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Parameter for 'delaying' modelled flow

Hi, I am trying to calibrate a subcatchment. I have semi-automatically tried to calibrate catchment width, slope, Manning's n for pervious and impervious, depression storage for pervious and impervious. I came up with a flow curve shape which looks like the measured flow but the modelled flow is starting 30min earlier. I tried to change many of those parameters I described but still I can not reduce the 30min gap. Since it is a very small catchment I don't think this is due to spatial distribution of rainfall. So any other  idea why modelled flow starts 30min before measured?

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Replies

  • What is your rainfall time step interval?  Is it 30 minutes?  Have you tried to reduce the Wet Hydrology time step or start the simulation 1/2 hour earlier?  SWMM 5 does not compute the initial time step but only  lists the time step after a the reported time step.

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