HEC-RAS Known Issues

In at least one data set, the simplified physical breaching algorithm widens at the user-specified pace...but erodes vertically to the max extent almost immediately.

There seem to be several issues with the current release of the DLBreach call from HEC-RAS.  We are actively working on these.

The new Annual Load feature in 6.4/6.4.1 does not update based on user decisions.  It computes based on the Duan corrected, non-averaged, initial data input and will not update for clustering, piecewise linear, or other rating curve updates.  There is no work-around in 6.4.1, but this has been fixed for 6.5 and will be fixed in the 6.5 beta release. 

The sediment transport capacity calculator (in the Hydraulic Design editor) computes bad values if some of the cross sections are included in the "Sediment Reach." Workaround: Select all of the cross sections in the Sediment reach.  The tool appears to work if all of the cross sections are selected.

Hydrographs from Reference Lines are not plot values when using the Adaptive Timestep option.

The Rating Curve Calculator assumes US Customary Units. This means the labels are wrong and the Load<-->Concentration conversion is incorrect if users import SI data. If users are importing data from the USGS database, this is not an issue, because the tool imports in US Customary. But if users import their own data (through the clipboard) this labels and the concentration conversion will be wrong.  Workaround:  As long as users don't convert between load and velocity, only the labels are wrong.  None of the stats should be sensitive to units.  Just import data in the form you want to use (Load or Concertation).

Pumps Advanced Control Rules (from the Pump Editor in the Geometric Data Editor) are not saving if Geometry is edited in RAS Mapper.  Workaround: none.  However, you can create advanced Rules in the Unsteady Flow Editor to replace pump logic.

If there are more than 20 pumping stations in the model a  "Program Exception - access violation" will occur at the start of the run.  Additional text will be written out including "1708 Jobinit".  Workaround: Reduce the number of pumping stations to 20.  It would be time consuming and awkward, but it would be possible to replace a pumping station with a lateral structure or a SA 2D connector and then use a georeferenced gate or culvert for the pump.  And then use the Advanced Rules to replicate the pump flow and pump operations.

1D elements are not computing infiltration losses when the finite volume method is selected. This will result in the total precipitation entering the 1D system, not excess precipitation. 

When weir flow is computed for a structured connected to a 2D area, a profile of the water surface is developed from the cell faces connected to the structure. The development of this profile was not taking into account hydraulic connectivity between cells leading to a less accurate weir flow calculations. 

After editing the alignment of an existing Gate/Culvert/Outlet Time Series/Rating Curves for Hydraulics Structures within RAS Mapper, the edits will not be saved. New culverts will save.  Workaround: From the Geometric Data Editor, change the X,Y coordinates manually (use the Ctrl key to digitize the culvert/gate line).

2D Area hydraulic tables are recomputed during simulation if the 2D Connection Elevations were updated through RAS Mapper. Workaround: Update elevations from the Geometric Data Editor.

The National Weather Service's Weather Prediction Center provides 2 national gridded precipitation products in GRIB2 format: Quantitative Precipitation Estimates (QPE) and Quantitative Precipitation Forecasts (QPF). Currently, RAS is unable to import the QPF dataset due to its compression type. Workaround: Use HEC-MetVue or HEC-Vortex to convert the QPF data to DSS before use in RAS. 

HEC-RAS geospatial libraries cannot determine the projection data stored in GeoTIFFs exported from a common CAD application. This results in a failure when importing the geotiff to a RAS terrain. 
Workaround: Reproject the terrain to a desired projection in a GIS application before importing. Alternatively, import the terrain in RAS before defining a projection in Mapper, then set the appropriate projection (spatialreference.org) following import. 

"Error initializing the GDAL path variables. Please check HEC-RAS installation" error message is displayed when attempting to open RAS Mapper.