PUBLICATIONS -- release of report Documentation of computer programs In Reply Refer To: Monday, November 6, 1989 WGS-Mail Stop 411 OFFICE OF GROUND WATER TECHNICAL MEMORANDUM No. 90.01 Subject: PUBLICATIONS -- release of report "Documentation of computer programs to compute and display pathlines using results from the U.S. Geological Survey modular three- dimensional finite-difference ground- water flow model" by David W. Pollock. The attached report has recently been released as Open-File Report 89-381 pending publication in the Techniques of Water Resources Investigations (TWRI) series. The report describes and documents a particle tracking post- processing package designed for use with the U.S. Geological Survey modular finite-difference ground-water flow model. The package consists of two computer programs: (1) MODPATH, which computes particle coordinates along path lines, and (2) MODPATH- PLOT, which graphically displays numerical results generated by MODPATH. The particle tracking package is restricted to the analysis of steady-state ground-water flow systems. Graphics produced by MODPATH-PLOT are generated using the DISSPLA graphic subroutine library that is available on WRD Prime computers. This report should be made available to ground-water hydrologists who currently use the modular finite-difference ground-water flow model in their work, or who may be using it in the near future. Copies of the computer programs can be obtained from the Software Exchange System (SOFTEX), the WATSTORE Program Office, or the author. Additional copies of Open-File Report 89-381 can be obtained from the author. Eugene P. Patten Chief, Office of Ground Water Attachment Distribution: A, B, S, FO, PO