USGS: science for a changing world

Oregon District


U.S. Geological Survey

Open-File Report 97-240


    MODTOOLS is a set of computer programs for translating data of the ground-water model, MODFLOW, and the particle-tracker, MODPATH, into a Geographic Information System (GIS). MODTOOLS translates data into a GIS software called ARC/INFO. MODFLOW is the recognized name for the U.S. Geological Survey Modular Three-Dimensional Finite-Difference Ground-Water Model. MODTOOLS uses the data arrays input to or output by MODFLOW during a ground-water flow simulation to construct several types of GIS output files. MODTOOLS can also be used to translate data from MODPATH into GIS files. MODPATH and its companion program, MODPATH-PLOT, are collectively called the U.S. Geological Survey Three-Dimensional Particle Tracking Post-Processing Programs. MODPATH is used to calculate ground-water flow paths using the results of MODFLOW and MODPATH-PLOT can be used to display the flow paths in various ways. MODTOOLS uses the particle data calculated by MODPATH to construct several types of GIS output.
    MODTOOLS uses particle information recorded by MODPATH such as the row, column, or layer of the model grid, to generate a set of characteristics associated with each particle. The user can choose from the set of characteristics associated with each particle and use the capabilities of the GIS to selectively trace the movement of water discharging from specific cells in the model grid. MODTOOLS allows the hydrogeologist to utilize the capabilities of the GIS to graphically combine the results of the particle-tracking analysis, which facilitates the analysis and understanding of complex ground-water flow systems.


    MODTOOLS uses a set of AMLs (Arc Macro Langage) programs written for the GIS software called ARC/INFO and FORTRAN programs to construct several types of GIS output.


    Version 6.0 98/06/01 -- Works with MODPATH 3.x

Data Requirements

    Several files must be created before activating MODTOOLS. The number and types of files needed by MODTOOLS is determined by the type of GIS output produced. The minimum set of files are those required to describe the cell geometry of the finite-difference grid and cell properties. This set is commonly referred to as the "MAIN and NAME" files that are used by both MODPATH and MODTOOLS. Additional files are needed of MODFLOW and MODPATH to produce the many types of GIS output of MODTOOLS (see user manual for complete details).

Output Options

    MODTOOLS produces several types of GIS output that include results from ground-water simulations of MODFLOW and particle tracking of MODPATH. This output can be in the form of files that list data for each model cell or digital files that contain both the spatial arrangement of particle pathlines or other features and characteristics about the particle or cell.

System Requirements

    MODTOOLS is written in standard Fortran 77 and, generally, easily installed. MODTOOLS requires the use of ARC/INFO software to run a set of AML programs to create GIS output.


    Orzol, L.L., 1997, User's guide for MODTOOLS: Computer programs for translating data of MODFLOW and MODPATH into geographic information system files: U.S. Geological Survey Open-File Report 97-240, 86 p.

Related Documentation

    Harbaugh, A.W., 1990, A simple contouring program for gridded data: U.S.Geological Survey Open-File Report 90­144, 37 p.
    Harbaugh, A.W., and McDonald, M.G., 1996, User's documentation for MODFLOW­96, an update to the U.S. Geological Survey modular finite-difference ground-water flow model: U.S. Geological Survey Open-File Report 96­485, 56 p.
    Hinkle, S.R., and Snyder, D.T., 1997, Comparison of chlorofluorocarbon-age dating with particle- tracking results of a regional ground-water flow model of the Portland Basin, Oregon and Washington: U.S. Geological Survey Water-Supply Paper 2483.
    McDonald, M.G., and Harbaugh, A.W., 1988, A modular three-dimensional finite-difference ground-water flow model: U.S. Geological Survey Techniques of Water-Resources Investigations, book 6, chap. A1, 586 p.
    Orzol, L.L., and Truini, M., in press, Evaluation of factors that influence estimated zones of transport for six municipal wells in Clark County, Washington: U.S. Geological Survey Water-Resources Investigations Report 97-4224, 114 p.
    Pollock, D.W.,1994, User's guide for MODPATH/MODPATH-PLOT, version 3-A particle tracking post-processing package for MODFLOW, the U.S. Geological Survey finite-difference ground-water flow model: U.S. Geological Survey Open-File Report 94­464, [variously paged].
    Snyder, D.T., Wilkinson, J.M. and Orzol, L.L., 1996, Use of a ground-water flow model with particle tracking to evaluate ground-water vulnerability, Clark County, Washington: U. S. Geological Survey Open-File Report 96­328, 71 p.


      U. S. Geological Survey
      Leonard L. Orzol
      10615 S.E. Cherry Blossom Drive
      Portland, OR 97216

Last modified: Wed Sep 3 10:11:40 PDT 2003