View Full Version : Modelling Blockages

February 19, 2016, 06:57 AM
Hi all,

What's The Forum's opinion on the best way to model blockages in InfoWorks CS / ICM in wastewater pipes, and also rubble that's not consistent throughout the length of the sewer.

Many thanks all.

Kristian Ravnkilde
February 24, 2016, 12:14 AM
Blockage: insert 2 dummy nodes, link by an orifice corresponding to the clear part of the pipe. Inconsistent rubble: You could insert dummy nodes and add different depths of sediment in each length, but averaging it out is probably good enough. All depends how much difference it may make and how important it is to model it precisely.

March 2, 2016, 03:17 AM
Hi Kristian,

Many thanks for the reply.

Best regards,


Duncan Kitts
March 2, 2016, 06:12 AM
Generally with blockages, it depends where the blockage is. Other approaches are, although not all for rubble which I assume is at bottom of the pipe,:-

1. Represent the blockage via an increase in the Manning's n roughness value. In this case the blockage would be assumed to be on the bottom of the channel.
2. Change the pipe geometry to include a representation of the blockage. This would only really work if the blockage was at the bottom of the section (ie, on the bed). This is similar to the sediment depth suggestion.
3. Use a sluice gate or gated weir with RTC to represent the blockage. This has the benefit of allowing you to modify the blockage with time. In the case of the sluice gate, it allows you to represent the blockage occurring in the upper half of the section.
4. Use a user-defined link. Use the unblocked results to obtain a head-discharge relationship for the reach you are interested in. Then add a user-defined link in this location and modify the head-discharge relationship to include representation of the blockage. Ie, reduce the discharge at particular flow depths.

March 2, 2016, 06:25 AM
Many thanks Duncan. Very useful information for me.

Best regards,