Visual MODFLOW Overview
Visual MODFLOW Introduction
Visual MODFLOW Detailed Description
Visual MODFLOW 3-D Explorer
Visual MODFLOW Prices
Visual MODFLOW Demo

The Visual MODFLOW 3D-Explorer has also been improved with the addition of several new features and enhancements including:

• Animation sequence pausing, looping and recording to an AVI file
• Light source position control
• Enhanced contour label positioning and controls
• Concentration plumes are automatically clipped above the water table surface
• Revised project data structure to more closely resemble Visual MODFLOW

Go to VMOD 3D-Explorer Page

Clearly this new version of Visual MODFLOW includes an unprecedented number of improvements, new features and significantly enhanced analysis capabilities. However, these are just a few of the reasons why Visual MODFLOW is the most popular groundwater modeling software package in the world. Try a demo and see for yourself how quickly and easily you are able to generate and modify the model grid, assign and edit property zones and boundary conditions, and visualize the results.

Back to Visual MODFLOW Main Page .

Grid refinement is often necessary after the model has been created and run several times. However, the process of adding and moving layers may create invalid boundary condition data in grid cells that contain a head value less than the bottom elevation of the grid cell.

Visual MODFLOW now issues a warning message if the attempted grid modifications will create invalid boundary condition data, and the warning message provides an option to fix the offending grid cells.

Visual MODFLOW supports and includes Battelle's RT3D Version 2.5 (released in January 2002) for state-of-the-art reactive transport modeling. This latest version of RT3D contains significant improvements to the performance and analysis capabilities including a third-order total-variation diminishing advection solver (TVD), an iterative generalized conjugate gradient solver, and cell-by-cell sorption terms. These new solvers can decrease the often excessive run-times by a factor of 10 or more.

The Overlay Control feature has been completely redesigned to make it easier to modify the display settings and viewing priority of the overlays. The Overlay Control also now remembers the most recent Output display settings each time the simulation results are viewed. This avoids the time-consuming and tedious task of re-creating the overlay settings each time the Output data is viewed.

The Overlay Filter allows you to view only the elements you need to see. These include:

• Boundary Conditions
• Contours
• Model Grid
• Observation Wells
• Pumping Wells
• Particle Tracking
• Model Properties

Advanced settings for each element can be modified by selecting

Automatic calculation of conductance represents a major time-saver. With previous versions, conductance would be assigned a single value for a line segment. This approach was often unrealistic due to changes in river widths and required assigning conductance on a cell-by-cell basis.

Now, Visual MODFLOW 3.0 gives you the tools to automatically assign conductance along a river using the powerful features of the Array Calculator. If a River boundary condition is assigned using a line object, the Riverbed Conductance can be calculated using the formula:

$COND=$RCHLEN*$RBWIDTH*$K/$RBTHICK

Where: $COND = Riverbed Conductance in each cell along the line; $RCHLEN = Reach Length of the river in each cell along the line; $RBWIDTH = Riverbed Width in each cell along the line; $K = Vertical Hydraulic Conductivity of the riverbed; $RBTHICK = Riverbed Thickness in each cell along the line.

• Selecting the boundary name from a pick-list.
• Clicking on the River boundary on the map.

Object-oriented boundaries also take full advantage of the power functions included with the Array Calculator and removes the need to assign or edit boundary conditions on a cell-by-cell basis.

Object-oriented boundaries will give you the ability to treat groups of cells containing related boundary condition data as an "object". This means that all attribute data for a selected group of cells can be quickly selected and modified together through an easy-to-use editing menu.

Example: When assigning a River boundary, you can assign the river a unique alpha-numeric name. For projects with many rivers boundaries, this can be useful for quickly locating the river and modifying the attribute data values. There are two options available for selecting the object-boundary.

One of the most sophisticated options available with Visual MODFLOW 3.0 is the new built-in Array Calculator. This advanced feature now gives you the ability to define array variables for model parameters using built-in mathematical formulas. There is no longer a need to assign boundary condition values on a cell-by-cell basis. Visual MODFLOW now takes care of this automatically!

How can this help?

A common application for using mathematical expressions containing array variables is when assigning Drain Boundaries as a seepage face. If the ground surface is not flat (is it ever?), it becomes rather tedious to assign drain elevations for each cell equal to the top of the grid cell elevation. However, with Visual MODFLOW 3.0, the drain elevation can be defined for all cells in a polygon using the formula:

$DRAIN=$BOT+$DZ- 0.1

$DRAIN = Drain Elevation for each cell in the polygon; $BOT = Bottom of cell elevation for each cell in the polygon; $DZ = Thickness of each cell in the polygon

This formula will assign a Drain Elevation value corresponding to 0.1ft below the top elevation of each Drain cell grid. This represents just one of many possibilities for the Array Calculator!

