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Modelling Pond outlet and emergency flow in SewerGems

Hi

I am going to model a Pond which has 3 outlet: one HICKENBOTTOM RISER and two twin DI (ditch inlet) in SewerGems.

Also there is an emergency spillway and two inlet headwalls.

Could you please let me know:

1-Pond inlets should be used as outfall or headwall? and what type of Boundary condition should be used?(please see the attached files)

2-for composite outlet structures what types of the outlet structures should be used? what flow direction? headwater type and Tailwater type?

3-regarding to the attached (secure files) how can I fill out the items for Riser, orifice?

At the end I 'll appreciate you if you let me have a model from the attached files to help me to learn modelling the pond in SewerGems.

 

Thanks in advance

Hamid

 

  • Hello Hamid,

    There are a number of files available. Could you let me know what your files are called so I can be sure that I am looking at the right one?

    1) In general, a pond inlet is an outfall with a "Boundary Condition" set to Boundary Element, with the pond as the selected element.

    2) The outlet structure should consist of the elements involved. A spillway would likely be modeled as a weir, and the riser as a riser. I would need to know more about the other elements to provide additional information. Knowing the names of the files will be helpful for this.

    Flow direction will be up to what is expected and your engineering judgment. If flow is only expected in one direction though, typically you would choose Forward Flow Only. The headwater type would likely be set to pond associated with the outlet structure, though you can enter user-defined data as well. The tailwater type is up to your engineering judgment, though if a free outfall (and no tailwater effect) is expected, Free Outfall should be fine. If the flow out of the pond can change depending on tailwater conditions, some downstream element or user-defined tailwater will be needed.

    3) Please let us know the names of the files. We can then look into that.

    Thank you.

    Regards,
    Scott
  • 00000-POND-Cross-Section.dwg & outlet.zip

    I 'll appreciate you if you can model the outlet for me, because there is no example pond model to be used in sewergems and I just used civil-storm example files but all of those have give some errors after compute!
  • Take a look at the "Office project" example included with SewerGEMS. This is located within the "Office project" subfolder within the Samples folder.It includes three ponds with different outlet structures, including an orifice, riser and weirs.

    Some additional feedback on your numbered questions:

    1) You can use the headwall element in place of the outfall if you'd like. Additional headloss will be accounted for as appropriate. See below Technote, specifically the image linked to below it.

    http://communities.bentley.com/products/hydraulics___hydrology/w/hydraulics_and_hydrology__wiki/16005.headwalls

    http://communities.bentley.com/resized-image.ashx/__size/690x0/__key/communityserver-wikis-components-files/00-00-00-00-32/18.png

    2) and 3) As Scott mentioned, the configuration and data input depends on what outlet structure(s) you want to design and their sizes and specifications. If you have any specific questions that are not answered in the Help documentation or the community wiki, please post them on the forum.


    Regards,

    Jesse Dringoli
    Technical Support Manager, OpenFlows
    Bentley Communities Site Administrator
    Bentley Systems, Inc.

  • Thanks for your explanation.
    But the issue is I don't know what the "office project" sample file is about, what data given and what data is looking for, I wish I could find an explanation of the question and given data of that.
    anyways, I sent a dwg file which is include a pond drawings with plan and profile.
    in that case, there is rise with orifice and 2 ditch inlets ,
    I will wonder if you do a favour for me and model the outlet structure based on the example to I figure out what should I enter for the riser / orifice and... parameters.

    Best regards

    Hamid