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A Type‐Curve Method for the Analysis of Pumping Tests with Piecewise‐Linear Pumping Rates
Author(s) -
Zhuang Chao,
Li Yabing,
Zhou Zhifang,
Illman Walter A.,
Dou Zhi,
Wang Jinguo,
Yan Long
Publication year - 2020
Publication title -
groundwater
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.84
H-Index - 94
eISSN - 1745-6584
pISSN - 0017-467X
DOI - 10.1111/gwat.12981
Subject(s) - aquifer , dimensionless quantity , drawdown (hydrology) , mathematics , piecewise , aquifer properties , variable (mathematics) , piecewise linear function , hydraulic conductivity , statistics , soil science , groundwater , geology , geotechnical engineering , mathematical analysis , mechanics , physics , soil water , groundwater recharge
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 ( S s ) 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 S s 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 S s values between observation wells. The difference could be attributed to the spatial heterogeneity in K and S s . A future research topic may focus on the characterization of K and S s heterogeneity with the currently available drawdown data from variable‐rate pumping tests.