A slug test for determining hydraulic conductivity of unconfined aquifers with completely or partially penetrating wells

TLDR

The study presents a procedure to calculate aquifer hydraulic conductivity from the water‑level rise after sudden water removal. The method uses the Thiem equation of steady‑state flow, evaluates an effective radius via a resistance‑network analog for various geometries, and applies to both completely or partially penetrating wells in unconfined aquifers and to confined aquifers receiving recharge from the upper confining layer. An empirical relation between the effective radius and well‑aquifer geometry was derived, and the method’s results agree with those from other techniques for overlapping geometries.

Abstract

A procedure is presented for calculating the hydraulic conductivity of an aquifer near a well from the rate of rise of the water level in the well after a certain volume of water is suddenly removed. The calculation is based on the Thiem equation of steady state flow to a well. The effective radius R e over which the head difference between the equilibrium water table in the aquifer and the water level in the well is dissipated was evaluated with a resistance network analog for a wide range of system geometries. An empirical equation relating R e to the geometry of the well and aquifer was derived. The technique is applicable to completely or partially penetrating wells in unconfined aquifers. It can also be used for confined aquifers that receive water from the upper confining layer. The method's results are compatible with those obtained by other techniques for overlapping geometries.