HEC has largely transitioned away from GeoRAS because (including 6.0+) now includes RAS Mapper .
If you have older versions of GeoRAS, GeoHMS, or Arc Hydro installed, remove them first.
GeoRAS works best with a Digital Terrain Model (DTM) in TIN or high-resolution GRID/DEM format. Installation Guide for ArcGIS 10.8 hec georas for arcgis 108 upd
To run HEC-GeoRAS 10.8 successfully on ArcGIS 10.8, you must meet the following system and software criteria:
Both 3D Analyst and Spatial Analyst extensions must be installed and active. Operating System: It is strictly compatible with Windows . HEC has largely transitioned away from GeoRAS because
You should use the specific setup package for your version, such as HEC-GeoRAS 10.8.0.3 for ArcGIS 10.8.0/1.
While HEC-GeoRAS is considered a legacy extension, many engineers still rely on the specific update for compatibility with ArcGIS Desktop 10.8.x . The Hydrologic Engineering Center (HEC) officially stopped verifying versions after ArcGIS 10.2, but unverified versions for newer ArcMap releases are often available through community repositories and the Esri FTP site. Compatibility and Requirements Installation Guide for ArcGIS 10
If the toolbar doesn't appear after installation, you may need to right-click the toolbar area in ArcMap and select "HEC-GeoRAS" or reset your ESRI registry settings. Why Switch to RAS Mapper?