[GRASS-user] Longitudinal stream profiles

GRASS GRASS user
1

Hello,

I am trying to extract longitudinal stream profiles for stream channels (running 6.4.4 on OSX 10.9.5), and am curious if anyone has done this before and has any hints about what an efficient workflow would be.

My thought is to use r.streams.extract and r.streams distance, which should enable me to gather the required information. The one question I have is how to allow a user to choose the upper end of a channel, and have GRASS separate the information for that entire stream profile (from the selected point down to the outlet) into a new vector file.

I’d really appreciate it if anyone has done this in the past-- I can’t find much information related to this type of analysis online.

Thanks,

Charlie

2

Hello Charlie,

You could use the flag -o and method=downstream (which is the default method) with r.stream.distance to get two raster maps with distances and elevations to the outlet.

You should use v.points on the stream_vect map you obtained with r.stream.extract so you could then upload this distances and elevation values to the points stream vector map using v.what.rast.

Then you could go to R and read that vector map using the spgrass6 readVECT6 function and then perform your analysis in R.

That’s what I’ve done before, I’m hoping this could help you and looking forward to other implementations that doesn’t need to go to R.

El Tue Nov 04 2014 at 10:53:46 a. m., Charlie Shobe <Charles.Shobe@colorado.edu> escribió:

Hello,

I am trying to extract longitudinal stream profiles for stream channels (running 6.4.4 on OSX 10.9.5), and am curious if anyone has done this before and has any hints about what an efficient workflow would be.

My thought is to use r.streams.extract and r.streams distance, which should enable me to gather the required information. The one question I have is how to allow a user to choose the upper end of a channel, and have GRASS separate the information for that entire stream profile (from the selected point down to the outlet) into a new vector file.

I’d really appreciate it if anyone has done this in the past-- I can’t find much information related to this type of analysis online.

Thanks,

Charlie

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