Hydraulics and Hydrology
Tools and Models - HecGeoRas

HEC-GeoRAS 3.1.1 is an ArcView GIS extension that provides the user with a set of procedures, tools, and utilities for the preparation of GIS data for import into HEC-RAS, and generation of GIS data from RAS output. While the GeoRAS extension is designed for users with limited geographic information systems (GIS) experience, knowledge of ArcView GIS is advantageous. Users, however, must have experience modeling with HEC-RAS and have a thorough understanding of river hydraulics to properly create interpret GIS data sets.  ArcView GIS 3.2, for Windows OS, with the 3D Analysts Extensions is required. The Spatial Analyst extension is recommended.

GeoRAS allows the preparation of geometric data for import into HEC-RAS and processes simulation results exported from 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. 

Additional RAS Themes may be created/used to extract additional geometric data for import in HEC-RAS.  These themes include Land Use, Levee Alignment, Ineffective Flow Areas, and Storage Areas.

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.