HEC-RAS Known Issues

Period Average Data Interpolation Issue

A long standing issue was uncovered that impacted datasets using period average input data. The start of the time window was impacting how period average data was interpolated into instantaneous value data. This issue was causing a time offset to appear in the input hydrographs. This issues has been resolved inversion 6.3 and could be a cause for results to differ from previous versions in models using period average data with longer periods.

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 with new values. 

Save Geometry from Mapper Changes Lateral Structure HW Connection Settings

At some lateral structures, editing and saving the Geometry from RAS Mapper causes the structure's HW connection setting to change from User Specified to Default. 

Bridges In Multiple 2D Areas Prevent Unsteady Flow Simulation from Starting

When there are multiple 2D areas in a model that contain bridges, an error occurs that prevents the simulation from running: "allocatable array is already allocated". Workaround: If possible, use a single 2D area instead of multiple 2D areas with bridges. Use other SA/2D Connection types to model bridges in 2D areas.

Weir Breach Not Progressing When Using Normal 2D Equation Overflow Option

If the Normal 2D Equation Overflow Option is used for a Storage Area / 2D Connection and the connection is breached, the breach does to progress as expected. Additionally, breach flow is delayed from reaching the connected storage area until the pipe breach transitions to an overtopping breach. Workaround: Select the Weir Flow Overflow Computation Option for structures that are set to breach. 

Legacy Sediment Hotstart Approach Will Not Be Supported in version 6.3 plus

HEC-RAS has included a new, superior, hotstart option that can simply point to a sediment result file.  2D will use this in version 6.3.  RAS is dropping the old legacy gradational hotstart in version 6.3.  The sediment hotstart will also move from the output options to the computational options.

Storage Areas Not Receiving Time Series Precipitation Data

Storage areas are not receiving precipitation when a simple time series Precipitation Boundary Condition is used.

Save Geometry from Mapper Fills in Empty Low Chords at Some Bridges 

At some bridges, editing and saving the Geometry from RAS Mapper causes the bridge stationing data to be modified in the Geometry file. This occurs where bridges are or were using empty low chords.

Default Max Weir Submergence is Not Set for Inline Structure Created in Mapper 

Inline structures that are added from RAS Mapper are not getting the default Max Weir Submergence Ratios set. This prevents the the simulation from starting, and the following error is not displayed: "Weir maximum submergence ratio is not set". Workaround: Only add inline structures through the Geometry Editor, not Mapper. 

Unsteady Simulation Fails for 2D Areas with Large Numbers of Cells  

The Unsteady Flow Simulation fails to run for 2D Areas that have a large number of cells ( greater than 500K-750K). The resulting error message looks like this: "Error with program: RasUnsteady.exe  Process Count = 29  Exit Code = -1073741571". Workaround: 1.Where possible, reduce the number of cells in the 2D Area in places where higher resolution is not required. 2. Break up the 2D area into multiple 2D areas to reduce the number of cells in each area. 3. Revert to version 6.1, until 6.3 is available. 

Observed Data Not Being Displayed in Stage and Flow Hydrograph Plots

The Stage and Flow Hydrograph Plotter will not plot observed data with computed results for cross-sections that have Node Names. Workaround:  Remove the Node Names from the cross-sections at which you want to display observed data. You can access all the node names from the Geometric Editor: Tables | Names | Node Names...

Observed Data in SI Units Multiplied by Conversion Upon Each Compute

For models in SI units, observed timeseries data are multiplied by conversion to English units upon each compute. 

Pump Shutdown Time

The Pump Shutdown Time was being ignored.  The pump flow was going to zero in one time step.  Workaround:  There is not a simple workaround.  However, Rules could be added to the pump station and used to gradually reduce the flow before the pump is shut off.  These are the rules on the Unsteady Flow Data editor (where hydrographs are entered) not the Advanced Control Rules on the Pump Station Data Editor.

Hydrograph Output Interval (DSS) less than a minute and Detailed Output (Post Processor)

Using a Hydrograph Output Interval less than a minute (1 Second to 30 Second) can cause an error when trying to run the Post Processor.  This is a known issue for models that have gates (and may be an issue for other models also).  The first message will be 'Error running the unsteady post processor'.  The last error message will be 'Error reading dss pathname: /...'  Workaround:  The only option is to use an output interval of one minute or longer.  Or alternatively, when using a Hydrograph Interval of less than 1 minute to not run the post processor.

Ubiquitous Help Launch in Sediment Output Options and BSTEM Material Properties Editors

Any Key Press launched the help webpage on the Sediment Output Editor and the BSTEM Material Properties editor.  This should only be F1.  Workaround:  This is annoying...typing a three digit number launches three browsers.  But users can still enter all data.    

2D Sediment Model Crashes when using Non-erodible Surfaces

The 2D sediment model can crash when using the non-erodible surface bed material type. Workaround: Create an additional bed gradation consisting of a large grain size such as bolders and replace all non-erodible surfaces with this new bed gradation. 

Breakline Editor Creating Duplicate Refinement Breaklines

The Breakline editor may create duplicate breaklines if the order in the table is changed.  Trying to delete duplicates may cause a crash.   Workaround: Split overlapping breaklines so that they do not overlap. This way the order of the breakline enforcement does not matter. 

2D Bridge Output Issue

2D bridges have an output issue that affect both the stage/flow hydrograph plot and the RASMapper results. This only affects the output. After the 2D results have been computed, the output flows and velocities at some faces are incorrectly being overwritten based on new limits from the 1D bridge curves. This is causing the reported hydrograph flow from the 2D bridge to be lower than the actual flow. And on RASMapper, the velocities and flows shown at the faces at the centerline of the bridge may also be lower than the actual flows that were computed. The immediately adjacent faces (either upstream or downstream) are correct for those locations.

Pumps Pumping to Dry 2D Area

A pumping station pumping flow to a 2D area that was completely dry was not putting any flow into the 2D area.  (It was not triggering the flag to cause that 2D area to perform computations).  Workaround:  Put a small amount of water into the 2D area either using the Initial Conditions, Initial WSE Elevation, or use a Boundary Condition Flow to add a small amount of water to the 2D area.

Refinement Region Editor Creating Duplicate Refinement Regions

Refinement region editor may create duplicate refinement regions if the order in the table is changed.  Trying to delete duplicates may cause a crash.   Workaround: reorder the refinement regions by right clicking the region, and using the Send.. menu item.

A pumping station where the inlet and outlet are inside of the same 2D flow area (as opposed to pumping between two different 2D areas) pumps exactly twice the flow that it should.  Note:  It is pumping twice the flow shown on the pump stage/flow hydrograph output. This issue is present in previous versions (it is not new to v6.2).

2D Reference Line Flow

A 2D Reference Line is not computing flow (it is showing zero flow).   Workaround: turn on the optional face flow output.  From the Unsteady Flow Analysis run editor, choose the Options | Output Options menu item, click on the HDF5 Write Parameters tab, scroll down and turn on the Face Flow option.  Rerun the model.

Advanced Rules using Reference Line Flow

A 2D Reference Line for rules is not computing flow. (It is computing zero flow). See 2D Reference Line Flow above. This also true for any 2D advanced rules using reference lines for computing flow. Use Workaround as described above.

Water quality simulations do not function with unsteady flow hydraulic results. Workaround: Use steady flow hydraulics instead, or revert to a previous version. Note  This bug applies to the the previous version 6 releases as well. 

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