Hydrologic Engineering Center - River Analysis System (HEC-RAS)

Purpose:	1D hydraulic modeling
Developer:	U.S. Army Corps of Engineers Hydrologic Engineering Center (USACE HEC)
Key Features:	GIS capabilities; All components use a common geometric data representation, and common geometric and hydraulic computation routines
Latest Release:	Version 4.1, January, 2010
OS Platform:	Windows, UNIX
Cost:	Free
Related Software:	Flood Modeller, MIKE 11, SOBEK,
Website:	HEC-RAS home page

Introduction

HEC-RAS, first released in 1995 as the successor to HEC-2, models 1D hydraulic processes for a full network of natural and constructed channels. HEC-RAS contains 4 1D hydraulic components that model steady water flow, unsteady water flow surface profiles, movable boundary sediment transport, and water quality. HEC-RAS models steady flow using the energy equation and the standard step method, and unsteady flow using the Saint Venant equation. HEC-RAS has been used to design hydraulic structures, for bridge scour analysis, floodplain analysis, dam break and levee breach analysis, sediment transportation, evaluation of deposition in reservoirs, and water quality. Although applications are of multidimensional nature, the software's solutions involve one-dimensional calculations. Key features of the HEC-RAS model include a Graphical User Interface (GUI), data storage and management, and GIS-related tools and capabilities.

Advantages and Limitations

Advantages	Limitations
Graphical User Interface GIS capabilities Ability to import MIKE11 Cross Sections Training available via vendors (universities, engineering societies) Widely used across the world Detailed technical report and users' manual	Model code is not publicly available No support provided for users other than U.S. Army Corps of Engineers Only 1D modeling Modeling skews of hydraulic structures is limited to 30 degrees Cannot currently account for steep slopes above 10% inside the model

Input

Output

Sample Applications

Africa	East Asia and the Pacific	Europe & Central Asia	Latin America & the Caribbean	Middle East and North Africa	South Asia
Kenya (Hydrologic impacts due to dam)	Philippines (Flood Monitoring)	Hydraulic modeling of flood plains, lower Tisza River, Hungary	Chile (Environmental Effects due to Dams) Flooding analysis for Taquaraçu river, Brazil	Iraq (Channel Morphology)