On 02/15/2012 04:46 PM, Helmut Kudrnovsky wrote:
what does it means? Any reference? Main channel established in real network
or algorithms of modeling main channel?
the mentionned "real" mainchannel is the part of real Austrian river network
(i.e. listed in the annual Austrian hydrographical handbook as the river
'Isel')
It is popular argument against algorithmic approach. Usually computer
algorithms cannot reproduce arbitrary human decisions :-(
an example screenshot of river basin in the eastern part of the alps is
attached
where it is?
it's in the ticket, see
http://trac.osgeo.org/grass/attachment/ticket/1577/mainchannel4.gif
Helmut
Ok, this is not software issue. In attached example calculated main
channel is evidently longer than real main channel so software cannot
calculate it different. On my first look there are two possibilities:
- first: main channel is established according to basin area. If so try
to model stream network using SFD and next Gravelius hierarchy using
accumulation map as an option. Result should be correct. This is
impossible using MFD approach
- second: main channel is arbitrary chosen as "central channel". No idea
how to reproduce it without complex analysis of basin shape and network
topology.
J.
-----
best regards
Helmut
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