[GRASS-user] extract single watershed from r.stream.order-result

GRASS GRASS user
1

Hi,

I followed the GRASS GIS commands J. Jasiewicz used
in his r.fuzzy paper to extract the streams as rasters
from the spearfish dataset.

What I did so far:

r.watershed -f --overwrite elevation=elevation.10m@PERMANENT accumulation=accum

r.mapcalc accum_abs=abs(accum)

r.stream.extract --overwrite elevation=elevation.10m@PERMANENT threshold=200 stream_rast=stream

Now I'd like to select only one of all drainage networks (watershed). I am interested in the right network of the two main river networks in spearfish
Is there an easy way to get only that main watershed into a new map? I thought about identifying it via the main outflow pourpoint at 602140|4927950...
Any suggestions?

Best regards,
Johannes

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2

Hi again,

I found now a quite simple solution with the r.stream.basins module ...

What I did so far:

r.watershed -f --overwrite elevation=elevation.10m@PERMANENT
accumulation=accum

r.mapcalc accum_abs=abs(accum)

r.stream.extract --overwrite elevation=elevation.10m@PERMANENT
threshold=200 stream_rast=stream

#to extract the single river-network at the given outflow point I need
#also to extract the dirs:

r.stream.extract --overwrite elevation=elevation.10m@PERMANENT threshold=200 stream_rast=stream direction=dirs

# and then run following:

r.stream.basins" dir=dirs coors=602140,4927950, basins = basins)

r.mapcalc sample_stream=basin&&stream

/Johannes
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