Q1: What new features does Visual MODFLOW 2009.1 support for the new SEAWAT v.4 module?

Answer:
Visual MODFLOW supports the following new features available in SEAWAT v.4:

• A temperature species can now be added when defining a new transport variant, allowing you to simulate heat and solute transport simultaneously.
• Simulate the effect that fluid viscosity variations have on resistance to ground-water flow using the Viscosity (VSC) Package.
• Simulate fluid density as a function of temperature and one or more MT3DMS species and, optionally, a pressure term. You can also specify one of several non-linear equations to represent the dependence of viscosity on temperature.
• A new option in the simulation settings for the VDF package allows for solving the Variable Density Flow (VDF) equation to update the flow field only if fluid densities have changed by a user-defined value. This option can potentially reduce runtimes for simulations in which a new flow solution is not required for each transport time step.
• For the Time-Variant Constant-Head (CHD) package, auxiliary variables can now be used to designate the fluid density value associated with the prescribed head. You can now determine the reference head values at constant-head boundaries using one of the following options:
  • Use Simulated Density: The input head is converted to the reference head using calculated fluid density value at the cell.
  • Use Specified Density: The input head is converted to the reference head using a user-defined density value.
  • Use Average Density: The input head is converted to the reference head using the average of the calculated fluid density values of the overlying active cells.

Q2: How is a SEAWAT V.4 transport variant set up in Visual MODFLOW?

Answer:
Create a project selecting the SEAWAT engine as the flow engine, which will automatically assign a transport simulation. For an existing project click Setup/Edit Engines from the main menu to create a new variant, then select the SEAWAT engine.

Enter the Variant Parameters as needed. The salt species is by default included. To add the temperature species click on the Add Temperature button. You may then enter the required temperature species details. Click next/ok to finish the process. You may then proceed with your project using the salt and temperature species.

Q3: Where do I input my temperature details into my model?

Answer:
The temperature species input is found under the initial concentration property. You may import or assign the temperature details for the model.

Q4: What are some applications that SEAWAT v.4 would be used for?

Answer:
Some examples of applications for SEAWATv.4 include:

• Simulating the transport of heat and salinity in coastal aquifers, and thermally driven convection in deep aquifers
• ASR: Storage of freshwater in saline aquifers: simulate buoyancy effects, and the affect of groundwater temperature on the fluid viscosity.
• Geothermal investigations - The heat balance calculation and the impact of groundwater heat pumps on the groundwater temperature
• Affect of volcanic activities on groundwater and the water table
• Fate of wastewater injected into deep wells, and impact on the aquifer

Q5: What are some of the limitations of SEAWAT v.4?

Answer:

• SEAWAT v4. can be applied only to the saturated zone, single-phase flow. No vapor phase or solid water phase (rarely seen in soil though) can be modeled. So the upper limit of temperature range should be below the boiling temperature which varies with altitude and some other factors.
• SEAWAT v4. does not consider the latent heat exchange (due to phase change).
• A linear relationship between the solute concentration and fluid density is assumed. This assumption is based on the initial lab measurements by Baxter et al. (1911). This assumption at least holds true for TDS concentration up to that of sea water (Pinder and Cooper, 1970). Beyond that, you should check the validity of this linear assumption.
• Some other limitations may be inherent from SEAWAT’s previous versions. Detailed discussion was presented in Guo and Langevin 2002.

Q6: Are there other new features of Visual MODFLOW 2009.1?

Answer:
Visual MODFLOW 2009.1 now supports 200 model layers in the default grid. The default model grid is now 500 rows x 500 columns x 200 layers. Custom grids are available from technical support if a client requires a grid exceeding the default size.

Q7: Does Visual MODFLOW support a dual core processor?

Answer:
Visual MODFLOW 4.3 or later does incorporate the MT3DMS support for dual core processing. For MT3DMS transport variants that involve multiple species, you can now leverage the power of multiple processors (or dual core processor) on your machine. One or more species can be allocated to the available processors on your machine, and solved independently, effectively increasing the solving performance of Visual MODFLOW. To access this feature select Run/MT3DMS/Parallel Processing, then select the desired processor details.

Q8: How do I open a project that is not opening, but showing a message ‘cannot open invalid *.vmf file'?

Answer:
This error may indicate that the project has been corrupted in some way. However, this may also be related to a spelling mistake within the *.vmf file. Please ask for a copy of the project from the client. Once you have received the files, open the *.vmf file in Notepad and search 'Font'. If you find Font[Style or Font]Style this is incorrect. Replace the bracket with an underscore, save the file and open the project. This should resolve the issue.

Q9: How can I read the *BGT file, the MODFLOW file containing water budget data for MODPATH?

Answer:
This is available in the source code form as a part of MODFLOW/MODPATH distribution. This should be available on the USGS website. Please browse to the USGS website for further information.

Q10: How can I take my Visual MODFLOW model data into Visual MODFLOW 3D-Builder?

