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Ben22

Referencing of CROSS SECTIONS

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Chris,

My cross sections that I have exported from WMS to HEC-RAS are not getting referenced over from the merged Lidar/survey data from WMS. I was working on inputting my bridge deck in HEC-RAS and quickly noticed that the channel for the upstream and down stream cross section were 300 feet or so off alignment. I noticed when you select a cross section that you can geo ref it by points. Will I have to go through each individual cross section and reference them in by points or is there a quicker alternative that will reference all the cross sections in when I extract the cross sections in WMS? Thanks!

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Ben,

Let me try to answer each of your questions individually. I'm still trying to understand what the problem is though.

My cross sections that I have exported from WMS to HEC-RAS are not getting referenced over from the merged Lidar/survey data from WMS.

Have you done the following commands after creating your 1D Centerline and 1D Cross Section coverages, making sure your arc attributes are set correctly, and after reading your LIDAR data?

1. (In Map Module) Extract cross sections

2. Map->1D Schematic

3. (In Hydraulic Modeling Module) define Material Properties and Model Control from the HEC-RAS menu

I was working on inputting my bridge deck in HEC-RAS and quickly noticed that the channel for the upstream and down stream cross section were 300 feet or so off alignment.

If there's a problem with the alignment of your cross sections, you should make sure you're using the latest version of WMS. Some problems related to cross section stations were fixed in the last year or two. Another thing you can try is to go to the WMS map module and select Recompute All Stations from the River Tools menu and then re-extract your cross sections. Changes to your cross section or stream centerline alignments after originally creating your cross sections would make it necessary to run these functions again. After doing this, go to the 1D Centerline coverage and select Map->1D Schematic again to make a 1D schematic of your hydraulic model.

I noticed when you select a cross section that you can geo ref it by points. Will I have to go through each individual cross section and reference them in by points or is there a quicker alternative that will reference all the cross sections in when I extract the cross sections in WMS? Thanks

Are you talking about the function to Georeference cross sections in WMS? I actually wouldn't recommend using this function for what you need. Just make sure your cross sections are in the correct location in relation to your bridge and use the commands described above (with the most recent version of WMS) to get your stations in the right location. You will have to re-export your HEC-RAS model from WMS after fixing these issues and define your bridge deck parameters in HEC-RAS.

Hope this helps and you are able to get things working.

Chris

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Chris,

Your second solution of recomputing my stations fixed the stationing for the cross sections and set them on the correct alignment. Thanks again!

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Is it possible to calibrate the cross sections according to a datum (Thalweg or Left and Right banks), so that the cross sections have the same stationing as the stationing from bridge plans?

Edited by Ben22

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Ben22,

The only option you have is you can manually define the stations for each of the cross sections in your model. You do this by going to the cross section attributes for each cross section in the Hydraulic Modeling module of WMS and then set the Computational station for the cross section. You would need to define this station for each cross section. Then you would need to re-export your HEC-RAS model.

NOTE: I did discover an error in saving/reading your WMS file when you manually define the computational stations as I described, so I would not recommend this approach right now. I will try this in our development version of WMS and see if it's fixed. We have been working on the stationing code.

Unfortunately, it's not currently possible to automatically define a stationing other than the default stationing in WMS. The default stationing is in your model units (either feet or meters) and is based on the distance from the most downstream point on your stream centerline arc in your 1D Hyd Centerline coverage. The capability of automatically defining stationing from some point is another option we want to add sometime in the future.

Let me know if I can help with anything else.

Chris

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Chris,

Thanks for the response! Yes, it would be helpful if you could possibly station the cross sections for the upstream and downstream bounding cross sections near the bridge according to bridge plan stationing or a known stationing. Then the rest of the cross sections would be calibrated according to the upstream and downstream stationing. This would make the HEC-RAS model more representative to the original stationing.

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