What Node and Link Invert Elevations Does SWMM 5 Use?

Note:  What Node and  Link Invert Elevations Does SWMM 5 Use?

SWMM 5 uses the following Node information from the user:

·         Node Invert Elevation,
·         The Node Rim Elevation which is the Node Invert Elevation + the Maximum node depth
·         The Ponded Area when the Ponded  Area option is used
·         The Surcharge Depth above the Node Rim Elevation

SWMM 5 uses the following link information from the user:

·         The Link Upstream Offset Depth or Offset Elevation and
·         The Link Downstream Offset Depth or Offset Elevation
·         The Link Maximum Depth or Diameter

SWMM 5 calculates the following information internally:

·         The Pipe Crown Elevation at the upstream and downstream link nodes.  The Pipe Crown is the Pipe Diameter + Link Offsets
·         The Node Highest Pipe Crown Elevation,  the new rim elevation will be used in the program
·         The Surcharge Depth above the Rim Elevation if the Node has a Surcharge Pressure Depth at the Node during the simulation,

o   If the Surcharge Depth is 0 then the program will either lose the flooded water or store the flooded water during the simulation

·         The Flooded Depth above the  Rim Elevation if the Node uses the Ponded Area Option

o   You have to enter a Ponded Area for the node AND use the Global Allow Ponding Option

SWMM 5 Rules for Pipes

·         The Pipe Invert Cannot be below either upstream or downstream node invert – the program will print a warning in the rpt file and set the offset to 0 internally,
·         The Pipe Crown Cannot be above the Rim Elevation of the Node – the program will raise the Rim Elevation when this happens and print a warning in the rpt file.

The use of Offset Depth or Offset Elevation for the Link Offsets is based on the user choice at the bottom of the SWMM 5 GUI Map.

Or in the Tools/Preference/Operation dialog of InfoSWMM/H20MAP SWMM