Mathematical modeling has become an increasingly important and valued tool in the market, whether for assessing water availability, simulating the impacts of aquifer drawdown or managing contaminated areas.
Visual MODFLOW Flex is one of the most complete software packages for building mathematical models to simulate the flow and transport of contaminants in groundwater.
With this tool, it is possible to create an integrated conceptual and numerical hydrogeological model, in an optimized way and saving the time needed for simulations.
Visual MODFLOW has been a leader in the simulation market for the last 30 years and is constantly evolving. Recently, version 9.0 of Visual MODFLOW Flex was released, bringing a series of new features and improvements, most notably the ability to support MODFLOW-6, the newest core version of the groundwater modeling code developed by the United States Geological Survey (USGS).
This new version raises the standard of Visual MODFLOW Flex, which now works with the finite control volume method in addition to finite differences, delivering a mathematical solution as flexible as that of finite elements, enabling the creation of unstructured meshes and expanding the tool’s application potential.
MODFLOW-6
MODFLOW-6 code/algorithm is a completely redesigned version of MODFLOW with an entirely new and more readable input file structure that combines the main features of the most popular versions/variants of MODFLOW released over the last two decades:
- Structured meshes, groundwater flow processes and core boundary conditions (MODFLOW-2000/2005)
- Unstructured meshes and ghost node correction (MODFLOW-USG)
- Newton-Raphson formulation (MODFLOW-USG, MODLFOW-NWT),
Dual domain solute transport (MT3D-MS) - Multiple connected/nested model grids (MODFLOW-LGR)
- Density-dependent flow and solute transport (SEAWAT)
Some new and exclusive features:
- Full 3D anisotropy tensor support (via the XT3D formulation),
- Separate time series input files
- Time-varying conductivities and storage parameter values
- Several stress package instances and
Change/swap packages
Source/Use: Public domain/USGS: (MODFLOW 6: USGS Modular Hydrologic Model | U.S. Geological Survey).
This figure shows a triangular mesh in which the size of the triangular cells is reduced in areas with relatively large hydraulic gradients, such as around the shore of a lake, near pumping wells and along a stream. This type of layered mesh can be represented using the Discretization by Vertices (DISV) package in MODFLOW 6.
MODFLOW 6 currently contains two types of hydrological models: the Groundwater Flow Model (GWF) and the Groundwater Transport Model (GWT). The GWF model for MODFLOW 6 is based on a generalized control volume finite difference (CVFD) approach in which a cell can be hydraulically connected to any number of neighboring cells. Users can define the model mesh using:
- A regular MODFLOW mesh consisting of layers, rows and columns
- A layered mesh defined by (x, y) pairs of vertices, or
- A general unstructured mesh based on concepts developed for MODFLOW-USG
XT3D Flow Formulation
A new groundwater flow formulation has been developed specifically for the GWF Model in MODFLOW 6 (and to represent dispersion in the GWT Model). This new flow formulation is called the XT3D option. The XT3D option extends the capabilities of MODFLOW, allowing the simulation of fully three-dimensional anisotropy on regular or irregular grids in a way that properly takes into account the full three-dimensional hydraulic conductivity tensor. It can also improve the accuracy of groundwater flow simulations in cases where the model grid violates certain geometric requirements. Thus, the XT3D option is an alternative to the Ghost-Node Correction (GNC) package, which was developed for MODFLOW-USG.
Connected Linear Network (CLN)
The Connected Linear Network (CLN) process was developed for MODFLOW-USG to model one-dimensional connected features that are much smaller than the cells in a groundwater flow model. [1] The CLN process can be used to replace multi-cell wells that would use the MNW1 or MNW2 package in other versions of MODFLOW. Another gain of this process is the possibility of representing discrete units in the model, such as faults, fractures, karst conduits as well as interventions of engineering structures, such as horizontal drains and tunnels.
Water Services and Technologies is the official representative of Waterloo Hydrogeologic in Brazil, developer of Visual MODFLOW Flex, offering personalized service in projects and training in the use of the tool.
For more information on this tool or to request a quote, please contact our team at [email protected]
See more at:
https://www.waterloohydrogeologic.com/modflow-6-next-gen-groundwater-modeling/
https://www.usgs.gov/software/modflow-6-usgs-modular-hydrologic-model
