Diversion
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Diversions are used to divide an inflow into two outflows according to a distribution rule. This can be used to model structures that withdraw water from rivers for water supply or irrigation purposes, branches in canals, diversions at the inlet or outlet of reservoirs, stormwater overflows, etc.
Four approaches are possible for defining the distribution rule.
Threshold Value (Option 1)
In this case the second outflow only becomes active if the inflow exceeds the threshold of Qcrit. In the threshold value approach, the 2nd outlet (e.g. stormwater overflow) is only activated once a critical inflow Qcrit is exceeded, causing the throttled outflow to back up, reaching the overflow threshold. Since in reality a perfect division of the outflows after reaching the threshold value is usually never achieved, a diversion coefficient can also be specified in order to better represent actual conditions.
It is defined as: [math]\displaystyle{ \mbox{diversion coefficient}= \frac{Q_{in}(Q_{out}=5 \cdot Q_{crit})}{Q_{crit}} }[/math]
Percentage Distribution (Option 2)
With this approach, the inflow is split into two outflows Qout1 and Qout2 according to a constant percentage ratio.
Rating Curve (Option 3)
A relationship determined using hydraulic calculations or derived from operating rules between the discharge Qout1 and the inflow can be specified in the form of a rating curve. The second outlet Qab2 will then output the remaining dicharge.
Regeln und Steuern (Option 4)
Für einen der zwei Abläufe kann eine Skalierung über einen Systemzustand, optional kombiniert mit Tages-/Wochen- und/oder Jahresgang, erfolgen. Der andere Ablauf ergibt sich dann aus dem verbleibenden Abfluss.