HEC-RAS Known Issues

The SCS Curve Number reset time is not set to the user-specified value and instead defaults to 24 hours only for 1D cross-sections and storage areas. This works properly for 2D cells. 

Cell Manning's n is being overwritten by face-averaged values by mistake because the cell Manning’s n value is not initialized correctly. Unfortunately, there is no workaround that utilizes spatially variable roughness values. 

If you define a sediment boundary condition with concentration (mg/L) it should not be converted.  But versions 6.3.1 and earlier applies a metric-ton conversion increasing the load by about 10%.  Work Around: Define your rating curve in Load.

In 6.3.1 the sediment rating curve feature tries to connect with the USGS server whether the user expects to download data or not, and the calculator can crash if there is not internet signal or if the signal is weak.  6.4 fixes this issue.

When you type a number into the concertation calculator in the Non-Newtonian editor it launches the user support webpage, making it very annoying to use.  This has been fixed in 6.4.

If you try to interpolate gradations across a structure in the sediment model RAS will crash at runtime with an uninformative runtime error.
Work around: Drag gradations instead of interpolating them or make sure that all structures are bounded by gradations selected from the drop down menu.

When a geometry is saved in RAS Mapper the Multiple Opening Analysis Data is lost.

When using the "Spatially varied Manning's n on face" options for a 2D area, n values set for Calibration Regions are not applied to cell faces that are partially covered by the Calibration Region. Instead, the default n value for the 2D area is used. Note that this bug only impacts cells faces that are partially inside a Calibration Region. 

For some models using and adaptive timestep, the Post Processor fails to finish and instead shows an error that reads "fortl: severe (157): Program Exception - access violation". The only known workaround at this time is to run the simulation without an adaptive timestep. 

Some models with structures that utilize user defined gate curves are unable to save geometry edits made in RAS Mapper. When attempting to save an error message will appear: "Error reading geometry data from file"

Reference lines are not allowed in a 1D only model. A runtime crash will ensue for models that have 1D elements only and Reference Lines.

Period Average to Instantaneous Value Interpolation Shifted Resulting Timeseries 1 Period Later

When period a time series of period average input data is interpolated to instantaneous value data, the resulting times series was shifted a period later. A fix was made in RAS 6.3, but this did not resolve the issue fully. Now, when using period average data the center of the period is used for interpolation to instantaneous value data, eliminating the shift that was occurring. 

Save Geometry from Mapper Changes Junction Lengths

At some junctions, editing and saving the Geometry from RAS Mapper causes the junction lengths to be recomputed and replaced automatically with new values that were inaccurate. Now, junction length computations are accurate, and a user must elect to re-compute Junction Lengths from RAS Mapper.

Observed Rating Curves Not Plotting on Reference Lines and Cross-Sections Hydrographs

Observed Rating Curves were not plotting on cross-sections and Reference Line hydrographs

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.