John Stamm writes:
Hello. I am working with r.watershed, and there are a few raster
files that are put out by the program. One is slope length. Can
anyone tell me what this variable represents? Is it the distance
to the channel? I am interested in finding the mean and max distance
from the divide to the channel for a half-basin. Can I use this
variable? Thanks for any help.
As far as I know, slope length is just what is says: the length of a
slope from the point where it starts (slope > 0 degrees) to the point
where it stops (correct me, anyone, if there's more to it!). This will
probably be the same as the distance from divide to channel in many cases.
Your problem may be solved using some simple r.buffer technique (or a cost
surface, if you like it more fancy). Let r.buffer calculate the distance from
the channels for any point. Then overlay the map with the divides (don't know
if this is produced by any of the programs you use, or if you use some
digitized maps, but the procedure is the same), and you'll have
no problems finding mean and max distances using r.mapcalc and/or r.stats.
Hope this helps.
Philip Verhagen
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