Estimation of Unsteady, Three‐Dimensional Drawdown in Single, Vertically Heterogeneous Aquifers

Abstract A quasi, a mixed, and a weighted three‐dimensional model are applied to approximate the three‐dimensional, unsteady drawdown in vertical pumping and observation wells, fully or partially penetrating a single, vertically heterogeneous, anisotropic aquifer. Cases of confined, semiconfined, and unconfined flow conditions are considered. Numerical examples are used to quantify the numerical error of the methods, introduced by the vertical heterogeneity of the aquifer. Results of pumping test data analysis in a three‐layer, anisotropic aquifer with multiple screens in the pumping well are presented.