling the geostatistical model with a dynamic flow model in a simulation inversion framework, we identify specific channel structures that are consistent with transient aquifer test data at six observation wells. We perform shortest-path analysis to characterize the geometry of the simulated channels and to locate critical high-permeability conduits that control the system's response to pumping. In one area, all successful inverse solutions identify the same set of stacked channel deposits, a geologic feature that provides an explanation for anomalous response behavior observed during the aquifer test. [ABSTRACT FROM AUTHOR]

The article discusses the study which aims to expose the application of slope-matching procedure (SMP) method for short-duration field tests in arid-region aquifers of the Kingdom of Saudi Arabia. The subsurface hydrogeological behaviours of the bored land pieces at and around the well locations were analyzed. The study concludes that aquifers in arid-region alluvial-filled wadis are not homogeneous due to lateral facies changes and horizontal layering of alluvium underlain by weathered and fractured zones.

Artesian confined aquifers do not need pumping energy, and water from the aquifer flows naturally at the wellhead. This study proposes correcting the method for analyzing flowing well tests presented by Jacob and Lohman (1952) by considering the head losses due to friction in the well casing. The application of the proposed correction allowed the determination of a transmissivity ( T = 411 m2/d) and storage coefficient ( S = 3 × 10−4) which appear to be representative for the confined Guarani Aquifer in the study area. Ignoring the correction due to head losses in the well casing, the error in transmissivity evaluation is about 18%. For the storage coefficient the error is of 5 orders of magnitude, resulting in physically unacceptable value. The effect of the proposed correction on the calculated radius of the cone of depression and corresponding well interference is also discussed. [ABSTRACT FROM AUTHOR]

Traditional analysis of aquifer tests uses the observed drawdown at one well, induced by pumping at another well, for estimating the transmissivity ( T) and storage coefficient ( S) of an aquifer. The analysis relies on Theis' solution or Jacob's approximate solution, which assumes aquifer homogeneity. Aquifers are inherently heterogeneous at different scales. If the observation well is screened in a low-permeability zone while the pumping well is located in a high-permeability zone, the resulting situation contradicts the homogeneity assumption in the traditional analysis. As a result, what does the traditional interpretation of the aquifer test tell us? Using numerical experiments and a first-order correlation analysis, we investigate this question. Results of the investigation suggest that the effective T and S for an equivalent homogeneous aquifer of Gaussian random T and S fields vary with time as well as the principal directions of the effective T. The effective T and S converge to the geometric and arithmetic means, respectively, at large times. Analysis of the estimated T and S, using drawdown from a single observation well, shows that at early time both estimates vary with time. The estimated S stabilizes rapidly to the value dominated by the storage coefficient heterogeneity in between the pumping and the observation wells. At late time the estimated T approaches but does not equal the effective T. It represents an average value over the cone of depression but influenced by the location, size, and degree of heterogeneity as the cone of depression evolves. [ABSTRACT FROM AUTHOR]

The generalized radial flow approach to hydraulic test interpretation uses the flow dimension to describe the change in flow area versus radial distance from the borehole. The flow dimension of a hydraulic test may reflect several characteristics of the hydrogeologic system, including heterogeneity, boundaries, and leakage. We show that a radial flow system with a linear, constant-head boundary asymptotically reaches a flow dimension of four, while the flow dimension of a leaky aquifer is a function of time and the leakage factor. We use numerical techniques to show that a stationary transmissivity field with a modest level of heterogeneity has a flow dimension that stabilizes at two. We also show that the flow dimension for a nonstationary transmissivity field depends on the form and magnitude of the nonstationarity. The flow dimension observed during hydraulic tests helps identify admissible conceptual models for the tested system, and places hydraulic testing in its full hydrogeologic context. [ABSTRACT FROM AUTHOR]

Recent 2D hydrothermal modeling efforts published by Pepin et al. (2015) suggest that the low-temperature (~41°C) geothermal system in Truth or Consequences, NM is characterized by deep (2-8 km) groundwater circulation within permeable (10-12 m²) fractured crystalline rocks. Their models were constrained by geochemistry, temperature, flow velocity, and carbon-14 data but lack calibration to aquifer test data. On June 13, 2015, we conducted an aquifer test in a newly drilled 73-meter deep geothermal well within the town's hot-springs district. The production interval of this well is 24 meters long and is within fractured Precambrian metamorphic rocks. We installed pressure transducers in the production well and in two observation wells to monitor water levels during the test. The production rate averaged 1.8 x 10-2 m³/s (283 gpm) and the two observation wells were located 20 and 38 meters away from the production well, respectively. The two observation wells were shallower and completed in Quaternary alluvium. Production well water levels oscillated during the first two minutes of the aquifer test due to inertial effects. Net drawdown in the production well after 97 minutes of pumping was approximately 0.6 meters, while minimal drawdown was evidenced in the observation wells. Applying the Cooper-Jacob model provided a transmissivity estimate of 1.1 x 104 m²/day and thereby a permeability range of 5 x 10-10 to 2 x 10-12 m². These results are further evidence that the crystalline basement rocks within the Rio Grande Rift can be remarkably permeable when significantly fractured. [ABSTRACT FROM AUTHOR]