Visual MODFLOW Flex brings together industry-standard codes for groundwater flow and contaminant transport, essential analysis and calibration tools, and stunning 3D visualization capabilities in a single, easy-to-use environment.

Experience the new version release of Visual MODFLOW Flex 6.0

MODFLOW-USG Workflow Enhancements

Build your unstructured MODFLOW-USG model using the same workflow steps and tools as in a structured Finite Difference model:

o Define Modeling Objectives o Specify model properties o Add Boundary Conditions o Define ZoneBudget Zones o Add Particles

Define Quadtree Grids (Q-Grids)

VISUAL MODFLOW FLEX / 6.0

Refine vertical layers when creating unstructured grids

Make use of advanced translation settings which provide greater flexibility in how your model simulations are formulated

Support for the MODFLOW-USG Ghost Node Correction (GNC) package

Flex is now packaged with MODFLOW-USG v1.4, the latest official USGS version as of the release date of Flex 6.0.

Particle Tracking

Support for mod-PATH3DUv3.0*, which enables particle tracking in unstructured grid (MODFLOW-USG) models

* mod-PATH3DU is a free utility developed by S.S. Papadopulos, Inc. (SSPA) that must be downloaded and installed separately from the SSPA website.

Enhanced particle tracking capabilities allowing you to define: o Groups of particles that can be tracked and visualized separately o Separate particle release times for each particle group

o Locations of particles based on existing or drawn point, polyline, polygon, or well features

o Particles in cross-section views (i.e. row and column views) of a finite difference model o Particle elevations based on layer(s), surface(s), or a constant elevation

ZoneBudget Improvements

ZoneBudget is now supported in unstructured MODFLOW-USG models

You can use point, polyline, or polygon features to define Zone Budget zones and zones can be specified directly using feature

attributes from a data field

Visualization and Settings Visualize velocity vectors in finite difference and unstructured grids. View:

o In-plane velocity vectors

o Color maps of out-of-plane velocities

o Display average or Darcy velocities (total or in-plane) or by direction

Specify a line feature along which to show cross-sectional color maps of unstructured grid model properties and outputs

Cell Inspector now includes Layer/Model Top and Bottom elevations, and the magnitude and X-, Y-, and Z-components of the average/Darcy groundwater velocity

When creating horizons, you can preview how the rules will be enforced in the 3D Viewer rather than viewing the raw surfaces.

Packages, Properties, and Boundary Conditions

Field calculator/expression builder includes o cell geometry variables: Cell Bottom ($BOT), Model Bottom ($MBOT), Cell Thickness ($DZ), Cell Width ($DX), and Cell

Length($DY) and o additional functions: LOG, LOG10, NOT, ABS, DOT

Copy Model (Flow/Transport) Properties and Boundary Conditions to from one Layer, Row, or Column to other Layers. Rows, or Columns

Edit cells (active/inactive, zone budget) in row/column views.

Data Import/Export

Import distributed property values from Classic Models

Use a source data field to map feature elevations when importing point, polyline, and polygon data

Model outputs including groundwater heads, drawdown, velocity, and concentrations can be exported to text files

Export contours as polyline shapefiles

Usability and Other Enhancements

Observation Wells can be specified as separate groups

Performance improvements on project open and close operations for larger projects [

Output Control file translation supports keywords or codes and the standard or compact budget formats to provide support of MODPATH and mod-PATH3Du.

Added MT3D-MS and RT3D summary output (.OT) files to the open files dialog at the model run step

Defects Addressed (con’t)

Intermittent and unhelpful translation error “Vmac is running in the task bar, please close it and try again”. [19663]

Deleting particles by drawing a box does not actually delete particles [19741]

Well schedule not translated correctly if the project time unit is not in days [20918]

In some cases, particularly if the whole output water table exceeds the model ground surface it was rendered at Elevation=1 [20998]

Modifications to a pumping well boundary condition propagate to all runs under the same grid [21270]

Concentration observations contained incorrect column names [21314]

Project Clean-up/Remove orphan objects from model [21439]

If all boundary conditions of a given type were deleted, they would still run in the model due to advanced run settings. You are now prompted to remove the translated file or back-it up so that it no longer runs in the model [21651]

In some cases, the schedule for pumping wells with relative times does not import correctly [22133]

In some cases, assigning a schedule to a conceptual boundary condition results in an error message that the schedule occurs before the model start date even if this is not true [22158]

Concentration observations incorrectly handled for simulations with multiple species [22168], [22183], [23152]

Transient Fluxes (Model Results) are not shown or exported, only Flux from first time step. [22240]

Fluxes not displaying properly in 3D Viewer [22277]

Cells remain active if boundary condition is applied to 'Top' of model domain [22339]

MODFLOW-USG, BCF package fails to translate if property values are edited [22347]

