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JKM

Merging Sections

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Chris,

I'm making progress on this model, which has over 100 cross sections. The sections are created with the DEM and then "merged" with channel data. I'm in the process of exporting everything out to RAS. When I do, some of the channel sections appear to have georeference issues. See the attached plot. I merged each section the same way and they do not all have the same problem.

Can you tell me what causes this and direct me as to how to fix it without recreating all of the cross sections?

Thanks!

John

RASsrceen.pdf

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John,

There is definitely something wrong with your model in RAS. I'm not sure what has happened, and I've never seen this problem. My guess is that it has to do with the way you are merging your cross section information inside of WMS. I'm not sure how you are doing this. I'd recommend going through the WMS tutorial on managing cross sections on our wiki page here: http://xmswiki.com/xms/WMS:WMS_Tutorials#Hydraulics_and_Floodplain_Modeling

The exact name of the tutorial is "HEC-RAS – Managing Cross Sections".

If you have already done this and are sure you're doing everything the same as things are done in this tutorial, you could send your WMS files to the tech support group and tell them to send it along to me so I can look at it.

Information on contacting Tech support and sending files is located on our web page at: http://www.aquaveo.com/technical-support

Let me know if I can help with anything else.

Chris

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Thanks Chris, I think I see what caused the issue....As I merged the floodplain and channel sections together, I edited them to clean up the blended section. This involved adding a point here and there and moving a few as well. It seems like in one or both of these instances, the X and Y coordinate values were lost (0,0). The D & Z values are fine so the section itself looks good in the editor, but when the sections are exported to RAS, there are points from different sections that share the 0,0 coordinate and that is what is causing the the geometry in RAS to look the way it does.

So, how can I address this is WMS, as some section editing is typcially needed. And what if I do additional section editing in RAS once all of the structures (bridges) are added? I will be bringing pre and post model results back into WMS to show the floodplain change and want to make sure I don't have issue there...

Thanks for all the help!

John

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John,

I have looked at this in WMS and it is always best to use the "Merge" and "Filter" commands to correct issues with your cross sections from inside of WMS. Using the Add points tool or the move point tool could cause problems with the geo-referencing. You should be able to change the Z-coordinate of a cross section point in the WMS Cross Section attributes with no problems. So I would stick to the merge option when adding points from a survey cross section. If you use the add or move point tools, your cross sections will not be geo-referenced correctly and your RAS model will probably not be correct. This is something I will look at to see if I can fix, but the fix will not be available until a later time.

As for editing cross sections in RAS, you can edit the Z values in RAS and you can delete and filter cross sections without any problems. Do not change the station numbers in RAS. This will confuse WMS when you try to read the solution and you'll probably get an error. If you add additional cross sections in RAS, WMS will not read the solution at these additional cross sections and you will get an error message when you read the solution, but the solution at your existing cross sections should be read. You can add bridges and culverts to your RAS model and there will not be any problems reading the solution into WMS. Let me know if you have any other questions.

Thanks,

Chris

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Thanks Chris. As a follow-up, I think adding points is definitely a problem for the georeferencing. But I'm wondering if the moving of points to put the banks where I want them may be OK.....It looks like when a point is moved, it holds its X,Y and only adjusts the D and Z. While this means that these point may not be perfectly referenced, they are typically in a straight line so I'm thinking this may not matter. Would you agree?

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John,

The XY values should change if I adjust the point's D location. It's not really a big deal since the georeferencing remains the same and there are no changes to the XY values on the cross section if I move a point. But it is something I'd like to fix. I'd stick with editing only the Z values of points in the spreadsheet. If you edit the D values, the XY values will not correspond to the D value for whatever point you adjust.

Thanks

Chris

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