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Sean Czarniecki

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Everything posted by Sean Czarniecki

  1. You can just select cells manually and change the conductivity in the properties dialog....or set up a coverage with polygons to change just small areas when it maps over to MODFLOW. Test it out so that you can confirm everything else remains the same when you map it over.
  2. So let me tell you something that might help you to figure out what is going on. I had built a model using MODFLOW-USG....one of the reasons was because it managed dry cells without actually making them dry (model converged with no issue). Well, after months of working with this model, a newer MODFLOW-USG executable came out (and was being used in GMS) that eliminated that part of the programming (I guess it was not helpful to some people - enough complaints got the programming changed). Well, that certainly messed up my modeling. It wouldn't converge anymore. The solution was ultimately to set GMS to use the older executable. Soooo.....long story short.....the older MODFLOW-USG executable may solve your original model.
  3. It would only use it during transient runs.
  4. Open up your output file and see if it gives you more details about the issue. It could be that you've got more time steps than the variable allows. I'm not sure what that array value is, but it sounds like that could be the issue.
  5. The only ways you can fix this is to either add more layers or change the thickness of your layers.....neither of which you probably want to do. If you read up on MODFLOW, you will see that it prefers if you don't make big transitions, but it will still be okay if you have them. We often have a thin confining layer (e.g., 1 m thick) above a thicker layer. For that warning to go away, you would have to make the next layer below no greater than 1.5 m thick, then another below that no greater than 2.25 m thick.....etc. You can see that this is often not practical. I suggest you don't worry about that warning. Other people may feel differently.
  6. Warnings are not always a problem. The Cell Dimensions warning is telling you that the model results will be better if you have a smoother transition from smaller cells to larger cells (this will often come up based on layer thickness differences). The model will still work - this isn't usually a big concern. The second set of warnings is pretty clear - you need to establish hydraulic conductivities in layers 4 through 8....check your materials. You can also make these changes in other ways by opening the LPF package and editing layers individually, or by making coverages for each layer.
  7. The entire layer is blocked. If you need it to stop at a certain elevation, you need to set the bottom elevation of the layer at that elevation.
  8. Under the Grid menu, there is an option for MODFLOW Layers -> 2D Scatter Points. Under there, select the flow package properties.
  9. You have to go under display and go into General Mode instead of Ortho Mode. You will then be able to rotate the display in all directions. Note that if you are in a multi-layer model, you may need to select other layers and hide them as all layers become visible at the same time in General Mode.
  10. http://www.aquaveo.com/software/gms-learning go into the tutorials under the Conceptual Model modules (by going through 1 and 3, you should be able to figure out how to define different layer extents).
  11. Yes. However, if it is bigger than the current extent, you will have to expand the overall grid and then inactivate the cells outside of the current extent in your current layer. You can cut the layer using the grid tools and then change the extent of the second layer as necessary by inactivating cells beyond whatever extent you are looking for. You can do a lot of this by making a boundary polygon for each layer (see the GMS tutorials).
  12. Increase the recharge in the cells where you are simulating the canals. Just an option - may not be exactly what you are looking for.
  13. Hi Bill - I contacted the MODFLOW-USG developers and have sent them my native text files. I'll send a set of GMS files to tech support. Maybe you guys will see something. Thanks!
  14. Thanks for the suggestion - I may need to go down that path as I try to get through the problem. This is certainly frustrating, as I've done hundreds of runs which now don't work. I'm checking to see which well fields are causing the solution to not converge (and am narrowing it down), but the bigger problem is that the solution is now totally different in areas without wells because of what appears to be that change in the minimum saturation value.....
  15. I'm running the model with some wells pumping (in areas that shouldn't go dry even in low recharge times). Seems to work....but I wanted to provide a screen shot of the progress window. You will see that the error values just don't make sense (in the older version, they were reasonable).....and a weird text item came up during SP 18, TS 1. Doesn't make me feel too good....
  16. I've looked a little further at the version notes and think I see what may be the problem. GWF2BCF-LPF-U1 -- Removed the minimum saturation value. Difficult problems behave better by allowing saturation to go to zero and letting the solver handle it. Revised the way CLN-GW flows are written to the budget file. CLN2BASU1 -- Removed the minimum saturation value. So something that caused problems for other people appears to have been changed…..and this is likely what now doesn’t allow my model to solve properly. I just ran the model with no wells pumping and it converges. The model had been crashing when it got to the period of zero recharge, which would be when wells may be in cells which could go dry due to pumping due to lack of water. This is not good. If anyone has insight into if I'm interpreting the issue correctly, I would love to hear from you. To the GMS developers, if you can confirm that there wouldn't be any other reason for my non-convergence (e.g., any chance that it is actually some coding issue related it input files generated for the new MODFLOW-USG?), I would appreciate it. It would be great if there were an option to still keep the minimum saturation value for some models, but not for others. Based on the release notes, it doesn't look like that is an option.
  17. I looked into the version notes on MODFLOW-USG and can't tell if anything they updated would cause my particular model to crash. It would be sad if they corrected a bug which previously allowed my model to converge and now won't allow it. Nothing jumps out as fitting their bug corrections. Any chance that it is something related to merging the newer version into GMS? I do note that the progress window used to show what unit the CLN Heads were supposed to write to ("CLN HEAD UNIT 767") after every time step. It no longer does that, but that shouldn't have any impact on the convergence...I'm just noting a difference.
  18. I hope someone can help me out here. I finished a complex model back in February (I had used GMS 10.3.05). I have been asked to provide model files to someone else who will be using the most recent version of GMS (currently 10.3.07). I thought it was a good idea to do a test run using that latest version. The model didn't work....and the window showing modeling progress was showing some extreme errors that I definitely hadn't seen before. The model crashed after a few stress periods. I thought that it might be the software change (I hadn't changed anything else). Sure enough, I loaded the older version and it worked like it did before. In the progress window, I can see that the MODFLOW-USG version is different. 10.3.05 used Version 1.3.00 from 2015, whereas 10.3.07 uses Version 1.4.00 from 10/27/2017. Can anyone tell me what changes occurred that would result in my model not converging any more? This is bad news to me.....
  19. Go into the output control under MODFLOW. This information is also included in the .out file. After running the model and opening in GMS, these files will show up in the Project Explorer, where you can double click on them and open with a text editor.
  20. Can you select them, copy to your clipboard, and then paste in a spreadsheet?
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