VOSWMM

3.2.2 Outfall

An outfall is a component that can be the last node of the drainage system of a subcatchment.

An outfall node can only connect to a single link, and there is an option for the outfall to discharge onto the surface of a subcatchment.

Parameter Name Description Default Value
NHYD Hydrograph number. —
NAME Name of the component. —
COMMENT 1, 2, and 3 Comment for the command. —
Tag Optional category or classification. —
System Type Specifies the junction’s system type, whether it belongs in the overland, storm, or sanitary system. Blank
X The X coordinate of the outfall. 0
Y The Y coordinate of the outfall. 0
Ground Elevation The elevation for the ground level. 0
#Of inlets The number of inlets (catchbasin) assigned to the outfall. 0
Sag If the junction is laid upon a sag area.
Delineate Whether to delineate this junction or not.
Invert El. (m) Elevation of outfall’s invert. 0
Inflows External inflows received at the junction. No
Treatment Pollutant removal supplied at the junction.
Tide Gate Select Yes if the outfall contains a tide gate to prevent backflow. No
Type Type of outfall boundary condition. *Free

*Outfall types are:

Various stage relationships can characterize the boundary conditions at an outfall, including:

  • The critical or normal flow depth within the connecting conduit
  • A fixed stage elevation
  • A tidal stage presented in a table correlating tide height with the hour of the day
  • A user-defined time series detailing stage variations over time

Key input parameters for outfalls encompass the invert elevation, the type of boundary condition, the stage description, and the presence of a flap gate designed to prevent backflow through the outfall.