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Found 33 results

  1. Porosity in MODFLOW and MT3D

    Hello everybody I noted GMS has values for porosity in both MODFLOW and MT3D. In MODFLOW menu (MODFLOW options) one can enter values for porosity, although porosity is not used in flow computations as far as I know. Also in MT3D menu it is essential to enter porosity value. In the model I have (which is a SEAWAT model) I entered values for porosity in the MT3D options, but I noticed there are different values -by default- in the MODFLOW options. Which values does the model consider in this case? and why is there an option for porosity in MODFLOW? Thanks
  2. I'm trying to find a suitable work around for modelling flow pathways through abandoned mineworkings, some of which are above the water table (dry) and therefore subject to non-darcian flows. My data, however, is a blanket of worked seams and lacking any tunnel or shaft data (the hope was to use CLN utilising this network data). I am hoping someone may have some experience with battling similar issues? The data is all vector data used in ArcMap and I've noticed that some files will transfer into MODFLOW easily (such as DTMs), yet others like TINS do not. During the initial process, I have a few questions I hope someone with more experience may be able to answer. 1) How to site the workings at their respective heights using Arcmap shape files and TINs. (MODFLOW doesn't seem to like TINS but does recognise them). The shape files are divided by 20-50 meter barriers of solid seam (walls of major blocks), would this kind of shape file transfer when placed into MODFLOW easily distinguish between Open channel flow for the known workings, and a general value for the aquitard wall materials. 2) Once the workings are in place at their respective depths, is there a way within GMS to allow all surrounding lithologies to be generalised (i say this as the local geology is cyclotherms and is made more complex by the inclusion of coal mineworkings). I've included the 3D geology image below, exhibiting the space between the coloured seam workings. 3) Would the easiest way to produce connecting shafts between the various seams be by using wells? Thanks in advance, M
  3. Can you use the LAK Package if you do not have the "sub-surface characterization" component of the GMS software, and therefore, cannot create a TIN? How would you establish lake bathymetry without a TIN? Can you use a raster interpolated from 3rd party software? What happens if you leave the bathymetry portion of the LAK package dialogue blank?
  4. Importing TIN's (ARCMAP .adf) into GMS

    Hi all, A bit of a simple question but I can't find the answer anywhere in the help files. I've been provided with some ARCGIS TIN's (.adf files within the TIN folder) and I'm struggling to import them into GMS. Is there a conversion that must be completed before this will work or am I missing something really simple as GMS just spits out errors at present. Thanks in advance M
  5. I want to simulate the seepage of water through the base of a reservoir, but I do not know how to do it. I tried to use SEEP2D but I just know how to simulate the seepage of water through levees, earth dam, and sheet pile. Please show me which modules of GMS and which model (are currently supported in GMS) I should apply for this case. Kind regards, Quoc Tran
  6. Transient river leakage

    hello, i have a transient groundwater - surface water GMS model and I need to export river leakage values for single cell for all the time periods. is there a simple way to do that? i can access the leakage value via the sources/sinks menu but only for the selected timestep. thanks.
  7. Error in generating Velocity Vectors

