Autodesk Technologist with Information about Stormwater Management Model (SWMM) for watershed water quality, hydrology and hydraulics modelers (Note this blog is not associated with the EPA). You will find Blog Posts on the Subjects of SWMM5, ICM SWMM, ICM InfoWorks, InfoSWMM and InfoSewer.
The newer option for SWMM5 culverts uses three culvert classifications and associated equations to compute the inletcontrolled flow into a culvert using the FHWA (1985) equations. The culvert code in the culvert.c code of SWMM5 uses:
1. Two Equations for Unsubmerged culvert flow, 2. One Equation for the Transition flow, and 3. One Equation for Submerged flow.