Single well test is more common than aquifer test with having observation well, since the advantage of single well test is that the pumping test can be conducted on the production well with the absence of observation well. A kind of single well test, which is step-drawdown test used to determine the efficiency and specific capacity of the well, however in case of single well test it is possible to estimate Transmissivity, but the other parameter which is Storativity is overestimated, so the aim of this study is to analyze four pumping test data located in KAWRGOSK area by using cooper-Jacob’s (1946) time drawdown approximation of Theis method to estimate the aquifer parameters, also in order to determine the reasons which are affecting the reliability of the Storativity value and obtain the important aspect behind that in practice.
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