Analysis of flow dimension from a pumping test in a karst aquifer

Abstract

Pumping test is a well-known method for determining hydraulic characteristics of an aquifer. Diagnostic plot technique is applied to facilitate the identification of an appropriate groundwater flow conceptual model, and for interpretation of the pumping test data. The diagnostic plots of six observation wells around a pumping well at the Salman Farsi Dam Site showed simultaneous presence of integer and non-integer flow dimensions of pumping test around the pumping well. Type of flow pattern on two observation wells shows two-dimensional flow and that on four observation wells follows one-and-a-half-dimensional flow. The results revealed that flow pattern around the pumping well in the karst study area changes from two-dimensional within a distance of less than about 100 m from the pumping well to one-and-a-half dimensional at a distance from the pumping well larger than about 100 m. The change of flow dimensions with increasing distance from the pumping well is due to radial flow around the observation wells within a distance of less than about 100 m from the pumping well, and bilinear flow around the observation wells with a distance of more than about 100 m from the pumping well. Radial and bilinear flows are related to cone of depression and preferential flow paths, respectively.