IGWMC's version of the widely used 2-D finite difference flow model

Version 2.11 (June 1993)
Order No: FOS 12
Price: Contact for more info

PLASM as distributed by the IGWMC is a programs package based on the Prickett Lonnquist Aquifer Simulation Program (PLASM) first published in 1971 by the Illinois State Water Survey. It consists of three finite-difference simulation programs and a preprocessor. The programs simulate two-dimensional nonsteady flow of ground-water in heterogeneous anisotropic aquifers under water table, nonleaky, and leaky confined conditions. Included are options for time-varying pumpage from wells, induced infiltration from streams or shallow aquifers, and water-table-depth-dependent evapotranspiration. The finite-difference equations are solved using a modified alternating direction method. The versions included in this package are: 1) PLASM85, simulation of transient flow in a fully confined aquifer as prepared by the authors for IGWMC short courses; 2) CONPLASM, simulation of transient flow in a fully confined or leaky confined aquifer; and 3) UNCPLASM, simulation of transient flow in an unconfined (or water-table) aquifer. Both CONPLASM and UNCPLASM were prepared by IGWMC, based on the 1971 version. They facilitate a grid of 70 * 70 nodes.

IGWMC has developed the interactive preprocessor PREPLASM for CONPLASM and UNCPLASM. CONPLASM and UNCPLASM create a printable output file, an x,y,h file for postprocessing with a commercial contouring package, and a h,t file for selected nodes for line-graph postprocessing with commercial software.

The programs of the PLASM package have been compiled for the DOS environment. The simulation programs are in the public domain; PREPLASM is proprietary to IGWMC. The IGWMC-prepared package contains source codes for the simulators, runtime versions of all programs, and example data sets. The user's manual includes installation instructions, CONPLASM/UNCPLASM documentation, and the original PLASM documentation by T.A. Prickett and C.G. Lonnquist.


Intel 80i86 based computer with math coprocessor, 640 Kb RAM, about 1.5 Mb free disk space for programs and example data files, DOS 2.1 or higher.

Authors: T.A. Prickett and C.G. Lonnquist (Illinois State Water Survey).