Dear Guy :

RMS XP and RiverCAD XP allow you to select which version of HEC-RAS engine you want to use. We support HEC-RAS 2.2.1, 3.0 and 3.1. There are differences in computed water surface elevations between the different anaysis engines. All versions are accepted by FEMA, so you simply need to select which engine gives you a better water surface elevation for the work you are doing.

Earlier versions of RMS and RiverCAD used only HEC-RAS 2.2.1.

Sincerely,

Chris E. Maeder, M.S.
Senior Technical Engineer
chris.maeder@bossintl.com