Cooper Jacob method
The Theis equation can be written as
(22.4)
The W(u) is the well function and u is
(22.5)
The W(u) can be approximated as
(22.6)
Copper and Jacob (1946) suggested that for small value of r and large value of t, the W(u) can be approximated as
(22.7)
Thus the equation (22.4) can be written as
(22.8)
(22.9)
(22.10)
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Fig 22.4 Observed time drawdown relation with time in log scale