Abstract

This report describes the program FLOP3N, the mathematical background, the implementation and guidelines for running the program together with some results. FLOP3N is a particle tracking program for a system of homogeneous anisotropic layers, in which partially penetrating wells are active. Besides the wells, the user can specify a natural groundwater flow. The program calculates pathlines and travel times of water particles under steady state flow conditions, and so, the capture zones around groundwater abstraction sites. The calculations are based on an exact analytical solution for the corresponding three-dimensional problem. FLOP3N is specifically useful for all those cases where more simple approximations are not valid, because the standard assumptions that the vertical gradient is small or that the filters of the wells extend over the full height of the aquifer, are not applicable. Normally, for such cases one has to take one's resort e.g. to the class of finite-element methods, which are very demanding in general with respect to the input and are also time-consuming.