To run HEC-GeoRAS on ArcGIS 10.8, your system must meet specific software prerequisites: : Must be version 10.8.x.
: Version 4.2 or later is required for full functionality, though HEC-RAS 5.0+ is highly recommended for modern modeling. Core Functionality hec georas for arcgis 10.8
This guide covers everything you need to know about using HEC-GeoRAS with ArcGIS Desktop 10.8. What is HEC-GeoRAS? To run HEC-GeoRAS on ArcGIS 10