On Friday, I got a model which was set up in StormNET and as the model is run in SSA, got different output results for the hydraulic section, in comparison to the StormNET output report, even though the model was not changed and all the modeling parameters were same. First and foremost thing which came to my mind was the change in the EPA SWMM engine has caused the difference in the results.
Latest SSA version is using EPA SWMM version 5.0.021 in compare to the SNET using EPA SWMM version 5.0.014. However, I still had questions in my mind that what could be the other factors which contributed significantly for the different results for the links and the nodes in the two output reports. Though, SNET was not installed on my system. I took the help of Matt Anderson to compare the EPA SWMM 5.0.014 results with SSA. In the discussion came to know that apart from the change in EPA SWMM engine the culvert equation and the storage node floods (HGL above the node storage curve) contributed to the difference in the output results for SSA and SNET. I would like to share the data presented by Matt Anderson related to the corrections to the EPA SWMM engine between 5.0.014 (SNET) and 5.0.021 (SSA 2012).