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Inlet building changing surface elevation

For a validation study in Germany I'm forced to use inlets (27000 of them) as areas with specific water quantities over time. In my model I noticed that the elevation model used for the calculation significantly changes due to inlets but I can't find the relation or setting for this anywhere. This goes up multiple meters (up to 30 meter elevation difference)

I know how the calculation grid is established:

  • water bodies are lowered when making the calculation grid (turned off in advanced settings).
  • I know DESIGN_FLOOD_ELEVATION has impact on the buildings (set to 0 to validate).
  • I know bridges can have impact (turned off in advanced settings).
  • Weir dam multiplier, but their inlets not wiers.
  • General optimization also can't explain this differrence

What relation / impact can inlets have on the elevation model?

(Rain over time with specified areas don't go up to 27000 but would be way more logical for the purpose of this study)


  • Hello Len,

    Some feedback from our dev team:

    Inlets are currently designed to interact with their thresholds as good as possible. Therefore, when placed on sloped terrain, often a shore, the inlet selects the lowest point. The elevation used for the simulation will then be lower than expected. Even when you do not use thresholds, and only use an inletQ, this happens.


    For this use case Len has an alternative which requires 27.000 rain areas (see comment: (Rain over time with specified areas don't go up to 27000 but would be way more logical for the purpose of this study)).

    In the january preview release the max amount of rain areas was increased from 100 -> 32.000. Thus this should also solve his issue.

    I hope this answers your questions.

    Regards, Vincent

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