Breach flow formula (Water Overlay): Difference between revisions
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Flow through | Flow through [[Breach (Water Overlay)|breach]]es is calculated based on the [[Weir formula (Water Overlay)|weir formula]], including the consideration between free flow and submerged flow situations. | ||
The weir formula is supplied with the breach width (as stand-in for the weir width), which is always calculated with the [[Breach growth formula (Water Overlay)|breach growth formula]] before calculating the weir flow. | The weir formula is supplied with the breach width (as stand-in for the weir width), which is always calculated with the [[Breach growth formula (Water Overlay)|breach growth formula]] before calculating the weir flow. | ||
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*The water level w<sub>e</sub> cannot become lower than the surface height s<sub>e</sub>, defined by [[External_surface_level_(Water_Overlay)|EXTERNAL_SURFACE_LEVEL]] in case of an external entry area. In case of an input area within the project, the [[terrain height (Water Overlay)|surface height]] is determined per grid cell. | *The water level w<sub>e</sub> cannot become lower than the surface height s<sub>e</sub>, defined by [[External_surface_level_(Water_Overlay)|EXTERNAL_SURFACE_LEVEL]] in case of an external entry area. In case of an input area within the project, the [[terrain height (Water Overlay)|surface height]] is determined per grid cell. | ||
== | ==Related== | ||
The following topics are related to this formula. | |||
===Structures=== | |||
* [[Breach (Water Overlay)|Breach]] | * [[Breach (Water Overlay)|Breach]] | ||
===Formulas=== | |||
== | * [[Weir formula (Water Overlay)|Weir formula]] | ||
* [[Breach growth formula (Water Overlay)|Breach growth formula]] | |||
===Models=== | |||
* [[Surface model (Water Overlay)|Surface model]] | * [[Surface model (Water Overlay)|Surface model]] | ||
{{Template:WaterOverlay_nav}} | {{Template:WaterOverlay_nav}} | ||
{{Water Module buttons}} | {{Water Module buttons}} | ||
Revision as of 07:18, 19 June 2019
Flow through breaches is calculated based on the weir formula, including the consideration between free flow and submerged flow situations. The weir formula is supplied with the breach width (as stand-in for the weir width), which is always calculated with the breach growth formula before calculating the weir flow.
For the entry area, the area where the water originates from, the following also applies:
- The water level used is defined by either an input area or the external water level.
- In case of an external area, the surface height used is defined by external surface level. This height limits how far the water level can be lowered.
- In case of an input area, the average water level is based on the water level on the individual grid cells of the input area.
Each timestep, the external water level is changed based on the amount of water flowing in or out.
| t=0 | we,t = we,0 |
| otherwise | we,t = we,t-1 - ( (Δw * cell) / Ae ) |
Where:
- Δw = The water flow which takes place (out of the virtual external water source)
- cell = Cell size
- we,t = The water level of the entry area at time t.
- we,0 = The water level of the entry area; In case of an external area: EXTERNAL_WATER_LEVEL of the breach.
- Ae = The size of in the entry area; In case of an external area: EXTERNAL_AREA of the breach.
Notes
- The water level we cannot become lower than the surface height se, defined by EXTERNAL_SURFACE_LEVEL in case of an external entry area. In case of an input area within the project, the surface height is determined per grid cell.
Related
The following topics are related to this formula.
Structures
Formulas
Models
