1. General Model Information


Acronym: CANVAS

Main medium: terrestrial
Main subject: , hydrology, (eco)toxicology
Organization level: Ecosystem
Type of model: partial differential equations (finite elements,2D), partial differential equations (finite elements,1D)
Main application:
Keywords: soil, water,virus transport, unsaturated, saturated, flow, solute transport, richards equatin, convection-dispersion equation


P.S. Huyakorn

HydroGeologic, Inc.
1165 Herndon Parkway, Suite 900, Herndon, VA 22070


Park, N-S., T.N. Blandford, Y-S. Wu and P.S. Huyakorn


CANVAS is a composite analytical-numerical (FE) code for simulation of transport and fate of viruses in ground water. The code supports transient one-dimensional vertical flow and transport in the unsaturated zone and two-dimensional horizontal flow and transport in the saturated zone. It takes into account advection and dispersion of viral particles in the unsaturated and saturated zones, adsorption, inactivation (die-off) and colloidal filtration. CANVAS may also be used for delineation of ground-water pathlines and well capture zones. Both areal and line sources of various shapes in unconfined or confined aquifers can be accommodated. Barrier or stream boundary conditions that exist over the entire aquifer depth can also be simulated. CANVAS consists of various modules. The USCOL module simulates the flow of ground-water and the transport of viruses from a viral source to the water table. The viral breakthrough curve at the water table computed with this module is used as input for the LTG2D module. The USCOL module uses a semi-analytical technique to solve the one-dimensional, steady-state flow equation together with the Newton-Raphson method to find the non-linear roots of the equation. For the transport equation, a numerical approximation is obtained using an upstream-weighted finite element method and linear elements. Time integration is performed using a central difference formulation. SZFLOW computes steady-state, two-dimensional (areal) ground-water flow velocities within each (rectangular) finite element of the specified grid. This module also delineates ground-water flow pathlines and well capture zones. The modules uses the Laplace Transform Galerkin (LTG) technique for solution of the flow equation. LTG2D simulates two-dimensional transport of viruses in the saturated zone, using output of USCOL and SZFLOW as input. Steady-state transport is solved using the standard upstream-weighted residual finite element scheme. In its present configuration, the model handles up to a 75 X 75 grid, 10 sources, 10 soil layers, 25 pumping wells, 5 recharging wells, and 10 forward-tracked and 10 reverse-tracked pathlines.

The preprocessor, PRECV, allows the user to efficiently enter and edit input data and includes the graphical construction of the finite element grid and the placement and removal of multiple sources and pumping and injection wells. The postprocessor, CVGRAF, allows the graphical presentation of ground-water pathlines, viral breakthrough curves at the water table or at pumping wells, and ground-water pressures and saturations in the unsaturated zone beneath contaminant sources.

II. Technical Information

II.1 Executables:

Operating System(s): DOS, public domain

II.2 Source-code:

Programming Language(s): FORTRAN

II.3 Manuals:

II.4 Data:

III. Mathematical Information

III.1 Mathematics

III.2 Quantities

III.2.1 Input

III.2.2 Output

IV. References

V. Further information in the World-Wide-Web

VI. Additional remarks

Last review of this document by: Sep 30 1997
Status of the document:
last modified by Tobias Gabele Wed Aug 21 21:44:40 CEST 2002

Go back to Register of Ecological Models (R E M)