Graphical User Interface

GMS's graphical tools, with standard MS Windows functionality, make building models and viewing results very easy and intuitive. All modeling parameters are entered through interactive graphics and easy-to-use dialog boxes. Though the software reads and writes native model input/output files, there is no need to worry about formatting text files to get the models to run; nor will you need to search through text output files to find the results from the model run.

The Project Explorer Window of GMS has been developed to give you GIS-style, quick access to data layers and display settings. By simply clicking on data layers you can:

• Turn display on/off
• Convert data to other formats/types
• Project data to a different coordinate system
• Control display settings
• Set the active data set for editing

The Project Explorer Window also allows you direct access to modeling parameters/tables for control of your groundwater model. You will find that managing data for modeling is easier than ever.

Thanks to simple CAD and GIS style tools and functionality, you will find that manipulating digital terrain data, GIS data, and subsurface data to build model geometry and compute model input parameters is very smooth. Further, presentation of results of your work will be impressive and easy to understand.

Graphics and Visualization

GMS is a powerful graphical tool for model creation and visualization of results. Models can be built using digital maps and elevation models for reference and source data. During the model building process, the graphical representation of the model allows quick review and presentation of your work. Fully 3D views, with contouring and shading of your model allow anyone to see and understand the domain and parameters of your analysis.

GMS utilizes the OpenGL graphics engines for all 3D visualization, both wireframe and shaded. This means that all displays are rendered using hardware acceleration. Fully shaded 3D images can now be rendered instantaneously. Complex 3D objects can be rotated in real time in either shaded or wireframe mode.

A groundwater model can be displayed in plan view or 3D oblique view, and rotated interactively. Cross-sections and fence diagrams may be cut arbitrarily anywhere in the model. Hidden surface removal, and color and light source shading can be used to generate highly photorealistic rendered images. Contours can be used to display the variation of input data or computed results. Cross-sections and iso-surfaces can be interactively generated from 3D meshes, grids, and solids, allowing the user to quickly visualize the 3D model.

Both steady-state and transient solutions can be displayed in an animated format (as if viewing a movie) using either vector, iso-surface, or contour animation. For example, animation of a transient solution allows the user to observe how head, drawdown, velocity, and contaminate concentration vary with time. In addition, GMS can also sweep an iso-surface through the 3D model. The minimum and maximum iso-surface values are determined from the model and the program will then linearly interpolate and display multiple iso-surfaces in rapid succession. This allows the user to quickly understand the spatial variation of a contaminant plume, for example.

GMS Supported Models

Numerical models are programs that are separate from GMS that are used to run an analysis on a model. Simulations can be built in GMS, and then run through the numerical model program. GMS can then read in and display the results of the analysis. GMS also has the option of using a “model wrapper” to run the model and display real-time results during the model simulation.

The following numerical models are currently supported in GMS. Each model is included with the GMS installation (model executable files and documentation) and is fully linked with the GMS software.

MODFLOW 2000 GMS includes a comprehensive graphical interface to MODFLOW 2000. MODFLOW is a 3D, cell-centered, finite difference, saturated flow model developed by the USGS. MT3DMS Simulation of multi-species transport by advection, dispersion, and chemical reactions of dissolved constituents in groundwater systems. SEAM3D A reactive transport model used to simulate complex biodegradation problems involving multiple substrates and multiple electron acceptors. MODAEM Analytic element model for simple flow and transport computations. SEEP2D A 2D finite-element groundwater model designed to be used on profile models such as cross-sections of earth dams or levees. PEST A model-independent, non-linear parameter estimator. The purpose of PEST is to assist in data interpretation, model calibration, and predictive analysis. T-PROGS Used to perform transition probability geostatistics on borehole data.

MODPATH A particle tracking code that is used in conjunction with MODFLOW. Particles are tracked through time assuming they are transported by advection. RT3D An advanced multi-species reactive transport model developed by the Battelle Pacific Northwest National Laboratory. FEMWATER A fully 3D finite-element model used to simulate density-driven coupled flow and contaminant transport in saturated and unsaturated zones. UTCHEM A multi-phase flow and transport model developed by the Center for Petroleum and Geosystems Engineering at the University of Texas at Austin. UTCHEM is ideally suited for pump and treat simulations. UTEXAS UTEXAS quickly analyzes dams, levees and other slopes for the critical failure surface and factor of safety. SAMG SOLVER The SAMG solver is an advanced solver ideally suited for large, complex models and is optimized to run with MODFLOW. The SAMG solver was developed for highly efficient, numerical solutions of large, sparsely populated matrix problems.

