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RMA4 Screenshot
Model Info
Model type Finite element water quality transport numerical model in which the depth concentration distribution is assumed uniform. It computes concentrations for up to 6 constituents, either conservative or non-conservative, within the computational mesh domain.

Resource Management Associates

United States Army Corps of Engineers (USACE)
Web site Archived RMA4 web site

General Section

  • Mesh Editing
  • Observation
  • Overview
  • Sensitivity

Models Section

  • RMA4

RMA4 is a finite element water quality transport numerical model. RMA4 was designed to simulate the depth-average advection / diffusion process in an aquatic environment. The model can be used for the evaluation of any conservative substance that is either dissolved in the water or may be assumed to be neutrally buoyant within the water column. The model is also used for investigating the physical processes of migration and mixing of a soluble substance in reservoirs, rivers, bays, estuaries and coastal zones. The model is useful for evaluation of the basic processes or for defining the effectiveness of remedial measures. For most applications, the model utilizes the depth-averaged hydrodynamics from RMA2. The input hydrodynamics solution can be either a steady state or a dynamic simulation and is used to compute particle dispersions.

The RMA4 model can be added to a paid edition of SMS.


RMA4 has been applied to:

  • Define horizontal salinity distribution.
  • Trace temperature effects from power plants
  • Calculate residence times of harbors or basins
  • Optimize the placement of outfalls
  • Identify critical area for oil spills or other pollutants spread
  • Monitor water quality criterion within game and fish habitats
  • Determine the limits of salinity intrusion
  • Perform flushing analysis
  • Turbidity monitoring
  • SMS does not support BOD/DO modeling with RMA4 because of issues with RMA4.

Using the Model / Practical Notes

  • RMA4 includes support of the SI card which controls what units the engine will use. If SI is set to 0, the model runs with English units. If it is set to 1, the model runs in metric units. SMS saves the SI card based on the coordinate system (projection) specified. However, it is recommended that metric units be used for RMA4. This applies to the hydrodynamics that are fed into RMA4 as well.
  • RMA4 is more sensitive to mass gain/loss than RMA2 across large closed boundary angles. The suggested minimum boundary angle between any two adjacent elements is 10°. This becomes a very great concern, as this applies simply to the wet/dry interface and not to the outer mesh boundary.
  • RMA4 should not be used to evaluate highly volatile materials such as gasoline, nor materials that do not mix with water, such as oil. Although RMA4 has been used to measure temperature effects from such locations as power plant discharges, this is not a recommended application. Although the documentation claims to be able to model up to 6 constituents, the SMS developers have never had success with more than a single constituent at a time. Multiple constituents require multiple boundary condition files, each with values for one of the constituents. Multiple constituents can be named and joined through the Data Calculator and exported to a single file for future use.
  • Card order matters. The RMA4 run control and full print files are very helpful for determining what options are being used.
  • The TABS models are built to expire after a set date. The latest version can be downloaded from the Software Updates section of the Aquaveo website.
  • If the model files included with the tutorial don't load after running the RMA4 model, the solution files may need to be deleted, after which the steps may need to be performed again from the beginning.

Graphical Interface

SMS provides a graphical interface that is designed to visualize the projects being created, easily modify project parameters, and view the solutions produced by the RMA4 model. See RMA4 Graphical Interface for more information.

Saving RMA4

When completing the File | Save As... command, the following files get saved in the *.sms:

  • *.mat referenced to new save location
  • *.mat referenced to new save location
  • *.qsl referenced to new save location (RMA4 solution file)
  • *.sol referenced to new save location and original location (RMA2 solution file)

RMA4 Files

Input and Output files for RMA4.

Input Files

  • Hydrodynamic Solution (usually an RMA2 *.sol file with a path name less than 67 characters long)
  • RMA4 Run Control (Boundary Condition) input (*.trn)
  • GFGEN Output Geometry (*.bin)

Output Files

  • Transport Solution (*.qsl)
  • Full Print Listing File (*.ot3)

Related Topics