Answer:

Individual input/output elements from your models can be exported from Visual MODFLOW, and then imported into Visual MODFLOW 3D-Builder, to assist with interpreting your results, or designing conceptual models from your existing model

Numerical Grid

To view the numerical grid as a full 3D object in Visual MODFLOW 3D-Builder

From Visual MODFLOW , select Input/Grid
File / Export / Data
Select TecPLOT .DAT format.
Select all the layers, and choose an attribute: layer top, bottom, or thickness

In Visual MODFLOW 3D-Builder, you can import this object, by:
Import Data / 3D Gridded Data
Select the TecPLOT .DAT file
View this in a 3D window

To view the numerical grid as a 2D layer in Visual MODFLOW 3D-Builder:

From Visual MODFLOW , select Input/Grid
File / Export / Image
Select AutoCAD.DXF (World Coordinates)

In Visual MODFLOW 3D-Builder, you can import this object, by:
Import Data / Polylines
Select the .DXF file
This can be viewed in 2D or 3D

Layer Elevations

To export layer top or bottom elevations from Visual MODFLOW, for use in Visual MODFLOW 3D-Builder:

From Visual MODFLOW , select Input / Grid
File / Export/ Data
Select Surfer GRD
Select Layer Top
This will generate one surface for the top (or bottom) of each model layer.
You need to repeat these steps, in order to generate a surface for the bottom, of the bottommost layer in your model.

In Visual MODFLOW 3D-Builder, you can import this object, by:
Import Data / Surface
Select the Surfer .GRD file; repeat for each surface in your model
The surfaces can be viewed in 2D or 3D
These surfaces can be used to build horizons in your conceptual model.

Properties

From Visual MODFLOW , you can export the property values for the entire grid, to a 3D Gridded TecPLOT .DAT format (for example X,Y,Z,Kx). This could be useful if you want to generate new models from your existing models.

From Visual MODFLOW, select Input/Properties
Select the desired parameter group (Conductivity, Storage, Initial Heads)
File / Export / Data.
Select TecPLOT .DAT
Select the desired parameters and layers

In Visual MODFLOW 3D-Builder, you can import this object, by:
Import Data / 3D Gridded Data
Select the TecPLOT .DAT file
Select the Unit category for this parameter, and the appropriate units; for example, select Conductivity, and the source units, ft/day
The 3D Gridded data can be viewed as a 3D Grid wireframe in 3D.
To use these properties in your conceptual model, define a new property zone, and select this 3D Gridded Data as the data source for your property zone; for more details, refer to the Visual MODFLOW 3D-Builder Help.

To export properties on a layer-by-layer basis:

From Visual MODFLOW , select Input/Properties
Select the desired parameter group (Conductivity, Storage, Initial Heads)
File / Export/ Data, Surfer GRD
Select the desired parameters and layers
One file will be generated for each selected model layer

In Visual MODFLOW 3D-Builder, you can import this object, by:
Import Data / Surface
Select the Surfer .GRD file;
The surfaces can be viewed in 2D or 3D
These surfaces can be used to define property values, when you create property zones.

Wells

In Visual MODFLOW , select Input / Wells/ Pumping Wells
From the wells database table, copy the desired wells from the grid, and paste into MSExcel.
For screen details, run a query in the project_name.mdb file.

In Visual MODFLOW 3D-Builder, you can import this object, by:
Import Data / Well
Select the .XLS file;
The wells can be viewed in 2D or 3D; wells can also be used to define pumping well boundary conditions.

Boundary conditions

Boundary condition locations can be exported to DXF or raster image: From Visual MODFLOW , select Input/Boundaries
Select the desired boundary condition (and hide all other non-desired overlays).
File / Export / Image. Select AutoCAD DXF, in world coordinates.

In Visual MODFLOW 3D-Builder, you can import this object, using,
Import Data / Polyline
Select the .DXF file
This can be viewed in 2D or 3D
You may then create new data object (polygon or polylines), and using the CAD file as a background, trace over the existing boundary conditions, to represent rivers, recharge zones, etc.

Output

Visual MODFLOW has the limitation that it allows you see the results from only one simulation at a time. With Visual MODFLOW 3D-Builder, you can load calculated heads from various simulations, for comparison, into the 2D/3D viewer environment. Heads From Visual MODFLOW , you can export heads for the entire grid, to a 3D Gridded TecPLOT .DAT format (for example X,Y,Z,Heads). This could be useful if you want to use the heads as boundary conditions for a new specified head boundary condition From Visual MODFLOW , select Output
File / Export / Data.
Select TecPLOT .DAT
Select the desired layers

In Visual MODFLOW 3D-Builder, you can import this object, by:
Import Data / 3D Gridded Data
Select the TecPLOT .DAT file
Select the Unit category for this parameter,
The 3D Gridded data can be viewed as a 3D Grid wireframe in 3D.
To use these heads in your conceptual model, define a new boundary condition, assigned to the sides of the simulation model domain, and select this 3D Gridded Data as the data source for your boundary condition; for more details, refer to the 3D-Builder Help.

