Breach growth formula (Water Overlay): Difference between revisions
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First, the difference in height of the water on either side of the breach is calculated. | First, the difference in height of the water on either side of the breach is calculated. | ||
: ''H = abs( max(0, EL - | : ''H = abs( max(0, EL - H<sub>b</sub>) - max(0, WL - H<sub>b</sub>) )'' | ||
Using the height difference, the breach width increase is calculated. | Using the height difference, the breach width increase is calculated. | ||
: ''ΔB = 1.3 * (( | : ''ΔB = 1.3 * ((g^0.5 * h^1.5) / cs<sub>b</sub> ) * log10 (1 + (0.04 * G / cs<sub>b</sub> ) * Δt / 3600)'' | ||
The current breach width is then equal to the last calculated breach width, plus the calculated additional breach width. | The current breach width is then equal to the last calculated breach width, plus the calculated additional breach width. | ||
| Line 14: | Line 14: | ||
Where: | Where: | ||
* B = The total calculated breach width, initially equal to | * B = The total calculated breach width, initially equal to W<sub>b</sub>. | ||
* Δt = Computational timestep. | * 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. | ||
* | * f<sub>m</sub> = Material factor, set to 1.3 (average for sand and clay levees) | ||
* | * g = Acceleration factor of gravity | ||
* | * H<sub>b</sub> = The [[Breach height (Water Overlay)|BREACH_HEIGHT]] attribute of the breach. | ||
* | * W<sub>b</sub> = The [[Breach width (Water Overlay)|BREACH_WIDTH]] attribute of the breach. | ||
* | * cs<sub>b</sub> = The critical [[Breach speed (Water Overlay)|BREACH_SPEED]] attribute of the breach. | ||
* | * w<sub>e</sub> = Current external water level. | ||
==See also== | ==See also== | ||
Revision as of 10:12, 15 April 2019
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
- ↑ 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)