Dagan Slug Test Solution for Unconfined Aquifers

Well-aquifer configuration for Dagan (1978) slug test solution in an unconfined aquifer

A mathematical solution by Dagan (1978) is useful for determining the hydraulic conductivity of unconfined aquifers when the control well is screened across the water table. Analysis involves matching a straight-line solution to water-level displacement data collected during an overdamped slug test.

AQTESOLV provides visual and automatic methods for matching the Dagan solution 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 Dagan slug test solution:

  • aquifer has infinite areal extent
  • aquifer is homogeneous and of uniform thickness
  • aquifer potentiometric surface is initially horizontal
  • control well is screened across the water table
  • a volume of water, V, is injected or discharged instantaneously from the control well
  • aquifer is unconfined
  • flow is steady

Solution
Options

provides the following options for the Dagan method:

  • partially penetrating wells

Benchmark

Benchmark for Dagan (1978) solution

AQTESOLV benchmark for Dagan (1978) solution matched to an overdamped slug test in an unconfined aquifer using recommended head range (Butler 1998). Butler (1998) reported K=0.56 m/day for these data.

References

Dagan, G., 1978. A note on packer, slug, and recovery tests in unconfined aquifers, Water Resources Research, vol. 14, no. 5. pp. 929-934.