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I am using r.watershed to get a stream map (which I assume is rivers). However the output rivers is always 1 pixel wide. I would've assumed that if I run this on say Iraq I would see the Tigris and Euphrates stand out / be abit larger.

Is there a way to tweak r.watershed to do this or is there another GRASS tool for this?

I am running on SRTM elevation maps if that makes a difference.

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  • Can you draw the stream size based on the flow accumulation value?
    – gvanhavre
    Oct 30 '20 at 18:21
  • flow accumulation value - is that essentially river size? do I get that from the accumulation output from r.watershed? Oct 31 '20 at 0:01
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    I think you are confusing between geomorphology structures, and water flow. The r.watershed module does not know anything about water, rather it calculates streamlines based only on topography. You will get stream lines in the desert regions of Iraq, for example, where there are no flowing rivers at all.
    – Micha
    Oct 31 '20 at 7:56
  • And like @Micha, I'd add that river size is a relative concept, particularly in regions where rainfalls are episodic. The suggestion to use accumulation values will show the growing size of the bassin, not the actual flow. So it's just a proxy...
    – gvanhavre
    Oct 31 '20 at 9:51
  • @Micha is there a module to get me the rivers? Oct 31 '20 at 10:13

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