Short name: HECRAS 2D
Long name: Hydrologic Engineering Center’s (CEIWR-HEC) River Analysis System (HEC-RAS)
Model type: 1D, 2D, 1D/2D
Usage: · Riverine discharge flow and height stage (water surface elevation)
· Flood extent and 2D flow paths
· Flood hazard mapping (velocity and depth)
· Design flood modelling – planning and design of levees and flood mitigation structures
· Mixed flow regimes
Background: The HEC-RAS system contains several river analysis components for: (1) steady flow water surface profile computations; (2) one- and two-dimensional unsteady flow simulation; (3) movable boundary sediment transport computations; and (4) water quality analysis. A key element is, that all four components use a common geometric data representation and common geometric and hydraulic computation routines. In addition to these river analysis components, the system contains several hydraulic design features that can be invoked once the basic water surface profiles are computed.
. Steady Flow Water Surface Profiles
. One- and Two-Dimensional Unsteady Flow Simulation
. Sediment Transport/Movable Boundary Computations
. Water Quality Analysis
The first version of HEC-RAS (version 1.0) was released in July of 1995. Since that time there have been several major releases of this software package.
Developer: Hydrologic Engineering Centre, U.S. Army Corps of Engineers
Grid Shape: Unstructured
Grid Type: Finite Volume
Model Assumptions:
– 2D Shallow Water Equations (St Vennant)
– 2D Diffusive Wave Equations (DWE)
Assumptions:
– Vertical fluid motion is negligible;
– Velocity is vertically averaged at the cell center (depth averaged flow);
– Energy head is computed at the cell center;
– Manning’s roughness assigned on cell face using roughness value at cell face center;
– Manning’s roughness assumed constant across each cell face, although each cell face can have its own value;
– Rain on grid is applied uniformly to all cells of the 2D flow area;
– Rainfall initial abstraction and other losses need to be accounted for prior to assigning precipitation data;
– At least one external boundary condition must exist on the 2D mesh;
– Time step selection should consider cell size and wave speed.
Input data:
• DEM, topography, hydraulic structures, surface characteristics/roughness
• Ability to model 1D elements of hydraulic structures(bridge or culvert)
Input format: GIS Format; USACE Survey Data Format; HEC-2 Data Format; HEC-RAS Format; UNET Geometric Data Format; MIKE11 Cross-Section Data; CSV Format.
HEC-RAS text file formats: project file .prj (current plan, units, project description); geometry file .g01 (cross-sections, hydraulic structures, modeling approach); steady flow file .f01 (profile information, flow data, boundary conditions); unsteady flow file .u01; quasi-unsteady flow file .q01; plan file .p01 (list of associated inputs, all simulation options).
Input time interval: –
Input Data – model runtime:
• Gridded rainfall
• Inflow boundary conditions (tide, upstream flows)
• Dambreak / releases
Optimization: Manning’s n Values tables; Flow vs Roughness factors; Graphical plots with observed data (profile, cross section, hydrograph plots); steady flow optimization feature
Data Assimilation: Yes
Ensemble: None at this time
Uncertainity: physical parameter sensitivity analysis ?
Simulation Time Interval: range of time intervals used, uniform and variable time steps available for the 1D and 2D unsteady flow modelling
Model Output Time-Series:
• ARCGIS Shapefiles
• Gridded velocity, depth, flow
Time-Series format: Hierarchical Data Format (HDF-5); map-based format
Model Output Statistics: Mean, standard deviation, minimum and maximum
Statistics Format: HDF-5 ?
Installation: Automatic installation package
User Education: BSc
Degree of Difficulty: 3
GIS support: RAS Mapper: Land classification layers can be used for identifying specific parameter values for Manning’s n values, soil data and infiltration parameters
Data Preparation: RAS Mapper
Model Parameters: manning roughness, time-step and mesh size, numerical coefficients (turbulent mixing coefficients, weir coefficient)
Parameter Estimation: RAS Mapper
Model Calibration: Manning’s n Calibration regions with RAS Mapper;
Manning’s n Values tables; Flow vs Roughness factors; Graphical plots with observed data (profile, cross section, hydrograph plots)
Model Verification: Same as above
Can it be run within a workflow or platform and used for real-time flood forecasting: Yes. FEWS adapters exist.
Model setup interface: Integrated mapping and visualization GUI can be used for model setup
Visualization of model output: Integrated mapping and visualization GUI
Hardware Requirements: PC
Parallelization: Can use multiple CPU Cores
Operating System: MS Windows
Language of Core Code: Fortran
Open Source: No
Last Update and Version: 2021 (version 6.0)
Next Update and Version: –
Active Development Community: Yes
Download URL: https://www.hec.usace.army.mil/software/hec-hms/downloads.aspx
Free to Download and Use: Yes
Language of Software Interface: English
Online Support URL: https://www.hec.usace.army.mil/software/support_policy.aspx
Training Material URL (including example data sets): https://www.hec.usace.army.mil/software/hec-ras/documentation.aspx
• Training courses
• Online training
• Support forums – via internet and CoP
Language of Trainings: English
Guidance Material URL (including case studies and benchmarking of performance/speed): https://www.hec.usace.army.mil/software/hec-hms/documentation.aspx
Language of Guidance: English
References: Bergstrom, S. (1995) The HBV Model. In V.P. Singh (Ed.) Computer models of watershed hydrology, pp. 443-476, Water Resources Publications, Highland Ranch, Colorado, USA.
Developer: US Army Corps of Engineers
https://www.hec.usace.army.mil
Mailing Address:
Department of The Army
Corps of Engineers
Institute for Water Resources
Hydrologic Engineering Center
609 Second Street
Davis, CA 95616-4687
HEC Phone: +1 530.756.1104
HEC Fax: +1 530.756.8250