How do we look at the various measures of "fullness" in a pipe of link in SWMM 5? Here we look at some graphs from InfoSWMM.
d/D is the pipe depth over the full depth of the link
q/Q is the current link flow over Qfull for the link (Q full is the full flow of a link based on Manning's equation) This Qfull is based on the bed slope of the link. You can have a q/Q or q/Qfull greater than 1 if the water surface slope is greater than the bed slope of a link. This is especially true for flat links where SWMM 5 has a minimum slope of 0.001
The image shown below shoes that at the peak flow in the links is greater than 1 even though the pipe is not full (d/D less than 1) for this model of flat slopes. Qfull is a comparison metric and not the result of the simulation.
|d/D, q/Q for a Link in SWMM 5, InfoSWMM and H2oMap SWMM|