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Bruce Campbell

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  1. Hi -- I'm getting different water-level results with GMS 10.4.7 files when I switch from a PEST calibrated binary version to native text files. Here's the workflow: 1) Build and calibrate the models using PEST in GMS, 2) Get good results and acceptable calibration, using pilot points for aquifer horizontal hydraulic conductivities (HK) and specific yield (Sy) (for the surficial aquifer), 3) Interpolate the calibrated pilot point HK and Sy data to a 2-D grid created from the 3-D grid (same cell size and alignment) with the same interpolation methods as PEST used, 4) Repla
  2. Does the 10.4.3 version of GMS produce text files that incorporate PEST variables/parameters without having to do it manually?
  3. Hi -- I'm having trouble getting all of the water level residuals out of a multi-layer transient MODFLOW model in GMS 10.3.8. I need to get the residuals out layer-by-layer. For instance, in the surficial layer of the model, I have 224 observation points but the number of water levels associated with each point varies. There may be only 1 water level with a observation point or there may be 100's of water levels with another observation point over a period of time simulated by the model. When I go through the Plot Wizard, I can get one residual per observation point but can't see a way to get
  4. Hi Sylvain -- I've had good results using a 2-D grid. I) create a 2-D grid from the 3-D grid 2) do a linear (or other type) interpolation of your raster recharge data to the to 2-D grid. These will stack up for your 120 rasters under the 2-D grid 3) Go to MODFLOW -> Optional Packages -> Recharge and the use the 2D Dataset - > Array to put the 120 datasets into the model at the appropriate stress period
  5. Hi Michal -- I do all of my pest work outside of GMS. I set up the pilot points and other variables in GMS, save and run the files - up to the point where the *.PST file is written. I stop the execution in GMS and do all of the PEST work in DOS prompt windows. The *.PST file usually requires extensive edits but when I get in all back together, PEST works fine.
  6. Hi -- Wanted to see if an attribute could be added to the water-level observation coverage indicating a PEST observation group. Of course. this would have to travel through the PEST setup process and end up in the *.PST file, somehow. In conversations with John Doherty, he recommends putting the water-level observations into groups - by aquifer / model layer / other, to help with the PEST process. I've tried to think of way to edit the *.PST file but haven't been successful.
  7. Hi Michal -- I've had this same problem. What I've done is interpolate the pilot point values to a 2-D grid (hopefully, the same as the model 3-D grid) and then import the interpolated values into the corresponding model layer input. For example, horizontal hydraulic conductivity pilot points for the models surficial layer are interpolated to the 2-D grid then in your MODFLOW package, use the "2D Dataset -> Layer" command to place the interpolated horizontal hydraulic conductivity values into layer 1 of the model. Do this for all of your pilot point sets. Remove all other PEST variables, se
  8. Hi Petra -- Sounds like a good compromise to reduce the number of model cells. Groundwater modeling always seems to be a series of compromises... Here's the NWT solver settings that Rich passed along. I went back and looked at his description of the settings and he wrote that these settings would be a good starting point for large NWT models, 1.0E-1 1500.0 100 1.0e-8 2 1 1 SPECIFIED CONTINUE 0.90 0.00001 0.000 0.10 0 50 3.0 0.9 linmeth=1 (GMRES); =2 (xmd) 1 0 3 7 1 0.0 1 5.0E-3 1.0e-3 100 XMD I've had good results with these settings and was able to reduce my runtimes.
  9. Hi Petra -- I've been struggling with long run times for a couple of large (up to about 8 million active cell) models, also. I'm doing PEST parameter estimation calibration runs across my local network and see differences in run times depending on the computer capabilities. On older machines (4-5 years old) the run times are usually around 10 hours. On a brand new machine (Dell Latitude - lots of RAM and a fast processor) the run times are about 4 hours. I'm using MODFLOW-NWT and have a unconfined surficial layer and have gotten very good results. I suspect the difference in run times you see
  10. Hi -- Have a suggestion for assigning the altitudes for the various MODFLOW surface-water packages such as SFR2, STR, DRN, or RIV. In simple models this is usually not a problem but in more complex models with topography that varies across the model, it's a challenge. Using TIN's to assign the altitudes works well usually but I've had it lead to problems with hundreds to thousands of model cells when the process assigns the surface water feature to a altitude below the bottom of the cell. I suspect this is caused by the various interpolation steps required to get the cell altitudes into a TIN
  11. Can existing boreholes, TINS's, solids, etc be transferred from a GMS-created MODFLOW model directly into the subsurface analyst module of AHGW? Or do you have to start over?
  12. Hi Michael -- Thanks for the quick reply. Having this feature in the STR and SFR2 in GMS would make these two packages much more user friendly. Right now, I'm working on a model with about 8,800 stream reaches so it's not practical to assign them by hand. Is it possible to bring the elevation data into GMS associated with the stream arcs through the GIS module (importing a shapefile)? This would involve getting the elevation data together with the NHD (National Hydrologic Dataset) flowlines outside of GMS, somehow. I've got a good GIS guy and maybe he can figure it out. Do you think this would
  13. Does the new version of GMS have the feature in the SFR2 package to get land surface altitudes - assigned to stream reaches from a TIN? The Drain and River packages have this capability which is very handy. I'm still using the 9.0 version.
  14. Hi Alan -- Asked Rich about this and here's his response: Steve Westenbroek's TSProc is used to post-process the GAGE output. It is the TSProc output that I subsequently feed to PEST via an instruction file. So, I'm attaching the TSProc output and the corresponding PEST instruction file for reading it, but know that the same thing can and is routinely done with the SFR2 GAGE output. You will need to change .zipp to .zip He sent a file that I can send to you, also.
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