The Win95/98/NE/NT version of MicroFEM is a new program, based on the DOS package Micro-Fem. It takes you through the whole process of ground-water modeling, from the generation of a finite-element grid through the stages of preprocessing, calculation, postprocessing, graphical interpretation and plotting. Confined, semi-confined, phreatic, stratified and leaky multi-aquifer systems can be simulated with a maximum of 20 aquifers.

Irregular grids, as typically used by finite-element programs, have several advantages compared to the more or less regular grids used by finite-difference codes. A model with a well-designed irregular grid will show more accurate results with fewer nodes, so less computer memory is required while calculations are faster. MicroFEM offers extensive possibilities as to the ease of creating such irregular grids. Two grid generators are included; one is designed for irregular geometries as often encountered in regional studies, while the other is useful for engineering applications that often require high contrasts in node spacing, e.g. sheet piling and excavations. Adding and erasing nodes, connection swapping and further modifications to the grid can be done interactively.

Other MicroFEM features include the ease of data preparation and the presentation and analysis of modeling results. A flexible way of zone-selection and formula-assignment is used for all parameters: transmissivities, aquitard resistances, well discharges and boundary conditions for each layer.

Depending on the type of model this can be extended with layer thicknesses, storativities, spatially varying anisotropy and topsystem parameters. To inspect and interpret model results, maps and profiles can be used to visualize contours, heads, 3D-flowlines, flow vectors, etc. Time-drawdown curves and water balances can be selected with just a few keystrokes or mouse clicks. Its capacity, speed and flexibility have made MicroFEM a most widely used ground-water modeling tool.

The WIN-version of MicroFEM has only recently been released and a free lite-version is available for downloading. This WIN version differs from the DOS version in many respects. However, several parts of the DOS programs could be transferred to the WIN version with few modifications only. Apart from the standard Window type of graphical user interface the general setup and practically all options of the DOS package have been retained, e.g. the characteristic way of handling a model by using marked nodes, labels and different modes. Many modeling tasks are performed in much the same way for both versions. Most programs of the standard package (FemGrid, FeModel, FemProf, FemBaln, FemPlot) and the optional DOS extensions FemMesh, FemCat, FemCurv and FemPath are integrated in the WIN95/98/NT version. Inverse modeling, as in FemInvs, is not (yet) included.