As a final step before importing the interpolated data into the model, the user can define the number of property zones that will be imported into the model. Prior to this feature, the user would manually enter this information with the point-and-click of a mouse. Now the interpolated data can be imported into the model with any number of property zones. For hydraulic conductivity, if there is a specific region of the model where higher or lower ranges of property values make it more sensitive, it can be useful to create several different property zones to effectively "isolate" these regions.

Once Visual MODFLOW has run the interpolation, results are viewed through a fully customizable graphical interface.

You have full graphical access to:

• Contour Settings
• Color Map Settings
• Series Settings
• Legend Settings
• Title Settings
• Axis Settings
• Transparency Settings
• Symbol color and size, etc.

Enhanced graphical representation of interpolated data, plus the ability to view the results over your site map is a real PLUS!

For many projects, the interpolated distribution of data may not accurately represent the actual situation found in the field. In these cases, Visual MODFLOW allows the user to include "control points." These are placed at strategic locations on the map helping to account for data otherwise missing from the data set.

Control points are graphically assigned with the mouse and are represented as a blue and red station symbol. Once assigned, control point attributes can be edited through the "Assign Control Points" dialogue. The control points will be included as 'real' data when you re-interpolate the data.

Model property data can be imported from typical file formats encountered when designing numerical groundwater models. These include:

• ASCII text files (*.TXT)
• Microsoft Excel Spreadsheets (*.XLS)
• GIS shape files (*.SHP, point or line formats)

In addition, three reliable and frequently used interpolation techniques for hydrogeologic data have been wrapped inside Visual MODFLOW. These include:

• Inverse Distance Squared - a very fast and efficient, weighted average interpolation method
• Kriging (Advance features included) - geostatistical method that produces visually appealing maps from irregularly spaced data
• Natural Neighbor - based on the Thiessen polygon method used for interpolating rainfall data

Visual MODFLOW Pro 3.0 now allows you to import model property values from discrete data points and interpolate these values for use when assigning conductivities, storage, and initial heads. This is extremely valuable for several major reasons:

1) Interpolating between data points creates a smooth distribution of property values. This reduces the extreme gradients sometime found with properties such as hydraulic conductivity and results in a much more stable model.

2) Interpolated properties can be directly imported in the model without having to assign properties manually.

3) The range of property values imported into the model is 'user' specified through the graphical interface. You can assign any number of ranges and let Visual MODFLOW do the rest!

Conductance may be calculated automatically using the default conductance formula - a key feature to version 3.0!

When digitizing stream segments, Visual MODFLOW Pro automatically numbers the segments in downstream order and prompts the user for the stream attribute data for each segment. The grid cells corresponding to the location of the stream segments will be assigned these new stream attributes, including:

• Start/Stop Time
• Streambed-Top
• Streambed-Bottom
• Width
• Roughness
• Segment In-Flow
• Streambed Conductance
• Streambed Kz

Visual MODFLOW Pro 3.0 now fully supports the Stream Routing Package (STR) used to simulate the interaction between surface streams and groundwater. Unlike other groundwater models, Visual MODFLOW Pro uses a grid-independent line object to represent the stream segment and associated parameter values. Rather than linking all stream attribute data to the grid cell, the data is now linked to the line-object giving the user the flexibility to modify the line object independent of the model grid. As a result, the grid may be modified at any time without adversely affecting the stream data.

In addition to MODFLOW-2000 integration, Visual MODFLOW Pro includes the new Link-Algebraic Multi-grid Package (LMG) (documented in the U.S. Geological Survey Open-File Report 01-177, Mehl and Hill, 2001). The LMG Package links MODFLOW-2000 with an advanced technique for solving matrix equations, the freeware algebraic multi-grid (AMG) solver produced by the GMD - German National Research Center for Information Technology. The LMG Package has some distinct advantages over other solvers available with MODFLOW-2000 for problems with large grids (more than about 40,000 cells) and (or) a highly variable hydraulic-conductivity field. Testing conducted by the U.S. Geological Survey indicates that execution times using the AMG solver may be 2 to 25 times faster than execution times using MODFLOW's PCG2 Package with the modified incomplete Cholesky preconditioner.

New Features in 3.0

MODFLOW-2000 Support
Stream Routing Package
Data Interpolation Component
Built-in Array Calculator
Object-Oriented Boundaries
RT3D 2.5 Support
Auto-Conductance Calculation
Overlay Control
 

Visual MODFLOW Pro 3.0 now supports MODFLOW-2000, the latest development by the USGS for running flow simulations. MODFLOW-2000 has been logically integrated into Visual MODFLOW Pro's graphical user interface to ensure fast and efficient model development. MODFLOW-96 is also still available for those requiring the previous version of MODFLOW. As the industry standard, Visual MODFLOW Pro still offers the most complete package in one easy-to-use, intuitive interface.

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What's New With Visual MODFLOW?