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Waterlevel boundery condition

When modelling a flood in Tygron i would like to set a boundery condition in the most downstream point in the modelled area. Unfortunately that is not an option within Tygron. In order to achieve such an effect, it is necessary to add an inlet with a negative flow in combination with a weir. That is possible, but it is rather cumbersome and the results are not very predictable.

I would therefore appreciate it when a waterlevel boundery condition is added in the water overlay.


  • Hi @WRIJ GvdH,

    There are more ways to model boundary conditions, for example by using a breach or a water level area.

    Can you explain more about the boundary condition and the simulation you are modeling in your project?

    Tygron support team

  • I'm modelling a small river, from which a dambreak takes place, in a situation with a big dicharge on the river.

    To get the water level right at the position of the dambreak i have to simulate the river water levels correctly. So is need 2 things:

    1) a fixed downstream water level and

    2) i have to calibratie the dimensions or roughness of the channel to get the right water level slope given a certain discharge. (for your idea: the slope is appr. 1,5 m over 5 km and the discharge 100 m3/s)

    As mentioned above: i tried to get the fixed downstream water level by inserting an inlet with a big negative flow (when waterlevel is higher then 11 mNAP) in combination with a weir upstream of the inlet. The inlet should keep the water level at 11 mNAP but that didn't happen. A few meters from the inlet position the water level was already 12 mNAP. Maybe that's because the inlet is a point location and causes is steep water slope nearby?

  • Hi @WRIJ GvdH,

    Not sure if I understand it correctly, but I think you are modelling a breach with an input area, is that correct?

    You can also model the breach with an external water level area in where you can define the water level at the position of the dambreak, so you don't have to simulate the river water levels correctly.

    Here you can read how to model a breach with an external water level area.

    Tygron support team

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