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Use of Multi-Node Wells in Transport modeling

Rich Carbonaro

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I have a question related to the use of the Multi-Node well packages (either MNW or MNW2) within a transport simulation. With the well package (WEL), you can set up a coverage and specify the concentration of each species in the water you are injecting into the model. This approach is extremely useful and works really well as long as your conceptual model matches up with the simulation settings (i.e. RT3D, MT3DMS, etc.).

With coverages for the MNW packages, it does not appear that you are given the option to specify these concentrations. I was experimenting with a work around where you set up a polygon coverage of starting concentrations within the cell with the multi-node well. This approach is a bit cumbersome but appears to work. My question is a bit open-ended but is there a way to specify the concentration in the injected water in the conceptual model for a multi-node well? If the answer is "no", is there a procedure for doing this properly in the grid approach?

As always, thanks for your response!

- Rich Carbonaro

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Currently the concentration for MNW1 can only be specified in the Grid interface to MT3D (not conceptual model). Also, I want you to be aware that MNW2 is not supported by either MT3D or RT3D. Further, MNW1 is not supported by RT3D.

When you run MODFLOW make sure to go to the Output Control Package and turn on the "extended header" for the *.hff file. To assign concentration to a cell with MNW1 boundary conditions, you should

1 - Select the cell

2 - Right click and choose the Sources/Sinks... menu command.

3 - Select the MT3DMS: Point SS item in the left side of the dialog.

4 - Click the Add BC button at the bottom of the dialog to create the MT3D boundary condition.

5 - A new item will appear in the spreadsheet. Change the value of the Type (ITYPE) to multi-node well (MNW1) and enter the concetration for any species.

6 - Exit the dialog and set the rest of your MT3D options and run MT3D.

Let me know if you are still confused or need any more clarification.

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  • 9 months later...


I have done some testing of MNW1 and MNW2 with MT3D within the GMS environment and wanted to follow-up on this issue. As of version 1.0.5, MODFLOW-NWT writes the MNW2 fluxes to the flow transport link file. The release notes are here: http://water.usgs.gov/ogw/modflow-nwt/release.txt

Through testing in GMS v 10.0, I was able to produce reasonable results for solute transport using MODFLOW-NWT/MT3D and the MNW2 package. Solute passes through non-pumping MNW2 wells from high head to low head (as it should). I specified a source of solute as ITYPE = 27 in the source sink mixing package (same ITYPE as MNW1) and was able to inject solute through an MNW2 well. Mass balance errors were small (as long as you specify a reasonable DT0 value) leading me to believe that you can do transport modeling while using the MNW2 package as long as you are using MODFLOW-NWT version 1.0.5 or later (which GMS does use).

Please let me know your thoughts on this - I'd like to have confirmation that this works from the experts.



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  • 4 months later...

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