Thiem Equation for Steady-State Flow in a Confined Aquifer1

1Thiem, G., Hydrologische Methoden; Gebhardt, Leipzig, 1906.

One piezometer and one pumping well:


where:

rw = radius of the pumping well (m)
sw = steady-state drawdown in the pumping well (m)


Assumptions2:
  1. The aquifer is confined.
  2. The aquifer has an infinite areal extent.
  3. The aquifer is homogeneous, isotropic and of uniform thickness over the area influenced by the test.
  4. Prior to pumping, the piezometric surface is horizontal over the area that will be influenced by the test.
  5. The aquifer is pumped at a constant discharge rate.
  6. The well is screened over the entire thickness of the aquifer ensuring entirely horizontal flow.
  7. The hydraulic gradient between the pumping well and the monitoring well is at steady-state.
  8. The water removed from storage is discharged instantaneously with decline of head.
  9. Storage in the well can be neglected (the diameter of the well is small).


References:

1Thiem, G., Hydrologische Methoden; Gebhardt, Leipzig, 1906.
2Kruseman, G.P. and N.A. de Ridder, Analysis and Evaluation of Pumping Test Data (Second Edition), Publication 47; International Institute for Land Reclamation and Improvement, Wageningen, 1994.