Inlet formula (Water Overlay): Difference between revisions

Revision as of 16:13, 4 December 2020

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 $T_{l,t}$ is defined:

Q_{lth}=max(0,T_{l,t}-w_{t})

If a positive inlet q Q_t is defined:

Q_{t}=\Delta t\cdot Q_{t}

If a capacity Q_total is defined:

Q_{c}=Q_{total}-\sum _{0..t-1}Q_{i}

After calculating the capacities, the actual water inflow is calculated. If any of the terms are undefined, they are not included.

\Delta w={\frac {max(0,min(Q_{lth},Q_{t},Q_{c}))}{A}}

Case 2 Outlets:
When calculating outlets, first the capacities are calculated.

If an upper threshold T_u,t is defined:

Q_{uth}=min(0,T_{u,t}-w_{t})

If a negative inlet q Q_t is defined:

Q_{t}=\Delta t\cdot Q_{t}

If a capacity Q_total is defined:

Q_{c}=-Q_{total}-\sum _{0..t-1}Q_{i}

After calculating the capacities, the actual water ouflow is calculated. If any of the terms are undefined, they are not included.

\Delta w={\frac {min(0,max(Q_{uth},Q_{t},Q_{c}))}{A}}

Where:

$Q_{0..n}$ = The calculated previous amounts of flow.
$Q_{lth}$ = The desired lower water level at the inlet's location, based on the LOWER_THRESHOLD of the inlet.
$Q_{uth}$ = The desired upper water level at the outlet's location, based on the outlet's UPPER_THRESHOLD of the inlet.
$Q_{t}$ = The amount of water inflow (or outflow when negative) possible based on the INLET_Q of the inlet and timestep Δt.
$Q_{c}$ = The total amount of water inflow (or outflow when negative) allowed based on the total capacity of the inlet.

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.

@@ Line 35: / Line 35: @@
 Where:
 * <math>w_t</math> = The [[Surface water level formula (Water Overlay)|water level]] on the surface relative to {{datum}}, at time t.
-* <math>T{l,t}</math> = The [[Lower threshold (Water Overlay)|LOWER_THRESHOLD]] of the inlet at time t.
+* <math>T_{l,t}</math> = The [[Lower threshold (Water Overlay)|LOWER_THRESHOLD]] of the inlet at time t.
 * <math>T_{u,t}</math> = The [[Upper threshold (Water Overlay)|UPPER_THRESHOLD]] of the inlet at time t.
 * <math>q_t</math> = The [[Inlet q (Water Overlay)|INLET_Q]] of the inlet at time t.