GMS:MODFLOW Grid Workflow

This is a top level workflow. This workflow includes all of the specific workflows needed in creating a general MODFLOW project using the grid approach. Newer and infrequent GMS users should start here.

To build a MODFLOW grid approach model in GMS, use the following steps:

1. Start GMS.

1. Start GMS, or clear existing projects in GMS. If GMS is already running, select File | New. A new project can also be started by clicking New . 2. If necessary, register or update GMS. 1. Register GMS and components. Launch the GMS Registration Wizard. The option to register is given when opening an unregistered version of GMS. Use the Help | Register command to change registration options using the Aquaveo License Registration dialog. Follow the Registration Wizard instructions. Review the registered components in the Aquaveo License Registration dialog. 2. Update GMS. GMS can be updated by doing any of the following: Select Download if prompted to update when starting GMS. Select Help | Check For Updates. Go directly to the GMS download page. 3. Set the display projection. Select the Edit | Units... command. In the Units dialog, set the time, mass, force, and concentration. Click the button and set the horizontal and vertical projection in the Display Projection dialog. If necessary, use the Horizontal Projection dialog to set a global projection.

2. Import data.

1. Gather and open image files. Images are imported into the GIS module in GMS. 1. Open local images. Load images from local computer files using the File | Open... command. Alternatively, drag and drop the file into the Graphics Window in GMS. 2. Import images from the web. Use the Add Online Maps macro. Select a location in the Virtual Earth Map Locator. If a projection has not been set for the project, set a new project in the Display Projection dialog. Use the Data Service Options dialog to select a web service. 2. Gather and open geometric data files. 1. Import map data. Use the File | Open... command to import map data such as Map files, boundary ID files, or boundary XY files. Alternately, drag and drop the file into the Graphics Window in GMS. 2. Import GIS data. Use the File | Open... command to import GIS data files such as Shapefiles or raster files. Alternatively, drag and drop the file into the Graphics Window in GMS. 3. Import scatter data. Use File | Open... to open files with scatter data. Alternatively, drag and drop the file into the Graphics Window in GMS. Use the File Import Wizard to specify how to import the data. 4. Import CAD data. Verify the CAD file type is readable by GMS before importing it. GMS can import DXF and DWG files. Use the File | Open... command to launch the Open dialog (or drag and drop) to import the CAD files. The data should load in layers into the Project Explorer. 5. Review and set object projections. Right-click on an object in the Project Explorer and select the Projection | Projection command. Set the horizontal and vertical projection using the Object Projection dialog. To set a global projection, use the Horizontal Projection dialog. 3. Gather hydrologic data files. Gather data files for hydrologic and hydraulic data. These include data such as hydrographs, water levels, and rating curves. They will be imported when setting boundary conditions and when doing model calibration.

3. Review and edit elevation data.

1. Review elevation data for errors. 1. Use the Dataset Info dialog. Find the "Z", "elevation" or "depth" datasets on the geometric object (mesh, TIN, grid, raster) that is being reviewed Right-click on elevation data and select Properties. Review information in the Dataset Info dialog to see that the range of values are as expected. 2. Use contour display options. Turn on Contours in the Display Options dialog and set contour options. The "Color Fill" option is recommended for this. Look for inconsistent points (points with values much higher/lower than their neighbors or regions where no data points exist). Verify that the region being modeled is covered by the elevation/depth data and there are no holes. 2. Remove erroneous points. After reviewing the imported data, points covering regions of no data should be deleted. 1. Edit dataset values. Open the Dataset Info dialog through the dataset Properties right-click command. Open the Edit Dataset Values dialog. 2. Define active or inactive points. Open the Dataset Info dialog through the dataset Properties right-click command. Open the Active/Inactive Flags dialog. 3. Manually remove points. Use the Select Scatter Point tool to select erroneous points. Review and edit point data in the XYZF Bar. Delete erroneous points. 3. Merge elevation datasets. Using the Select Scatter Point Set tool, select multiple scatter point sets in the Graphics Window. Select the Scatter Points | Merge Scatter Point Sets command. In the Scatter Point Set Name dialog assign a name to the new scatter set.

4. Creating a grid.

Create either a 3D grid or a 3D UGrid by completing one of the following: 1. Creating a 3D grid. 1. Create a 3D grid from scratch. Right-click in the Project Explorer and select New | 3D Grid.... In the Create Finite Difference Grid dialog, enter the information for the X-, Y-, and Z-Dimension of the grid. 2. Create a 3D grid using a grid frame. Right-click in the Project Explorer and select the New | Grid Frame... command. Using the Select Grid Frame tool, right-click on the grid and select the Fit to Active Coverage command. Select the Feature Objects | Map → 3D Grid... menu command. In the Create Finite Difference Grid dialog, enter the information for the X-, Y-, and Z-Dimension of the grid. 2. Creating a 3D UGrid. Create a 3D UGrid in one of the following ways: 1. Create a 3D UGrid from scratch. Right-click in the Project Explorer and select New | UGrid 3D.... In the New UGrid dialog, enter the information for the X-, Y-, and Z-Dimension of the grid. 2. Create a 3D UGrid from a coverage. Right-click on the desired coverage and select the Map To | UGrid command. In the Map → UGrid dialog, set the Dimension drop-down to "3D". Enter the rest of the information for the grid, including the X-, Y-, and Z-Dimension information.

6. Set up the MODFLOW simulation.

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