Lateral Structure Coefficients

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 […]

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Q & A: Flow Attenuation

Question: When running an unsteady flow model with a single inflow hydrograph, why does my discharge decrease in the downstream direction for a given output profile? Answer: This is called flow attenuation.  You see this to varying degrees in all unsteady flow models and it is a real phenomenon.  The shallower the reach, or the […]

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Steady versus Unsteady Flow

Written by Chris Goodell, P.E., D. WRE | WEST ConsultantsCopyright © RASModel.com. 2010. All rights reserved.I was recently emailed this question regarding steady flow versus unsteady flow results: “My question is fairly basic. I have heard from a couple of other engineers that when flood levels are generated with usteady flows that it is typical […]

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