[GRASS-user] calculation valley floor width in GRASS or some index indicating valley floor width?
Stefan.Blumentrath at nina.no
Sun Apr 6 13:03:15 PDT 2014
After a second thought on this, personally, (given that I understood your aim correctly) I would probably use a workflow like:
r.watershed in order to extract the streams (which are not unlikely to meander or split up into different courses in wider U-valleys)
r.stream.distance in order to extract the elevation above stream
r.param.scale (probably with different neighborhood sizes) for identifying flat areas and valley sides (based on the "elevation above stream" raster)
r.mapcalc for modeling the bottom of the valley as flat areas (slope threshold) below an elevation threshold above the stream
r.reclass.area for removing some unwanted islands
r.mapcalc for inverting the valley bottom map (valley bottom = NoData, rest = 1)
r.grow.distance for measuring the distance from the inverted valley bottom
r.neighbors for measuring the maximum distance within one (or more) neighborhood(s) - depending on expected maximum valley width - as an estimate on total valley width.
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