Radial Flow in Vertically Graded Hydraulic Conductivity Aquifers

Abstract

Type curve expressions are derived analytically for drawdowns around a fully penetrating well in vertically graded hydraulic conductivity aquifers. A linear increase in the hydraulic conductivity with depth is adopted in this paper. Solution of the relevant groundwater movement equations are achieved by the application of Boltzmann transformation individually for the continuity and laminar flow law equations. Necessary type curves are presented for determining the aquifer parameters from an aquifer test performed in the field. The analytical results show that the conventional Theis and Jacob methods are not applicable in the cases of vertically graded hydraulic conductivity aquifers. In addition, a straight line method is proposed for the late time‐drawdown data. However, both type‐curve and straight‐line procedures developed in the paper yield the Theis and Jacob method equivalents, respectively. The application of the methodology is given for fissured and fractured hard‐rock aquifer test data obtained in the field.