Straight-Line Method Generalization for Aquifer Parameter Estimations

Abstract

Aquifer parameter determination in practical hydrogeological studies exposes one of the most significant steps in groundwater resources assessment and management. Successful parameter estimation necessitates both a reliable methodology and field data. Different analytical solutions in the forms of type curves depend on well and aquifer configuration such as porous or fractured media; confined, unconfined, and leaky conditions; and small- and large-diameter wells. Most often Cooper-Jacob (CJ) straight line is used for aquifer parameter estimations from late time-drawdown data in cases of confined and unconfined aquifers. This straight-line method is attractive because of its simplicity and straightforward calculations without tedious and dubious type-curve matching procedure. The warranty of the CJ method application depends on the fact that the late time-drawdown measurements fall along the final portion of the Theis type curve. The main purpose of this paper is to present a general type straight-line model to determine aquifer properties of a confined leaky (semiconfined) aquifer by using the pumping test results. The CJ method is applicable in cases in which the straight-line slope on dimensionless semilogarithmic paper is equal to 2.3 only.