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River confluence message: uniform flow calculation didn't converge

  • Apr 07 2020
  • mel.guirro

I would like to simulate a tributary river as an input in the main river (a river confluence). I’ve seen the manual and I know this is possible in Nays2DH. I have tried in many ways with different grid systems and it always shows the error message “uniform flow calculation didn’t converge (main channel)” or “flow calculation didn’t converge (tributary channel)”

I’ve searched about this error message and I’ve found that someone had the same problem here:

Calculation didn’t converge

It was said that the problem may be the riverbed slope, but I have tried changing it and it didn’t work.
Any other ideas to solve this problem?

Thank you very much!


  1. UC-1h says:

    Is the following helpful?
    In this case, the first discharge in the time series should be non-zero.

  2. mel.guirro says:

    Yes, it seems this helped! Thank you very much.
    But now it shows the message “Calculation is failure”.
    Without the confluence, the calculation runs normally.


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