All Forums

diameter of manhole


I Want to model flow in Manhole. This is an Urban Drainage  System with  1.2 m pipe connencting 2m manhole. I want to know how I can model the flow profie in manhole using SWMM? How can I determine the diameter of Manhole?



You need to be a member of SWMM 5 or SWMM or EPASWMM - (not formally associated with EPA) to add comments!

Join SWMM 5 or SWMM or EPASWMM - (not formally associated with EPA)

Email me when people reply –


  • Hi, You can enter the default area of a manhole under Simulation tolerances as the Area of a Manhole.  

    There is a default area for all manholes in SWMM defined in the – this default is 1.22 square meters – you do not input a diameter.   If you have a manhole or storage with a different area/diameter then you make it  a storage node and define its surface area  as a function or a table.



    • Hi, I would like to know, how SWMM calculates the energy loss and water level drop at the entrance of the conduit, when water flows from the manhole to the pipe.  Is the diameter of the manhole (i.e the velocity in the manhole) taken into account (besides the velocity in the pipe)? In that case, is the above mentioned assumption of manhole's area of 1.22 square meters still in use?

      Thank you for help.

    • I did not understand whether it is possible to model manhole with various size using SWMM or not?should we model manhole with junction elements?

      I want to know  how can we model a manhole with drop structure betwen them? I want to see water surface profile in drops  with various manhole size. I modeled a drop structure. but in my model I couldnot observe the velocity decrease in flow. I will be thankful if you kindly help me regarding this issues.




This reply was deleted.