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Everything posted by Jonas

  1. I often experience problems when running a PEST parameter estimation model with SVD-assist. I find it quite arbitrary when it work and when it does not work. For some occasions it seems to work just by moving the modelling files to another computer and run the model on that workstation. For my current model, SVD works but SVD-assist does not. To reach reasonable results with NSMC is even more problematic, in particular for transient models. I run the latest nightly build and NWT as solver. Someone with similar experiences or suggestions to a more streamlined and stable model procedure?
  2. Thanks for your quick reply Michal, I agree on that it seems like PEST is doing its job but GMS does not read in the result properly. But I can't find the reason for this since the same modelling procedure has worked for other models. Quite frustrating. How do use the PARREP utility? Should I use it outside of GMS interface? Kind regards, Jonas
  3. This is what typically happens when running with SVD-assist. As can be seen from the blue marked line, PEST is able to reduce the error to 98.885 from the initial error of 155.76. But, then something goes wrong since this solution never comes up as a iteration before the parameter estimation is finished.
  4. I use Kriging and variograms to describe spatial variability of pilot points for HK and RCH in a PEST parameter estimation simulation. I use the log values for both HK and RCH. For one pilot point set it works perfectly fine to use a logarithmic semivariogram, which also looks reasonable. These HK values are in the range between 1e-4 to 1e-6 m/sek. For pilot point sets with lower values (in the range between 1e-8 and 1e-10) I get the following message when I try to build a logarithmic semivariogram: Warning. There were no points calculated; bad lag parameters! A semivariogram (that is not logarithmic) does however allow me to build a variogram. I have two questions: 1. What is the reason for this warning? 2. Would it be a significant difference in interpolation between a semivariogram and a logarithmic semivariogram? I am happy to receive any comments and ideas on these issues. Kind regards, Jonas
  5. Hi Julian, I decided to use another variogram method than the semi-logarithmic for the cases when I got the error. If you have problems with the Kriging procedure, have you tried one of the recent nightly builds?
  6. Hi, I experience the tool for defining stress periods as dates/times as quite buggy. Please refer to screenshot below. First, there is a different format between the first row and the second two rows (month as number "10" instead of letters "Oct"). But the most significant issue is that the "length" changes to weird numbers when the date and time is changed. In the example below the first stress period has a negative number but I have also experienced zero as length. My workaround has been to not make changes as date/times by unmarking the "use dates/times" box, calculate the corresponding length between and then change back to "use dates/times". This works but not so convenient. Another issue is that I have seconds as time format in my model but to get the length right I have to divide the seconds by 2 in the "length" box to get the date/times right. Finally, the model terminates with an error when I use date/times but works when I am un-tickning the box mentioned above (not using date/times). Any ideas on how to get these issues sorted out? Kind regards, Jonas
  7. Unfortunately I still experience the stress-periods as quite buggy. The images below show stress periods as date/times and as seconds respectively. The result is from a PEST NSMC simulation with a transient pump-test as calibration target. During the initial forward runs and PEST calibration without NSMC I did not experience the same issue with the date-time series. The simulation itself seems to work fine but the problem arises when creating graphs and comparing the simulated results with my observations. Since I think there is a bug behind the issue I would appreciate if someone from the GMS development team could look into it. Kind regards Jonas
  8. Thank's Dirk. You advice worked for me as well.
  9. Hi, When i customize the variogram for the pilot points of the HK-field in the nsmc I and II tutorials, and also in my own models, I encounter the problem showed in the attached figure. It seems like the whole field is generated from only one point and not all available ones. I also edited the already set up variogram in the tutorials, and then changed back to its original form and still got the same problem. Any ideas on how to solve this issue? Kind regards, Jonas
  10. Thanks Alan, the nightly build solved the issue.
  11. Hi again! I attempt to use Null Space Monte Carlo in a similar manner as presented in PEST - Null Space Monte Carlo I tutorial ( As presented in the attached text file I have some model that converge although most models does not converge for some reason (Ideas on how to adress this are also appreciated). As seen in the text file, there are different calculated values for the pilot points between the four converged solutions. The bpa files for the different solutions are also different. All good so far. My issue is that there is no difference between the grid files of the HK parameter for the four different solutions. Any ideas on how to solve this issue? Could it have something to do with the Kriging process? Best regards, Jonas T40_nsmc.txt
  12. For others interested in this issue, the support team has now fixed the bug that caused the issue of PEST and null space MC with the NWT solver. Download the latest nightly build (Jan 25th) from: Woodward, it was a pleasure to read your article, "Uncertainty in the modelling of spatial and temporal patterns of shallow groundwater flow paths: The role of geological and hydrological site information" in Journal of Hydrology where you have applied this method.
  13. Thank you Alan, I have done so. Looking forward for their response. Woodward, the more simplified converges in almost all cases. The problem is that non-unique grids are created.
  14. Now I have simplified the model a lot to only one layer and use the LPF package. It seems that the only solver that creates unique grid files is 2000. For 2005 and NWT it is the same issue as previous specified. Others with similar experience? Kind regards, Jonas
  15. I use the NWT solver with UPW in my model. When I changed to the same solver in the NSMC I tutorial, the same thing happens. Different values in the bpa files but non-unique grid files with HK values between the different solutions. Ideas on this issue are appreciated!
  16. Hi! I have set up a model for a municipal water supply in an glacifluvial esker. I want to calibrate the hydraulic conductivity (HK) against steady-state heads in the esker material with PEST and pilot points. I also have other materials in the model but with a fixed HK. The recharge is also calibrated with PEST in three different polygons. The picture below shows layer four (of five). Left shows materials (only bedrock and esker in this layer) together with locations of the pilot points. The middle part shows calibrated heads after PEST has been running. Right shows HK after calibration with PEST. My issue is that the area with esker material (left) does not overlap the area that is calibrated with pilot points in the rightmost picture (non red area). Something that looks strange in particular is the straight paths from the middle to the south of the model that get the same HK as the bedrock although the material is set to esker. It is the same issue in the other layers of the model. Ideas on how to solve this issue are appreciated. Kind regards, Jonas
  17. I created the zones based on solids. For some reason the materials got the right values according to the zones but some cells got wrong values of HK. I changed this manually by selecting these cells. This worked. Could this be a bug in GMS maybe?