ABSTRACTThe purpose of this paper is to elucidate the phenomenon of brine upconing beneath a discharge well partially penetrating an unconfined aquifer in which fresh water is underlain by saline water. In order to predict the maximum uncontaminated fresh water production for given aquifer conditions and well geometry, the potential distribution in the flow region must be known. However, since the partial differential equation describing the flow is nonlinear and so are the boundary conditions, it is not possible to arrive at an exact analytic solution to the problem. Therefore, a less rigorous but tractable approach is to solve this problem using simplifying and physically plausible assumptions. A comparative study is made of the approximate analytic solutions available at the present time and the validity of the assumptions used is evaluated. Factors affecting the stability of the brine cone beneath a skimming well and conditions leading to entrainment of salt water along with fresh water production are also discussed.