Theis Well Function Calculator

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

The integral in the Theis equation is commonly known as the Theis well function, w(u):

w(u) = -0.5772 - ln(u) + u - \frac{u^{2}}{2 \cdot 2!} + \frac{u^{3}}{3 \cdot 3!} - \frac{u^{4}}{4 \cdot 4!} + \cdot\cdot\cdot (1)

u = \frac{r^{2} S}{4 T t} (2)

where r is radial distance from pumping well to observation well [L], S is storativity [-], T is transmissivity [L²/T] and t is elapsed time since start of pumping [T].