Frequently Asked Questions


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    Entered: 2012-11-1
  • Question:

    General: How do I define a Q/h rating curve as boundary condition in MIKE 21?


    A rating curve can be applied at outflow boundaries. Boundary levels are hence calculated at each time step during the simulation from outflow discharge, according to a Q/h table. This Q/h table has to be defined in an external time series.

    To apply this boundary type in MIKE 21 classic, set the formulation to ‘Flux’, and then select ‘Rating curve’ instead of ‘Constant’ and browse to the external time series.


    When using MIKE 21 FM, set the boundary type to ‘Specified discharge’, and the format to ‘Rating curve’ and browse to the external time series.


    This external time series has to be defined with a ‘Relative Item Axis’, which allows defining the water level as axis item. Hence, set the axis units to ‘meter’. Finally, set the item type to ‘Discharge’ in the lower table.


    The times series containing the rating curve should thus look similar to the following one.