Why is a Hot Start File important in SWMM 5 and InfoSWMM

A Hot Start File in InfoSWMM  or SWMM 5 is important as it provides initial   depths, initial flows and  initial settings for the hydrology and hydraulics features of the SWMM 5 engine.    You  have three options:

1. Save a hot Start File at the  end of the  simulation,
2. Use a hot Start File  at the beginning of  the simulation,
3. Create a hot start file  from  the a  time during  the  Map Display

If you change any of the network  types or add new links and nodes then  the Hot Start file needes to be recreated.  InfoSWMM use the Tab File in  the Run Manager to name the Hot Start File (Figure 1).   Each and  every Scenario in InfoSWMM  can  use or Save a different scenario with different starting  and ending  times  (Figure 2).  If you USE  a Hot  Start  File then:

1. The  new  simulation  starts at the end  of  the  old  simulation
2. You can  run a Quasi Steady State Simulation and use a very short simulation time of minutes if you use a Hot Start File
3. Figure 3  shows  the effect of Using a Hot Start File

Figure 1. File Tab for Saving or Using a  Hot Start file in InfoSWMM  or  H2OMap SWMM.   There  is  a similar dialog in  SWMM5.

Figure 2.  Each Scenario in  InfoSWMM  and  H2OMap  SWMM can have a   different set of report  and simulation options.

Figure 3.   The Saved Time Series for the  Outfall (Blue) and  Use (Green)  Outfall  Time Series.