Breach growth formula (Water Overlay)

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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 - BH) - max(0, WL - BH) )

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

ΔB = 1.3 * ((G^0.5 * H^1.5) / BS) * log10 (1 + (0.04 * G / BS) * 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 BW.
  • Δt = Computational timestep.
  • ΔB = The calculated width increase of the breach.
  • H = The difference between the height of the water columns on either side of the breach.
  • MF = Material factor, set to 1.3 (average for sand and clay levees)
  • G = Acceleration factor of gravity
  • BH = The BREACH_HEIGHT attribute of the breach.
  • BW = The BREACH_WIDTH attribute of the breach.
  • BS = The BREACH_SPEED attribute of the breach.
  • EL = 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)

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