Breach height (Water Overlay)

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This attribute can be defined as values over time, using an array of values defining interpolation-time. This allows users to more dynamically define the height used in the Breach flow formula.


A levee with a datum height of 4 m is breached after 1800 seconds. It lowers down to -4.15 m in 900 seconds.

This can be simulated with the following array: 0 4 1800 4 2700 -4.15

The height value (h) used is:

  • h = 4 between 0 and 1800 seconds;
  • h = linearly interpolated between 4 and -4.15 based on time t within 1800 and 2700 seconds;
  • h = -4,15 m after 2700 seconds.


  • The initial surface height at the breach (both active and inactive) cells are lowered to the lowest value of the defined breach height array. This means that the elevation model immediately has a "hole" where the breach can potentially be. The breach height values of the array are only used for the computation of water flowing through the breach, not over its Area.
  • The breach height as an array can also be used to stop a breach from flowing in water after x amount of seconds. However, as mentioned in the note above, it cannot be used to raise the actual surface height in the simulated area.
  • When using a dynamic BREACH_HEIGHT, a maximum of 10.000 values (5.000 pairs) can be defined.


See also