Welcome to the RAS Solution Forums HEC-RAS Help Sediment Transport/Quasi-Unsteady

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  • #5829
    Anonymous
    Guest

    Hi,

    I have constructed a sediment transport model and am having issues getting the water surface elevations for a 24hr sediment transport simulation with just one flow value to match the water surface elevations for a steady flow simulation at the same flow.

    In more detail, I’ve inserted a flow series at the uppermost boundary and filled in one row at 2045 cfs for 24.1 hours. I have three flow change locations and each has a lateral flow series boundary with one flow and 24.1 hours as the duration. My downstream boundary is a stage series with one row filled in at 5.35 ft for a duration of 24.1 hours.

    The steady flow simulation has this same flow at the uppermost boundary and the downstream boundary is defined with the known WS of 5.35 feet.

    When comparing the two, the downstream most cross sections both match at 5.35 feet which means the downstream stage boundaries are being recognized. The upstream most cross sections also match. However, the majority of the interior cross sections differ, on a scale of multiple feet at times.

    Can anyone help with this? The geometry, flow, downstream stage, and flow change locations are all the same across the two simulations. I want to verify that my sediment transport simulation is set up correctly before I remove a dam in the river and model the sediment transport.

    Thank you for the help

    #9415
    cameron
    Participant

    Have you thought of using HEC-RAS 5.0 for the sediment transport model? in 5.0, you can do sediment transport in Unsteady.

    #9416
    Anonymous
    Guest

    Currently, I am trying observe the difference between the prediction in sediment transport trend using the quasi-unsteady and completely unsteady sediment transport module of HEC-RAS 5.0. However, while using the complete unsteady feature of unsteady flow simulation, I couldn’t find several sediment output features available under quasi unsteady-simulation. Model is not unstable either and performing fine as far as hydraulics is concerned. In sediment output prompt lots of output options are missing and sediment output (old) menu is not activated either.

    #9417
    cameron
    Participant

    Have you tried changing the sediment output options level to something else? The level is what controls what outputs are written and it might have changed in 5.0. Make sure you are also using the latest version released to the public of August 2015.

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