Type curve and numerical solutions for estimation of Transmissivity and Storage coefficient with variable discharge condition

Zhang, Guowei

doi:10.1016/j.jhydrol.2012.11.003

Cited by 16 publications

(12 citation statements)

References 9 publications

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“…This new type-curve method is essentially similar to that of Theis (1935) and Zhang (2013), but it avoids introducing the commonly used well function for dimensionless transformation. Instead, it adopts the widely used dimensionless form of variables as that of Zhan and Bian (2006), Wen et al (2008), and etc.…”

Section: Methodsmentioning

confidence: 99%

“…where s = s(r, t) = h 0 − h(r, t) is the drawdown at the time t and radial distance r, h 0 is the initial static hydraulic head throughout the confined aquifer, h(r, t) is the transient hydraulic head at the time t and radial distance r, K and S s are the hydraulic conductivity and specific storage of the confined aquifer, respectively, b is the aquifer thickness, and Q(t) is the time-varying pumping rate. The analytical solution of the boundary value problem, that is, Equations 1 to 4, is given as (Tsang et al 1977;Zhang 2013)…”

Section: Analytical Solutionmentioning

confidence: 99%

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A Type‐Curve Method for the Analysis of Pumping Tests with Piecewise‐Linear Pumping Rates

Chen¹,

Zhou

et al. 2020

Groundwater

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Aquifer hydraulic parameters are commonly inferred from constant‐rate pumping tests, while variable pumping rates are frequently encountered in actual field conditions. In this study, we propose a generally applicable dimensionless form of the analytical solution for variable‐rate pumping tests in confined aquifers. In particular, we adopt a piecewise‐linear fitting of variable pumping rates and propose a new type‐curve method for estimating the hydraulic conductivity (K) and specific storage (Ss) of the investigated confined aquifer. For each test, a series of type curves, which depend on the variable pumping rates, the location of observation wells and the introduced first dimensionless inflection time, need to be provided for matching the observed drawdown data on a log‐log graph. We first demonstrate the applicability and robustness of this method through a synthetic pumping test. Subsequently, we apply this method to analyze drawdown data from four pumping tests conducted within a multilayered aquifer/aquitard system in Wuxi city, Jiangsu Province, China. The parameter estimates are then compared with those reported by PEST. The K and Ss values estimated by the new type‐curve method are found to be quite close to PEST‐based estimates. Parameter estimation results demonstrate the difference in K and Ss values between observation wells. The difference could be attributed to the spatial heterogeneity in K and Ss. A future research topic may focus on the characterization of K and Ss heterogeneity with the currently available drawdown data from variable‐rate pumping tests.

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Section: Methodsmentioning

confidence: 99%

Section: Analytical Solutionmentioning

confidence: 99%

A Type‐Curve Method for the Analysis of Pumping Tests with Piecewise‐Linear Pumping Rates

Chen¹,

Zhou

et al. 2020

Groundwater

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show abstract

“…This new type curve method is essentially similar to that of Theis (), Sen and Altunkaynak (), and Zhang (), but it avoids introducing the commonly used well function. Instead, it adopts the dimensionless form of variables as that of Zhan and Bian () and Wen, Huang, and Zhan ().…”

Section: Graphical Methodsmentioning

confidence: 99%

“…Thus, the mathematical model can be expressed as follows:

\frac{\partial^{2} s}{\partial r^{2}} + \frac{1}{r} \frac{\partial s}{\partial r} = \frac{S_{s}}{K} \frac{\partial s}{\partial t}, t \geq 0,

s ((), r, 0) = 0, r > 0,

s ((), \infty t) = 0,

lim_{r \to 0} - 2 italicπKbr \frac{\partial s}{\partial r} = Q ((), t),

where s = s ( r , t ) is the aquifer drawdown at time t and the radial distance r from the pumping well; K and S s are the hydraulic conductivity and specific storage of the confined aquifer, respectively; b is the aquifer thickness. The analytical solution of the initial‐boundary problem, that is, Equations to , is expressed as follows (Zhang, ):

s ((), r, t) = \frac{1}{4 italicπKb} \int_{0}^{t} \frac{Q ((), τ)}{t - τ} exp ([], - \frac{r^{2} S_{s}}{4 K ((), t - τ)}) italicdτ .

…”

Section: Analytical Solutionmentioning

confidence: 99%

“…For instances, considering a linearly decreasing pumping rate, Sharma, Chauhan, and Ram () proposed a type curve method for parameter estimation and verified the method through a laboratory experiment. Zhang () further explained the type curve method of Sharma et al () and provided a validation using a numerical model. Sen and Altunkaynak () proposed a straight‐line method for estimating aquifer parameters, where the pumping rate was exponentially decreasing with time.…”

Section: Introductionmentioning

confidence: 99%

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New graphical methods for estimating aquifer hydraulic parameters using pumping tests with exponentially decreasing rates

Chen

Zhou

Zhan

et al. 2019

Hydrological Processes

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Actual pumping tests may involve continuously decreasing rates over a certain period of time, and the hydraulic conductivity (K) and specific storage (Ss) of the tested confined aquifer cannot be interpreted from the classical constant‐rate test model. In this study, we revisit the aquifer drawdown characteristics of a pumping test with an exponentially decreasing rate using the dimensionless analytical solution for such a variable‐rate model. The drawdown may decrease with time for a short period of time at intermediate pumping times for such pumping tests. A larger ratio of initial to final pumping rate and a smaller radial distance of the observation well will enhance the decreasing feature. A larger decay constant results in an earlier decrease, but it weakens the extent of such a decrease. Based on the proposed dimensionless transformation, we have proposed two graphical methods for estimating K and Ss of the tested aquifer. The first is a new type curve method that does not employ the well function as commonly done in standard type curve analysis. Another is a new analytic method that takes advantage of the decreasing features of aquifer drawdown during the intermediate pumping stage. We have demonstrated the applicability and robustness of the two new graphical methods for aquifer characterization through a synthetic pumping test.

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Non-Darcian effect on a variable-rate pumping test in a confined aquifer

Zhou

Chen

et al. 2020

Hydrogeol J

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Type curve and numerical solutions for estimation of Transmissivity and Storage coefficient with variable discharge condition

Cited by 16 publications

References 9 publications

A Type‐Curve Method for the Analysis of Pumping Tests with Piecewise‐Linear Pumping Rates

A Type‐Curve Method for the Analysis of Pumping Tests with Piecewise‐Linear Pumping Rates

New graphical methods for estimating aquifer hydraulic parameters using pumping tests with exponentially decreasing rates

Non-Darcian effect on a variable-rate pumping test in a confined aquifer

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