# Hyder et al. (KGS Model) Slug Test Solution for Confined and Unconfined Aquifers

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Additional Topics

A mathematical solution by Hyder et al. (1994), also known as the *KGS (Kansas Geological Survey) Model*, is useful for determining the hydraulic conductivity of **unconfined** and **nonleaky confined** aquifers. Analysis involves matching a type curve solution to water-level displacement data collected during an overdamped slug test.

AQTESOLV provides visual and automatic methods for matching the KGS Model to slug 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 KGS Model:

- aquifer has infinite areal extent
- aquifer is homogeneous and of uniform thickness
- aquifer potentiometric surface is initially horizontal
- control well is fully or partially penetrating
- a volume of water, V, is injected or discharged instantaneously from the control well
- aquifer is confined or unconfined
- flow is unsteady

## Solution

Options

AQTESOLV provides the following options for the KGS Model:

- partially penetrating wells
- hydraulic conductivity anisotropy
- wellbore skin effect
- observation wells

## Benchmarks

## References

Hyder, Z., J.J. Butler, Jr., C.D. McElwee and W. Liu, 1994. Slug tests in partially penetrating wells, Water Resources Research, vol. 30, no. 11, pp. 2945-2957.