EGL Energy Gradient line Profile in Sewergems V8i

Question

why EGL (Energy grade line )profile is suddenly drops just before the catch basin and then rise and vise versa with HGL(Hydraulic Grade line)

Jesse Dringoli · Accepted Answer

Hello Raja, 
 
Please refer to Scott's post further above - the article he references addresses this situation: 
 
 communities.bentley.com/.../10149.hydraulic-grade-discontinuity-at-steep-pipes-or-across-nodes-frontwater-analysis 
 
To elaborate, using your specific model: If you look at the "Profile Description" field for each of your pipes, you'll see that they are flowing in the Steep regime. For example CO-6 is a Composite S1 S2 and CO-7 is a S2. With a hydraulically steep pipe, the program uses a frontwater analysis. With two steep pipes in series, this can cause a discontinuity in the profile. This is the situation that is happening in your model - the calculations are starting at the upstream end at critical depth and working their way downstream. So, in the case of CO-7 for example, the hydraulic grade is calculated in a downstream direction, eventually settling near Normal depth at the downstream end. However, the next downstream pipe is also hydraulically steep, causing the HGL to jump back up to critical depth at its upstream end. 
 
The drop in EGL that occurs midway along the pipe (CO-6) is due to a hydraulic jump, where the velocity suddenly drops. 
 
The aforementioned article goes into additional detail to help explain.

Scott Kampa · Answer

Hello Raja, 
 
Also, if you are using the StormCAD or SewerCAD solver, this may be caused by steep slopes in the profile. The following link has some information on this: communities.bentley.com/.../10149.hydraulic-grade-discontinuity-at-steep-pipes-or-across-nodes-frontwater-analysis 
 
Regards, 
Scott