HEC-RAS 6.5 Release Notes & Not so new HEC-RAS 6.4.1 New Features

As of September 2024, HEC-RAS is on version 6.5 that was released back in February. Version 6.4.1 was released in June of 2023. Let's start with the latest and greatest.

New (ish) 6.5 Features

The best new feature is the model comparison tool. This is accessed from the main interface. This is a great way to compare different plans (i.e., proposed vs. existing, or what exact changes were made, were there really blocked obstructions added in the proposed conditions, etc.). There was a professor, Ismail Haltas, who created a similar tool called RAS Review (an online web tool that required some basic file knowledge of HEC-RAS), but this integrated tool streamlines the whole process.

Skew on 2D connections (i.e., can now skew 2D bridges) is another useful feature. This one is pretty self-explanatory. More features include simplified 2D bridge improvements, national levee database incorporation, improved weir computations, improved bug fixes for floodway encroachment analysis, a suite of sediment transport tools, and many others.

The full list can be accessed here: https://www.hec.usace.army.mil/confluence/rasdocs/rasrn/latest/new-features

Not so new 6.4.1 Features

Some of these are still worth elaborating on since they add a lot of functionality.

Two massive features IMO

1.      2d unsteady encroachments. I haven’t tested this, but this could be huge for a lot of FEMA streams. 2D has been avoided in technical situations where it was called for due ot the fact there was a floodway present. Link to RAS write up: https://www.hec.usace.army.mil/confluence/rasdocs/rasum/latest/performing-a-floodplain-encroachment-analysis/2d-unsteady-flow-floodway-encroachment-analysis

2.      Reference area query and volume time series. This provides users the ability to add a “reference polygon” and aggregate or average results for all the cells in that area. Previously my workflow for this was export depth raster, clip to selected cells, then run zonal statistics (but wait, you cant on an integer raster, or something like that, idk go ask your gis guy/girl). Blahhh

Other cool features include improved raster export options, large woody debris terrain mods (for those of yall doing stream restorations), the interface for clipping and exporting new terrains is slightly updated, and several others. Ohh, and they changed the ras mapper (the new icon looks pretty slick. Very refinement culture).

Full list of improvements/features: https://www.hec.usace.army.mil/confluence/rasdocs/rasrn/hec-ras-6-4-new-features

Download: https://www.hec.usace.army.mil/software/hec-ras/download.aspx

Rumor on the street is there is pressure/subsurface computations coming to HEC-RAS. There is in fact a way to do it currently, its just not great. It involves lidded XSs and the Priessman slot theory. I suppose you could also do a typical gate with a 1D structure or 2D SA/conn and set it to a rating curve. But that is not a very elegant solution.