how to reorder cross sections

[Anonymous]

I’m new to HEC-RAS. I’m delineating the floodplain and after importing my Geo-RAS produced geometric data I see somehow I’ve gotten the cross sections ordered wrong. The channel is about 27,000 ft long (~8.2km). But upstream to downstream the XS numbers go #14,900 to #26,100, and then still going downstream #200 to #14,300. Looking at the profile the 14,900 is the highest in elevation, and the other points are also the correct elevation,just in the wrong place in the whole. The profile graph descends left to right (from mid elevation to the loweest) then jumps up to the highest elevation and then descends again to the “starting” mid-elevation.

I thought I did everything in Geo_HAS correctly (downstream, left bank flow paths first then right, etc). I did use a “real” stream center line delineated from my lidar DEM. Could that be the problem? Can I edit this in HEC-RAS without return to Geo_RAS and trying to fix it there? Its probably easy, but the tool is still a mystery.
Thanks in advance.

[Tim Bedford]

Chris,
How many cross sections are we talking here? Something similar I have done is change XS’s with the “interpolate line” tool which is apart of 3D analyst in ArcMap draw a line directly over my GeoRAS created XS cut line plot the profile (another tool in 3D analyst) export that data, then exchange the station-elevation data in RAS with my copied excel data.

If that makes any sense or seems appropriate I can walk you through it in a little more detailed fashion, otherwise all I can think of to help is “copy current cross section” function in the Cross Section Data.

Good luck

[Anonymous]

Thanks Tim,
I think I’ll go back and redo the whole. Its approx. 50 XS of 128 that are out of order, or maybe its really all 128. The river flows the wrong way in steps. I think it might be a relict of using my lidar raster delineated stream line to get my polyline for HEC-RAS. The RS numbers are in order and the elevations do not correspond. The mystery grows, as I was trying various things to get the software to ‘read’ the flow and geometry differently and I changed the river units (from feet to river miles) and now I’ve a weirder profile, as it added the river in miles to the river in feet. The profile now looks like three NNNs. Bizarre. Thanks for trying.

[Author]

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