# Moench Solution for Constant-Head Tests in Leaky Aquifers

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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.

AQTESOLV 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

AQTESOLV 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.