If you do HEC-RAS for the flood or water quality modeling, HEC-GeoRAS may help you. In general, HEC-GeoRAS is a plugin in ArcGIS, to help to process geospatial data from the raster image. 1) It is very helpful that allows the preparation of geometric data for import into HEC-RAS and 2) helps to display the GIS outcome, based on the outcome of HEC-RAS. This software can be download from this link.
Preparation of geometric data for import into HEC-RAS
To create the import file, the user must have an existing digital terrain model (DTM) of the river system in the ArcInfo TIN format. The user creates a series of line themes pertinent to developing geometric data for HEC-RAS. The themes created are the Stream Centerline, Flow Path Centerlines (optional), Main Channel Banks (optional), and Cross Section Cut Lines referred to as the RAS Themes.
These are the best tutorial that I obtained from youtube:
Helps to display the GIS outcome
Water surface profile data and velocity data exported from HEC-RAS simulations may be processed by HEC-GeoRAS for GIS analysis for floodplain mapping, flood damage computations, ecosystem restoration, and flood warning response and preparedness.
The tutorial to export the data from HEC-RAS to GeoRAS as follows:
Credit: Yasir A. for the good tutorials.