Breach growth formula (Water Overlay)

From Tygron Support wiki
Revision as of 10:12, 15 April 2019 by Frank@tygron.nl (talk | contribs)
Jump to navigation Jump to search

Breaches can grow when water flows from the virtual external water source into the hydrological model[1].

First, the difference in height of the water on either side of the breach is calculated.

H = abs( max(0, EL - Hb) - max(0, WL - Hb) )

Using the height difference, the breach width increase is calculated.

ΔB = 1.3 * ((g^0.5 * h^1.5) / csb ) * log10 (1 + (0.04 * G / csb ) * Δt / 3600)

The current breach width is then equal to the last calculated breach width, plus the calculated additional breach width.

Bnew = Bold + ΔB

Where:

  • B = The total calculated breach width, initially equal to Wb.
  • Δt = Computational timestep.
  • ΔW = The calculated width increase of the breach.
  • Δh = The difference between the height of the water columns on either side of the breach.
  • fm = Material factor, set to 1.3 (average for sand and clay levees)
  • g = Acceleration factor of gravity
  • Hb = The BREACH_HEIGHT attribute of the breach.
  • Wb = The BREACH_WIDTH attribute of the breach.
  • csb = The critical BREACH_SPEED attribute of the breach.
  • we = Current external water level.

See also

References

  1. Verheij, H.J. ∙ Aanpassen van het bresgroeimodel in HIS-OM: Bureaustudie ∙ found at: http://resolver.tudelft.nl/uuid:aedc8109-da43-4a03-90c3-44f706037774 ∙ (last visited 2019-03-08)

Template:WaterOverlay nav