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|
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