I am getting a -21.0% Flow Continuity Error in my Sewergems model so I exported it and ran it in the SWMM 5.1 software and got a -0.16% Flow Routing Continuity Error.
I'm wondering what could cause such a drastic change in results.
A few notes. The model has two ponds modeled and one outfall. One inlet that is upstream of the pond has a -800.76% continuity error for it's surface node (in sag inlet - "Node 828f_Surface). Obviously this is causing the most problems but I'm not sure how to fix it since the inlet is not overflowing or surcharged. The rest of the nodes listed in the "Highest Continuity Errors" section within Sewergems are in the 9-36% range.
I am using Sewergems CONNECT Edition Update 1 (10.01.01.04) within Microstation V8i SS4 and EPA SWMM 5.1.012. I will try to upload the "Outfall D6_NEW" file for reference.
To add, I just tried making the orifice in my pond outlet structure 2" smaller and it reduced the overall "flow continuity error" in Sewergems to -9.3%, but the "Node 828f_surface" error actually increased to -1061.70%.
This might help the overall error, but I'm still wondering why the SWMM program would solve the same model and have such a smaller error as well, with my original input values .
Hello Jared,
Have you tried setting the SWMM calculation options to reduce your continuity errors?
Often when designing large or complicated models it would give somewhat higher continuity errors or unstable results.
Here is the relevant article in this regard;
Troubleshooting unstable SewerGEMS model results using the Explicit SWMM Solver
Hope this helps.
Regards,
Yashodhan Joshi
I have looked at this article before and adjusted quite a few of the SWMM calculation options. None have reduced the error at the one inlet's surface node however. Additionally, I believe the same options are exported to the SWMM file so when I run it within SWMM 5.1, the results shouldn't really be that different..
We are looking into this issue. I will let you know when I have some more information for you.
Scott