HGL & EGL in profiles and Links downstream of inlets

[wdprice3]

Firstly, I am just learning SSA, so sorry if these are basics I've missed. I'm doing a basic storm network analysis (channels, pipes, inlets, ponds). 1) HGL/HGL Max always track bottom of link in profile views; how can I get it to show the HGL through the links? The EGL has never shown in profile... Data tables show depths/flows/etc. Also junctions/inlets always have a small blue line through them - what is this line, as nothing in the display options changes them. They almost appear to be HGLs, but they don't match the HGL for the link (which is tracking the link invert)... Also, there are no HGL options available when running multiple storms... how do you see such results? 2) I have a simple test model set up where sub basin -> junction -> ditch -> inlet (upstream link) -> outfall. However, the pipe (or any link) connected to the downstream end of the inlet always has 2-4 times more flow than what's produced in the basin/shown in other features. If I convert the inlet to a junction, all the numbers work out. Where is this extra flow coming from? Have I missed a setting or option; or am I modeling inlets incorrectly? Thanks

[wdprice3]

Let me also say that I did see threads mentioning to change the ponded area for the inlets. I've been through several iterations of changing this area, and yes I get better results, but not nearly good enough. I can't hand something to a client with such discrepancies. Using Rational Method for hydrology. There should be no mass losses in my model. Guess I'll have to look at doing HEC-22 by hand....

[fcernst]

Using Rational Method for hydrology...

If the above is true you are using the wrong tool (SSA) for your peak flow storm sewer network analysis. Hydraflow Storm Sewers uses a "form" of the HEC 22 methodolgy that you should be using. 

[wdprice3]

I'm not sure how the method of hydrology really matters here... ? I primarily need a tool for the hydraulic analysis, and SSA seems to be the only program that can pull together hydrology, swales, pipes, inlets, junctions, and ponds into one model. And as far as I know, HSSE, HHE, HydroCAD, etc. don't bring all of these interconnected pieces together.

[fcernst]

I'm not sure how the method of hydrology really matters here... ?

This is a misuse of the Rational Method. Dynamic modeling software requires the use of hydrograph methods such as EPA SWMM, SCS or your local unit hydrograph method.

[wdprice3]

Unless you are referring to SSA's failings, I must disagree that the Rational Method is being misused for a peak flow analysis. And this still doesn't address my original questions. I can investigate the hydrology methods later, when it comes time to do pond routing. The hydraulics are my primary issue right now.

[fcernst]

Using the Rational Method with a dynamic software like SSA for pipe sizing is the problem.

The correct application of the Rational Method for pipe sizing involves the use of a system tc (time of concentration) along with CxA. Software such as Storm Sewers and StormCAD do this. 

[wdprice3]

I've added SCS hydrology to my model; however, I am still not being shown correct HGLs or shown EGLs at all. Any advice?

[Matt.Anderson · Accepted solution]

Hydrology method discussion aside - I assume that in profile view you are viewing the HGL/EGL values at the initial onset of the analysis, ie, at time equal start.

Use the Output > Output Animation dialog box to step thru the analysis reporting time to simulate the flow thru the system.

[wdprice3]

Thanks, that works. A bit odd, as I figured showing max EGL/HGL would show the maximum for the simulation run (without animating). So it appears that I must also run the animation then the max EGL/HGl will show correctly. Thanks.

[fcernst]

I've added SCS hydrology to my model

This is not an acceptable hydrologic method for urban storm sewer pipe design.

The SCS method was devloped primarily as a hydrologic method to be used for earth dam design, spillway design and flood prevention. The method was derived from data within primarily agricultural watershed environments. 

The Rational Method is the industry standard of practice hydrologic method for storm sewer system design for typical subdidvision and highway drainage applications. 

[FatFreeCheese]

Long time reader, first time poster.

I am having difficulty exporting the EGL line generated in the Profile Plot. When I expand the CAD Export Options, there are twenty layers and they are all selected. When I open the exported CAD file in Civil 3d (2012 and 2014), there are only 19 layers with the missing layer being the EGL line. Has anyone encountered this problem before?

Thank you.

[clinton_merrell]

Matt, 

I was having this same problem and stumbled onto your message after hours of head scratching.  I'm doing a peak flow analysis similar to the OP... Is there a way to to get the profile plot to plot to the moment of the peak by default? That way we don't have to do through the whole animation everytime we run the analysis just to see the peak?

Or for that matter, is there even an easy way to jump right to the peak other than trying to pick it out from the date and time dropdown in the output animation dialog box?

[tonykhoury]

I am using SCS and i am having the same error . Please see attached.