Thiem Equation Calculator

by Glenn M. Duffield, President, HydroSOLVE, Inc.

The transmissivity of a nonleaky confined aquifer may be computed from steady-state drawdowns around a pumping well discharging at a constant rate using the Thiem Equation (Thiem 1906):

T = \frac{Q}{2 π (s_{1} - s_{2})} ln (\frac{r_{2}}{r_{1}}) (1)

where Q is pumping rate [L³/T], r₁ is radial distance from pumping well to first observation well [L], r₂ is radial distance from pumping well to second observation well [L], s₁ is drawdown in first observation well [L], s₂ is drawdown in second observation well [L], and T is transmissivity [L²/T].