SOLUTRANS is a 32-bit Windows program for modeling three-dimensional solute transport based on the solutions presented by Leij et. al. (1991) and Leij et. al. (1993) for both equilibrium and non-equilbrium transport.

The interface and input requirements are so simple that it only takes a few minutes to develop models and build insight about complex solute transport problems. With SOLUTRANS you can, in a matter of minutes, model solute transport from a variety of source configurations and build important insights about key processes. SOLUTRANS offers a quick and simple alternative to complex, time-consuming 3-D numerical flow and transport models.

This is a model of two superpositioned parallelipiped initial source volumes
with nonequilibrium sorption. The source areas retain significant
nonequilibrium mass, and are visible at the left side of the plume.
This is a plot of concentration on the plane z=0, which
cuts through the initial source volumes.

SOLUTRANS Capabilities

The solutions in SOLUTRANS all assume a uniform one-dimensional flow field in the positive x direction. There is three-dimensional dispersion with different coefficients allowed in all three directions. One set of solutions assumes equilibrium in the solute and adsorbed phases (Leij et. al., 1991), while another set of solutions allows nonequilibrium (kinetic) conditions (Leij et. al., 1993).

With the nonequilibrium solutions, the solute may be out of equilibrium with some of the adsorption sites. Van Genuchten and Wagenet (1989) and Leij et. al. (1993) describe two common ways of conceptualizing nonequilibrium transport; a ``two-site'' concept and a ``two-region'' concept. Both concepts lead to similar partial differential equations that are, in fact, written as a common dimensionless partial differential equation. In the two-site concept, some fraction of adsorption sites are at equilibrium while other sites are not. At the nonequilibrium (kinetic) sites, a first-order rate law governs adsorption. In the two-region concept, there is mobile pore water and immobile pore water and both are in equilibrium with the sorption sites that they are in contact with. Solute migrates by advection and dispersion in the mobile region, and first-order diffusion transfers solute mass from the mobile region to the immobile region (Coats and Smith, 1964; van Genuchten and Wierenga, 1976).

Separate first-order decay coefficients may be specified for the equilibrium and the nonequilibrium phases. The nonequilibrium models allow you to examine the distribution of equilibrium (mobile water) concentrations, nonequilibrium (immobile water) concentrations, and the total (aqueous + adsorbed) concentration.

Unlike the solutions of Domenico and Robbins (1985, Groundwater, v. 23, p. 476.) and Domenico (1987, Jour. Hydrol. v. 91, p. 49), these solutions do not make approximations that cause errors near the source. These are exact solutions which involve some numerical integration.

Both the equilibrium and nonequilibrium solutions allow four different source geometries:

  • rectangular inlet area
  • circular inlet area
  • parallelipiped (rectangular box) initial volume
  • cylindrical initial volume

The ten solutions implemented in SOLUTRANS are listed below:

  1. Rectangular inleat, equilibrium, steady-state
  2. Rectangular inlet, equilibrium
  3. Rectangular inlet, nonequilibrium
  4. Circular inlet, equilibrium, steady-state
  5. Circular inlet, equilibrium
  6. Circular inlet, nonequilibrium
  7. Parallelepiped initial volume, equilibrium
  8. Parallelepiped initial volume, nonequilibrium
  9. Cylinder initial volume, equilibrium
  10. Cylinder initial volume, nonequilibrium

Using the superposition features built into SOLUTRANS, it is possible to model contaminant sources that have irregular distributions in time and space as shown here . See the figure above for an example of source superposition.

All these solutions may be used to create simpler two-dimensional, one-dimensional, and diffusion-only solutions, if needed.

SOLUTRANS User Interface

SOLUTRANS has a seamless, Windows-standard user interface. It has been designed to be very simple and fast. Most common modeling operations are executed at the push of a button on the main screen. Mathematical model input data are accessed directly in a spreadsheet-like grid. Data can be imported and exported using the Windows Clipboard.

SOLUTRANS can produce three types of plots: 1) concentrations vs. distance along a line, 2) concentrations vs. time at a point, and 3) surface plots of concentrations vs. location on a plane. Press here to see examples of plot types (1) and (2), and see the above plot for an example of type (3).

Plots are made on the screen, and may be exported to the Windows Clipboard or to disk files in either bitmap (.BMP) or metafile (.WMF) format. Concentration data may also be exported directly in comma-delimited ASCII files for use with other visualization software programs. Data may also be exported in .GRD format files for surface plotting using SURFER software.

The following forms of on-line help are available: tips that automatically display when you pause over a control, context-sensitive help (F1 key), and a Windows-standard help file. The help file is indexed, searchable, printable, and it contains embedded jumps to related topics.

SOLUTRANS Documentation

Most of the information about how to use the software is in the on-line help system. The SOLUTRANS Manual is a 7 x 9 inch spiral bound booklet containing the following sections.

  • Introduction - describes the software and how to install it.
  • Tutorial - step-by-step development and modification of a SOLUTRANS model, showing screens as they appear in the process.
  • Method Employed - a detailed section describing the governing equations and the general nature of the analytic solutions employed.
  • Modeling Tips - includes advice about parameter units, computational speeds, superposition, 1-D, 2-D, and diffusion-dominated transport models, etc.
  • Program Checks - 42 separate checks of the solutions implemented in SOLUTRANS. The model input files for the check models are included on the software diskettes.
  • References

SOLUTRANS System Requirements

  • 32-bit Windows operating system (Windows 95/98/NT as of this writing)
  • 4 MB of hard disk space
  • 8 MB of memory

Licenses and Support

  • The commercial SOLUTRANS license is a typical software license; one license allows installation on one computer at a time.
  • The academic license is a site license available for qualified educational institutions and is restricted to academic, non-commercial purposes.
  • Purchase of either license includes unlimited support to make sure that SOLUTRANS operates properly on your system.


Coats, K. H. and B. D. Smith. 1964. Dead-end pore volume and dispersion in porous media. Soc. Petrol. Engr. Jour., v. 4, p. 73-84.

Leij, F. J., T. H. Skaggs, and M. Th. van Genuchten. 1991. Analytical solutions for solute transport in three-dimensional semi-infinite porous media. Water Resources Research, v. 27(10), p. 2719-2733.

Leij, F. J., N. Toride, and M. Th. van Genuchten. 1993. Analytical solutions for nonequilibrium solute transport in three-dimensional porous media. Journal of Hydrology, v. 151, p. 193-228.

Leij, F. J. and S. A. Bradford. 1994. 3DADE: A computer program for evaluating three-dimensional equilibrium solute transport in porous media. U. S. Salinity Laboratory Research Report No. 134, Riverside, California.

Leij, F. J. and N. Toride. 1997. N3DADE: A computer program for evaluating nonequilibrium three-dimensional solute transport in porous media. U. S. Salinity Laboratory Research Report No. 143, Riverside, California.

van Genuchten, M. Th. and J. C. Parker. 1984. Boundary conditions for displacement experiments through short laboratory soil columns. Soil Science Soc. of Am. Jour., v. 48, p. 703-708.

van Genuchten, M. Th. and R. J. Wagenet. 1989. Two site/two region models for pesticide transport and degradation: theoretical development and analytical solutions. Soil Science Soc. of Am. Jour., v. 53, p. 1303-1310.

van Genuchten, M. Th. and P. J. Wierenga. 1976. Mass transfer studies in sorbing porous media: 1. analytical solutions. Soil Science Soc. of Am. Jour., v. 40, p. 473-481.