VIRALT Order No: FOS 48

VIRALT is a modular semi-analytical and numerical code that simulates the transport and fate of viruses in ground-water. The code provides both steady-state and transient transport analyses taking into account the major physical processes including: advection and dispersion of viral particles in the vertical dimension in the unsaturated zone and along ground-water pathlines in the saturated zone; adsorption; and inactivation (die-off). VIRALT was developed to delineate ground-water pathlines and well capture zones, and to compute viral concentrations in extracted water. Contaminant sources of various shapes can be handled. Both areal and line sources in unconfined or confined aquifers can be accommodated. Typically, areal sources may be used to represent leaky septic tanks, cesspools or areas of surface and subsurface disposal of waste water. Line sources may be used to represent leaky sewer lines or pipes. Barrier or steam boundary conditions which exist over the entire aquifer depth can be simulated. Several test problems are presented to verify the code and demonstrate its utility. These problems range from simple radial flow with a circular leaky sewer pipe to a two-well system in an areally extensive aquifer.

VIRALT data input and output are facilitated by a user-friendly, menu-driven interface with help screens. Graphical output can be sent to a pen plotter or printer, or graphical output can be saved in HPGL format for inclusion in advanced word processing and desktop publishing programs. The public domain VIRALT program is distributed with executable image and example data sets. The documentation includes installation, theory, and user's manual, and example problems.


Intel 80386 based computer, 2 Mb extended RAM, DOS 3.0 or higher, at least 2 Mb free disk space, math coprocessor, CGA graphics (EGA or VGA recommended).

VIRALT runs on Widnows up to 99, it is incompatible with Windows 2000/XP

Authors: Nam-Sik Park, T.N. Blanford, and P.S. Huyakorn (HydroGeologic, Inc. for US EPA).