Why do I get a message "Diversion flow is ignored by HEC-22 junction loss calculations at this node"?

  Applies To 
  Product(s): StormCAD, CivilStorm, SewerGEMS
  Version(s): 08.11.03.XX +, 10. XX..XX. XX
  Area:  Calculations
  Original Author: Jesse Dringoli, Bentley Technical Support Group


When computing a model with the HEC-22 Energy structure loss method applied to a node downstream of a diversion link, the below user notification appears. Why is the diversion flow ignored in this case?

"Diversion flow is ignored by HEC-22 junction loss calculations at this node. Plunging, Angled Inflow, and other potential contributing losses are not computed for diversion links."

Problem ID#: 92042


The reason why the flow from upstream diversion links is ignored in the HEC-22 structure loss calculations for the downstream structure is because there is not enough information to be able to compute all the factors involved. With the HEC-22 structure loss method, the total headloss through the structure is the sum of various correction factors, some of which account for depth of flow in the upstream pipe. Depth is not currently calculated in diversion links, therefore the HEC-22 structure loss cannot account for the flow that comes from that diversion.

Note: If there are multiple upstream pipes, structure loss will still be calculated for the ones that are non-diversion links.