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Difference in peak flow

Hi,

I'm working on a combined sewer model, using SewerGEMS. I'm trying to determine the maximum sanitary load that we can add before the pump station overflows during a rainfall event. My problem is that there's a difference in the flow entering the pump station when I try to put the inflow at different nodes in the sewer system. The flow entering the pump station is bigger when the inflow is far from it. The sanitary load is fixed. Does anyone know why the model reacts like this?

Thank you

  • We would need a copy of your model, to see how the model is set up.

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    Regards,

    Sushma Choure

    Bentley Technical Suppport

  • I've uplaoded my file (2416-10-03-Regulateur_Saint-Louis.stsw.zip), Thank you!
  • Hello Marie,

    I took a look at your model.
    The none of the pumps are delivering any flow at any time step, you may want to check that.
    To check the problem with the inflow getting added, i added fixed inflow at some manholes at long distance, but i didn't get any odd results.

    Could you please explain further, may be by leading us to particular location in your model, if the flow is added there, you are getting wrong results?

    The scenario I looked at is, ES-01516.

    Regards,

    Sushma Choure

    Bentley Technical Suppport

  • Hello Sushma,
    I my model there is 2 pump station and one votex chamber. In all scenarios (Actuel_Qmoy, Emissaire_autoroute, Bassin_retention, TPU_Ferme, Actuel_Qmax, Statuquo) PMP-4 doesn't start (very small watershed) and PMP-3 starts at least 4 times. For example, when I use the scenario Statuquo, and add fixed inflow (10 L/s) at node 123-005 and run the model the flow in conduit ES-21129 is 175L/s. If I delete the fixed inflow at node 123-005 and add 10 L/s at node 124-818 and run the model again the flow is not the same (178L/s) in conduit ES-21129. Does it help to understand my problem?

    Thank you
  • Hello Sushma,
    I just want to know if I explained my problem well enough and if you an idea why my model reacts like this?

    Thank you and have a nice day