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] <mailto:[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]
<mailto:[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
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UCSB, Santa Barbara, CA.
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