HEC-GEORAS on a small stream in North Branch, Clear Creek Zhihao 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