Hi,
I used the software some time ago and it worked nicely. And as Johannes
explained, the only data needed is the river network and the basin boundary.
I'll try to translate the algorithm behind the software but I'm a bit
confused by it so I could be doing a worse job then a google translator...
1) If a river segment is connected to the river network at only one point
and the segment does not touch the basin boundary, those are the first
order streams rivers and their flow direction can be defined from the
unconnected end to the connected end
2) If the endpoint of a river segment touches other segments that have
their flow directions determined and the flows converge, then:
The flowdirection of the segment goes from the examined endpoint to the
other end;
You can calculate the stream order by looking at the stream orders of
the segments that flow into the analyzed segment.
If the segments that touch an endpoint does not have their flowdirection
determined, then the flowdirection the analyzed endpoint cannot be
determined and that indefinition caries out throuhg the river network (fig2
in the example).
The software does not work if you have loops in your river network.
Here is the link of the manual explaining the algorithm, but it's in
portuguese
http://www.fgel.uerj.br/labgis/hydroflow/Help/helphydroflow.html
Cheers
Daniel
On Tue, Jun 18, 2013 at 11:19 AM, Johannes Radinger <
johannesradinger@gmail.com> wrote:
1) Concerning the flow direction / network direction
So far what I can understand from the html-manual, the only two
input data is the map with the river network and a line or polygon file
the defines the catchement. The flow direction within the network
is then defined by the outflow point which is the only line of the river
that touches or intersects with the catchment border. Unfortunately,
neither I am a native Brasilian (which makes reading the manual difficult)
nor
I am able to read or understand the source code behind the model
2) Concerning the license
It is licensed under GNU GPL:
http://www.fgel.uerj.br/labgis/hydroflow/Help/helphydroflow.html?\{D3EB24A2\-0B1B\-4CA1\-B0C6\-F05855A23C8D\}\.htm
@Madi: No unfortunately I haven't tried HydroFlow yet. I first have to
figure out how to compile it using qmake on my ubuntu machine. Concerning
v.strahler: AFAIK also this module needs a DEM to identify flow direction,
which is often not available when you have only the river vector. And of
course HydroFlow also provides other measures of stream order beside
Strahler...
I hopefully get the tool installed quite soon. I will then report how well
it is working.
/Johannes
On Tue, Jun 18, 2013 at 3:08 PM, Markus Metz <
markus.metz.giswork@gmail.com> wrote:
On Tue, Jun 18, 2013 at 1:52 PM, Johannes Radinger
<johannesradinger@gmail.com> wrote:
> Hi,
>
> I found following interesting Brasilian program called HydroFlow:
> http://www.fgel.uerj.br/labgis/hydroflow/en/downloads_ingles.html
>
> This tools calculates the Stream order (e.g. Strahler, Shreve)
> based on a shapefile input of the river network and a shapefile that
defines
> the border (catchment?). If I am informed correctly such a tool that
does
> not require any form of a DEM (or accumulation map etc.) is not
existing for
> GRASS yet.
One bit of requirement information must be provided in addition to the
shapefile: the outlet of a river network. If the lines of the
shapefile follow drainage dirction, this is possible, because then per
network only one line will go towards an end point. You could look at
the description or source code if possible to find out how HydroFlow
identifies the outlet of a river network.
Markus M
>
> There are just two questions that appeared to me:
>
> 1) Has anyone installed and tried the programm already in Ubuntu/Linux?
>
> 2) The tool is licensed as open source. So, could such a algorithm also
be
> implemented as
> a add-on to GRASS? I am not sure but I can imagine that this might be of
> interest also to
> other GRASS users!?
>
> /johannes
>
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