MODFLOW-USG Complex Stratigraphy Workflow

GMS supports building MODFLOW-USG models with multiple types of unstructured grids. To generate 3D unstructured grids with complex stratigraphy, use the following processes:

1. Convert geometry to a UGrid, selecting complex stratigraphy during conversion.
Select the Feature Objects | Map → UGrid... menu command. In the Map → UGrid dialog, enter parameters for the UGrid. Quadtree UGrids Voronoi UGrids VTK Unstructured Grids

2. Use borehole data to create a 3D UGrid.
Select the Boreholes | Horizons → UGrid… menu command. Use the Horizons to UGrid wizard.

3. Create a MODFLOW-USG model.

1. Create a MODFLOW simulation. Select the 3D grid or UGrid in the the Project Explorer. Select the MODFLOW | New SImulation... command. 2. Set up the MODFLOW Global/Basic Package options. If necessary, select the MODFLOW | Global Options... command. In the MODFLOW Global/Basic Package dialog, set all the appropriate parameters: Version Model type Run options Stress periods Packages Units LGR options Layers Arrays IBOUND Starting heads Top and bottom elevations Confining beds Porosity

4. Map to MODFLOW.
Select the conceptual model . Select Feature Objects | Map → MODFLOW . Select the appropriate options in the Map → Model dialog.

5. Run MODFLOW.
Save the project. Run MODFLOW .