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List of Known Problems:

The following is a list of currently know issues in Version 5.0.6 of HEC-RAS. These bugs have been fixed for the next release of the software.

  1. Manning's n Regions Override Bug. If you used the Manning's n Region option in the RAS Geometry Editor (not RAS Mapper), there may be an issue with your final Manning's n values not being correct within that Region. Unfortunately, in the RAS Geometry Editor, if you draw a region polygon in the counter clockwise direction, the polygon is ending up with a negative area (the shapefile standard is to store it in the clockwise direction). Because it has a negative area, the polygon is actually not being used to override any of the Manning's n values.

    How to check if you have this problem: Go into RAS Mapper, and expand the Geometry layer in question. Go to the Manning's N layer and expand that layer. Then right click on the "Override Regions" layer and select "Open Attribute Table". If any of your polygons have a negative area, they are actually
    not being used.

    How to fix this Problem: The easiest way to fix this issue is to use RAS Mapper. Right click on the "Override Regions" layer in RAS Mapper and select "Edit Geometry". With the "Override Regions" layer highlighted (magenta color), right click on the polygon that has the negative area, then select "View/Edit Points" option. This will bring up a table showing the coordinates for the polygon. At the top of the window, under the area labeled "Table Tools", select the button with two arrows in opposite directions. This button will reverse the order of all the points in the table. Select "OK" to close the editor.

    Confirm in RAS Mapper that all of the polygons have a positive area by opening the Attributes Table for the Override Regions layer. Reprocess the property tables, then confirm the values in RAS Mapper by actually clicking on a mesh Face and asking it to "Plot Property Table", then select "Face: Manning's n Elevation". The values in the property tables are actually, what is used in the computations.

  2. Uniform Lateral Inflow Bug. When using a uniform lateral inflow along a 1D river reach, HEC-RAS is not correctly putting all of the flow into the river from the uniform lateral inflow hydrograph when the lateral inflow extends across a bridge/culvert or an inline structure. The issue is that HEC-RAS is using the length across the bridge/culvert or inline structure to compute the total length, which is then used in computing the Q/ft. The flow is then put in between the cross sections based on the Q/ft computed, times the length between the cross sections. However, no flow is put in between the cross sections upstream and downstream of a bridge/culvert or an inline structure. Therefore, that portion of the flow is not being put into the river. This issue was introduced in Version 5.0.4, and has been in the software since then. This issue has been fixed for the next HEC-RAS release.

    Work Around: For Versions 5.0.4 through 5.0.6, users will need to split up uniform lateral inflows, such that they do not cross bridges/culverts, or inline structures, but they must stop upstream of these structures and a new one must start downstream of these structures. This issue was fixed for the next HEC-RAS release.

  3. Floodway Inundation Boundary Mapping Issue. Inundation Boundary polygons created by RAS Mapper for floodway analysis will not be properly created if cross-section station-elevation data starts with non-zero stationing. This problem does not occur for stationing data that starts at zero. At this time, the work around is to adjust all cross section data to start at zero using the Options | Adjust Stations | Add a Constant menu item and add the left station offset value.

  4. RAS Mapper not Saving all Breakline Options Issue. The software is not saving when the user activates the option to "Enforce a 1 Cell Protection Radius" for some data sets. This is a problem, as you continue to edit/modify your mesh, as the breaklines may not function, as you want them to. This issue was fixed for the next HEC-RAS release.

  5. External SA/2D Hydraulic Structures Issue. If the user has an external SA/2D Hydraulic Connection (i.e., connecting a storage area to a 2D area, or a 2D area to another 2D area), and have entered a
    geo-referenced centerline for the structure, but the length of the station/elevation data does not match
    the length of the structure, there is an issue. The program connects to the 2D cells only based on the geospatial centerline and its length. If the station/elevation data has a length that is longer than this line, then the computational engine has a length of the structure that is not connected to any actual cell, and this causes the software to make incorrect flow calculations if that part of the structure is wet. The user interface should be checking for this and not allowing a user to have a centerline and station/elevation data that are not the same length. This issue will be corrected for the next release. For now, anytime you use an SA/2D Hydraulic Structure, ensure that the centerline length and the stationing length are the same.

  6. 1D Velocity and DV Mapping in RAS Mapper Issue. In Version 5.0.6, if you have cross sections that do not start at a zero stationing, RAS Mapper is not correctly mapping velocity and Depth x Velocity in the 1D model region. A work around for this is to convert all of your cross sections to start at a zero cross section stationing.

  7. Alternative Overbank Deposition Method Issue. HEC-RAS included an alternate overbank deposition method (see Version 5.0.6 Release Notes) that constrained overbank deposition to positive net deposition for each computation increment rather than each mixing time step (which often reduces the computed overbank deposition). The interface to turn this option on has a bug, so the new option is always on by default. The new option is an improvement in most applications, so it is appropriate for most new models. However, if users want to use the old approach to match legacy model results, they must use Version 5.0.5 of HEC-RAS until a new version of HEC-RAS is released.

  8. Max Water Surface Profile Issue. The maximum water surface output profile does not include any of the unsteady warm-up time steps. However, the initial conditions (steady backwater) water surface profile is included in the potential maximum water surface profile. If the initial condition profile has a higher WSE at some given location than the unsteady run, the initial condition profile will be reported as the maximum WSE for that location. This bug has been fixed for the next release of the software.