What is good guidance for where to set the threshold? I am in the coastal plain, but In the very upper part ~10 miles from the piedmont, so it is not terribly low gradient (I am going to quantify this "not terribly low gradient" soon). I don't see the -b flag for r.watershed 6.4svn checkout (probably a week ago) in the man pages. I said realistic because you can set the threshold to 1 for a 1m res dem. There are lines that don't even look like streams all over the place. Is it possible to extract streams with the landscape (Mongomery) as a guide for the threshold? I want to be able to do this so all of the stream ordering is done on a consistent stream network among watersheds. If this is not possible then I will use a threshold and use this for all stream network extraction on all of the other dems that I need to process so they are all comparable. I appologize if this doesn't make sense, but I will explain in greater detail if I need to. kindest regards,
Stephen Sefick On Thu, Aug 5, 2010 at 9:35 AM, Jarek Jasiewicz <jar...@amu.edu.pl> wrote: > stephen sefick pisze: >> >> I would like to use the Montgomery method to extract streams (exp~2 >> from the paper). What should the threshold value be? And in general >> what should the threshold value be? I am working in the southeastern >> coastal plain (USA), which is characterized by low gradient (if this >> helps). > > for flat areas Montgomery's method is not a good option. Generally that > method was created and tested on areas with gradient > 5%. >> >> I am using 1m resolution LIDAR data. I would like to extract >> the most realistic map of streams that I can. > > Chmmm... what you mean realistic? Maybe use existing stream network will be > the best solution? > For coastal plains where is no real vallyes the r.watershed's treeshold with > -b option seems to be best option >> >> I am also trying to >> track down the inttermitance perminance threshold. Any guidance would >> be greatly appreciated. >> kindest regards, >> >> > > -- Stephen Sefick ____________________________________ | Auburn University | | Department of Biological Sciences | | 331 Funchess Hall | | Auburn, Alabama | | 36849 | |___________________________________| | sas0...@auburn.edu | | http://www.auburn.edu/~sas0025 | |___________________________________| Let's not spend our time and resources thinking about things that are so little or so large that all they really do for us is puff us up and make us feel like gods. We are mammals, and have not exhausted the annoying little problems of being mammals. -K. Mullis _______________________________________________ grass-user mailing list grass-user@lists.osgeo.org http://lists.osgeo.org/mailman/listinfo/grass-user