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Sum of runoff in status report doens't match the hydrograph

Posted by Christina on January 10, 2013 at 2:52am

Hi, 

I've got a question concerning the total amounts of runoff calculated in  SWMM5.

I noticed that the total amount of runoff given in the status report doesn't match the amount of run off that I get when I sum up the amounts of runoff for each time step given in the table (hydrograph) in SWMM5. It's mostly just a small difference, but shouldn't it be the same? 

Thank you!

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Replies

  • Robert Dickinson January 10, 2013 at 4:22am

    The runoff is part of the wet weather flow into the manholes and generally matches the sum of the hydrographs at the outfalls minus flooding and storage losses in the network.    The sum of the hydrographs are at the report time step and the runoff is calculated at the computational time steps (usually smaller) and those two totals are usually close but not exactly the same.

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