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--�_ 71T V M. <br /> MOM <br /> {1 <br /> t <br /> �r method will be used. There are two methods developed to <br /> calculate or determine the various aquifer parameters: one <br /> by Theis (1935) and the other by Cooper and Jacob (1946) , <br /> both of which are briefly discussed below. <br /> !3+ 1) Theis Solution <br /> is <br /> Theis solution is a graphical procedure for evaluating T <br /> and S. The transient flow differential equation was <br /> developed by Theis as: <br /> s = Q W(u) /(4`TVT) (2) <br /> ,. where: s = drawdown of piezometric surface <br /> 4 = pumping rate <br /> W(u)= well function <br /> and: <br /> u - 3.2 ^a/ (4Tt) . ., . (3) <br /> iM <br /> where: r = the distance between the pumping and <br /> Fobservation wells <br /> Ii - <br /> Rearranging and taking logarithms of Equations l and 2. <br /> yields: <br /> log (s) = log (Q/411T) + log W(u) (4) <br /> and: <br /> log r2/t = Log (4T/S) + log (u) (5) <br /> i From the above relationships, a logarithmic plot of s <br /> versus r2�t and a lag-log plot of W(u) versus u will be <br /> similar. By superimposing these two plots, a match point <br /> can be determined. Using the four coordinates of the <br /> match point and Equations 2 and 3, the transmissivity (T') <br /> and storage coefficient (S) of the aquifer can then be <br /> determined. <br /> 2) Cooper-Jacob_ Solutian <br /> The Cooper-Jacob solution is also a graphical solution for <br /> the general transient flow equation. By plotting the <br /> drawdown versus time for a monitoring well on a <br /> �- semi-logarithmic graph, a portion of the plotted curve <br /> r' . <br />