When you click the outlet structure element on the Layout toolbar, your mouse cursor changes into a outlet structure element symbol. Clicking in the drawing pane while this tool is active causes a outlet structure element to be placed at the location of the mouse cursor.

The outlet control structure hydraulics normally result in relationships (as we expressed and internally used in the form of E-Q-T), however in some unusual conditions, characterized by an extremely undersized downstream conduit from the control, the use of EQT can result in instabilities for extreme flows (as compared with the downstream conduit capacity). In order to prevent such instability from happening, the model adds a flow filter to limit the flow from the control if the flow exceeds overflow level. The overflow level is:

Q(over) = 1.5 * Q(capacity) +0.5 (cfs)

If the Q given by EQT, Q(eqt), exceeds the overflow level, the model uses the following filtered new flow:

Q(new) = Q(over) + 0.05 * ( Q(eqt) – Q(over))