I have a huge vector layer as a line, that represents the river. The problem is that the flow direction is sometimes wrong (goes uphill). But I can't correct that manually, cause the layer is too big.
I also have a DEM for the entire area. So is it a way to reverse only the lines that go uphill? I mean something like selecting the line that the
end_point is at a higher altitude than the
start_point, and flipping the selection?