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Based on "Generating a series of cross sections (profiles) along a line?" post, how can I force the cross-section lines to be created, thus collecting elevation data, from LEFT to RIGHT facing the downstream end of the river based on the example Steven Kay has provided?

I see that it depends on the CRS, but is there a way to actually force them?

I need to import the cross-sections of a river in HEC-RAS 2D and they need to be created specifically in such way from the beginning.

I am using QGIS 3.6.

  • I know there is a function in HEC-RAS 2D ver 5.0.7 -> Geometric Data -> GIS tools -> GIS cut lines -> Reverse cut lines which allows you to switch direction of all or some of the cross sections. But I was still wondering whether there is an integrated function in QGIS for time management purposes. – Overlord84 May 2 at 1:59
  • Yes, there is plugin to do so: Swap Vector Direction – Marco May 2 at 19:18
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I cannot answer your specific question, but I can help you to cope with the task.

I do not create cross sections automatically, but one by one, even then it is hard to keep the consistency and it is quite common the end with a couple of cross sections with the opposite direction.

Adjusting the cross section breakpoints to match the expected flow lines and avoiding intersections is already time consuming, so I think correcting the direction is a minor task compared with the whole process.

To find the wrong ones, the ones with the inverted direction, I just use the "arrow style" for the lines. Once I found them, I reverse the order with the plugin "Swap Vector Direction".

  • All I needed I think was that "Swap Vector Direction" plugin. Unfortunately, I cannot spend hours creating cross sections for rivers that are hundreds of km long. I'd much rather spend a bit more time creating a precise centreline and use the "Cross profile" function, and then re arrange the weird ones manually and then swap direction. Done ;) – Overlord84 May 3 at 0:15

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