Ascertaining the maximum hydraulic grade when we have a pump and wetwell modelled in civilstorm

We have created a storm water model wherein we have a series of ditches and pipes that drain to a sump (in civilstorm terms a wet well) from there a pump is continuously pumping out. For the extent of area that we have we know that for sure there will be overflow, but we wanted to know when there is an overflow what will be the maximum hydraulic gradient line in the entire conveyance system. But our model is showing just the overflow discharge we could not see the maximum hydraulic gradient line. Can we know if there is a way that exists to ascertain the maximum HGL in civilstorm for this condition? 

  • Hello Shobana,

    You could add color coding to your model for the maximum hydraulic grade. This would allow you to see how the maximum hydraulic grade changes across your system. 

    To see numerical results, it would depend on the solver you are using. For the Implicit solver, you can see the maximum hydraulic grade by opening the Calculation Summary (Home > Summary or Analysis > Summary). Click the Details button and click the General Summary tab. You will see the maximum hydraulic grade as one of the results. For the Explicit solver, open the Calculation Summary and go to the Nodes tab. 

    It is possible to see maximum hydraulic grade results in the element flextables as well. If the Hydraulic Grade (Maximum) field is not in the flextable, you can click the Edit button to add it. Note: maximum hydraulic grade is not a reported field for pumps. It is for wet wells and pressure junctions. See this link for information on editing the flextables: Customizing FlexTables for viewing and reporting data.



    Hello Scott,
                       Thank you for the response. We have the color code turned on, the issue is it is showing the maximum hydraulic gradient line as max operating elevation of wetwall for the entire conveyance system. As there is an overflow, it is supposed to show the actual maximum hydraulic gradient line, but it is not showing the maximum hydraulic gradient line beyond the top of wet well. We tried increasing the wet well top for that case it is again showing maximum hydraulic gradient line upto the wet well. Our intention is to view the actual maximum hydraulic gradient line for the conveyance system which we know for sure that will be more than the top of wet well as there is a overflow. So would like to know how to get that information from civilstorm.
    Thank you!
    Shobana P.

    General Business

  • To add to Scott's answer -

    When flooding occurs at 1D elements like catchbasins and wetwells, the maximum HGL will be equal to the top/rim elevation. Is this what you mean when you say that you could not see the maximum HGL? (you want to see it rise above the top based on spilling into the surrounding land?)

    Your sump could be modeled as a pond polygon element with its elevation-area (or elevation-volume) curve configured to include the surrounding land that water will spill into during overflow conditions, to estimate the extent of the flooding. The pump can be configured to discharge from the pond. See: Modeling Ponds with Pumps

    Or, consider the options listed in this article: Modeling wetwell overflow

    if you want to simulate the excess water spilling over the top of the sump and into the surrounding land (and then determining how deep the flooding gets), you may also want to consider the 2D Modeling functionality available in the latest version of CivilStorm and SewerGEMS. This enables you to drape a terrain model to create a 2D grid which interacts with the 1D network, so that you can simulate the 2D flooding and resulting water depth. See: 2D Modeling in SewerGEMS and CivilStorm


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

  • Sorry, I just saw your reply now. Please see the tips in my previous answer. If you are extending the top of the wetwell and still seeing the maximum HGL equal to the wetwell top elevation, then the software may be predicting that water would continue pooling up that high. If the surface area spreads out above the actual sump top, then you may need to use a different approach to simulate that increase in surface area. 

    I would also recommend looking at some graphs of HGL of the surrounding area to see if perhaps they are unstable, causing the unexpected high max HGL. Review the mass balance error in the Calculation Summary as well. If the results are observed to be unstable and/or a high mass balance error is seen, this will need to be addressed first before results can be scrutinized. These articles can help (I recommend using the Explicit (SWMM) solver for most situations):

    If your wetwell is enclosed and you need to model surcharging, you may need to extend the top even further using the "chimney" approach described here. However, my understanding is that your wetwell is being used to simulate a depression in the land which acts as a pond. So, the depth-area or pond element approach may be better as it enables you to model the larger surface area above the real top of the sump (whereas the wetwell models vertical side walls unless you use the depth-area approach)

    The 2D Modeling feature is another option to explore.


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

  • Hello Jesse,

    I have the same scenario that Shobana is experiencing. Although I have an add on question.

    I have a system of ditches connected to a wet well. I have a pump connected to the wet well to pump out the flow in.

    My question is if Civil Storm considers the volume of storage upstream of wet well as:

    a. Only wet well storage

    b. Wet well storage + Storage in dtiches