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 




Comments

annie o Roberts said…
The rule " elevation of the node invert has to be equal to the lowest invert elevation of the inflow and outflow conduits" was actually a warning in SWMM 4 (post 1988) and an error in SWMM 3 (1981 to 1988). The reason it was an error in SWMM 3 is there was no default area of a junction; the junction area was based solely on some combination of the surface area of the upstream and downstream connected links to the node. If the node invert was below the inverts of the connecting links then the surface area of the node in SWMM 3 would have been zero - a bad idea for the node continuity equation which uses the surface area as a denominator. Refer essay writing service reviews to get reviews of different essay writing company.

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