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I made this example to show how oscillations occur for legitimate reasons and the best ways to test the oscillations in InfoSWMM and SWMM 5:
Oscillations due to downstream obstructions, downstream mixed solutions and downstream boundary conditions:
In this case the oscillation in some links is due to the culvert comparison which limits the flow based on the inlet equation. You can see the flow changes if you turn on show control actions in the run manager. The program will then show the changes in the HTML report file. The flow oscillation is due to the water being stored at the upstream node of the culvert followed by the excess flow going into the culvert.
How to check the validity of the solution: Use a Map Display of the Link Result Variable Link Volume. If you do a map display of the link total volume you will see that the total volume passing through each link is in balance. You were using a 30 minute report time step, you can see and understand the oscillations bette
This was made later in my CDM/CDMSmith career and includes improvements made in 2006 to 2008 for SWMM 3 to SWMM 5 modelsSWMM4to5_Converter.exe
Subject: 3 Types of Manholes in SWMM 5 and InfoSWMM
There are three types of interior manholes in SWMM 5 and InfoSWMM as regards water surface elevations above the Node Rim Elevation:
1st Excess Water leaves the Node as flooded water if the water surface elevation equals the Rim Elevation (Figure 1 and Gravity Mains),
2nd Excess Water is stored in the manhole as pressurized depth if the Node Surcharge Depth is used (Figure 2 and Force Mains)
3rd Excess Water is stored above the Node Rim Elevation (Surface Ponding and Figure 3)
Figure 1. The default node in SWMM 5 and InfoSWMM has just the Manhole Invert Elevation, the program calculated elevation of the highest connected link and the Node Maximum Depth or Rim Elevation. If the Water Surface Elevation exceeds the Rim Elevation then any excess flow is lost as flooded flow.
Figure 2. A force main or pressure in SWMM 5 and InfoSWMM has the Manhole Invert Elevation, the program calculated elevation of the highest connected lin
