New equations for determining the formation constants of an aquifer from pumping test data

New equations are given, based on an extended theory, that take into account the following factors: the compressibility and anisotropy of the main aquifer; the partial penetration of the ion well; the depth at which the drawdown in an observation well is measured; the existence of a low‐permeability layer, hereafter called ‘the aquitard,’ above the aquifer; and the saturated and unsaturated zones above the water table. A practical method of evaluating the formation constants for an aquifer from pumping test data is fully discussed. Type curves based on the new equations are used to analyze data from a pumping test in the thick Bunter sandstone formation of Shropshire (Great Britain). A correction for the water derived from storage within the ion well is found to be necessary.