I am working with QGIS and I have a DTM of a river. I need to extract multiple cross sections (one every 10m), and they must be perpendicular to the river center line. Can you tell me how to do that, with the passages?

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    Hi Elena, welcome to GIS SE! Try to divide your project into atomic, specific, or non-trivial tasks. Do you have already the center line of the river? Do you have it densified with a vertex each 10m? Do you have perpendicular lines? If yes, you can ask about how to extract the cross sections from the DEM. If not, you can ask about the specific step where you are stuck. Jan 26 '20 at 15:29

Try Cross Profiles tool in the Processing Toolbox > SAGA > Terrain Analysis - Profiles.

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(1) Make sure to reproject your DEM to XY(m) coordinates.

(2) Prepare your river center line(s), perhaps by digitizing manually.

(3) Start the tool and set each parameters:

  • DEM: Your DEM layer
  • Lines: Your river line(s) layer
  • Profile Distance: 10m
  • Profile length: The length of profile you need.
  • Profile Samples: Number of sampling points along the cross profile. Please calculate this number beforehand by profile length(m) * 2 / sampling interval(m).

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