Stormwater Management Model (SWMM) Information for watershed water quality, hydrology and hydraulics modelers (Note this Blog is not associated with the EPA). You will find Blog Posts and Twitter Embeds on the Subjects of SWMM5, InfoSWMM, InfoSewer, SWMMLive, InfoSWMM SUSTAIN, SWMM4 and SWMM in general.
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The Link Time Step in SWMM 5, InfoSWMM and H2OMap SWMM
Introduction: This set of blogs uses the 1000 year rainfall/runoff/hydraulics model that you can download athttp://swmm2000.com/forum/topics/1000-year-simulation-with-rainfall-in-swmm-5 to show the inner workings of SWMM 5 and by extension InfoSWMM and H2oMap SWMM using a QA/QC version of SWMM 5 with extended graphics. I always hope that seeing the inner workings of a SWMM 5 feature helps to understand the code, sensitivity and importance of a parameter. It also helps show sometimes when a parameter is not important.
Discussion: Here we look at the link time step for a 100 year simulation. If you use the Variable Time Step in SWMM5 with the CFL Adjustment factor the program will compute the needed link time step at each simulation time step based on the last time steps depth, velocity and width. The link time step is
Link Time Step = Adjustment Factor * CFL Explicit Time Step for the Controlling Link
The time step is larger for low flows and decreases as the flow in the link increases (Figure 1). The time step ranges between the maximum step allowed by the user during the simulation and the time step lengthening value in the Dynamic Wave Tab of the Simulation options. The program will use the minimum of the time steps for ALL links. The minimum time step at each simulation step is multiplied by the Adjustment Factor. The time steps used during the simulation are listed in the Routing Time Step Summary table where you can find the average, minimum and maximum time steps. The smaller the Adjustment Factor the smaller the link time steps during higher flow.
Figure 1. The Link Time Step over a 100 Year Period for Link Venant
Soffit Level (pipe technology)The top point of the inside open section of a pipe or box conduit. The soffit is the highest point of the internal surface of a pipe or culvert at any cross-section. The soffit is also referred to as the pipe obvert. So it is not quite the Crown of the Pipe. Here is an image I found that hopefully explains it better.
Engine Error NumberDescription ERROR 101: memory allocation error. ERROR 103: cannot solve KW equations for Link ERROR 105: cannot open ODE solver. ERROR 107: cannot compute a valid time step. ERROR 108: ambiguous outlet ID name for Subcatchment
New InfoSWMM linked 2D Link and 3D Node graphics help you understand one of the most critical outputs in any Stormwater, Combined Sewershed or Sanitary Sewershed Network Model the value and timing of how full the pipes and nodes are over time and how this changes during Wet Weather Flow (Runoff or Infiltration Inflow).These new graphs are included in InfoSWMM v 14.6 and InfoSWMM SA V2 (InfoSWMM SA is not an Esri Extension in ArcMap but uses Arc Engine for GIS processing power) has many new graphical and map display tools that help answer the following modeling questions in a easy to understand group of linked Time Track Graph, 2D Graphs and 2D Thumbnails. If you are modeling a Stormwater Network and need to know the d/D or depth over maximum depth over time and at the peak of the Runoff event you can view linked graphs as shown in Figure 1.If you are modeling a Sanitary Network and need to find the d/D for Rainfall Induced Infiltration and Inflow (RDII) you can see the RDII fl…