: The tool automatically calculates geometric data like stationing, bank reach lengths, and Manning’s n values.
: You must have both Spatial Analyst and 3D Analyst enabled.
Technically, official support from the USACE Hydrologic Engineering Center (HEC) for GeoRAS ended after version 10.2. However, later versions have been made available via the Esri FTP site to support subsequent ArcGIS Desktop releases:
Using HEC-GeoRAS for ArcGIS 10.8: Compatibility and Best Practices
HEC-GeoRAS acts as a bridge between the GIS environment and the hydraulic engine: