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Sean Czarniecki

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Everything posted by Sean Czarniecki

  1. Sean Czarniecki

    draining water to the ground using canals

    Increase the recharge in the cells where you are simulating the canals. Just an option - may not be exactly what you are looking for.
  2. Sean Czarniecki

    Head is computed for dry cells (below bottom of the cell)

    What version of MODFLOW are you using?
  3. Sean Czarniecki

    Changes to MODFLOW-USG?

    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.....
  4. Sean Czarniecki

    Changes to MODFLOW-USG?

  5. Sean Czarniecki

    Changes to MODFLOW-USG?

    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!
  6. Sean Czarniecki

    Changes to MODFLOW-USG?

    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.....
  7. Sean Czarniecki

    Changes to MODFLOW-USG?

    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....
  8. Sean Czarniecki

    Changes to MODFLOW-USG?

    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.
  9. Sean Czarniecki

    Changes to MODFLOW-USG?

    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.
  10. Sean Czarniecki

    Modflow List File

    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.
  11. Sean Czarniecki

    RCH output

    Can you select them, copy to your clipboard, and then paste in a spreadsheet?
  12. Just for kicks, you might try lowering your specified head to see if you can achieve a reasonable calibration. Have you accounted for evapotranspiration? Could your recharge be too high? Are your calibration measurements being influenced by any tidal effects (you said "coast," but are running steady state, which is an average condition....perhaps your measurements were taken under a lower tidal influence)? Just some things to consider.
  13. Sean Czarniecki

    Water level change with recharge

    Not knowing what your boundary conditions are, I'll assume that the cell goes dry in an area which isn't impacted by boundary conditions (even if no-flow). Your starting head may be too different than what the final elevation is going to be. The calculations will do an interation which may come to a solution below the bottom of the cell (think of the iterative process as a wave where the model goes up and down at smaller amplitudes until it gets to the solution). If the low value is below the bottom of the cell and there is no rewetting, the cell is dry and won't rewet. You might have to try starting heads that are actually lower to be closer to the final solution. Just my initial thinking.
  14. Sean Czarniecki

    Modflow 2000-transient model result

    You've provided some good information. However, I can only provide you my thoughts based on what I see. It is unclear to me which layer(s) you are pumping in. Based on the K of layer 1, that wouldn't be a great layer to withdraw water from, compared to Layer 2. It is not shocking to see Layer 1 cells drying out around the wells, based on the low K value. I'm not seeing anything really wrong with your head results. They will not be exactly the same (which is how you have upward/downward gradients in an aquifer).
  15. Sean Czarniecki

    Modflow 2000-transient model result

    When you have a confined layer, it typically doesn't dry out. Therefore, if it *should* dry out, there is a good chance that you are going to see unrealistic heads in the model for that layer. You might want to make Layer 1 be unconfined and see how that goes.....or the Layer 2 head may be more appropriate to use (depending on what you are trying to show and how close it is to Layer 1 in the other cells).
  16. Sean Czarniecki

    Tracking particles in Modflow-USG doesn't works

    Older versions can still be used if you find a newer one has a bug. I have done that many times in the past....and if you have any issue with the license, getting a temporary one usually isn't a problem.
  17. Sean Czarniecki

    Cell dimension change more than 50% in .............

    Note that it is just a warning and not an error. The model will still run. Typically, it is preferred to have cell sizes transition from smaller to larger without too big of a jump. Better for numerical calculations. This warning is probably due to your layer thicknesses being more than 50% different....and is not unusual, especially when dealing with lower layers in a model.
  18. Sean Czarniecki

    Observations in MODFLOW-USG

    Boy, you want us to actually read the documentation? Thanks - I was actually hoping that you could point me to something like that!
  19. Sean Czarniecki

    Observations in MODFLOW-USG

    At one point during my current project (a transient MODFLOW-USG simulation), I was attempting to create observation points to make some plots. It didn't seem to be working. I know that I've had some minor issues in the past getting the observations to work correctly, so I didn't think too much of it and got the info I needed in another way. However, I found myself with a little time today and figured that I would look into it a bit more. I pulled up an old model where I had a transient simulation to see if I had done anything different (I did not). I then ran my model using MODFLOW-2005 (after removing USG-specific stuff) and even though I didn't converge, the observations points appear to have worked. Are observations not set up to work in MODFLOW-USG?
  20. Sean Czarniecki

    Potential Bug in CLN Well pkg?

    I had a transient model set up where each of my well flows were going to be the same for each stress period, so I checked the "Use previous" box in the CLN Well Package dialog. When I got my model results, the first stress period had the correct total flow in the output file, but all the other stress periods only showed the flow from the first well. I tested things further by unchecking the "Use previous" box for other stress periods. The correct total flow was shown for those stress periods. I am now running with all stress periods not having the "Use previous" box checked. Just an FYI. This is GMS 10.2.5 build date of May 17, 2017.
  21. Sean Czarniecki

    Fonts and Icons in 10.3

    I'm sure there is an easy way to change the project explorer fonts and icon sizes in 10.3 (they are much larger than I would like on my screen...much different than 10.2), but I'm not finding it. If anyone knows and can pass on that info, I would appreciate it. Thanks!
  22. Sean Czarniecki

    Potential Bug in CLN Well pkg?

    Just wanted to let you know that this is still not fixed in the latest build (GMS 10.3.3). I haven't checked the latest build of 10.2.
  23. Sean Czarniecki

    CLN well head results in binary file

    I would like to see head results at each individual CLN well in my model. They are supposedly output into a binary CLN_HD file....but I can't seem to look at them in GMS. Can anyone help me out here? The CLN_CB file gets pulled in to the model after the run, but the CLN_DD, CLN_HD, and CLN_IB files do not appear to be. This is time-critical - if anyone has a way for me to see these results, I would appreciate it. (note that I'm using GMS 10.3.3 - I don't think that the CLN_CB file even got pulled into GMS 10.2, but I haven't fully looked into it) Thanks!
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