Michel, thank you - i'll try your r.mapcalc and vector suggestions. Janet On Thu, Mar 3, 2016 at 8:22 AM, Michel Wortmann <[email protected]> wrote:
> HI Janet, > can you specify what you mean by 'fully connected stream network'? > 'connected' doesnt mean much on a raster map or did you convert it a vector? > I would try to build your stream network from the accumulation raster map > by thresholding it with a certain catchment size (in cells). Eg. > r.mapcalc exp='streams=if(accumulation>1000, 1, null())' > That way you see what is happening in the accumulation map as a result of > the DEM. > Best, > Michel > > > On 03/02/2016 08:42 PM, Janet Choate wrote: > > Hi Will, > When running r.watershed on a small 35 hectare watershed, it produces a > fully connected stream network. However, when running r.watershed on a 6400 > hectare watershed, the stream network is not fully connected. > No preprocessing with regards to merging different raster maps, however, I > did try using r.fill.dir first to deal with any possible depressions that > might be causing non-connected stream segments. > thanks, > Janet > > On Wed, Mar 2, 2016 at 11:22 AM, Will Fields <[email protected]> > wrote: > >> Hi Janet, >> >> Can you give some more information about what you mean by larger >> watershed basins? Did you do any preprocessing of the elevation raster >> before you tried to extract the stream networks? Were you using an >> elevation raster that had been merged from different rasters? I've ran >> into issues in the past where "seams" along the original edges of a raster >> resulted in odd stream networks. >> >> Will >> >> On Wed, Mar 2, 2016 at 11:40 AM, Janet Choate < <[email protected]> >> [email protected]> wrote: >> >>> Hi GRASS community, >>> When creating a stream network with r.watershed, I end up with some >>> isolated stream segments - particularly in larger watershed basins. Does >>> anyone know how to generate a stream network that is fully connected, or >>> how to correct this issue? >>> thank you, >>> Janet >>> >>> >>> >>> _______________________________________________ >>> grass-user mailing list >>> [email protected] >>> http://lists.osgeo.org/mailman/listinfo/grass-user >>> >> >> > > > -- > Tague Team Lab Manager > 1005 Bren Hall > UCSB, Santa Barbara, CA. > > > _______________________________________________ > grass-user mailing > [email protected]http://lists.osgeo.org/mailman/listinfo/grass-user > > > > _______________________________________________ > grass-user mailing list > [email protected] > http://lists.osgeo.org/mailman/listinfo/grass-user > -- Tague Team Lab Manager 1005 Bren Hall UCSB, Santa Barbara, CA.
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