Storage Effect in Falling Head Permeameters

Abstract

Hydraulic conductivity (K), a proportionality constant in Darcy's Law, is one of the most fundamental parameters in groundwater studies. A falling head permeameter (FHP) test is one way to determine K, and its results are computed assuming a zero specific storativity of the tested sample. This study closes this gap by analyzing the effect of specific storativity on the K calculation in FHP tests. The authors develop a solution for flow in FHP tests considering a nonzero specific storativity in the Laplace domain and use the de Hoog algorithm to attain the inverse Laplace transform of this solution to yield solutions in real-time domain, then enter into this solution a wide range of values of hydraulic conductivity and specific storativity to examine the significance of storage effects when using a FHP to determine the hydraulic conductivity of a porous sample. The study confirms that the specific storativity has a nearly negligible effect, and the solution with a zero specific storativity assumption can be practically used for FHP data interpretation. (c) 2017 American Society of Civil Engineers.