GGSD Program Details for CANVAS

CANVAS

Category	Contaminant transport (2D analytical)
Platform	DOS
Status	Public domain
Description	CANVAS is a composite analytical-numerical code for simulation of transport and fate of viruses in ground-water. The code provides transient transport taking into account advection and dispersion of viral particles in the unsaturated and saturated zones, adsorption, inactivation (die-off), attachment and detachment kinetics and colloidal filtration. 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. 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 stream boundary conditions that exist over the entire aquifer depth can be simulated. Consists of various modules. USCOL: simulates the flow of ground-water and the transport of viruses from a viral source to the water table. Uses a semi-analytical technique to solve the 1D, 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. The viral breakthrough curve at the water table computed with this module is used as input for the LTG2D module. SZFLOW: computes steady-state, 2D (areal) ground-water flow velocities within each (rectangular) finite element of the specified grid and delineates ground-water flow pathlines and well capture zones. Uses the Laplace Transform Galerkin (LTG) technique for solution of the flow equation. LTG2D: simulates 2D transport of viruses in the saturated zone, using output of USCOL and SZFLOW as input. Steady-state transport is solved using the upstream-weighted residual finite element scheme. Model handles up to 75x75 grid, 10 sources, 10 soil layers, 25 pumping wells, 5 recharging wells, and 10 forward-tracked and 10 reverse-tracked pathlines. The pre-processor, PRECV, allows the user to 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 post-processor, CVGRAF, allows the graphic presentation of ground-water flow path-lines, viral breakthrough curves at the water table or at pumping wells, and ground-water pressures and saturations in the unsaturated zone beneath contaminant sources.
Cost	US Dollars 95
Data formats supported	None stated
Supplier in United States of America	International Ground Water Modeling Center