HEC RAS Lateral Structure - newbie

[hmv519]

I have two streams that eventually converge into one. I know there is some flow sharing between the two so I have attempted to enter a lateral structure and have the TW over multiple cross sections. I entered the embankment stations and elevations and the corresponding user specified intersections for the HW and TW cross sections. It all looks well and good until I look at the schematic plot. The embankment extends beyond my last downstream cross section and a number of cross sections appear to cross over the embankment. I have already re-entered all of my XS cut line coordinates and my reach line coordinates to the nearest 0.0001!

The last embankment station matches the last TW cross section station yet there is a line segement in the schematic that continues downstream then reverses direction back to the last TW cross section. I should add that I exported the data from AutoCAD C3D so there are some vertices/stations that are not necessarily at intersections of cross sections. I have already tried to delete these out and I still get the same schematic.

Is there a trick I am missing?

 

[gbam]

First off, review the hydraulic reference manual for modeling confluences.

Second, can you upload the schematic you describe.

 

[hmv519]

Flow sharing is occuring in some areas well upstream of the confluence.

See attached schematic. Maybe my words aren't describing it correctly.

 

[gbam]

Okay now I see. I think that the schematic plot will show the "weir" lataral segment as a straight line eventhough it may be curved. Just like when you import a curved centerline, it is broken in to segments. Have you looked at the perspective view? If so, how does it look?

I have gotten something similar when I had a curved weir for a levee (outside Bend), it showed as a straight line, because I hand coded the profile into the lateral editor.

I think its just how the program shows it. Remember that HECRAS/2 are one directional models. Curves are faked in, per se.