Analytical formulae for the shape of the interface in a semi-confined aquifer

Abstract The paper briefly reviews the geohydrological problem and deals with the nonlinear ordinary differential equation of the second order, which describes the interface between flowing fresh groundwater above stagnant saline groundwater in a semi-confined aquifer. The analytical solutions of this differential equation are derived. The graphical presentation of the solutions, the interpretation of them and the evaluation of these solutions in geohydrological terms are considered. This paper is the companion to that by Van Dam and Sikkema in the present issue, dealing with an approximate solution of the same problem.