TopicSupporting Material

HEC-RAS Verification and Validation Document

This document contains analytical and textbook datasets, laboratory datasets, and real world data with observed measurements. HEC-RAS computational results are compared to all of the datasets to verify the solutions of the equations, and to validate HEC-RAS's use for a wide range of computational problems. (Updated September 2020)

Benchmarking of the HEC-RAS Two-Dimensional Hydraulic Modeling Capabilities

This document summarizes how the HEC-RAS software performed in the two-dimensional modeling benchmark tests developed by the United Kingdom's (UK) Joint DEFRA (Department for Environment, Food, and Rural Affairs) Environment Agency. (Updated April 2020)

Modeler Application Guidance or Steady vs. Unsteady and 1D vs. 2D vs. 3D Hydraulic Modeling

All models, numerical or scale-physical, are simplified representations of the real world (prototype). Fortunately, there are numerous practical engineering problems for which simplified numerical models of the prototype are sufficient to provide usable descriptions of system behavior. The challenge for the modeler is to select an appropriate model to solve their particular engineering problem while recognizing that the model is not a perfect representation of the prototype. Selection of a model begins with developing an understanding of which aspects of the complex, real-world system are most important to the engineering problem being addressed. The purpose of this document is to provide entry to mid-level hydraulic engineer’s with guidance on when to use Unsteady Flow modeling instead of Steady flow modeling; and how to select between one-dimensional (1D), two-dimensional (2D), or three-dimensional (3D) modeling for a given problem


Using HEC-RAS for Dam Break Studies

This document provides information on how to use the HEC-RAS (River Analysis System) software when performing a dam break analysis. The document presents the unique hydraulic modeling aspects that are required, plus routing the inflow flood through a reservoir; estimating dam breach characteristics; and, downstream routing/modeling issues


BSTEM Technical Reference and User's Manual

The HEC-RAS software has included mobile bed capabilities since version 4.0. These capabilities compute vertical bed changes in response to dynamic sediment mass balance and bed processes. However, many riverine sediment problems involve lateral bank erosion that does not fit the current computational paradigm. The Bank and Stability Toe Erosion Model (BSTEM) developed by the United States Department of Agriculture Research Station is a physical based model that accounts for the dominant stream bank processes but requires an intermediate level of complexity and parameterization.


Comparison of One-Dimensional Bridge Hydraulic Routines from HEC-RAS, HEC-2, and WSPRO

The hydraulics of flow through bridges is an important aspect of computing water surface profiles. The computation of accurate water surface profiles through bridges is necessary in flood damage reduction studies, channel design and analysis, and stream stability and scour evaluations. There are several one-dimensional water surface profile computer programs available for performing these types of computations. The purpose of this study was to evaluate the effectiveness of the new bridge hydraulics routines in HEC-RAS at sites with extensive observed data, and to compare HEC-RAS to HEC-2 and WSPRO, with respect to bridge modeling performance.

Flow Transitions in Bridge Backwater Analysis

Bridges across floodplains may require special attention in one-dimensional hydraulic modeling if they cause severe contraction and expansion of the flow. The accurate prediction of the energy losses in the contraction reach upstream of the bridge and the expansion reach downstream of the bridge using one-dimensional models presents particular difficulty. Modeling these reaches requires the accurate evaluation of four parameters: the expansion reach length (Le), the contraction reach length (Lc), the expansion coefficient (Ce), and the contraction coefficient (Cc). This report presents research conducted by the author to investigate these four parameters through the use of field data, two-dimensional hydraulic modeling, and one-dimensional modeling.

Making Your HEC-RAS Model Run Faster

The purpose of this document is to provide guidance on model modifications that can be made to an HEC-RAS unsteady flow model (1D and/or 2D) in order to improve computational speed, while maintaining model accuracy.