achim wrote: > Thanks for reply, > > but thats not exactly what I am searching for. I can not to use the > accumulation values, because > > > i) I want to figure out the watersheds on parts of the network > (beginning from certain points of the river network to separate some > basins on different levels; r.water.outlet would do that, granted that flow direction has the same format like r.watershed's flow direction > ii) I am going to do some statistics on stream lengths /accumulations on > network parts > Is the suggestion by Margherita Di Leo to get streams not working?
> iii) I need to separate parallel flowing streams from each other which > does not work on my current resolution > I think v.generalize can separate parallel lines with method=displacement. > > PPS: > >> r.mapcalc 'log_accumulation=log(abs(accumulation)+1)' >> > QUESTION: > why abs? accumulation values should be positive!? > Depends on the module used to create flow accumulation. r.watershed produces negative flow accumulation values for areas where flow accumulation is a likely underestimate (basin extending beyond region extends or parts of the basin are masked out). Also see r.watershed manual. The mapcalc approach may not work well on MFD accumulation maps; there the stream output of r.watershed would help. Markus M _______________________________________________ grass-user mailing list [email protected] http://lists.osgeo.org/mailman/listinfo/grass-user
