VS2DT 3.0

VS2DT 3.0 is a computer program developed by the U.S. Geological Survey for solving problems of water flow and solute transport in variably saturated porous media.

VS2DT originated as a standalone program that reads simulation setup data from input files, and writes simulation results to output files. Prior to the release of the present software, VS2DT was released as version 2.5. In revising VS2DT from version 2.5 to 3.0, no new features were added. Rather, the code was modified so that it can be run in an interactive manner, and the definition of the van Genuchten parameter "alpha" was revised to be consistent with established usage. The present software integrates VS2DT 3.0 with a preprocessor and postprocessor so that simulations can be run in a visual-interactive environment.

Major features of VS2DT 3.0 include the following:

Use of finite-difference approximations to solve the Richard's equation for flow, and the advection-dispersion equation for transport.
Simulated regions can be one-dimensional columns, two-dimensional vertical cross sections, or three-dimensional axially symmetric cylinders.
Boundary conditions for flow include: specified pressure head, specified flux, infiltration with ponding, plant transpiration, bare soil evaporation, and seepage faces.
Unsaturated hydraulic characteristics may be represented by: van Genuchten, Brooks-Corey, and Haverkamp equations, as well as tabular data.
Transport processes include advection, dispersion, first-order decay, equilibrium adsorption as described by Freundlich or Langmuir isotherms, and ion exchange.

Users are strongly encouraged to obtain and read the following two reports that document VS2DT:

Healy, R.W., 1990, Simulation of solute transport in variably saturated porous media with supplemental information on modifications to the U.S. Geological Survey's Computer Program VS2D, U.S. Geological Survey Water Resources Investigations Report 90-4025, 125 p.

Lapalla, E.G, Healy, R.W., and Weeks, E.P., 1987, Documentation of computer program VS2D to solve the equations of fluid flow in variably saturated porous media, U.S. Geological Survey Water Resources Investigations Report 83-4099, 131 p.

Copies of these reports can be obtained through email to infoservices@usgs.gov, by phone at 303-202-420 (FAX 303-202-4695), or by mail to USGS Information Services, Box 25286, Denver Federal Center, Denver, CO 80225.