SimRAS, a Multipurpose HEC-RAS Simulation Tool

WEST Introduces SimRAS!

SimRAS is a multipurpose HEC-RAS simulation tool with a simple graphic interface. It allows the user to assign a statistical distribution to one or more key parameters in the chosen HEC-RAS 1-D or 2-D model. Completely automated, SimRAS runs the HEC-RAS model multiple times, selecting randomized values of the key parameters for each run (consistent with a Monte Carlo analysis). When complete, the results can be used to determine the risk of a particular event occurring, evaluate parameter sensitivity, and/or determine most likely outcomes.


• Easy-to-use GUI interface minimizes learning curve, allowing efficient, error-free simulations.
• Facilitates statistical distribution type and parameter selection with dynamic plots
• Guided input selection
• Instant results reporting through dynamic tables and figures
• Python based program allows easy modification to individual projects
• Live feedback during simulation
• Utilizes HEC-RAS standard database (HEC-DSS) for all parameter and results storage
• Truncated distributions fully supported

• Dam Break Modeling
• Levee Breach Modeling
• River Model Sensitivity Analyses
• Emergency Action Planning
• Uncertainty Analysis
• Risk Analysis
• Design of Simulated Experiments
• Floodplain Delineation

Recently, WEST Consultants used SimRAS to complete a probabilistic breach outflow analysis on a major dam in Montana. WEST worked with the Federal Energy Regulatory Commission (FERC) to define the breach outflow parameters and then used SimRAS to successfully map the 1% flooding risk by rapidly computing thousands of different, randomized scenarios. The results will be used to reassess the hazard classification of the dam.

SimRAS is optimized for levee and dam breach studies, with work currently underway to extend the capabilities to simulate all types of river models.

SimRAS is applied risk assessment. By directly simulating the probability distributions for all key parameters, risk analysis of dams and levees can be rapidly determined, allowing risk-based floodplain mapping that accounts for every identified uncertainty and is easily shown through standard mapping procedures.

Supported distributions:
• Normal (Gaussian)
• Skew-normal
• Lognormal
• Triangular
• Uniform

Supported parameters:


• Final breach bottom width
• Final breach elevation
• Breach slopes
• Weir coefficient
• Breach formation time
• Initial piping elevation


• Manning’s roughness (channel and overbank)
• Hydrology
• Bridge parameters
• Temperature
• Culverts
• Inline structures
• Encroachments

WEST Consultants is internationally recognized as an expert on HEC-RAS, with extensive experience applying HEC-RAS to thousands of projects on behalf of the United States Army Corps of Engineers (USACE), the Federal Emergency Management Agency (FEMA), the Federal Highway Administration (FHWA), the Federal Regulatory Commission (FERC), and many other federal, state, and local clients. WEST is a contractor to the USACE Hydrologic Engineering Center (HEC) and is the on-site HEC-RAS instructor for the American Society of Civil Engineers (ASCE). WEST has developed numerous stand-alone and HEC-RAS supporting software including WinXSPRO, WEST-EDI, and the RIPRAP Design System.

For more information please contact:

Brent Travis, Ph.D., P.E., D.WRE
Director of Applied Research

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