GMS Modules

The GMS interface is separated into several modules; these modules contain tools that allow manipulation and model creation from different data types. The modules of GMS are:

Map Module GIS Module TIN Module Solids Module 2D/3D Scatter Point Module

2D Grid Module 3D Grid Module 2D Mesh Module 3D Mesh Module

Map Module

The Map module provides a suite of tools for using GIS objects to build conceptual models, displaying digital background maps, and displaying CAD drawings.

Map objects are used to provide GIS capabilities within GMS. These objects include points, arcs, and polygons. Feature objects can be grouped into layers or coverages. A set of coverages can be constructed representing a conceptual model of a groundwater modeling problem. This high level representation can be used to automatically generate MODFLOW and MT3DMS numerical models. Feature objects can also be used for automated mesh generation for FEMWATER or SEEP2D numerical models.

Images are typically maps or aerial photos. GMS supports many standard image file formats such as PNG, TIFF and JPEG. Images are displayed in the background for on-screen digitizing or model placement or simply to enhance the display of a model. Images can also be draped over surfaces and texture mapped to generate highly realistic shaded images.

AutoCAD and DXF files can be imported into GMS and displayed in the Graphics Window to assist in model placement or simply to enhance the display of a model. CAD data can also be converted to feature objects.

GIS Module

The GIS Module greatly simplifies the process of importing and converting GIS data from external sources. To fully utilize the GIS module, a license of ArcGIS (formerly ArcView) is required. In this case, portions of ArcGIS are effectively run inside of GMS using the ArcObjects library. This makes it possible to use the GIS module to open virtually ANY GIS database supported by ArcGIS.

Once a GIS database is opened, the data are displayed in the GMS window using the ArcGIS map rendering engine. This results in beautiful, professional looking maps that can be displayed in the background of a GMS modeling project. The user has access to all of the standard ArcGIS tools for modifying the display of the map.

Once a GIS database is imported and displayed, the user can select a portion of the map using either a simple graphical selection or an SQL query. The selected data can then be converted to standard GMS feature objects using a simple and intuitive GIS Property Mapping Wizard. The user is prompted to indicate how each of the columns in the GIS attribute data should be mapped to corresponding GMS feature object properties.

TIN Module

The Triangulated Irregular Network (TIN) module is used for surface modeling. TINs are formed by connecting a set of XYZ points (scattered or gridded) with edges to form a network of triangles. The surface is assumed to vary in a linear fashion across each triangle. TINs can be used to represent the surface of a geologic unit or the surface defined by a mathematical function.

Several TINs can be modeled at once in GMS. A TIN may be created within GMS by several methods or can be imported from other systems. TINs can be used in GMS to build solid models and 3D meshes or they can be converted to other types of data such as scatter points for interpolation to grids.

Solids Module

The Solid module of GMS is used to construct three-dimensional volumes called "solids". Once a solid is created, cross sections can be cut anywhere on the model and the solids can be shaded to generate realistic images. The “Horizons Method” of constructing solids is the most advanced tool available for creating solids quickly and accurately.

Solids are used for site characterization and visualization. Solids can also be used to define layer elevation data for MODFLOW models or MODFLOW HUF package data. They can also be used to define a layered 3D mesh.

2D Grid Module

The 2D Grid module is used for creating and editing two-dimensional Cartesian grids. 2D grids are primarily used for surface visualization and contouring. This is accomplished by interpolating to the grid and then shading the grid. The figure below is an example of interpolating contaminant concentration data to a 2D grid and then shading the 2D grid.

3D Grid Module

The 3D Grid module is used to create 3D Cartesian grids. These grids can be used for interpolation, iso-surface rendering, cross sections, and finite difference modeling.

Interfaces to the following 3D finite difference models are provided in this module.

- MODFLOW
- MODPATH
- MT3DMS
- RT3D
- SEAM3D
- UTCHEM

2D Mesh Module

The 2D Mesh module is used to construct two-dimensional finite element meshes. Numerous tools are provided for automated mesh generation and mesh editing. 2D meshes are used for SEEP2D modeling and to aid in the construction of 3D meshes. The figures below show an example of a SEEP2D model.

3D Mesh Module

The 3D Mesh module is used to construct three-dimensional finite element meshes. Numerous tools are provided for automated mesh generation and mesh editing. These meshes can be used for interpolation, iso-surface rendering, cross sections, and finite element modeling with FEMWATER.

2D / 3D Scatter Point Modules

The 2D and 3D Scatter Point modules are used to interpolate from sets of 2D scattered data to other objects (meshes, grids, TINs). Several interpolation schemes are supported, including kriging. Interpolation is useful for setting up input data for analysis codes and for site characterization. The interpolation methods supported by the Scatter Point modules are:

• Linear
• Inverse Distance Weighted
• Clough-Tocher
• Natural Neighbor
• Kriging

GMS also supports Jackknifing, which is used to compare interpolation schemes.