    Dear members, I am trying to generate velocity vectors in a density dependent model. The GMS is displaying error, pic of which is attached below. I have been generating velocity vectors and never faced any such problem. I am not able to work out solution to this problem. Any help would be appreciated. Thank You
  8. Hi everyone, I am currently doing a project regarding in-situ chemical oxidation of BTEX using persulfate solution, and trying to use RT3D to represent the process. As reading the literature the reaction should be a pseudo 1st-order kinetic reaction model, but the only relevant option I found in the reaction package is the inst. aerobic degradation of BTEX which only offers oxygen as the electron acceptor. In this case, could someone familiar with the persulfate or other similar oxidation mechanisms tell how to construct the RT3D model? convert the persulfate concentration to an equivalent oxygen concentration? or should I try more options other than MODFLOW? Regards Dylan
  9. Hi all, I have come up with some errors when running the tute model of TUTE: MODFLOW – Generating Data from Solids that indicate “changing heads are below the bottom of cell xxx". It is so weird that a tute brings up a problem like this. Having read a thread in the forum suggesting to remove the BC of constant heads from the sources sinks coverage, I found many cells dry out with red triangular flags after a modflow run. I knew it was different from what is instructed in the tute sheet, but it seems plausible for me that without those BC these cells could dry out. A further question is, i was constructing a more complex multi-layer solids model and tried to convert to modflow. My BCs are constant heads set on the arc of the coverage boundary, kind of surrounding my small catchment of interest, and they are definitely all below the bottom of my first, second and part of the third layer, so how to define the default layer range? (i.e. from 1 to 1, 3 to 12 as I have 12 layers in total, or 1 to 12?). PS: in this coverage I define wells, specific head, layer range for source sink and layer range for areal properties, and tick used for BC option. The first trial I have set was 1 to 12 (dont know if appropriate), converted map to modflow, and could see the blue dots assigned from layer1 to 12 of my conceptual model. All of them indicate the some heads I define in the coverage. (Really? Does it have to be a 58 m head in the even very bottom of my rock layer of 30 m elevation?). As expected, the model warned that lots of heads were below cells' bottom. When removing all of them in sources sinks and running the model in steady state, I found it never converge. A feeling was that I did it wrong when defining BCs. This is where I got confused. Could anyone kindly help? I am using GMS Version 10.0 Thanks for any help Rgds Dylan
  10. 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
  11. I am using GMS 10.1.3 and trying to import a MODFLOW NWT model obtained from the USGS. The model appears to import okay, but when I run MODFLOW, it quits after several seconds with the note "MODFLOW terminated with error!" The OUT file states "model stopping due to reach altitude error." Upon further examination of the OUT file, there are warnings for each stream segment that "upstream elevation is equal to or lower than downstream elevation" and the streambed properties listed in the file indeed streambed elevations all set to zero. Looking at the SFR2 package through GMS shows all stream segments ELEVUP and ELEVDN set at zero for stress period one. For all other stress periods, there is data provided for ELEVUP, but ELEVDN remains universally set at zero. I can copy the ELEVUP data from a later stress period and apply this to stress period one, but without ELEVDN data, the altitude errors still occur, terminating MODFLOW. It appears that when importing the file, GMS does not pick up the streambed elevation data. Any help will be much appreciated.
  12. Tom said to mention this here on behalf of technical support. When exporting native text MODFLOW files, the files are not updated with new information. For example put new information into the MODFLOW | Global Options | Optional Packages | RCH package and click OK. Unless the project is manually saved after making the edit and before exporting the native text file those changes aren't saved, but users may not realize clicking OK doesn't update the files. It may be helpful for the user to receive a reminder that 'You have not yet saved your changes to the model. Would you like to save these changes before exporting the native files?' or something along those lines.
  13. Coverage Setup for Wells

    I'm a newer user building a MODFLOW model that I will then need to teach others how the model was constructed, I am establishing a coverage for the WEL package that will use a point shapefile from another model to inform the location and pumping/abstraction rates. One of the attributes in the shapefile is "Layer", identifying the layer of the well in the 10 layers of the model. I was shown how to create the coverage but I wanted to understand the rationale for selecting the Layer Range item in the Source/Sink/BCs list. I'm guessing this allows the use of the Layer attribute to map the points to specific layers in the Solid and Grid models, assuming they appear within layers 1 to 10, as specified. Also, I had a question about the "Use to define model boundary (active area)" check box. I have conflicting information as to when that should be checked in a coverage. My intuition tells me that is would only apply to feature objects that define the model boundary and not necessarily other boundary conditions that are applied to the model boundary conditions. For example, given one coverage (a polygon) that defines the extent of the active region of the model across all layers is create with the "Use to define..." item checked. If separate coverage was created that defines a constant head on layers along one edge of the active model domain, already identified as active in the other coverage, does the box need to be checked? When should it be check and not? Is there a danger in checking the box when it shouldn't. Any insights are appreciated Ted
  14. Hi, I need to know if it's possible (and how) to export with GMS grid parameter data of a model into shapefile such as : - Ibound - Hydraulic conductivity, Anisotropy - Porosity, Ss I've already exported CCF file with the Export function (see my previous topic) but it didn't include all the modflow code/parameters. Can you help ? Thanks
  15. Export Cell by Cell flow files

