4ttT

where W(uA,uB,F) is the well function, and

Spr2 4Tt

(for early drawdown data) 9.8(45)

(for later drawdown data) 9.8(46)

and r2Kv

The values of W(uA,F) and W(uB,F) are given in Tables 9.8.3 and 9.8.4. The type curves are used to evaluate the field data for drawdown and time with the use of the following procedure (Fetter 1988):

1. Superpose the late drawdown-time data on the type-B curves for the best fit. At any match point, determine the values of W(uB,F), uB, t, and s. Obtain the value F from the type curve. Calculate T and Sp from

4TtUB

2. Superpose the early drawdown data on the type-A curve for the value F of the previously matched type-B curve. Determine a new set of match points, and calculate T and Se from

The calculated value of T should be approximately equal to that computed from the type-B curve. 3. Determine Kh and Kv from

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