Hydraulic Modeling

In HEC-RAS, lateral structures are used to model flow being conveyed out of a river and into an adjacent area (e.g., another river/stream, a 2D area, or a storage area). In this way, lateral structures are useful because they allow the user to model situations where water is leaving a stream/river system. By default, HEC-RAS … Read more

The Manning’s roughness coefficient, which is also commonly referred to as Manning’s n, is an empirical parameter that represents energy loss due to a variety of things such as friction losses, flow separation, turbulence, and very sudden contractions or expansions. Manning’s n values are applied to Manning’s equation, which calculates open channel flow. There are … Read more

As a water resources engineer, many of the hydraulic models you prepare will be steady flow. This is because steady flow models are simpler and require less time to prepare. In many instances, this is appropriate. However, there are times when a more computationally sophisticated model is required to represent the physical processes that occur … Read more

Manning’s roughness coefficient, which is also commonly referred to as Manning’s n, is an empirical parameter that represents energy loss due to a variety of things such as friction losses, flow separation, turbulence, and very sudden contractions or coefficients. Relatively recently, the United States Army Corps of Engineers released versions of HEC-RAS that include two-dimensional … Read more

The Manning’s roughness coefficient, which is also commonly referred to as Manning’s n, is an empirical parameter that represents energy loss due to a variety of things such as friction losses, flow separation, turbulence, and very sudden contractions or expansions. Manning’s n values are applied to Manning’s equation, which calculates open channel flow. In HEC-RAS, … Read more

One of the biggest challenges faced by river engineers today is stabilizing degrading channels. Urbanization and the associated increase in the amount of impervious area have caused an increase in runoff and stream flow rates. As a result, many stream beds have experienced a reduction in channel slope through downcutting or increased channel meander. For … Read more

A culvert is a relatively simple structure, typically a pipe or box, that projects through an earthen embankment to allow flow to be conveyed from an area upstream of a roadway to the downstream end of a roadway. Culverts consist of an inlet, an outlet, and a culvert barrel. Common culvert shapes include circular pipes, … Read more

Bridge scour describes the process of flowing water eroding the streambed or bank near a bridge. It is important to consider bridge scour because it is the most common cause of bridge failures (FHWA, 2012). HEC-RAS uses the methodology outlined in the Federal Highway Administration’s Hydraulic Engineering Circular No. 18 (HEC-18) to estimate scour at … Read more

Introduction Engineers and scientists are using GIS tools to develop HEC-RAS models more and more. As a result, imported cross-sections may have more than 500 points (the limit per cross-section in HEC-RAS). In addition, interpolated cross-sections can easily contain more than 500 points if the bounding cross-sections have more than 255 points. Luckily, the HEC-RAS … Read more

One-dimensional (1D) hydraulic modeling is based on open channel flow principles and calculations. The physical properties of open channels can vary widely, especially in natural channels. For this reason, it is very important to ensure that the cross-sectional geometry in your HEC-RAS model represents reality as closely as possible. Therefore, it is essential that a … Read more