Pump formula (Water Overlay): Difference between revisions
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Inlets are hydraulic structures can pump water in and out of the project area and are connected with a water body outside the project area.__NOTOC__ | |||
The amount flowing in or out of inlets is calculated for the cell the inlet resides on. | The amount flowing in or out of inlets is calculated for the cell the inlet resides on. | ||
Case 1: Inlet: | ''Case 1: '''Inlet''':''<br> | ||
When calculating inlets, first the capacities are calculated. | When calculating inlets, first the capacities are calculated. | ||
If a lower threshold | If a lower threshold T<sub>l</sub> is defined: | ||
: ''Q<sub>lth</sub> = max( 0 , T<sub>l,t</sub> - w<sub>t</sub> )'' | |||
If a positive Inlet q is defined: | If a positive Inlet q is defined: | ||
: ''Q<sub>t</sub> = Δt * q<sub>t</sub>'' | |||
If a capacity Q<sub>total</sub> is defined: | |||
: ''Q<sub>c</sub> = Q<sub>total</sub>''- ΣQ<sub>0..t-1</sub> | |||
If a capacity | |||
After calculating the capacities, the actual water inflow is calculated. If any of the terms are undefined, they are not included. | After calculating the capacities, the actual water inflow is calculated. If any of the terms are undefined, they are not included. | ||
: ''Δw = max( 0 , min( Q<sub>lth</sub> , Q<sub>t</sub> , Q<sub>c</sub> ) ) / A'' | |||
''Case 2 '''Outlets''':''<br> | |||
Case 2 Outlets: | |||
When calculating outlets, first the capacities are calculated. | When calculating outlets, first the capacities are calculated. | ||
If an upper threshold | If an upper threshold T<sub>u</sub> is defined: | ||
: ''Q<sub>uth</sub> = min( 0 , T<sub>u</sub> - w<sub>t</sub> )'' | |||
If a negative Inlet q is defined: | If a negative Inlet q is defined: | ||
: ''Q<sub>t</sub> = Δt * q<sub>t</sub>'' | |||
If a capacity Q<sub>total</sub> is defined: | |||
: ''Q<sub>c</sub> = -Q<sub>total</sub> - ΣQ<sub>0..t-1</sub>'' | |||
If a capacity | |||
After calculating the capacities, the actual water ouflow is calculated. If any of the terms are undefined, they are not included. | After calculating the capacities, the actual water ouflow is calculated. If any of the terms are undefined, they are not included. | ||
: ''Δw = min( 0 , max( Q<sub>uth</sub> , Q<sub>t</sub> , Q<sub>c</sub>) ) / A'' | |||
Where: | Where: | ||
* w<sub>t</sub> = The water level on at time t, relative to [[Datum|datum]]. | |||
* T<sub>l,t</sub> = The LOWER_THRESHOLD attribute of the inlet at time t. | |||
* T<sub>u,t</sub> = The UPPER_THRESHOLD attribute of the inlet at time t. | |||
* q<sub>t</sub> = [[Inlet q (Water Overlay)|INLET_Q]] attribute at time t. | |||
* Δt = Computational timestep. | |||
* Q<sub>total</sub> = The [[Inlet capacity (Water Overlay)|INLET_CAPACITY]] attribute of the inlet. | |||
* Q<sub>0..n</sub> = The calculated previous amounts of flow. | |||
* Q<sub>lth</sub> = The amount of water inflow desired based on the inlet's [[Lower threshold (Water Overlay)|LOWER_THRESHOLD]] attribute. | |||
* Q<sub>uth</sub> = The amount of water outflow desired based on the outlet's [[Upper threshold (Water Overlay)|UPPER_THRESHOLD]] attribute. | |||
* Q<sub>t</sub> = The amount of water inflow (or outflow when negative) possible based on the INLET_Q attribute and timestep Δt. | |||
* Q<sub>c</sub> = The amount of water outflow possible based on the total capacity of the outlet. | |||
* A = Size of the Inlet/Outlet area in m<sup>2</sup>, based on the amount of cells and cell size. Current implementation only has one cell. | |||
* Δw = The amount of water flow which takes place. | |||
==See also== | ==See also== | ||
* [[ | * [[Inlet (Water Overlay)|Inlet]] | ||
{{Template:WaterOverlay_nav}} | {{Template:WaterOverlay_nav}} | ||
Revision as of 14:10, 15 April 2019
Inlets are hydraulic structures can pump water in and out of the project area and are connected with a water body outside the project area.
The amount flowing in or out of inlets is calculated for the cell the inlet resides on.
Case 1: Inlet:
When calculating inlets, first the capacities are calculated.
If a lower threshold Tl is defined:
- Qlth = max( 0 , Tl,t - wt )
If a positive Inlet q is defined:
- Qt = Δt * qt
If a capacity Qtotal is defined:
- Qc = Qtotal- ΣQ0..t-1
After calculating the capacities, the actual water inflow is calculated. If any of the terms are undefined, they are not included.
- Δw = max( 0 , min( Qlth , Qt , Qc ) ) / A
Case 2 Outlets:
When calculating outlets, first the capacities are calculated.
If an upper threshold Tu is defined:
- Quth = min( 0 , Tu - wt )
If a negative Inlet q is defined:
- Qt = Δt * qt
If a capacity Qtotal is defined:
- Qc = -Qtotal - ΣQ0..t-1
After calculating the capacities, the actual water ouflow is calculated. If any of the terms are undefined, they are not included.
- Δw = min( 0 , max( Quth , Qt , Qc) ) / A
Where:
- wt = The water level on at time t, relative to datum.
- Tl,t = The LOWER_THRESHOLD attribute of the inlet at time t.
- Tu,t = The UPPER_THRESHOLD attribute of the inlet at time t.
- qt = INLET_Q attribute at time t.
- Δt = Computational timestep.
- Qtotal = The INLET_CAPACITY attribute of the inlet.
- Q0..n = The calculated previous amounts of flow.
- Qlth = The amount of water inflow desired based on the inlet's LOWER_THRESHOLD attribute.
- Quth = The amount of water outflow desired based on the outlet's UPPER_THRESHOLD attribute.
- Qt = The amount of water inflow (or outflow when negative) possible based on the INLET_Q attribute and timestep Δt.
- Qc = The amount of water outflow possible based on the total capacity of the outlet.
- A = Size of the Inlet/Outlet area in m2, based on the amount of cells and cell size. Current implementation only has one cell.
- Δw = The amount of water flow which takes place.