Inlet formula (Water Overlay): Difference between revisions
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When calculating inlets, first the capacities are calculated. | When calculating inlets, first the capacities are calculated. | ||
If a lower threshold T<sub>l</sub> is defined: | If a lower threshold T<sub>l,t</sub> is defined: | ||
: ''Q<sub>lth</sub> = max( 0 , T<sub>l,t</sub> - w<sub>t</sub> )'' | : ''Q<sub>lth</sub> = max( 0 , T<sub>l,t</sub> - w<sub>t</sub> )'' | ||
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When calculating outlets, first the capacities are calculated. | When calculating outlets, first the capacities are calculated. | ||
If an upper threshold T<sub>u</sub> is defined: | If an upper threshold T<sub>u,t</sub> is defined: | ||
: ''Q<sub>uth</sub> = min( 0 , T<sub>u</sub> - w<sub>t</sub> )'' | : ''Q<sub>uth</sub> = min( 0 , T<sub>u</sub> - w<sub>t</sub> )'' | ||
Revision as of 14:41, 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,t 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,t 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 desired lower water level at the inlet's location, based on the LOWER_THRESHOLD attribute.
- Quth = The desired upper water level at the outlet's location, 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 total amount of water inflow (or outflow when negative) allowed based on the total capacity of the inlet/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.