FIG. 9.5.2 One-dimensional combined flow.

FIG. 9.5.2 One-dimensional combined flow.

FIG. 9.5.3 Radial combined flow. (Reprinted from O.D.L. Strack, 1989, Groundwater mechanics, Vol. 3, Pt. 3, Prentice Hall, Inc.)

The location of the interzonal boundary xb is obtained from Equation 9.5(5) when Equation 9.5(4) is substituted

9.5(3) for $1 and $2, and $ = 1/2 KH2 as x = H- - H2 b 1 1

Note that xb is independent of the hydraulic conductivity K. Also note that when <j)i = H, xb = 0 (entirely unconfined flow) and when = H, xb = i (entirely confined flow).

Radial Flow

If the drawdown near the well caused by pumping dips below the aquifer thickness H, then unconfined flow occurs in that region as shown in Figure 9.5.3. The expression for the potential $ is the same for the entire flow region as

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