Breach flow formula (Water Overlay)
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. The downstream water level can optionally be measured with an additionally configured Breach Level Area, or an automatically placed
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. Failed to parse (unknown function "\deltaw"): {\displaystyle w_{e,t+1} = w_{e,t} - \frac{\deltaw}{A_e} }
Where:
- Δw = The calculated water flow which takes place, based on the weir formula.
- 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.
- Features
- Breach
- Formulas
- Weir formula
- Breach growth formula
- Models
- Surface model
- Models
- Surface • Ground • Rain • Evaporation • Infiltration • Elevation • Breach • Sewer • Storage • Tracer flow • Border • Order
- Model formulas
- Timestep • Season • Surface water level • Groundwater level
- Flow formulas
- Surface flow • Surface infiltration • Ground flow • Ground infiltration • Surface evaporation • Ground evaporation • Ground bottom flow
- Hydraulic structure formulas
- Culvert • Weir • Breach growth • Breach flow • Pump • Sewer Overflow • Inlet • Drainage
- Related