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Found 13 results

  1. PEST, SVD and SVD-assist

    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. PEST Jacobian Calculation

    PEST has the ability to calculate the Jacobian once and use the same Jacobian for subsequent parameter estimation for faster simulations, but less-accurate results. This is a request for an option within GMS to run PEST with only a single Jacobian Calculation, but for more than one run. This should enable large calibration projects to be much more efficient where accuracy is relatively less important due to the size of the project.
  3. PEST and Kriging

    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
  4. Hi, I am trying to get GMS to calibrate a specified flow boundary that I assigned to my model. The boundary was created by using a coverage polygon. However, when I try to initialize the boundary to PEST, I can't get PEST to recognize the specified flow boundary. Does GMS support PEST calibration of specified flow boundaries? Is there a step that I'm missing? -Josue
  5. Null Space Monte Carlo

    Hi again! I attempt to use Null Space Monte Carlo in a similar manner as presented in PEST - Null Space Monte Carlo I tutorial (http://gmstutorials-10.1.aquaveo.com/MODFLOW-StochasticModeling-NullSpaceMonteCarloI.pdf) 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
  6. 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
  7. Transient calibration using PEST

    Hi, I've been trying to calibrate my transient model using PEST, however I'm experiencing some difficulties. It executes the estimation process and finishes the parameter estimation but it fail's to give me any new values for the chosen parameters. This only happens when I try to calibrate it as a transient model. When I run it in steady state there are no problems and it estimates new values for my parameters. When I run it as a transient model there is a message in the PSLAVES windows that pops which states that the "Total sum of squared, weighted residuals: NaN", and I think the problems lies here. However I'm not sure how to fix it. If anyone has any idea what's causing this and could help me with a solution I would be very grateful. Jonas
  8. Change PSLAVE directory

    When running PEST in parallel, it would be good if you could specify where the PSLAVE directories are saved to. In cases of large projects, it would allow the ability to save the files to a different drive to avoid crashing due to lack of room on the C drive.
  9. I am running a model and refined it using the pilot points and am using the HUF package rather than the LPF package as suggested in the tutorial. I am trying to import the optimum values back to the model and do not see a way to attach them to the associated material. I have tried running the model after importing the optimal values and I again get my initial huge errors as the pilot points were never imported. If you have any advice on how to import these values it would be much appreciated. Version is 10.0.11 Greg
  10. Hi, When I try to merge multiple coverages that have specified observed flow to a specific arc group, the merged coverage does not contain all arc groups from the original coverages, but only some of them (not the same arcs every time). Any suggestions how to deal with this, or a different approach to assigned multiple instances of observed flow to complex arc groups? I know there are ways to manually group the arcs in a single coverage and take it from there, but I have an intricate system of streams that is classified according to stream width. The 'observed flow' is used as a workaround by setting its weight to 0, as I need the jacobian matrix calculated by PEST for further analysis; manually grouping all these arcs is not really a workable option. Any advice is appreciated, thanks in advance. Pytrik
  11. I am running a transient PEST model with pilot points, using HK and RCH values. However, during the run I notice that the RCH values are not changing between optimization iterations. None of the points are defined as fixed. I created the RCH scatter points by duplicating the HK scatter points then editing the values. Could the additional "Active" field (populated with "1"'s) in the new RCH scatter point file be causing the problem? Both pilot-point-defined Parameters are referencing the correct scatter point sets. I am using 18 pilot points, but have over 100 Observation Points so I do not think I am violating that ratio. Thanks for your help! Chris
  12. Dear All, I have been using PEST for calibrating my project using GMS. I have defined a set of pilot points for HK and want to assign a different min. & max. for each point in the calibration process. Does GMS support such idea? Any insights/helps would be appreciated. I look forward to hearing from you soon.
  13. Hi All, I am tyring to calibrate a steady-sate MODFLOW model using PEST in GMS 8.0. Does anyone know where can the initial Marquardt lambda (RLAMBDA1) value be specified? I have performed an initial (unsuccessful) run and it seems that the default value is set 0.01. However, I would like to increase this value somewhere in between 1 to 10. Yet, I can't seem to find any input dialog for this option. Any help is much appreciated! Cheers Bernard