HEC-GEORAS on a small stream in North Branch, Clear Creek Zhihao Wang Sep 2011
Feb 22, 2016
HEC-GEORAS on a small stream in North Branch,
Clear CreekZhihao Wang
Sep 2011
HEC-RAS◦perform one-dimensional steady and unsteady
flow river hydraulics calculations
HEC-GeoRAS◦pre- and/or post-process GIS data and HEC-RAS
results for flood inundation mapping using ArcGIS
HEC-GeoRAS creates a file of geometric data for import into HEC-RAS, and enables viewing of exported results from RAS.
Pre-process
Post-process
TIN of part of the North branch, Clear Creek
HEC-GeoRAS requires a DTM (digital terrain model) in the form of TIN or GRID.
30mDEM
8mDEM, 23m z tolerance
8mDEM, 1m z tolerance
Flow rate generated by GeoWEPP (referred to as runoff)
Create RAS layers: ◦Stream centerlines, Banks, Flow paths, Cross
section cutlines, other optional layers◦By creating empty layers and digitize manually
Stream centerlines
Banks
Flow paths
Cross section cutlines
Assign attributes to:◦Stream centerlines (names, topology, length)◦Flow paths (left/right/center)◦Cross section cutlines (river/reach name, bank
stations, elevation…)
Manning’s value
Extract GIS data HEC-RAS geometric data
Cross section view in HEC-RAS
Set up the flow rate data
2-year scenario simulation results
Conventional tillage
Conservation tillage
No tillage