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User's Guide for MODTOOLS: Computer Programs for Translating Data of MODFLOW and MODPATH into Geographic Information System Files

By Leonard L. Orzol

USGS Open-File Report 97-240, 86 p., 11 figs., 10 tables.

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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.

Report availability:

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A printed version of the full report is available free (while supplies last) from:

U.S. Geological Survey, 10615 S.E. Cherry Blossom Drive, Portland, OR 97216 (ph: 503-251-3201, e-mail

and (at a nominal charge) from:

U.S. Geological Survey, Information Services, Box 25286, Denver, CO 80225 (ph: 1-888-ASK-USGS, e-mail

Note: When ordering the report, please supply the report title and number, your name, and your mailing address. Thank you.

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