To export heads on a layer-by-layer basis:

From Visual MODFLOW, select Output, Maps/Contouring/Head
File / Export / Data, Select Surfer .GRD
Select the desired layers
One file will be generated for each selected model layer

In Visual MODFLOW 3D-Builder, you can import this object, by:
Import Data / Surface
Select the Surfer .GRD file; repeat for each layer in your model
The surfaces can be viewed in 2D or 3D
These surfaces can be used to define property values, or for boundary condition values (for example, initial heads for future run)

To export heads on a layer-by-layer basis, to Shapefiles,

From Visual MODFLOW, select Output, Maps/Contouring/Head
File / Export / GIS, Select ESRI Shapefile, World Coordinates.
Repeat for additional layers.

In Visual MODFLOW 3D-Builder, you can import this object, by:
Import Data / Polyline
Select the Shapefile
This can be viewed in 2D or 3D.

Pathlines

To export pathlines on a layer-by-layer basis, to Shapefiles:

From Visual MODFLOW, select Output, Maps/Pathlines
File / Export/ GIS, Select ESRI Shapefile, World Coordinates.
Repeat for additional layers.

In Visual MODFLOW 3D-Builder, you can import this object, by:
Import Data / Polyline
Select the Shapefile

The time markers are imported as points; to import, select,
Import Data / Point
Select the points shapefile

This can be viewed in 2D or 3D.

Concentrations

Concentration data can be exported similar to Heads.

You may contact technical support to request a copy of this document in *.pdf format.

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Q11: Is Lake Package (LAK3) Supported in Visual MODFLOW 2010.1?

Answer:

Visual MODFLOW 2010.1 provides support for Lake Package, which allows the user to simulate Lake-Aquifer interactions in transient or steady-state flow conditions using the MODFLOW Lake Package (LAK3).

The LAK3 package is supported in the following engines: MODFLOW 2000, MODFLOW 2005, SEAWAT and MODFLOWSURFACT.

For more information on the LAK3 package, please refer to the following USGS publication: Documentation of a Computer Program to Simulate Lake-Aquifer Interaction Using the MODFLOW Ground-Water Flow Model and the MOC3D Solute- Transport Model.

Q12: Can I import MODFLOW Packages into existing Projects?

Answer:

MODFLOW packages can now be directly imported into any existing Visual MODFLOW project. The packages supported for import include the following:

HFB1, HFB6, DRN, CHD, RIV, GHB, LAK, WEL and Zone Budget

Q13: Can I export property zones and boundary conditions data from Visual MODFLOW 2010.1?

Answer:

Visual MODFLOW 2010.1 now provides more flexibility for importing and exporting data to/ from your Visual MODFLOW project. The following options are now available:

Q14: Is Visual MODFLOW 2010.1 supported on Windows 7?

Answer:

Visual MODFLOW 2010.1 is now supported on Windows 7 operating systems, including Professional, Enterprise and Ultimate editions.

Q15: Is Evapotranspiration Segments Package (ETS1) supported in Visual MODFLOW 2010.1?

Answer:

Visual MODLOW 2010.1 provides support for the Evapotranspiration Segments Package (ETS1), which allows simulating evapotranspiration by defining a multi-segment function that relates evapotranspiration rate to hydraulic head. This capability provides a degree of flexibility not supported by the original EVT Package, which by contrast, simulates evapotranspiration with a single linear function.

Q16: If I change the units in Visual MODFLOW 2010.1 after creating the model, would the values already in the model be transformed to their equivalent values in the new system of units?

Answer:

It is important to remember that Visual MODFLOW does not have the ability to convert units. Changing the units in the existing model would only changes the unit labels, model parameter values would not be automatically converted to the new unit settings.

All MODFLOW files during translation are converted to consistent units of length and time. This would be the specified units of length and time when the model was created. However, Visual MODFLOW allows the user to enter certain values in more convenient units such as recharge in mm per year and pumping rates in gallons per minute. Therefore these values have to be converted to the same units as your default length and time units.

Q17: When trying to convert my MODFLOW data files using the mf96to2k.exe, the error appears “array is too large for this conversion”, how can I convert my project data with larger array?

Answer:

Please contact Technical support @ This e-mail address is being protected from spambots. You need JavaScript enabled to view it for another mf96to2k.exe file that supports a larger array.

Q18: How can I delete zones, (i.e. conductivity, recharge, etc.) in Visual MODFLOW?

Answer:

Unfortunately it is not possible to delete zones in Visual MODFLOW. You can overwrite the existing zones with a new zone, but you cannot delete zones.

Q19: I am not able to create a model with more than 499 rows and 499 columns, what should I do?

Answer:

The maximum allowable dimensions of the grid are 500 grid lines (499 columns) in the X-direction by 500 grid lines (499 rows) in the Y-direction by 200 layers in the Z-direction. Thus, the maximum number of unknown hydraulic head values is 50,000,000. If these dimensions are insufficient for a specific problem, please contact Schlumberger Water Services technical support at This e-mail address is being protected from spambots. You need JavaScript enabled to view it for a customized version of Visual MODFLOW compiled specifically for larger grid dimensions.

Q20: I am not able to view Transport Mass Balance Graphs, what should I do?

Answer:

Transport Zone Budget graphs are only available when the MT3D96 (not available for new projects/variants) or MT3D99 transport engines are used.

END FAQ