When using a uniform grid, the CM->NM conversion does not add conceptual BCs assigned to model top to Layer 1 rather than the upper-most active layer [22397]

When importing heads file as 3D gridded data to a Rotated Grid Project, error "Object reference not set to instance of object appears" [22542]

Inconsistent/compound units are not correctly converted for certain RT3D reaction parameters [22543]

Water table for USG does not take ponding into account [22868]

Reinstalling Visual MODFLOW Flex does not replace MODFLOW-SURFACT with the demo version in the engines folder [22914]

Flex does not always cleanly delete elements from the Model Explorer, resulting in large file sizes [23010]

In some cases, MODFLOW-USG conceptual model conversion results in incorrect parameter values, and causes parameter editing to fail [23045]

Out of memory error when attempting to display certain DXF files in 2D view of Flex viewer or standalone 2D viewer [23122]

Multiple Lake BCs result in a multiple key error upon translation [23162]

Known Issues with VMOD Flex The following issues may occur in Flex under described/applicable conditions. Where available, a workaround is provided.

[17290] In some cases, when working with an extracted sub-grid model, whose parent model used a .HDS file as input for starting heads, the initial heads may not be correct. Workaround: use the validate option to see and correct the issue or extract the heads from the parent model into surfaces and assign to the appropriate layer(s).

[17402] When adding more species, closing the project, and NOT saving the changes, newly added species are saved regardless. Workaround: delete unnecessary species from the project.

[19663] Unhelpful translation error “Vmac is running in the task bar, please close it and try again”. Workaround: open Windows Task Manager, by right-clicking on the Windows Task Bar and close Vmac instance there.

[20310] Property and boundary condition zones may appear to be incorrect for child grids in 2D- or composite Viewers, particularly for the recharge and evapotranspiration packages. This is caused by the parent grid values being drawn on top of the child grid values in the viewer and parent grid properties are generally null within child grids. Workaround: reorder the layers.

[20994] Imported storage values from a Classic Project may have values of NaN (not a number). Workaround: This issue may caused by a partially corrupted Classic File. If this occurs, temporarily remove the file called [Project Name].$STRG from the Classic Folder. This file may be located inside a sub-folder of the affected Classic project. Save it in another location while importing your project into Flex. The import of storage zones should proceed normally after doing this. Restore the file to its original location once the import is complete.

[21053] When importing pumping schedule date based on absolute time, Visual MODFLOW Flex fails to identify some time/date errors. Specifically, it does not record an error when the Pumping start date falls AFTER the pumping end date. Workaround: inspect dates in the Excel well file to be imported to verify that pumping starts on or after the model start date or import the well schedule using relative times.

[21079] In certain cases where grids have previously been generated, the grid refinement buttons in the View Finite Difference Grid step may not work following a subsequent model grid creation. Workaround: ensure that the grid is the active/turned on in the view (sometimes the conductivity grid is activated on top of or instead of the grid itself)

[21128] Adding a transient boundary condition to a steady-state model where none previously existed and subsequently converting the model to transient may result in incorrectly translated time discretization (.DIS) and output control (.OC) input files. Workaround: The user may have to step out of and return to the Translate workflow step to force a refresh of the master schedule

At the View Maps step, sometimes the 3D view does not display data and legend. Use new 3D window to display data instead.

When running a model from a subgrid unable to use initial heads from a previous MODFLOW run option.

User is unable to select RCH or EVT for edit if another boundary condition is assigned to the cell and is currently turned on for display – user needs to turn off other boundary conditions to be able to select RCH or EVT for edit.

Edits to RCH and EVT zones are saved immediately, however edits to time schedule are not – this can cause the time schedule to get out of sync.

When assigning RCH and EVT zones to a USG model – each zone is assigned as its own Boundary Condition

After importing wells when viewing the Layer View – the Layer combo box becomes disabled (unable to view other layers of model) – user needs to close and reopen the workflow tab and the combo box will become enabled again

If the parent node for a boundary condition is selected (to turn on all of the individual boundary conditions) in the model explorer – when user selects Edit – the boundary condition disappears from view. User needs to uncheck the parent node and select the individual boundary conditions in the model explorer.

Some boundary conditions (Recharge, Evapotranspiration, and Wells) are not removed from border cells when extracting/creating a subgrid as expected (since they should be replaced with a constant head boundary that takes all

boundary condition affects into consideration). User must make wells not active or delete them and reassign recharge and evapotranspiration rates to the border cells to be zero so that these effects are not duplicated.

PEST: when plotting parameter sensitivity values, if a parameter is log-transformed, the sensitivity is expressed with respect to the log of that parameter. The relative composite sensitivity of a log-transformed parameter is determined by mutiplying the composite sensitivity of that parameter by the absolute log of the value of that parameter.

