Moench Solution for Leaky Confined Aquifers

Well-aquifer configuration for Moench (1985) pumping test solution for leaky confined aquifers

Moench (1985) derived a mathematical solution that is useful for determining the hydraulic properties (transmissivity and storage coefficient of aquifer; vertical hydraulic conductivity and storage coefficient of compressible aquitards) of leaky confined aquifers. Analysis involves matching the solution to drawdown data collected during a pumping test. The Moench solution accounts for wellbore storage and wellbore skin.

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.

Other solution methods for leaky confined aquifers include the following:

Assumptions

The following assumptions apply to the use of the Moench pumping test solution for leaky confined aquifers:

  • aquifer has infinite areal extent
  • aquifer is homogeneous, isotropic and of uniform thickness
  • aquifer potentiometric surface is initially horizontal
  • control well is fully penetrating
  • flow to control well is horizontal
  • aquifer is leaky confined
  • flow is unsteady
  • water is released instantaneously from storage with decline of hydraulic head
  • aquitards have infinite areal extent, uniform vertical hydraulic conductivity and storage coefficient, and uniform thickness
  • aquitards are overlain or underlain by an infinite constant-head plane source
  • flow in the aquitards is vertical

Solution
Options

provides the following options for the Moench pumping test solution for leaky confined aquifers:

  • large-diameter pumping wells
  • variable pumping rates
  • multiple pumping wells
  • multiple observation wells
  • boundaries

Benchmarks

Benchmark for Moench (1985) solution for a pumping test in a leaky confined aquifer with incompressible aquitard
Comparison of AQTESOLV (blue line) using Moench (1985) solution and Hantush and Jacob (1955) well function for an incompressible aquitard, r/B=0.1 (symbols).
Benchmark for Moench (1985) solution for a pumping test in a leaky confined aquifer with a compressible aquitard
Comparison of AQTESOLV (blue line) using Moench (1985) solution and Hantush (1960) well function for a compressible aquitard, β=1 (symbols).

References

Moench, A.F., 1985. Transient flow to a large-diameter well in an aquifer with storative semiconfining layers, Water Resources Research, vol. 21, no. 8, pp. 1121-1131.