To use the Matrix Diffusion Transport (MDT) package in an existing MODFLOW 6 project, use the following processes:
| 1. Begin with an existing MODFLOW 6 project.
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- The existing MODFLOW 6 model can be created using the conceptual model or grid based approach.
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| 2. Add a GWT model to the simulation.
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- The MDT Package is only available as part of a GWT model in MODFLOW 6. If necessary, follow these steps to add a GWT model to the MODFLOW 6 simulation:
| 2. Create the transport model.
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- Right-click on the MODFLOW 6 simulation and select New Package | GWT.
- In the New Groundwater Transport (GWT) Model dialog, select the UGrid to use and any optional packages.
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| 3. Modify package inputs for each desired package.
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- Right-click on the package in the Project Explorer and select the Open command.
- Modify the inputs in the package dialog.
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| 4. Set up the GWF-GWT exchange.
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- Right-click on the MODFLOW 6 simulation and select New package | GWF-GWT.
- Right-click on the MODFLOW 6 simulation and select Open to open the Simulation Options dialog.
- In the EXCHANGES section, click the boxes under the columns EXGMNAMEA and EXGMNAMEB to specify which models the exchange is connecting.
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| 5. Set up the IMS solver package for the transport model.
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- Often, an additional IMS solver package is desirable for the GWT model. To create it:
| 1. Create the IMS solver package.
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- Right-click on the MODFLOW 6 simulation and select the New Package | IMS command.
- If needed, give it a new name to differentiate it from any other IMS solver packages.
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| 2. Define the settings of the IMS solver package.
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- Right-click on the package in the Project Explorer and select the Open command.
- Modify the inputs in the package dialog.
- These inputs include:
- COMPLEXITY
- Options under the NONLINEAR section.
- Options under the LINEAR section.
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| 3. Specify which model the IMS solver package corresponds to.
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- Double-click on the MODFLOW 6 simulation to open the Simulation Options dialog.
- In the SOLUTIONGROUPS section, click the boxes under the SLNMNAMES section to select which model corresponds to each IMS solver package.
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| 3. Add the MDT package to the simulation.
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- Right-click on the
 GWT model and select New Package, then select the desired package from the list.
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| 4. Modify MDT package inputs.
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- Right-click on the package in the Project Explorer and select the Open command.
- Modify the inputs in the package dialog.
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