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Using QGIS 3.28.2-Firenze. I created a depressionless DEM, created a shapefile with points I want to measure flow from by using "Add Point Feature", ran D8 Flow Pointer, and then ran TraceDownslopeFlowpath, but I did not get any flow paths shown.

What step am I missing to show the flowpaths?

Similar Question: Calculating flowpaths downstream of a point

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  • Here is a snapshot of the output. No flow path lines were drawn when I went to the layer and tried to classify the values. Flowpoints are numbered 1-7. I must be missing a step. dropbox.com/s/1dapc2gks0w9hxr/Capture.JPG?dl=0 Jan 23, 2023 at 21:03
  • As I dig into this, I think it has something to do with assigning a z value to the shapefile with points. When I use the "Identify Features" tool, there is only an X and Y value to the point. I've tried to use the v.drape and v.to.3d tools but I can't get them to assign a Z value. I'm still digging into this. Jan 23, 2023 at 22:14
  • OK, I assigned Z values by using the "Drape (set Z value from raster)" and ran the "TraceDownslopeFlowpath" tool and it worked! But I don't understand what the different colors signify since the color changes from red to blue on the same main stream. dropbox.com/s/kivldacz7tqugf1/Diff%20colors.JPG?dl=0 Jan 23, 2023 at 22:41

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