[GRASS-user] Hydrological grass question: main channel length for each subbasin
Michel Wortmann
wortmann at pik-potsdam.de
Sun Feb 16 08:07:59 PST 2014
Hi list,
I'm looking for a way to calculate the main channel length and width for
a large number of subbasins within a river basin. I understand that the
r.stream.* addon / R.basin gives me the main channel length along with a
tone of other statistics but only for one catchment. Of course, I could
loop over all my subbasins and calculate the statistics one by one, but
I fear that will be time consuming and I dont actually need all the
other analysis.
I have got an efficient way to calculate the mainstream for each
subbasin as a vector, but I'm struggling to get from there to the
distance of the longest segment in each subbasin. Maybe someone has an
idea to complete this idea of a work flow:
raster=mainstreams (thinned raster with unique categories for each subbasin)
r.to.vect to vectorise, this unfortunately gives me line segments
crossing over subbasin boundaries
somehow make stream segments from each subbasin
v.to.db to measure the distance of each line segment
choose the longest distance for each subbasin
Any suggestions/help would be much appreciated.
Regards,
Michel
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