TITLE

Determination of hydraulic parameters of an unconfined aquifer by a single well pumping test

AUTHOR(S)
Khaliq, Abdul; Bakhsh, Allah; Iqbal, Muhammad; Ayub, Muhammad
PUB. DATE
November 2014
SOURCE
Soil & Environment;2014, Vol. 33 Issue 2, p175
SOURCE TYPE
Academic Journal
DOC. TYPE
Article
ABSTRACT
Pumping tests are used for the estimation of the hydraulic parameters of the aquifer. Conventional methods - such as Theis & Cooper-Jacob - that have been developed based on the assumption of homogeneity of aquifers were used for the analysis of these tests. Because of this supposition, the investigation of the pump test data produces representative individual parameter estimates of the volume of disturbed aquifer adjoining the pumping well. Actually aquifers are assorted. Therefore, the apparent flow parameters change as the cone of depression due to pumping progresses over time. In the early days apparent flow parameters reflect local conditions in the vicinity of the well, while in later times, the apparent flow parameters are closer to a weighted average of the disturbed spatial aquifer. In this article, two well-known tools, namely AQTESOLV and MODFLOW, were used as an aid for the analytical and numerical approaches, respectively. The parameters of aquifer were determined and compared using these two techniques. An axisymmetric well model for an unconfined aquifer was developed in Groundwater Vista and simulations were performed using MODFLOW. The method used the observed drawdown as target of calibration at a single observation point to estimate the hydraulic conductivity, storage coefficient, and radius of influence. Pumping test data of number of wells were analyzed and for demonstration purpose results of 2 wells were presented. The results are compared with analytical approach of Neuman and Tartakovsky-Neuman procedure given in AQTESOLV software. The correlation coefficient between observed and predicted head by numerical model for TW1 and TW2 was 0.997 and 0.991, respectively. It showed that the numerical estimations were found to be more representative of the aquifer in the study area since it simulated the groundwater flow behavior of the aquifer system better than the analytical solution.
ACCESSION #
99940679

 

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