The effect of backwater and depth downstream on the links and depths upstream in #SWMM5

Do not forget that the downstream links of your model can affect the d/D and other hydraulic terms in the current link.   The downstream link with backwater raises the downstream link depth which affects the depth and d/D in the link of interest.  For example, 

The d/D is higher in link CDT-2253 due the effect of a fuller pipe downstream (1).  The d/D is the value in the middle of the link and it averages the downstream and upstream d/D.    The flow in CDT-2249 is 160 and the d/D is 0.47 but even though the flow in CDT-2253 is the same, the d/D is higher as the pipe downstream Pipe-4520 is fuller due to a flow of 425.  The higher d/D in Pipe-4520 means that the downstream d/D of CDT-2253 is higher as
The d/D is the middle value and is the average of the depths at the upstream and downstream points of the link.
CDT-2249 has a d/D of 0.47 as it does not have a downstream effect.

HGL Graph in #InfoSWMM