Why don't my catchments that use the RTK method produce the hydrograph shape that my flow monitoring device in the system shows?

  Applies To 
Bentley SewerGEMS, Bentley CivilStorm, Bentley SewerCAD
  Version(s): 08.11.XX.XX
  Environment:  N/A
  Original Author: Mark Pachlhofer, Bentley Technical Support Group


Why don't my catchments that use the RTK unit hydrograph method produce the hydrograph shape that my flow monitoring device in the system shows?


In order to check that the shape of the hydrograph that you are getting is correct you might also want to have a look at the flows that you're getting in your upstream conduits at points before flows combine. For example, in the screen shot below the flow in question is designated by the red box and the highlighted red pipe. The three upstream pipe locations that you want to examine the hydrograph shape for are designated by the orange-yellow, pink, and the blue boxes. If the shape of the hydrograph that has more flow looks like the shape of the hydrograph that is produced downstream then the shape you're seeing is likely correct.  

Please have a look at your RTK valves and try to adjust them if they are not producing the shape that you're expecting. You may find that they can be changed slightly to achieve the shape that you are seeing in your flow monitoring results. This maybe an iterative process of trial and error entry to see which RTK value affects the shape of the hydrograph that you're trying to achieve. If you have multiple RTK table sets make sure that you have the correct ones assigned to the correct catchment areas.You can also try to reduce the calculation time step and shorten the computation distance (Analysis > Calculation Options) to see if that helps achieve more accurate results.

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  • When: Thu, Dec 10 2015 10:58 AM
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  • When: Mon, Dec 21 2015 3:02 PM
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