Version 5 of HEC-RAS allows the use of rating curves for inline structures (and lateral structures). Rating curves can be added through the Outlet RC feature in the inline structure editor. Inline structure rating curves can be useful for evaluating the impacts of structures, such as labyrinth dams, where it may be difficult to correctly […]
Want to simulate a time series of outflows for a dam? It’s easy. In Version 5.0.3 there’s a new feature called Outlet T.S. (Outlet Time Series) in the inline structure editor. Click the Outlet TS button and give your new time series a name. You might name it “Powerhouse” or “Fish Bypass” or something […]
HEC-RAS has the ability to simulate flow at hydraulic controls in a variety of ways. Bridges, culverts, inline structures, lateral structures, and SA/2D area connections can all act as hydraulic controls. Effectively, they break up the conservation equations used between cross sections in a 1D reach and/or cells in a 2D area with empirically derived […]
HEC-RAS allows for four different gate types that will compute the stage-discharge relationship of that gate for you based on the physical size/shape of the gate and a few empirical coefficients: Sluice Gates, Radial Gates, Overflow Gates (closed top) and Overflow Gates (open air). However, sometimes the built-in gate types don’t quite fit the gate […]
Lateral structures can be used in HEC-RAS to transfer flow from a river/reach to a storage area, or to another river/reach. With the coming release of HEC-RAS with 2D capabilities (estimated beta release January/February 2014), you’ll be able to hook a river/reach to a 2-D area using a lateral structure. Although its primary function in […]
This is a great presentation put together by Mr. Steven Piper of the Hydrologic Engineering Center that discusses in detail the use of “Rules” at inline structures. Dr. Michael Gee forwarded this presentation to me after seeing some discussion on the forum about the use of Rules for inline structures. Thanks for the suggestion Dr. […]
Though it’s not very common, it is possible to get negative flows over inline structures for unsteady flow simulations. It’s much more likely you’ll see negative flows over a lateral structure though. Negative flows are simply discharges in your model going the opposite direction than what you have defined as the downstream direction (or primary […]
So many of us know that if you experience instabilities at or near your inline structure, you should bump up the Inline Structure Flow Stability Factor from the default of 1 to the most stable value of 3. But what is really going on when you do this? Here’s an example of a RAS model […]