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ht512

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  1. Hi, Could anyone please kindly give me the precise definition of STORAGE in the Water Balance Table obtained after a Modflow run. I have been trying to figure out why the figure increases with drier conditions. Thank you. Tan
  2. Hi, I have been able to run my simulations with Modflow NWT with the UPW Package and I am now in the process of calibrating the model. What I have come to notice is that the materials' properties that I have defined in 'MATERIALS: Modflow' seem to have been swapped around when applied to the UPW package. Horizontal anis. seems to have taken values from Vertical anis; Specific yield takes values from Specific storage and vice versa. When I select the 'USE MATERIAL ID' option in UPW, the values in these parameters remain the same and a Modflow run creates a flat Error vs. Interation line and does not produce any usable result. Is this supposed to happen or has this been caused by a bug in the software? Also I would be very grateful if you could help with how you could apply adjusted materials properties to the model for the process of calibration. Many thanks for your help. H. Tan
  3. ht512

    TINs Component

    I have recently purchased GMS Modflow II and have tried opening the project that I put together through the trial version. Once the project is selected, all seems to be there except the TINs that were created prior to the purchase. The program states that 'GMS is not enabled to read the following data: TIN data. You may need to purchase additional components or you may need to change the program mode in the preference dialog.' I have checked the program's registration and everything seems to be enabled and have tried changing the program mode to 'GMS Site' where TINs mode is stated to be available. The same error comes up with regards to TINs and a some additional components. How can I fix this problem? And if an additional component need to be purchased, can you please kindly inform me which one it is. Thank you. Hongthai
  4. The "Do not stop ..." option is used for transient simulations. When this option is on, if the MODFLOW model does not converge for a particular time step, it continues to the next time step rather than aborting. http://www.xmswiki.com/xms/GMS:PEST_ASP_Package#Do_Not_Stop_on_Non-Convergence
  5. Thanks Sean. Will let you know if I find anymore info on it.
  6. Hi Sean, Thank you for your reply. Those reactivated cells with 'Warning: Time var. spec. head in an inactive cell i=xx, j=xx, k=1' had 'Starting head lower than bottom elevation in cell i=xx, j=xx, k=1' instead. From what I understand these are just dry cells and they do not affect the ability of the model to run. It would be great if you could provide more information about the NOSTOP option. Thank you again. Hongthai
  7. Hi, This is how I proceeded to fixing the two errors mentioned before; 1) Starting head lower than bottom elevation in cell [...]: CELLS WERE IN K=1 AND WERE DEACTIVATED 2) The changing head boundary is below the bottom elevation of cell [...]: CELLS WERE IN K=1 TO K=4. THEIR SPECIFIC HEADS WERE DELETED FROM 'SOURCES/SINKS' BUT CELLS REMAINED ACTIVE After cell deactivation in layer 1 the following error appear: 3) Warning: Time var. spec. head in an inactive cell i=xx, j=xx, k=1. These cells were identified and activated again through changing their IBOUND value to 1. Tried running the model but did not work until 'Do not stop on non-convergence (NOSTOP)' was selected int he PEST-ASP Options. The results seems to be in line what what I have been expecting but would be grateful if you could kindly explain the implications of the NOSTOP option so I am aware of any errors that may come with the results. Thank you again. Hongthai
  8. Hi Sean, Thank you for your reply. I will try this tomorrow and let you know how I get on. Hongthai
  9. Hi Alan and Sean, Thanks to your guidance, I have been successful in running transient simulations (10 stress periods, 10 days time steps) for parts of my study area using MODFLOW-NWT. The current problem that I am having now is running the same simulation for my entire study area which is about 544km2. There are only three boundary conditions that I am using; 1) Wells, 2) Recharge and 3) Specified Head (CHD). I am using the last to specify the coastline in the model. When checking for model errors for a small sample area, two things come up; 1) Starting head lower than bottom elevation in cell [...] and 2) The changing head boundary is below the bottom elevation of cell [...]. I have been able to run the simulation regardless of these errors and the results seem appropriate. Same errors appear when trying to simulate the whole study area but MODFLOW does not converge. The only parameter I have tried changing so far is the MAXITEROUT in the Newton Solver (to 2000) but this has not changed anything. I have the *.out file for the simulation should you want to see it. Please let me know what is the best way to send this you (the text file is 14.4MB). Your advice is greatly appreciated. Hongthai
  10. Hi Alan, Thank you very much for you reply. I will address all the things you have mentioned over the weekend and will let you know how the model gets on. Hongthai
  11. Hi Sean and Alan, Thank you very much for your kind replies. I have changed the maximum number of iterations in the solver package and everything seems to run fine using the MODFLOW2000. I have tried switching to MODFLOW-NWT and so far it has worked fine as well. Both models seems to work for transient but not steady state simulation. Rewetting does not allow the models to converge under the circumstances I have tried. Could you kindly advise to why this may be. After obtaining the results from the successful transient runs, I would like to view the simulated heads on different day of the run. I have tried clicking on the dates on the time scale to the bottom left of the user interface but the head does not seem to move. Is there a display option that I need to activate for this to work? Thank you again for all your help. Hongthai
  12. Hi Alan, Thank you very much for your prompt reply. Yes that is indeed the case. Once switched off, ModFlow still stops at the same place. Please kindly advise. Thank you.
  13. Hi, I am working on a project examining the effect of land-use and climate change on groundwater flow for a specific area in Thailand. The model covers approximately 550km2 and has 10 layers, covering 5 geological layers (I have experimented with less numbers of layers but does not seem to get the interaction between the geological structure right). So far, I have tried running the model with two basic boundary conditions; recharge and lake, to see if ModFlow would work. I was successful in running the model once but tinkered with the re-wetting option and have been unsuccessful in running the model since. Having relentless changed the various settings before running ModFlow again and again, the model seems to stop at [25 of timestep 1 of period 1; MODFLOW-2000 terminated without converging; MODFLOW terminated with error!]. The problem persisted when the whole model was set up again, stopping at the same point and with a different error, [The LAK Pakage is used in flow simulation; the Link-MT3DMS file must be saved with EXTENDED header.; MODFLOW terminated with error], having already chosen the extended header format for output control. Could anyone kindly provide some guidance to why this may be? Your time in much appreciated. Tan
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