If you are importing a Visual MODFLOW project with distributed properties, please be sure the $CND file (and $STR, $IHD) files have been generated in Visual MODFLOW. To do this, open your project in Visual MODFLOW Classic Interface, go to Inputs/Properties. Select Tools/Cell Inspector. Turn on All Flow properties. Then, scroll through each layer in your model. When you are finished, save and close the project, and import into VMOD Flex.

Rotated grids appear rotated in the 2D views.

When showing a cross-section through a child grid (for LGR) that has been rotated, the gridlines do not show up correctly. Workaround: Use 3D Viewer.

When displaying a grid that contains a child grid (for LGR), and viewing in the Flex Viewer, the selected row, column, or layer is applied only to the parent grid; it is not applied to the child grid.

When importing Points, Polygons, or Polylines from a .DXF file, only the entities within the .DXF $EXTMIN and $EXTMAX will be imported; any entities outside these extents will not be imported. Therefore, please be sure to prepare your .DXF file properly, prior to importing. Add to documentation

Some data object style settings are not saved to the project, e.g., point color, symbol size, etc.

For some objects, the 3D viewer does not fully support color rendering/labeling

Polygons with multiple parts are not rendered properly in the 2D Viewer; the holes in the polygons will appear the same color as the polygon(s) they overlap.

When draping polygon or polyline over a surface, this is an approximation, since it relies on the vertices of the polygon or polyline to position this in 3D; there may be gaps/locations where it is not completely draped. The same problem occurs when viewing areal or linear boundary conditions in 3D Viewer

Vertical datum shifts are currently not supported. VMOD Flex assumes that all data you import is in the same vertical datum.

When using Kriging interpolation component, you may need to adjust the min and max radii in order to get an ideal interpolation; these parameter values will depend on your data set. Default values are 100 and 100, you will likely need to increase or decrease these values. push to documentation – this is not a bug

A 3D Gridded data object will not be positioned correctly in a 3D Viewer if the grid origin is modified during the import process.

Grid rotation is not supported for imported 3D Gridded TecPlot (.DAT) data objects.

In 3D Viewer, child grids may not display correctly if the parent grid only has one layer.

In the color by attribute style settings, the MIN, MAX and color interval values may not update when a new attribute is assigned.

In a minority of cases where the user has restricted rights on Windows, an error will occur when starting VMOD Flex due to the TEMP folder being set as read-only. Granting full access to the TEMP folder resolves the issue.

If recharge boundaries are defined with a time schedule with multiple time entries for the same date, translation will be treated as static instead of transient.

When working with a project in Local Cartesian coordinate system, coordinate conversion is currently not supported. Please ensure that any data you import is in the same coordinates, and length (XY) units, as your project local coordinates.

Creating 2D Cross-sectional models is currently not supported due to limitations in the assignment of properties and boundary conditions in the numerical model – Workaround: specify a model with a thickness or 1 row or 1 column.

In some cases, when opening a project from Hydro GeoBuilder or VMOD 3D-Builder, you may not be able to display and use specific grids or meshes. Workaround: Re-create the desired grids or meshes in VMOD Flex.

MODFLOW-USG Issues: o When defining the grid, if your conceptual model includes pumping wells, the wells object must be included as an

add-in for the grid definition. o In the conceptual model, Property zones defined with the method “Use 3D Gridded Data” is not supported when

converting to a USG numerical model o Boundary condition attribute method “Use Shapefile Attribute” is not supported when converting to a

USG numerical model. o Conversion of transient boundary condition objects, with attributes defined at vertices, will show an

error.

For existing projects, if your conceptual boundary condition has multiple parts, and you edit the attributes, you may face a problem that the “Edit Boundary Condition” GUI does not display the selection correctly (the 2D preview may not show the correct selection) or the attributes grid may be empty. If this is the case, re-create the conceptual boundary condition object.

Wall Boundary (HFB) is supported only on MODFLOW-2000 and MODFLOW-2005 models. When doing conceptual to numerical model conversion, only Deformed Grid types are supported.

Unsaturated Zone Flow (UZF) package is supported only on MODFLOW-2005 models.

During conversion from conceptual model to numerical model for properties, VMOD Flex will use the order in which the conceptual property zones were created to determine the order when assigning to grid cells; if a grid cell is occupied by more than one property zone for the same parameter group, the one that was defined last (most recently) will take priority.

No settings for adjusting MODPATH particle color/size, in the Output

MODFLOW-LGR flux visualization, in some cases the values may not be correct for those cells along the parent/child grid interface

MODFLOW-USG translation does not take into account boundary conditions that end at different times;

Flux visualization not available for MODFLOW USG models

Translate to FEFLOW Model option will not work with the new pumping wells object. Workaround: re-define the pumping wells in FEFLOW

PEST is not available for MODFLOW-NWT

Import model from VMOD Classic, with distributed property zonation, the values and multipliers may not import correctly