Lateral structure and cross sections HEC-RAS 5.0.4

[SaraA]

Hi everyone,

I had a 1D hydraulic model in HEC-RAS 5-0-4.

I just created the lateral structures, and now the cross sections or are longer or shorter from my lateral structure (see image attached).

My question is, What is the best way to adjust the length of my cross sections to the start of the embankment?
I just edited the cross sections deleting the Station/Elevation points overpassing the embankment, but the line of the cross-section does not seem shorter. I also tried to Edit/Move points to move the end of the cross-section to the start of the embankment, but I really do not know if this is the correct way.

Could someone explain to me how to do it?

Thank you in advance,

Sara

[Anonymous]

The station/elevation points are what is actually used for the computations. If you edit those, that will work even though the GIS cross section appears the same length on the geometry editor.

However, if you have good terrain data:

You can move the end of the cross section with the Edit/Move points but then you need to go into the cross section editor and click on the Cut from Terrain button. This will update the station/elevation data based on the shorter GIS cross section length.

[SaraA]

Hi Jarvus,

I did as you explained, but I get the following error when I reopened the geoemtry data.

XS Htab Starging elevations – The following XS’s had hTab starting values below the XS invert. The values were reset to defaults and wull be saved next time the geoemtry is saved.

River: Paglia Reach: Reach 1 RS: -12000

River: Paglia Reach: Reach 1 RS: -12100

Also when I run the simulation I get,

***** Warning! Extrapolated above Cross Section Table at: *****

Paglia Reach 1 from R.S. -12000.* to -12100

Thank you,

Sara

[Anonymous]

I have also gotten the invert adjusted. I’m not sure what causes it but it seems that is updating the HTAB tables to have a better starting value and it seems to work fine, at least for me. I would think of it as more a “message” than an “error”.

The Extrapolated Warning is a different story. If the data set is going unstable and getting crazy high water surfaces, than you need to focus on why it is going unstable.

If it is not going unstable, you may need to adjust your HTAB table. From the geometry editor, click on the HTAB Param button. For each cross section, the table must go higher than the highest water surface for that cross section. For most rivers, if the increment is “1” setting the number of points to a few hundred or so should work. If you have a reservoir that has cross sections inside of it, you may need to increase the size of the increment for those cross sections.

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