Moench Solution for Unconfined Aquifers

Well-aquifer configuration for Moench (1997) pumping test solution in water-table aquifer

A mathematical solution by Moench (1997) is useful for determining the hydraulic properties (transmissivity, elastic storage coefficient, specific yield and vertical hydraulic conductivity) of unconfined aquifers. Analysis involves matching the solution to drawdown data collected during a pumping test. The Moench solution accounts for delayed gravity response (delayed yield), wellbore storage effects and partial penetration.

AQTESOLV provides visual and automatic methods for matching the Moench solution to pumping test and recovery test data. This easy-to-use and intuitive software promotes rapid and accurate determination of aquifer properties.

Assumptions

The following assumptions apply to the use of the Moench pumping test solution for unconfined (water-table) aquifers:

  • aquifer has infinite areal extent
  • aquifer is homogeneous, isotropic and of uniform thickness
  • aquifer is unconfined
  • flow is unsteady

Solution
Options

provides the following options for the Moench pumping test solution for unconfined (water-table) aquifers:

  • large-diameter pumping wells
  • variable pumping rates
  • multiple pumping wells
  • multiple observation wells
  • partially penetrating pumping and observation wells
  • boundaries

Benchmark

AQTESOLV benchmark for Moench (1997) pumping test solution for unconfined aquifers with delayed yield
Comparison of AQTESOLV (blue lines) and computed values from program by Barlow and Moench (1999) for sample problem in 10-m thick unconfined aquifer (symbols).

References

Moench, A.F., 1997. Flow to a well of finite diameter in a homogeneous, anisotropic water table aquifer, Water Resources Research, vol. 33, no. 6, pp. 1397-1407.

Moench, A.F., 1998. Correction to 'Flow to a well of finite diameter in a homogeneous, anisotropic water-table aquifer,' Water Resources Research, vol. 34, no. 9, pp. 2431-2432.