Moritz Lennert wrote: > Hello, > > I'm trying to reproduce an exercise of the GRASS book, third edition, pp. > 145-146, which demonstrates the usage of r.water.outlet. Using exactly the > same commands as listed in the book, I get a basin which is hardly visible > unless zooming very closely to it. r.report reports a size of 0.0002 ha. Is > this normal ? > > > The relevant commands in the book are (for the NC dataset): > > g.region rural_1m -p (or g.region rast=elev_lid792_1m) > r.watershed elev_lid792_1m thresh=5000 accum=accum_5K \ > drain=draindir_5K basin=basin_5K > r.water.outlet drainage=draindir_5K basin=basin_A30 \ > east=638872.6 north=220042.6 > > The version of r.watershed used for the example in the book had some bugs, in particular a bias towards diagonal drainage direction which is mosz notable with high-res LiDAR DEMs like elev_lid792_1m. One consequence is that accumulation patterns shifted a bit and east=638872.6 north=220042.6 are most probably no longer falling onto a main channel leading to minute basins. Try plotting east=638872.6 north=220042.6 on top of accum_5K and adjusting the coords such that they fall onto the nearest main channel.
HTH, Markus _______________________________________________ grass-user mailing list [email protected] http://lists.osgeo.org/mailman/listinfo/grass-user
