The new particle tracking program mod-PATH3DU, developed by S.S. Papadopulos & Associates, provides a vital component for interpretation and analysis of MODFLOW-USG groundwater models. This program will be integrated into Visual MODFLOW Flex in a future release. The following images are some of examples of pathline analysis using mod-PATH3DU and UnStructured Grid models (Voronoi and Quad-Based grids) generated by Visual MODFLOW Flex.

mod-PATH3DU-MODFLOW-USG-Voronoi-Grid-Example

Backward tracking pathlines around two pumping wells, in a 2D steady-state model using Voronoi Grids.

mod-PATH3DU-MODFLOW-USG-Voronoi-Grid-Example5

Closer view of cell geometry and pathlines around a pumping well, in a 2D steady-state model using Voronoi Grids. Some pathlines track back to the river (blue), while others track to the constant head cells on the east boundary (shown in red).

mod-PATH3DU-particle-tracking-MODFLOW-USG-QuadGrid2

Backward tracking pathlines around two pumping wells, in a 2D steady-state model using Quad-Based grid refinement

particle-tracking-MODFLOW-3D-example

3D transient example illustrating forward pathlines released adjacent to the constant head cells (colored in red) in layer 1. Note that some pathlines track through the discontinuous aquitard in layer 2 (colored as solid green), and reach the water supply well in layer 3.

particle-tracking-MODFLOW-USG-QuadGrid1

3D steady-state example using Quad-Based grids. Backward pathlines track back to the constant head cells along the northern boundary.

particle-tracking-MODFLOW-USG-Voronoi-Grid3

2D steady-state example using Voronoi grids, with refinement around the river and well. Pathlines are colored by the travel time (dark blue short travel time, light green is longer travel time).

comparison1

A comparison of pathlines from mod-PATH3DU using two UnStructured Grid geometries (Voronoi and QuadTree grids) and benchmarked with a structured uniform MODFLOW-2005 grid, with pathlines run using MODPATH. The conceptual model is the same 3D steady-state example utilized above.

comparison2

A 3D view of a benchmark comparison between mod-PATH3DU/MODFLOW-USG (Voronoi and QuadTree) and MODFLOW-2005 structured grid using MODPATH. The conceptual model is the same 3D steady-state example utilized above.

About mod-PATH3DU

S.S. Papadopulos & Associates, Inc. is pleased to announce the release of mod-PATH3DU, a particle path and travel-time simulator for structured and unstructured grids. The original PATH3D was one of the first particle tracking programs to support MODFLOW. Since that time, the MODPATH program has become the most widely used particle tracking program for MODFLOW simulators. mod-PATH3DU integrates the capabilities of PATH3D and MODPATH within a single program that is compatible with MODFLOW-2000/2005/USG. Simply register and download the program by following the appropriate links on www.sspa.com/software.