The test data of both confined and unconfined aquifers were analyzed by many practitioners that are used cooper-Jacob method to estimate the drawdown equation, regardless of the differences between theoretical and practical conditions. Transmissivity is estimated by fitting a straight line between time versus drawdown on semi-logarithmic paper. Single well aquifer testing can provide the value of Transmissivity,whereas preclude the cost and access of multi-well aquifer testing, so usually in this case the test data analyzed by Cooper-Jacob's (1946) straight line method due to it's simplicity. There are many papers and references that ordered to the Storativity value in case of the absence of observation well is not accurate,because it depends mainly on the radial distances between pumping well to point of measuring drawdown from those(G.P. Halford, et al,2006) attempt to obtain Transmissivity from single test data, so the articles related to the study area locations are including (Imad Al-Din Omer Hassan,1998),(Mariwan Akram Hama Saeed Chnaray,2003), (Dara Faeq Hamamin,2004),(Salahaddin Saeed Ali,2007),(Diary Ali Mohammad Ameen Al-Manmi,2008),(Shwan Omer Ismail Shwani,2008), Also (Masoud Hussein Hamed,2013). Razack, et al, 1991) tried to determine Transmissivity through specific capacity data, then (Keith J. Ballukraya, et al,1991) it derived an equation to estimate Storativity by recovery test, Also (M.
#Well drawdown math skin
The most important method to estimate the aquifer parameters are testing with having observation well, but it's cost more than conducting pumping test without observation well which is called single well test, so that since the last decade there are many experiences that are tried to discover a method to estimate the aquifer parameters through analyze single well test data such as (choi,Byung-soo,2007)which tried to find out the Storativity by determining skin factor and effective wellbore storage, and the method of (P. Keywords: aquifer parameters, single well test, Cooper-Jacob's straight line method 1. 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. PhD, Civil Engineering Department, College of Engineering, University of Salahaddin, Erbil, Kurdistan Region of Iraq, e-mail: JWAN SABAH MUSTAFA - Engineer, General Directorate of Dams and Reservoirs, Ministry of agricultural and water resources, Erbil, Kurdistan Region of Iraq, e-mail: 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. PERFORMING PUMPING TEST DATA ANALYSIS APPLYING COOPER-JACOB'S METHOD FOR ESTIMATING OF THE AQUIFERĭANA KHIDER MAWLOOD - Assist. Mathematical Modelling in Civil Engineering
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