View Full Version : Max Depth/Full Depth

February 14, 2017, 07:52 AM
When symbolizing pipes and using the data field Max Depth/Full Depth. How is this measurement calculated? Is it a measurement of depth throughout the length of pipe or a measurement only at the beginning and end for a pipe, during a simulation? Just trying to understand a little more about this data field and how its displayed. Thanks for the help.

Robert Dickinson
February 14, 2017, 04:04 PM
The value of d/D
in InfoSWMM is calculated as Link capacity or the Midpoint Capacity. d/D is better defined as the capacity or current cross-sectional area at the center of the link over the full cross-sectional capacity at full depth. The midpoint cross-sectional area is based on the mean depth in the center of the link and the average depth is the average of the upstream and downstream ends of the pipe.

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.

Bob Dickinson

February 15, 2017, 07:56 AM
Hi Bob,
Sorry, it must be my limited experience when it comes to modeling but I'm still not sure if my question was answered. Attached is a recent model run and how my pipes have been symbolized based on Max Depth/Full Depth. Pipes along Mayfair Cres show 60-75% full while a more critical area of concern is a pipe along Pembridge Cres showing greater than 90%. These are all gravity mains. So, based on your comments these areas represent depths only at the midpoint of the link not depths for the start or end of the link? I'm assuming the same idea would apply to forcemains? One of the reasons I'm looking for a little more clarification is that I was under the assumption it was displaying end of the pipe depths. Link capacities at midpoint brings up a few more concerns/questions in my model.
Again, thanks Bob for the quick response to my original question. I appreciated any additional info on this topic you might have.
Have a good day.


Robert Dickinson
February 15, 2017, 07:59 AM
Hi, The Max Depth/Full Depth that is displayed is based on the value at the middle of the link but it is based on information at the upstream and downstream ends of the link. See also my email that i just sent to you.