Why are the results in the Hydraulic Reviewer showing large deviation results at a wet well?

Product(s): SewerGEMS, CivilStorm
Version(s): 10.XX.XX.XX, 08.11.XX.XX
Area: Output and Reporting

 

Problem

Why is the Hydraulic Reviewer showing large deviation of results at a wet well?

Solution

Even if the overall model continuity error is good, you can still see a large deviation value if the pump related to the wet well is cycling very quickly. If the elevation difference between the on and off elevations for the pump is small, this can make it difficult to get valid results for deviation percentage, particularly if there is a lot of flow from the pump. Some adjustment to the calculation options, including the time step, may help with the overall results. If you're using the Explicit (SWMM) solver, try using a Routing Step of 1-5 seconds) 

However, the best option may be to verify the pump data is correct, including the pump definition and the on and off elevations.

See Also

What is the continuity error and what's a good percentage for it?

Troubleshooting unstable SewerGEMS and CivilStorm results using the implicit solver

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