Surcharged d/D in InfoSWMM and H2OMap SWMM
The value of d/D in InfoSWMM is calculated as Link capacity or the Midpoint Capacity Whereas the Surcharged d/D is calculated from the end node depths or Surcharged d/D = Average depth in the middle of a link or ½ (Upstream Depth + Downstream Depth) / Maximum depth Midpoint Capacity = the midpoint cross sectional area (based on the average depth) / the full cross sectional area If you look at the reports d/D or Midpoint Capacity is not quite the same as the Surcharged d/D which is based on the upstream and downstream depths and not the Capacity (a function of Area). I hope this explains why Surcharged d/D is equal to the Depth and not the same as the d/D or Midpoint Capacity . Inverse Color Attribute Browser in InfoSWMM and H2OMap SWMM showing various output data.