Using RockWorks to Define Layer Elevations, Zones, and Matrix Values in Groundwater Vistas

RockWorks and Groundwater Vistas include tools to facilitate the transfer of layer elevation and properties data from RockWorks to Groundwater Vistas. In the following, we describe a step by step process for using RockWorks during the creation of a MODFLOW model.

File Type Definitions

• Groundwater Vistas File Types
  • .gwv – Groundwater Vistas Model File – contains all of the input for a Groundwater Vistas groundwater flow model
  • .disrw – Discretization file created by Groundwater Vistas for import into RockWorks. Includes X and Y offset and cell/layer spacing and distance information.
• RockWorks File Types
  • .RwGrd – Gridded surface created in RockWorks. In this example, used to define MODFLOW layer elevations.
  • .RwMod – 3D block model created in RockWorks. Used to represent lithologic materials and material properties such as hydraulic conductivity
  • .matrix – File containing layer elevation information. Exported by RockWorks for import into Groundwater Vistas through the | Import | RockWorks Layer Elevation File menu.
  • .RwZone – File containing modeled zone numbers. Exported by RockWorks for import into Groundwater Vistas through the Props | Import | RockWorks Zone File menu.
  • .RwMatrix - File containing modeled matrix value. Exported by RockWorks for import into Groundwater Vistas through the Props | Import | RockWorks Matrix File menu.

Setting up corresponding projects in RockWorks and Groundwater Vistas

When transferring data between RockWorks and Groundwater Vistas, the project coordinates and units in RockWorks should match the Site Coordinates in Groundwater Vistas. An example of a Groundwater Vistas and RockWorks project with corresponding project boundaries is displayed below.

Note that the Coordinate Transformation values in the Groundwater Vistas model are ½ of a cell spacing away from the Minimum and Maximum Easting and Northing listed in the RockWorks project. Also, because this Groundwater Vistas MODFLOW model has constantly spaced rows and columns that match those of the RockWorks project, the number of rows and columns matches the number of nodes in the Y and X directions in RockWorks (respectively). The extents of the RockWorks and Groundwater Vistas models do not have to match exactly, but the extents of the Groundwater Vistas model should always fall inside the extents of the RockWorks Project boundary.

Using RockWorks Grids to define Groundwater Vistas MODFLOW Layer Elevations

If you have created a Stratigraphy model or other grids in RockWorks, you may want to use those grids to define layer elevations in a Groundwater Vistas MODFLOW model. In order to do this, you need to create a Groundwater Vistas .gwv file that falls inside the extents of your RockWorks project. You should make sure that the number of layers in the .gwv file matches the number of layers you have defined using RockWorks grids. In the example above, we have created a .gwv file with 9 layers, which means that we’ll need 10 RockWorks Grids (.RwGrd files) to define the top of the model and the base of each layer. Your initial Groundwater Vistas model will have flat layers, as displayed in the screen shot below. The image to the right shows the RockWorks grids that will be used to update the elevations of the MODFLOW model layers.

Step by Step Instructions

1. In Groundwater Vistas, go to Model | MODFLOW | Create Dataset. Anytime you create a new .gwv file OR make updates to a .gwv file, you should create this dataset before the next step. You do NOT need to run a model.
   
2. In Groundwater Vistas, go to Grid | Export | RockWorks Discretization. This creates a .disrw file, which is described in the File Type Definitions section above. The .disrw file will be created in the Groundwater Vistas working directory.
   
3. In RockWorks, select ModOps | Grid | Export | Grids -> GWV Matrix. Select the .disrw file created in the previous step. A summary of the model will be displayed. Click on the Next button.
   

   

4. In the next window, select the .RwGrd files that you want to use to define the layer elevations. These might be grids that are part of a Stratigraphy Model, or that were created using other gridding tools in the program. Click the Next button.
   

   

5. In the next Window, assign a name to the .matrix file being created, and choose the interpolation option that you want to use to estimate the elevations for each layer at each cell center. Click the Finish button to create the .matrix file.
   

   

6. In Groundwater Vistas, go to Props | Import | RockWorks Layer Elevation File. Select the .matrix file created in the previous step, and the Groundwater Vistas .gwv file will be updated with the imported elevations (as displayed in the image below).
   

