Moench Solution for Constant-Head Tests in Leaky Aquifers

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

A mathematical solution by Moench (1985) is useful for determining the hydraulic properties (transmissivity and storage coefficient of aquifer, vertical hydraulic conductivity and storage coefficient of aquitard and wellbore skin) of leaky confined aquifers. Analysis involves matching the solution to discharge data collected during a constant-head test. The Moench solution accounts for wellbore storage and wellbore skin.

uses a general formula (Van Everdingen and Hurst 1949) to transform the constant-rate solution by Moench (1985) to a constant-head condition.

AQTESOLV provides visual and automatic methods for matching the Moench solution to constant-head 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 constant-head test solution:

  • aquifer has infinite areal extent
  • aquifer is homogeneous, isotropic and of uniform thickness
  • aquifer potentiometric surface is initially horizontal
  • wells are fully penetrating
  • aquifer is leaky confined
  • flow is unsteady
  • aquitards have infinite areal extent, uniform vertical hydraulic conductivity and uniform thickness
  • aquitards are overlain or underlain by an infinite constant-head plane source
  • aquitards are incompressible (no storage)
  • flow in the aquitards is vertical

Solution
Options

provides the following options for the Moench solution for a constant-head test:

  • recovery

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.

Van Everdingen, A.F. and W. Hurst, 1949. The application of the Laplace transformation to flow problems in reservoirs, Petroleum Transactions, AIME, vol. 186, pp. 305-324.