Hydraulic Modeling

I am working on a one-dimensional (1D) dam-break model in HEC-RAS this week. Typically, I work with 2D HEC-RAS models, so this project has been somewhat challenging. Cross-section placement is an art, and I am slightly out of practice. Anyways, I have been having issues stabilizing the model. This is not an uncommon problem for … Read more

Preparing a stable unsteady HEC-RAS model is a common problem among hydraulic modelers. This is particularly true when preparing a dam-break model in HEC-RAS. An unstable HEC-RAS model results in numerical errors that grow until the results start to oscillate. As a result, the errors grow until the model computations cannot continue. There are many … Read more

If you have been using HEC-RAS for a while, there is a good chance that you have run into the “disappearing terrain” issue. Yes, I am talking about when your background terrain disappears from the Geometric Data Editor. Although it is annoying, this is a fairly common problem. Fortunately, I am going to share some … Read more

According to “Hydraulic Design of Safe Bridges” (FHWA, 2012), skew is defined as “a condition when a bridge opening is not perpendicular to flow or when a pier is not aligned with the flow.” It is important to account for the bridge skew angle because it can affect the amount of backwater at the bridge, … Read more

Introduction This blog post will introduce the steps involved in performing a simple sediment transport analysis using the HEC-RAS program.  HEC-RAS is capable of mobile boundary, and sediment transport modeling. A boundary is mobile when flow carries a lot of sediment through suspension and is in contact with the streambed. In these cases, the following … Read more

Boundary conditions are an important part of hydraulic modeling as they allow hydraulic modeling programs such as HEC-RAS to begin performing water surface profile calculations. In HEC-RAS, users enter boundary conditions in the Steady Flow Data Editor and the Unsteady Flow Data Editor. The following article is an introduction to applying boundary conditions in HEC-RAS … Read more

What is the HEC-RAS Controller? The HEC-RAS Controller is part of the HEC-RAS application programming interface (API). An API is a collection of tools and protocols used in programming. The HEC-RAS API is comprised of three classes: the HEC-RAS Controller, HEC-RAS Flow, and HEC-RAS Geometry. The HEC-RAS Controller, which is the largest class of the … Read more

Although HEC-RAS allows users to add structures to two-dimensional (2D) hydraulic models, adding structures can create instability issues within your model. It’s for this reason that modelers may choose to remove bridge decks. This is appropriate when the modeler is not interested in evaluating detailed bridge hydraulics. In some cases, Light Detection and Ranging (LiDAR) … Read more

In a previous blog post, I wrote an introduction to automating HEC-RAS using the HEC-RAS Controller. For this blog post, I will be showing you how to write a simple program that retrieves output data using the HEC-RAS Controller. Getting Output Using the HEC-RAS Controller Download the Appropriate Files For this exercise, I will be … Read more