HESS Hydrology and Earth System Sciences HESS Hydrol. Earth Syst. Sci. 1607-7938 Copernicus Publications Göttingen, Germany 10.5194/hess-16-441-2012 Transient drawdown solution for a constant pumping test in finite two-zone confined aquifers Wang C.-T. 2 1 Yeh H.-D. 2 Tsai C.-S. 2 Taiwan Branch, MWH Americas Inc., Taipei, Taiwan Institute of Environmental Engineering, National Chiao Tung University, Hsinchu, Taiwan 13 02 2012 16 2 441 449 Copyright: © 2012 C.-T. Wang et al. 2012 This work is licensed under the Creative Commons Attribution 3.0 Unported License. To view a copy of this licence, visit https://creativecommons.org/licenses/by/3.0/ This article is available from https://hess.copernicus.org/articles/16/441/2012/hess-16-441-2012.html The full text article is available as a PDF file from https://hess.copernicus.org/articles/16/441/2012/hess-16-441-2012.pdf

The drawdown solution has been widely used to analyze pumping test data for the determination of aquifer parameters when coupled with an optimization scheme. The solution can also be used to predict the drawdown due to pumping and design the dewatering system. The drawdown solution for flow toward a finite-radius well with a skin zone in a confined aquifer of infinite extent in radial direction had been developed before. To our best knowledge, the drawdown solution in confined aquifers of finite extent with a skin zone so far has never before been presented in the groundwater literature. This article presents a mathematical model for describing the drawdown distribution due to a constant-flux pumping from a finite-radius well with a skin zone in confined aquifers of finite extent. The analytical solution of the model is developed by applying the methods of Laplace transforms, Bromwich contour integral, and residue theorem. This solution can be used to investigate the effects of finite boundary and conductivity ratio on the drawdown distribution. In addition, the inverse relationship between Laplace- and time-domain variables is used to develop the large time solution which can reduce to the Thiem solution if there is no skin zone.

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