   

Using RockWorks Lithology Models to define Zones in Groundwater Vistas

Lithology models (or other block models composed of a limited number of “g” values defining material type) can be used to define zones in a Groundwater Vistas MODFLOW model. This requires that you have created a Groundwater Vistas .gwv file and that the extents of the MODFLOW model fall inside the extents of the RockWorks block model.

Step by Step Instructions

The first two steps are the same as the steps in the previous discussion. If you have imported a .matrix file to define layer elevations in Groundwater Vistas, it is necessary to regenerate the MODFLOW Dataset and then the .disrw file that contains information about the geometry of the MODFLOW model.

1. In Groundwater Vistas, go to Model | MODFLOW | Create Dataset.
   
2. In Groundwater Vistas, go to Grid | Export | RockWorks Discretization. This creates a .disrw, which is described in the File Type Definitions section above. The .disrw file will be created in the Groundwater Vistas working directory. Note that if you have not changed the MODFLOW Root File Names for the Groundwater Vistas output, any .disrw files that you created previously will be overwritten. You can change these Root File Names when you save a new .gwv file or by going to Model|MODFLOW|Packages.
   
3. In RockWorks, create a block model composed of integers that represent material types or zones in a MODFLOW model. If you have created a lithology model, the values will be pulled from the G-Value field in the Lithology Types table.
   
4. In RockWorks, select ModOps | Solid | Export | Solid -> GWV Zone. Define the following input:
   1. Groundwater Vistas Discretization File: The .disrw file created in the previous step
   2. Solid Model: The Lithology .RwMod file (or block model containing material type information)
   3. Filter Method: Choose from a number of different interpolation algorithms. If multiple blocks from the .RwMod file fall inside a MODFLOW model cell, the program will use this filter method to assign a value to that cell.
   4. Zone File Output – this is the name of the file that RockWorks create. It will have a .RwZone file extension.
      
5. In Groundwater Vistas, go to Props, and select the Property for which you want to import the Zone data. This will typically be Hydraulic Conductivity, but could be any type of data that is stored as zones.
   
6. Then, go to Props | Import | RockWorks Zone file. Choose the .RwZone file that you created previously. This will assign a zone to each cell for the Property that is current selected (as displayed in the image below).
   

   

Using RockWorks Block Models to define Matrix properties in Groundwater Vistas

Block models created in RockWorks can be used to define matrix properties in a Groundwater Vistas MODFLOW model. This requires that you have created a Groundwater Vistas .gwv file and that the extents of the MODFLOW model fall inside the extents of the RockWorks block model.

Step by Step Instructions

As with the previous discussion, a .matrix file needs to be created through Groundwater Vistas to define the MODFLOW model geometry.

1. In Groundwater Vistas, go to Model | MODFLOW |Create Dataset.
   
2. In Groundwater Vistas, go to Grid | Export | RockWorks Discretization. This creates a .disrw, which is described in the File Type Definitions section above. The .disrw file will be created in the Groundwater Vistas working directory. Note that if you have not changed the MODFLOW Root File Names for the Groundwater Vistas output, any .disrw files that you created previously will be overwritten. You can change these Root File Names when you save a new .gwv file or by going to Model|MODFLOW|Packages.
   
3. In RockWorks, create a block model composed of values that represent a material property used by MOFLOW (such as hydraulic conductivity).
   
4. In RockWorks, select ModOps | Solid | Export | Solid -> GWV Zone. Define the following input:
   1. Groundwater Vistas Discretization File: The .disrw file created in the previous step
   2. Solid Model: The .RwMod file used to define the matrix property
   3. Averaging Method: Choose from a number of different interpolation algorithms. If multiple blocks from the .RwMod file fall inside a MODFLOW model cell, the program will use this filter method to assign a value to that cell.
   4. Matrix File Output – this is the name of the file that RockWorks create. It will have a .RwMatrix file extension.
      
5. In Groundwater Vistas, go to Props, and select the Property for which you want to import the Matrix data. Be sure that this parameter is defined as a matrix under the Props|Options menu.
   
6. Then, go to Props | Import | RockWorks Matrix file. Choose the .RwMatrix file that you created previously. This will assign an averaged value to each cell (as displayed in the image below).
   

   

Back to Grids -> GWV Matrix
Back to Solid to GWV Zone
Back to Solid to GWV Matrix

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