    Hi everyody, I work with GMS 10.1. I need to export the information of flows of a steady state model realised on Modflow 2005 with GMS. Is there a way to recuperate a file in ASCII form (or equivalent) with flow values of every faces of the mesh's of the grid ? Thanks for your help
  16. I've a Local Model of a site that include a slope from 300 to 350 m asl. A cross-section is attached to the post. I set up a Modflow Ugrid model with only 1 layer. Now I'm asked to insert a Barrier, so I need a new layer because Barriers don't reach the bottom of the aquifer. Is it correct to insert a new layer with constant top elevation (320 m abs) and set inactive the cells where the top elevation is less than 320? The Coverage for the Boundary condition (CHD at elevation 300 m asl, see attached cross section) is to be set to Autoassign BC including lower cells? How can I set the same boundary condition if it starts at an elevation of 325 m asl and ends at 300 m asl? Thank you aquaveo-h1.pdf
  17. I've create a multi layer Modflow model (3 layers) converted from a Solid Model (LPF, material ID). The idraulic properties are assigned by means of material ID, one for each layer. a. HK_a for layer 1 b. HK_b, for layer 2 c. HK_c, for layer 3 Now I need the to include a new building with foundations below the ground elevation and above layer 2. The building foundation has a different HK_d << HK_a, HK_b, HK_c. I create a new coverage with material properties and layer range. I assign the new HK to the polygon representing the buiding. I try Map to Modflow but when I query the Modflow cells the HK value is not changed. How can I assign it to cells inside the polygon representing the buiding area? My workround is to select intersecting cells by polyon and manual assign the material ID. Thank you Daniele
  18. I've create a multi layer Modflow model (2 layers). I've a coverage (coverage 1) defining the domain. The coverage is divided in two polygons ( polygon A e B ) for setting the HK: a. HK_a, for polygon A, layer 1 to 2 b. HK_b, for a polygon B, only layer 1 c. HK_c, for the same polygon B, only layer 2 I duplicate coverage 1, coverage 1.1 e coverate 1.2. I make these assignments: -coverage 1.1 to layer 1 -coverage 1.1 to layer 2. Is it correct or there is a different approach? Thank you Daniele
  19. hello, i am trying to compare head value datasets from two models. the x and y dimensions and cell sizes are the same, however the second model has 4 layers instead of one. i just want to compute the head difference of the two models. thanks
  20. Time Varrying Head - Linear or Sinosidal

    Hi, I am trying to simulate a scenario where the boundary head is gradually varying with time. Another scenario I am trying is to simulate coastal aquifer with seaside boundary head varying as per tidal variations of sea level. As far as I know, in given stress period the specified head remains constant. Therefore continuous head variation cannot be achieved and it has to be approximated by series of step changes. This will result in huge number of stress periods. Is there any alternate more efficient way to simulate such scenario? Thanks in advance. Saubhagya
  21. I'm working on a model using GMS, and I need to convert the modflow hdf5 files from GMS to original modflow files (from HDF5 to ASCII) so I can use it in GW Vistas. I found a link which provide a way to do that, but I can't run gms2mf2k.exe provided in this link. http://www.et.byu.edu/~njones/modflow-hdf5/ How can I convert the HDF5 files? thank you
  22. Aloha, I have been trying to use the horizontal anisotropy function to model an area that has many dikes of similar strike. I'm not exactly sure what GMS is doing, however, becaue I can not find any documentation, on forums or the wiki, about how this feature works with the MODFLOW LFP package . For example is the anisotropy always aligned with grid cells? Is there anywhere else to access the feature besides the LPF dialog? If anyone can point me to documentation about this, or can explain it I would be much appreciative! Thanks,
  23. Hi everyone, I'm trying to run MODFLOW, using ModelMuse. My goal is running GSFLOW after I get some results from the ModelMuse. However, Whenever I try to run the ModelMuse, the ModelMonitor indicates me the "Errors and Warnings in Listing File". It says that 24:Illegal File Type in Name File: NWT or UPW. (I'm using MODFLOW-NWT). What should I do to fix this problem?
  24. Hello. I have a MODFLOW model developed using GMS. The model domain is like a rectangle rotated about 30degree clockwise. the north and south boundaries are no-flow boundary. But, the east and west boundaries are defined as general head boundary (GHB). The flow direction in the domain is always from northwest to southeast. I want to run the model as steady-state, I have quarterly measurements of water levels in couple wells inside model domain. My question is where should I get the head, and conductance to set-up my GHBs in the west and east boundaries? Is there any general rule that I should follow? Thanks, bk
  25. Hi everyone, I am trying to build a transient model to model lake-aquifer interaction using LAK3 package. At first, I’ve built a steady model without any problem. But when I change this model into the transient one, it can't run. I also checked my model. There is no error. If I inactivate the lake package, the transient model works correctly. I don’t know why this happens to my model? Does LAK3 package have a problem with transient modeling or special settings are needed? Thank you guys,
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