HEC-RAS Levee option doesn't seem to be working

[popriver]

I don't seem to have any luck in modeling levees in HEC-RAS. Currently I am using a levee to not allow flow into a low area to the left of the main river. I'm only using the option at one cross-section. I have the levee outside of the bank station, but the cross-section view still shows flow outside of the levee, even though the WSEL is below the elev of the levee. I have the same resulting WSEL when I run it without the levee as a sensitivity analysis, even tho the cross-sectional area outside the levee is significantly large (about equal to or larger than the area in the main channel). Is there a step I'm missing, I wonder? I didn't think you need to model a levee at two continuous cross-sections to make them effective.

 

[Ryb01]

A view of the X-section showing your range of flows would help ....You don't have to model a levee at two cross sections, however, ras interpolates between two sections at a time. With that being said you may want to add in "chords" u/s or d/s of your levee to properly code in the flow constraint.

In your cross section data window is there;
1) A levee station showing on your X-Section?
2)Levee in the lengend on the right side?

 

[popriver]

Thanks for your help. I am not interpolating cross-sections. I've attached a print screen of the cross-section. (There is a lateral structure on the right at the end of the cross-section.) I was thinking this might be happening because the invert on the left side of the levee is lower than on the right side. But I ran a sensitivity analysis, and raised the streambed on the left hand side, and still had the same problem.

 

[chicopee]

Your levee may not be long enough. Check your XYZ plot under different flows.

 

[Ryb01]

The invert of one channel vs the invert of the other channel will not have an effect on the function of the levee if your channel bank stations are coded correctly. I'm assuming that you wanted the flow to be contained within the right side of the channel? If so, bank stations look okay.

I'd maybe try two things for additional consideration;
1) Try ending the cross section at the left bank, does ras produce a water surface elevation higher than the left bank? If so, what your seeing in the model is probably correct
2) Are you running more than one flow profile causing the bank to overtop?

 

[popriver]

Well, you were right. I tried changing the cross-section, deleting the low part to left of levee, and got the same resulting wsel. So it wasn't really putting the flow over there, it just showed it graphically in the cross-section I guess. A bug perhaps. Also, in the original gometry file, it didn't show the flow going outside the levee in the xyz plot. So thanks to both of you.