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Unsaturated zone parameters for Moench solution in unconfined aquifer

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Unsaturated zone parameters for Moench solution in unconfined aquifer

The dialog window "Unsaturated zone parameters" is used for entering parameters of variably-saturated zone. The parameters are required  for the Moench solution accounting for borehole storage and skin for an unconfined aquifer. Inclusion of unsaturated zone and capillary frindge is optional and allows simulating additional inflow from unsaturated zone during aquifer tests.

The dialog window opens by pressing the button "Parameters" from the dialog window "Matching parameters". The button "Parameters" is enabled if the option "Unsaturated zone" is checked.

 

Dialog window "Unsaturated zone parameters".

 

Explanatory table

Abbreviations in the table are the same as used in the USGS computer program that is reported in Barlow and Moench (2011)

Field "Soil-moisture retention exponent"

Empiric parameter to calculate water saturation in Gardner's solution, 1/m.

ACC in program WTAQ version 2

Field "Relative hydraulic conductivity exponent"

Empiric parameter to calculate relative hydraulic conductivity in Gardner's solution, 1/m.

AKK in program WTAQ version 2

Field "Initial unsaturated zone thickness"

AMM in program WTAQ version 2

Field "Maximum unsaturated zone thickness"

AXMM in program WTAQ version 2

 

Impact of parameters on solution

AMM >= AXMM

Infinite thickness of unsaturated zone

AMM < AXMM

Finite thickness of unsaturated zone

ACC approaches infinity

Unsaturated zone doesn't impact drawdown

AKK approaches 0

Unsaturated zone doesn't impact drawdown

AMM approaches infinity

Unsaturated zone doesn't impact drawdown

ACC <= AKK

Compulsory condition for the solution

 

References:

Barlow P, Moench A.F. WTAQ version 2 - a computer program for analysis of aquifer tests in confined and water-table aquifers with alternative representations of drainage from the unsaturated zone.  2011. U.S. Geological Survey. Technique and Methods 3-B9.